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EML 4905 Senior Design Project
A B.S. THESIS
PREPARED IN PARTIAL FULFILLMENT OF THE
REQUIREMENT FOR THE DEGREE OF
BACHELOR OF SCIENCE
IN
MECHANICAL ENGINEERING
HAZMAT SAFETY AND
RECONNAISSANCE UNIT
FINAL REPORT
Daniel Pico
Christian Palomo
Samuel Caillouette
Advisor: Professor Sabri Tosunoglu
November 20, 2015
This B.S. thesis is written in partial fulfillment of the requirements in EML 4905.
The contents represent the opinion of the authors and not the Department of
Mechanical and Materials Engineering.
i
Ethics Statement and Signatures
The work submitted in this B.S. thesis is solely prepared by a team consisting of Daniel Pico,
Christian Palomo, and Samuel Callouette and it is original. Excerpts from others’ work have
been clearly identified, their work acknowledged within the text and listed in the list of
references. All of the engineering drawings, computer programs, formulations, design work,
prototype development and testing reported in this document are also original and prepared by
the same team of students.
Daniel Pico
Team Leader
Christian Palomo
Team Member
Samuel Caillouette
Team Member
Dr. Sabri Tosunoglu
Faculty Advisor
ii
TABLE OF CONTENTS Chapter Page
Abstract ...................................................................................................................................... 1
1. Introduction .......................................................................................................................... 1
1.1. Problem Statement ........................................................................................................... 1
1.2. Motivation ........................................................................................................................ 2
1.3. Literature Survey .............................................................................................................. 3
1.4. Survey of Related Standards ............................................................................................ 8
2. Project Formulation ........................................................................................................... 11
2.1. Overview ........................................................................................................................ 11
2.2. Project Objectives .......................................................................................................... 11
2.3. Design Specification ...................................................................................................... 12
2.4. Addressing Global Design ............................................................................................. 14
2.5. Constraints and Other Considerations ............................................................................ 16
3. Design Alternatives ............................................................................................................ 18
3.1. Overview of Conceptual Designs Developed ................................................................ 18
3.2. Design Alternate 1 .......................................................................................................... 19
3.3. Design Alternate 2 .......................................................................................................... 21
3.4. Design Alternate 3 .......................................................................................................... 24
3.5. Feasibility Assessment ................................................................................................... 25
3.6. Proposed Design ............................................................................................................. 26
3.7. Discussion ...................................................................................................................... 27
4. Project Management .......................................................................................................... 27
4.1. Overview ........................................................................................................................ 27
4.2. Breakdown of Work into Specific Tasks ....................................................................... 27
4.3. Breakdown of Responsibilities Among Team Members ............................................... 29
4.4. Patent/ Copyright Application ........................................................................................ 31
4.5. Commercialization of the Final Product ........................................................................ 31
4.6. Discussion ...................................................................................................................... 31
5. Engineering Design and Analysis ...................................................................................... 31
5.1. Overview ........................................................................................................................ 31
5.2. Kinematic Analysis ........................................................................................................ 32
iii
5.3. Stress Analysis ............................................................................................................... 35
5.4. Mechanical Analysis ...................................................................................................... 35
5.5. Material Selections ......................................................................................................... 39
5.6. Finite Element Analysis ................................................................................................. 42
5.7. Motor analysis and selection: ......................................................................................... 44
5.8. Battery Selection ............................................................................................................ 47
5.9. Communication system .................................................................................................. 53
5.10. Speed Controllers ....................................................................................................... 57
5.11. Camera ........................................................................................................................ 60
5.12. Electrical Circuit ......................................................................................................... 62
5.13. Proposed Drive Train Cost Summery ......................................................................... 65
6. Prototype Construction ...................................................................................................... 66
6.1. Overview ........................................................................................................................ 66
6.2. Description of Prototype ................................................................................................ 66
6.3. Prototype Design ............................................................................................................ 67
6.4. Parts List ......................................................................................................................... 69
6.5. Construction ................................................................................................................... 70
7. Testing and Evaluation ...................................................................................................... 89
7.1. Testing and Evaluation ................................................................................................... 89
7.2. Design of Experiments – Description of Experiments ................................................... 89
7.3. Towing Test.................................................................................................................... 90
7.4. Battery Consumption Test .............................................................................................. 92
7.5. Speed Test ...................................................................................................................... 93
7.6. Stair Climbing Test ........................................................................................................ 94
7.7. Improvement of Design:................................................................................................. 97
7.8. Discussion: ..................................................................................................................... 98
8. Design considerations ........................................................................................................ 98
8.1. Health and Safety ........................................................................................................... 98
8.2. Assembly and Disassembly .......................................................................................... 101
8.3. Manufacturability ......................................................................................................... 104
8.4. Maintenance of the System .......................................................................................... 104
8.5. Risk Assessment ........................................................................................................... 105
9. Design Experience ........................................................................................................... 106
iv
9.1. Overview ...................................................................................................................... 106
9.2. Standards used on the project ....................................................................................... 107
9.3. The contemporary issues .............................................................................................. 108
9.4. The Impact of the design in a global and societal context ........................................... 109
9.5. Professional and Ethical Responsibility ....................................................................... 109
9.6. Life-Long Learning Experience ................................................................................... 110
9.7. Discussion .................................................................................................................... 111
10. Conclusion ....................................................................................................................... 111
10.1. Conclusion and Discussion ....................................................................................... 111
10.2. Evaluation of Integrated Global Design Aspects ..................................................... 115
10.3. Evaluation of Intangible Experiences ....................................................................... 116
10.4. Commercialization Prospects of the Product ............................................................ 120
10.5. Future Work .............................................................................................................. 121
11. References ........................................................................................................................ 124
Appendices ............................................................................................................................. 128
A. Detailed Engineering Drawings of All Parts, Subsystems and Assemblies ...... 128
B. Multilingual User’s Manuals in English, Spanish and French .......................... 147
C. Excerpts of Guidelines Used in the Project: Standards, Codes, Specifications and
Technical Regulations .................................................................................................. 154
D. Copies of Used Commercial Machine Element Catalogs (Scanned Material) . 155
E. Detailed Raw Design Calculations and Analysis (Scanned Material) .................. 166
F. Project Photo Album ............................................................................................. 182
v
List of Figures
Figure 1: Proposed Drivetrain ....................................................................................................... 19 Figure 2: Jaws of Life ................................................................................................................... 20 Figure 3: Complete assembly........................................................................................................ 21 Figure 4: Exploded Assembly- ..................................................................................................... 22
Figure 5: Drive is stopped, free body diagram of robot static situation ....................................... 33 Figure 6: Net weight of 1/3 scale robot and corresponding static torque ..................................... 33 Figure 7: Dynamic model, drive is in motion climbing ................................................................ 34 Figure 8: Gear System .................................................................................................................. 35 Figure 9: Bearing Free Body Diagram.......................................................................................... 37
Figure 10: Related nomenclature and application conversion factor............................................ 37
Figure 11: Simulation of tread track using POM Acetyl Copolymer ........................................ 42
Figure 12: Stainless Steel Chain link ........................................................................................... 42
Figure 13: Panel without Pocket ................................................................................................. 43
Figure 14: example of panel with pocket ................................................................................... 43 Figure 15: MMP-TM57 Geared Motor [21] ................................................................................. 46 Figure 16: MMP-TM55 Geared Motor ......................................................................................... 46 Figure 17: Amp flow E30-400 Motor [22] ................................................................................... 47
Figure 18: Drive Motor Current Draw .......................................................................................... 48 Figure 19: Parallel vs. Series configurations [23] ......................................................................... 50
Figure 20: Power Sonic PSH-1280f2 [24] .................................................................................... 51 Figure 21: Performance Specifications for PSH-1280F2 Battery [25] ......................................... 52 Figure 22: Arduino Mega [26] ...................................................................................................... 53
Figure 23: Raspberry Pi [27]......................................................................................................... 55
Figure 24: Vex microcontroller brain, Controller, Receiver [28] ................................................. 56 Figure 25: Code applied for tank drive onto robot ....................................................................... 57 Figure 26: Comparison of Vex Motor Controllers [29] ................................................................ 58
Figure 27: Victor SP Interface Dimensions [28] .......................................................................... 59 Figure 28: D-Link 931L ip Camera [30]....................................................................................... 60
Figure 29: Example Circuit Diagram for Voltage Regulator [31] ................................................ 62
Figure 30: Circuit Diagram of Prototype Robot ........................................................................... 64 Figure 31: Prototype Model of the HAZMAT ROBOT ............................................................... 68
Figure 32: Installing each of the support blocks for each side ..................................................... 72 Figure 33: Setting up each of the steps ......................................................................................... 72 Figure 34: Completed stairs and assembly not including table .................................................... 73
Figure 35: Completed stairs and table front view ......................................................................... 73 Figure 36: Completed stairs Isometric view ................................................................................. 74
Figure 37: Water Jetting Facility .................................................................................................. 75 Figure 38: Inner and outer plate’s appearance after Water Jetting ............................................... 76 Figure 39 (Fadel CNC Milling Machine [32] ............................................................................... 77 Figure 40: Flat end mill used for CNC manufacturing [33] ......................................................... 77 Figure 41: Appearance of Inner and Outer Panels after CNC operation ...................................... 78
Figure 42: Appearance of Motor Receivers after CNC operation ................................................ 78 Figure 43: Knee Mill on the left side Drill press on the right Side ............................................... 80 Figure 44: Knee Mill Machining features on sprocket ................................................................. 81
vi
Figure 45: Lathe used to create holes and create press fit ............................................................ 81
Figure 46: Reamer tools used to create press fit ........................................................................... 82 Figure 47: Vertical Band Saw [35] ............................................................................................... 82 Figure 48: Horizontal Band Saw [36] ........................................................................................... 83
Figure 49: Bench Grinder [37] ...................................................................................................... 83 Figure 50: Tread Jig ...................................................................................................................... 85 Figure 51: Tread Chain K-1 Tabs ................................................................................................. 85 Figure 52: Chassis of Robot not including bottom and battery housing plates ............................ 86 Figure 53: Chassis of robot including bottom battery housing plates .......................................... 86
Figure 54: Final assembly with batteries and additional components except the suspension ...... 87 Figure 55: Assembly without motors and tread system) .............................................................. 87 Figure 56: Final side assembly without outer panel ..................................................................... 88 Figure 57: Complete assembly of Hazmat Reconnaissance Robot .............................................. 88
Figure 58: 60.5lb. Cinder block on Concrete ................................................................................ 91 Figure 59: 36.5 lb. Cinder Block on Concrete .............................................................................. 92
Figure 60: Distance of weight relative to center of Mass ............................................................. 95 Figure 61: 5lb. counter weight ...................................................................................................... 96
Figure 62: 10lb. counter weight .................................................................................................... 96 Figure 63: 12 lb. counter weight ................................................................................................... 97 Figure 64: Left Fuse that has been popped, Right Fuse in good condition [41] ......................... 100
Figure 65: Illustration of removal of side panel for tread maintenance ...................................... 101 Figure 66: result of removing side panel and tread system ........................................................ 102
Figure 67: Wing Nut [42] .......................................................................................................... 103 Figure 68: Latch [43] .................................................................................................................. 103 Figure 69: Hairpin Cotter Pin [44] .............................................................................................. 103
Figure 70: Shelf life of Selected Battery Power Sonic PSH-1280 [25] ...................................... 105
Figure 71: Force hand calculation page 1 ................................................................................... 166 Figure 72: Force hand Calculation Page 2 .................................................................................. 166 Figure 73: Force hand Calculation Page 3 .................................................................................. 167
Figure 74: Suspension designs .................................................................................................... 167 Figure 75: Suspension Hand Calculation Page 1 ........................................................................ 168
Figure 76: Static Suspension Hand Calculation Page ................................................................. 168 Figure 77: Bearing Free Body Diagram...................................................................................... 169
Figure 78: Static analysis of robot on incline ............................................................................. 170 Figure 79: Dynamic analysis of robot on incline ........................................................................ 171 Figure 80: Analysis of robot climbing stairs............................................................................... 172 Figure 81: Minimum power requirement for stair climbing ....................................................... 173 Figure 82: Motor comparison for full size design ...................................................................... 174
Figure 83: Battery and stair sample hand calculations ............................................................... 175 Figure 84: Stair Construction Calculations ................................................................................. 176
Figure 85: component dimensions Page 1 .................................................................................. 177 Figure 86: Component Dimensions Page 2 ................................................................................ 178 Figure 87: Component Dimensions Page 3 ................................................................................ 179 Figure 88: Machinability component Mach set up ..................................................................... 180 Figure 89: component suspension dimensions ........................................................................... 181
vii
List of Tables
Table 1: Breakdown of work into specific tasks ........................................................................... 28 Table 2: Timeline of Project ......................................................................................................... 29 Table 3: Breakdown of Responsibilities among Team Members ................................................. 30 Table 4: Nomenclature for Kinematic Diagram and Equations for Static and Dynamic Analysis
....................................................................................................................................................... 32 Table 5: Weibull Parameters ......................................................................................................... 38 Table 6: Material Selection Properties for common metal grades ................................................ 40 Table 7: Projected Weight Analysis and Torque by considering varying degrees of incline ....... 44 Table 8: Power Requirement when submitted to a 70 degree incline........................................... 45
Table 9: Motors considered for selection ...................................................................................... 47 Table 10: Items in circuit .............................................................................................................. 63
Table 11: Cost Breakdown............................................................................................................ 65 Table 12: Part List for Robot ........................................................................................................ 69 Table 13: Nomenclature used for construction ............................................................................. 70 Table 14: Towing Test Results ..................................................................................................... 91
Table 15: Battery Consumption Test ............................................................................................ 93 Table 16: Speed Test Results ........................................................................................................ 94 Table 17: Stair Climbing Test ....................................................................................................... 95
1
Abstract
The following information and data describe a unique robotics platform devised for the
purpose of assisting HAZMAT personnel with the preliminary investigation of a scene. The
apparatus features a tank-style chassis, a four degree-of-freedom arm, the Jaws of Life, and a
modular clamping system for the attachment of various sensors. This robotics platform
represents a different approach to the application of robotics to first responder applications.
1. Introduction
1.1. Problem Statement
HAZMAT Firemen and women risk their lives when they enter a contaminated scene. The
current method of controlling a HAZMAT scene involves manually inspecting the scene and
establishing a perimeter. Once the perimeter is controlled, HAZMAT crews will put on the
required protective gear and move into the scene, using hand-held tools and an array of sensors
to investigate the scene. Some of those tools or devices can be cumbersome for the user when
wearing HAZMAT suit. In addition to the awkward shape and bulk of the suit, HAZMAT
personnel have a very limited amount of time active on the scene because of the limitations of
their air supply. This air supply is further shortened because of the time delay for preparations
before entering the scene and decontamination after exiting the scene. Finally, while time is
passing, conditions of the scene could worsen and potentially endanger the HAZMAT personnel
as well as the general public. It is important for HAZMAT personnel to contain and resolve the
scene as quickly and smoothly as possible.
2
1.2. Motivation
For many years, companies such as NASA and Northrop Grumman have developed robotic
ROV platforms (Remote Operated Vehicle) for the military, police and other First Responder
applications. In the current robotics industry there are also a number of smaller companies that
focus solely on robotics. Some of these companies have boasted that their platforms will one day
perform the role of human first responders, capable of transport and rendering aid to the victim.
While projects like these have pure motives, they fall short in practicality and utility.
Furthermore, the platforms that have been successful, such as EOD and surveillance type
platforms still have inadequacies. Either the platform is so small and convenient to use that it
cannot withstand abuse or perform key tasks, or it is capable of performing a task and is
awkward in build and can become incapacitated relatively easy.
The field of HAZMAT Firefighting could benefit greatly from the implementation of
robotics platforms but the requirements are strenuous and varied. HAZMAT (Hazardous
Materials) is a term that pertains to the containment and disposal protocols of chemicals.
HAZMAT Firefighters are certified as firefighters first and then take on additional training to
become HAZMAT certified. While in the line of duty, these brave men and women risk
exposure to dangerous chemicals and are only protected by wearing special suits, which isolate
them and their air supply from the environment.
There are several disadvantages with this approach; the suit is large and limits the flexibility
of the wearer, and if the suit should become torn, there is an additional risk of being exposed to
contaminants, which can result in serious injury or death. Lastly, assuming the firefighters
investigated the scene and have identified what the chemicals are present, they have to exit the
scene, be decontaminated, and then have the suit removed and disposed of. This process could
3
take at least 30 minutes, or it can take several hours depending on circumstances. If HAZMAT
Firefighters could investigate the scene and prepare for addressing the problem simultaneously, it
would reduce the overall time on scene and thereby limit the exposure of the firefighters and the
general public. This can be accomplished by creating a robotics platform, which could perform
the investigation prior to human involvement.
Such a platform would need to be low to the ground for climbing stairs and minor obstacles.
It would need to have a sensor bed for the firefighters to mount the sensors that they would
normally carry in with them, as well as cameras for investigating the site remotely. Lastly, the
platform should have a robotic arm which cannot only open doors and interact with objects, but
could also perform forced entry. Many of the platforms in existence do not have forced entry
capabilities which work on a variety of doors, or the method applied is not suitable for the
volatile environment of a chemical spill or leak. It is because of these reasons that the best
solution for HAZMAT Firefighters is to have a specialized apparatus which meets their needs
and provides additional capabilities and flexibility on scene.
1.3. Literature Survey
The following reading is the literature survey and data gathered which will guide the rest
of the design. The first section will introduce the robot history. The second section will cover the
existing robot models. And the following paragraphs will give detail to various components
involved and several selection options. The final section will entail Hazmat literature history
involving tasks and procedures when facing a hazardous situation. [1]
4
Robot history
The first concept of machines being able to accomplish simple tasks where first created in
the early 1800th century using punch cards to send the instructions to an automated loom. Later
in 1899 the first remote-controlled vehicle could make simple forward left and right movements.
The word ROBOT was first used in a movie R.U.R. after the digital computer was built, and the
first computer was created robots where able to do much more complex tasks. In the 1980 there
existed a 6 DOF robot called the UNIMATE. This robot UNIMATE revolutionized the existence
and purpose of robots which brought about industrial robots used in situations which where
dangerous for the human. The robot ASIMO is the most advanced robot today and can achieve
very intricate tasks and has an artificial intelligence capability. Several applications of robots
executing dangerous tasks are robots today that are used by the bomb response unit. This Robot
can disarm explosive chemicals and can provide visual feedback to the unit. Another application
deals with the mining service, when methane gas is present in the work environment and an
accident occurs the environment is combustible and is unsuitable for personnel to repair the
damage. Sending in the robots could assist and prevent future health and safety issues. [1]
When considering a HAZMAT response unit there exists a Robot called the LT2/F
“Bulldog”. The Lt2 severs many similar functions to the senior design project. The Lt2 can open
doors and maneuver inside apartments and as well can use different manipulator attachments to
open the doors. The price for a robot with capabilities such as these cost $20,500 with 4-axis
rotation and a 6 axis rotation which costs $38,500. Another company designed and
manufacturing the LT2 designed a heavy duty Robot the HD2-s .The HD2-s has the capability to
move upstairs while at the same time also able to maneuver upstairs or down stairs. The cost of
the HD2-s is $13,000 for a simple networking package and $21,000 with a advancing more
5
robust networking package. Both systems come with a remote video and controller for the user.
[2] Another system already designed is MAARS (Modular Advanced Armed Robotic System)
this system can provide reconnaissance, surveillance, and target acquisition missions which
could safety provide the tasks needed by the personnel. [3] Another design named the BOZ XL
possess Jaws which have 16,500 lbs. of opening force. The Robot as well has the ability to
breach doors and windows. The BOZ XL is primarily used for dismantling and lifting cars and
breaching building doors. [4] Which began in October 1990 called HAZBOT III could identify
and locate the hazardous material incidences. [5]
Robot systems and components
Various rotational actuation systems have advanced throughout the years and every year
these systems are getting smaller, more reliable. For senior design the actuating research will be
focused on compact systems. When considering different rotational actuation systems, there are
Brushless dc motors and brush dc motors. The prices of the step motor depend on which torque
is needed to apply to the system and how much voltage or power is required from the step motor.
The price range is from $5 to over $1000 depending on the design parameters. (Reference)
Another type of rotational actuator is hydraulic this system is very dependable because it is
independent of signals or interference which would cause the robot to move in the correct
distance. There are various battery systems used on the robot designs there are many factors
which will determine which battery to use. For application of hazmat situation the battery would
be best to choose the lithium – Thionyl Chloride battery. This particular type of disposable
battery has been used in computers and electric meters, as well as for providing power to
wireless gas and water sensing equipment. [6] The issue with this battery is that this is
disposable. In the case of non-disposable batteries, would be best to use the lithium-ion batteries.
6
The usability of a lithium- ion battery is 3 years. The price of batteries depend on the power
required and the environment as specified earlier. The environments in a hazardous scenario
which may or may not submit the battery to various toxic chemicals and must be completely
insulated from the environment while at the same time be required to output high voltage to the
electrical components. The HAZBOT II system was able to unlock and lock doors as well as use
various cameras to allow for visual inspection of the site and a distance sensor witch relayed the
locations relative to the site. There were a variety of different issues which the HAZBOT need to
be implemented around such as a redesign to operate. The key features of the hazmat project at
JPL include the mobile operator control station which contains two displays and a tether reel to
send and receive the signal. The robot includes a motion system which can traverse forward and
reverse on level surface and inline planes. The system includes a 6 DOF manipulator and uses
non-arching electrical components. HAZBOT III began in October 1990 called HAZBOT III
could identify and locate the hazardous material incidences. [5]
Other applications which robots are being implemented on are bomb disposal and mining
operations, remote sampling and law enforcement. The purpose of implementing robots
throughout the various scenarios is not to replace the member of the workforce but to provide a
tool which to allow for the personal to more efficiently do the task. [5]
Extraction devices are necessary tool for the fire department to use. The examples of application
this is used on is forced entry, damaged window frame of wrecked automobile, automobile
catastrophe scenarios, and scenarios where there is an obstacle and the robot needs to be
implemented. [7]
7
There are many types of doorways when interviewing firefighting personal. The first type
of entry is for commercial use uses wood doors with metal handle. The following entry is a metal
door with metal handle. Users also may have the a garage style door which is made of metal and
slides down and slides up to open. This type of metal entry is the most difficult to breach because
there is no handle.
Tread System
Having a tread system allows the vehicle to move through the obstacle with a lower
chance of mud and other debris being carried by the robot. The tread configuration allows for a
combination of both forward and lateral trust capabilities. Another advantage to having a tread
system implemented for the terrain allows for more grip on the stairs and on other alteration
surfaces. The advantages to having a wheel system is that the robot may be able to travel faster
and dissipate less energy do to less contact between the tire and terrain. Due to the less contact
between the tire and terrain do to the reduced contact the robot will have more difficulty with
wheels then tires when moving up the stairs. [8]
Section Hazmat response unit
The following sections will describe the necessity of robotics for hazmat fire rescue. The
event which began the need for hazmat was in 1980 a truck had gone into an accident and spilled
the contents over all the roadway. The material was unknown and could have potentially caused
potential safety hazard. The material was used as a paint additive and food additive and did not
cause hazardous problems. The agencies however saw this as an issue and created a system
called the HAZCAT system. The HAZCAT system was implemented and formed in 1983 to
rapidly identify the unknown substances in the dangerous situations. When the situation arises
8
the fire department has to identify the hazardous materials involved in the incident, the
information may or may not be available to the department In which case the department has to
put on a suit which takes up to an hour. The suit is a multi-layer suit. The personnel require full
protective gear including a self-contained breathing. Once the personnel put the necessary outfit
on the personal are allowed to only work 15 to 30 min at a time. Fire department are equipped
with the sensors and detecting equipment necessary to find the chemical substance. [5]
1.4. Survey of Related Standards
Standards serve an important role in our lives all though we may not recognize it.
Standards help organize and unify ideas so they may be used seamlessly from one application to
another. For our purposes these standards will be used to help set goals and guidelines for our
design. Through this project a multitude of disciplines, engineering and other associated
standards will apply. Should a case arise where one standard coincides with another, the more
demanding standard will be adhered to in order to satisfy both sets of guidelines. General
Mechanical engineering standards that will be applied to this design will come from the
American Society of Mechanical Engineers (ASME) and American Society for Testing and
Materials (ASTM). These are generally a necessity for any mechanical engineering work that is
to be designed or constructed.
Our design of a Hazmat Safety Reconnaissance Unit (HSRU or HRU) contains many key
components, each with separate conditions and requirements. By reviewing each of the major
components in depth and looking at the standards and requirements they serve, the limitations
and goals that need to be met can be properly identified. These standards are not limited to the
mechanical design of the apparatus but also include the processes and testing that will be needed
in the full analysis of the project.
9
The standards that will be applied to the apparatus will be gone through individually and
their significance in our design will be discussed as a whole, due to the fact that many of these
standards may overlap for several components in the design. The American Society for
Mechanical Engineers is an old engineering society formed in the late 1800’s. This organization
has developed many standards and codes, a majority specifically for the mechanical engineering
discipline. These will be used in the design process for the use of their FOS (factor of safety),
failure, and other deign testing methods. These will allow conservative and reliable figures in our
design, which should be reflected in the actual build [9].
Another important set of standards that will play a factor is ISO, the International
Organization of Standards. ISO is an international organization that promotes worldwide
propriety for commercial and industrial standards. This organization holds several standards in a
variety of fields. For the scope of this project, ISO standards applied to the assessment of tools
and firefighting equipment will be used. Adhering to the ISO standards for tools will ensure a
more globally-minded design, for which it will be easier to source necessary components. [10]
Equally important is the consideration of the hardware to be mounted and used. The
desired form of transportation is through the use of a set of electric motors. The electric motors
follow standards from the department of Energy (DOE). These standards govern the efficiency
level of electric motors as of 1997 and in three categories of electric motors: general purpose,
definite purpose and special purpose. [11] Although the motors that are to be added to the system
are to be purchased from a vendor, the levels of efficiency are critical for electrical design for the
system. These standards will allow for a reliable battery selection process and allow for the
optimal battery to be selected to conserve space and weight.
10
One key aspect which should not be overlooked is material selection. The American
Society for Testing and Materials will serve as a main guide for all material aspects of the
design. The ASTM book of standards contains specific information, which covers topics ranging
from material testing to the design of intrinsically safe electrical equipment. [12]
Another major consideration for this project is contact with hazardous materials and
conditions. The safety of the people who will be to operating and servicing this equipment will
be considered and will need to follow guidelines. These standards will come from OSHA, which
stands for the Occupational Safety & Health Administration. OSHA is a part of the United States
Department of Labor they create standards based on safety for workers. Applicable standards
will come from 1926.65 of the code of standards and will serve as a limits and goals in our
design. [13]
Other standards and codes may become more apparent as progress is made. These will
primarily be testing standards as well as others that are not distinguishable given the current
design and goals.
Standards
ASME (American Society of Mechanical Engineers)
ASTM (American Society for Testing and Materials)
OSHA (Occupational Safety & Health Administration)
DOE (Department of Energy)
ISO (International Organization of Standards)
11
2. Project Formulation
2.1. Overview
The design is a robotics platform designed to be used in the presence of hazardous
materials. The robot is to be equipped with sensors to perform sweeps of contaminated areas and
relay information to a control center. The HRU will need to be able to traverse common
obstacles found in homes and in commercial buildings such as stairs and locked/unlocked doors.
Finally, the system will need to operate from a control station that can be placed a safe distance
from the contaminated area.
2.2. Project Objectives
The goal is to design a robotic platform for the purposes of HAZMAT scenarios. This
platform is intended to minimize the need for multiple entries into hazardous areas by First
Responders. In order for this system to minimize the amount of entries for the HAZMAT Crew,
it needs to be self-sufficient and self-contained, being able to relay information to the
crewmembers at the perimeter of the scene.
Main Objectives:
1. Robotic system that can operate under hazardous conditions
2. Design and implementation of Modular Clamping System for sensors and equipment
3. Ability to proficiently climb and descend stairs
4. Smoothly perform forced as well as non-forced entry
12
2.3. Design Specification
The HRU has been designed to fulfill the purpose of pre-human investigation of HAZMAT
scenes. The main objectives discussed in the previous section represent the cornerstones of
HAZMAT response and therefore the main tasks which the platform must be able to carry out. If
a robotics platform cannot perform all of the tasks, then it has not properly addressed the
challenges of the HAZMAT environment.
The primary goal is for this apparatus to be intrinsically safe. For any electrical device to be
“intrinsically safe” the general requirement is for any possible ignition sources to be sufficiently
insulated or limited so that an explosion or fire will not occur. In the case of this apparatus, there
will be several electrical circuits and all of them will be of considerable amperage due to the
demands that the design will place on the power sources. Additionally, there is the concern of
decontaminating the apparatus. In most cases, a simple hose down or special bath is used to
decontaminate a HAZMAT suit prior to its wearer removing it, therefore, it would be ideal for
this apparatus to be cleansable through similar methods. If all of these needs are to be met, the
only real option is to design every part of the system so that it is completely isolated and
insulated from the environment while staying relatively cool.
The second key objective which must be accomplished by this apparatus is for a clamping
system, which allows already existing sensors to be held and read remotely, to be implemented.
This is a vital part of the design and a key difference between this apparatus and the already
existing robots. HAZMAT teams have a wide variety of sensors and support tools on board their
truck. Additionally, as pointed out by HAZMAT firemen we consulted; the designs of these
sensors and hand-held units continue to change. Because these designs continue to change and
13
the crews are already trained on how to use them, it is more practical to have a modular system
with adjustability, as opposed to a set of sensors which are specific to this apparatus.
Another important feature for this apparatus is a drivetrain which will allow it to climb stairs
with ease. Climbing stairs is no easy feat for robots in general and it will be even more
challenging for this apparatus to do so given the current weight estimate of 500lbs. Like most
robotics platforms that can climb stairs, this apparatus will utilize a tank tread drivetrain. Unlike
most platforms available, it will have a theoretical max output torque of 400ft-lb while only
requiring 153ft-lb to do the job. Apart from climbing stairs it will be very useful to the operators
to have a little extra pushing power available. Equally important is the consideration of the
power required to move the apparatus up a flight of stairs as this will drive the selection of
batteries for the Powertrain. At max torque, each motor draws approximately 162 amperes or 648
amperes for the entire drive circuit. If the apparatus is to operate for 1 hour without stopping, this
is equivalent to 1296 Amp-hours over a 2 hour period.
The fourth and final objective, is for the apparatus to be able to open doors for its self. It is a
simple enough idea that we, as human beings, take for granted. It is not until one has to conceive
a method for opening a door without hands that one realizes the complexity of the task. Most of
all the apparatuses on the market which can open doors, do so by the use of a robotic
manipulator. This end manipulator is usually nothing more than a claw or vice which is deployed
to clench a handle and turn, or press a latch and pull. The end manipulator of this apparatus is the
Jaws of Life, created by Hurst Hydraulics. There are many advantages for using this tool as an
end effector. This tool not only offers the ability to open an unlocked door, but by use of the
spreading heads, a locked door could be pried open by applying leverage to the gap between the
14
door knob and the frame. With a spreading force of 10,000 lbs., there are few doors that will
remain locked as long as a proper purchase point is gained prior to deploying the tool.
2.4. Addressing Global Design
When considering a global market there are multiple design considerations that need to be
made for a seamless implementation of our unit. Considerations such as the physical design, the
materials, and basic controls can be viewed with an international audience in mind. To apple to
the globally ready robot the overall footprint of the robot (length and width) will be limited to the
minimum requirements for door and stairway openings. This will ensure the ability of the robot
completely survey an entire building. The following International building codes will be
implemented and English and International system of units will display both units when creating
design drawings and other procedures:
From the international Building code 2012:
Section 1008.1.1
Section 1009.7
Section R3117.1
These sections describe the international building codes for stairs and doorways.
Using most rigorous design / most rigorous material building code.
Continuing with the physical dimensions of the robot our second global aspect will be to focus
on the material selection of the robot. As with the life of any machine at some point or another
15
some component will need repair and or fail. However, the cost or the availability of the
components will very. Through the use of standard components along with using common
materials such as (aluminum, copper, and certain plastics) the difficulty of repairing/replacing
can be mitigated to the global consumers. As we know availability of certain materials will vary
from location to location, that is why any down time the unit has need to be reduced do to the
important job it performs. As well as incorporating these more available materials the use of
machine able materials will be added when possible. With the need for custom components to be
fabricated, much in the same thought of the availability the use of machine able material
becomes important for down time of the machine.
As stated before SI units will be used for all measurements that apply with the system. SI
units are an internationally accepted set of measurements for many forms of analysis. The use of
this system will ensure a greater compatibility for components. As wellbeing internationally
accepted system will allow for availability for parts and tools globally.
Other global considerations will fall under the controller of the device. It important for
the task the robot is needed to perform be simple and be second nature to the operator. When
conditions are critical experience of the operator is critical. With a more universally accepted
controller the learning curve of the system can be reduced as well allow for a more natural
experience.
Lastly in tandem with a multi-language user manual, a separate maintenance guide will be
created to for common operations the user may need to perform. This guide will contain step by
step instructions for the desired goal. However this guide will contain only pictures illustrating
the required task.
16
2.5. Constraints and Other Considerations
In order to ensure the Hazmat unit could operate in every given scenario the following
sections will describe the required dimensions for building a door and a stair case. The last
section will provide preliminary material requirements for the Hazmat unit.
In Section 1008.1.1 of the International Building code states, “The minimum width of
each door opening must be sufficient for the occupant load thereof and shall provide a clear
width of no less than 32 Inches (813mm). The maximum width of a swing door leaf shall be 48
inches (1219 mm) Nominal.” [14]
For the required dimensions of a stair case there are two codes. One code specifies the
minimum width of the stair and another code specifies the tread of the step. All codes specified
follow the 2012 international building code specifications. For the tread dimension refer to code
1009.7 page 254 of the international building code 2012 which states the minimum stair tread
must be 11 inches. This is the minimum required tread, however depending on the year the stairs
were built the stairs could have a minimum length of 9 inches (228.6). For the step height is also
included could be a minimum of 7.75 inches stair height (196.85 mm). In Section R3117.1 the
overall stair width must not be less than 36 inches (914.4 mm). [14]
The following information was found regarding the Material constraint for the Hazmat
Unit. The section summarizes the outside frame of the unit and the material to which the robot
could be made of and machined. Serval materials and properties are described, at the concluding
section the material chosen for construction was aluminum 6061 this material was chosen due to
cost and the physical properties which are desired over the alternate Materials. The concept is if
this material is chosen is to allow for the fire department like the medical faculty or other
17
companies when the instrument becomes contaminated to ship the material to a decontamination
specialist or 3rd party which could then decontaminate and ship the unit back to the fire
department or medical facility. A majority of medical facility use this practice to sterilize there
equipment and save material costs. [15]
Stainless steel grade 316. This material has a density of 0.29 lbs. /in3. This material is
used in the medical field particularly is used for dentistry and is manufactured into surgical
instruments and other instruments. The average cost for stainless steel is 0.79 $/lbs. companies
such as celitron medical technologies will accept stainless 316 contaminated and sterilize the
material. This material has a low machinability due to the material properties. [15]
Titanium Ti-6Al-7Nb is another constraint which may be used to construct the hazmat
unit. This material is used in the medical industry for implants due to the highly corrosive
resistant material and is 0.16 lb. /in3. The average cost for this material is roughly 20 $/lbs.
companies such as celitron medical technologies will accept titanium and sterilize the material.
This material has a low machinability. [15]
Aluminum 6061 is not used in the medical field without necessary coatings, such as an
anodized coating or powder coat. The density of Aluminum 6061 is 0.0975 lb. /in3. The material
is highly corrosive resistant. The average cost is 0.89 $/lb. companies such as Argonne National
Laboratory specialize in sterilization of material. The material has a high machinability. [15]
Deciding to focus on either anodized aluminum or powder coat aluminum the following
sections outline each coating process.
18
3. Design Alternatives
3.1. Overview of Conceptual Designs Developed
In this next section we will take a closer look at some of the design alternatives which were
considered for the solution to the challenge. The first design featured tank treads in the rear and a
wheeled, rotating assembly in the front, which would allow the robot to climb stairs. After
further research into the topic, it was discovered that the key to stair climbing was engaging the
first step. Once an apparatus has climbed the first step on a flight of stairs, it is just a matter of
maintaining traction.
The discovery of this principle gave inspiration to the second design which features a
completely treaded drivetrain instead of having arms for climbing. The advantage to this
approach is that it eliminates the need for extra motors and programming for the drive system.
However, one disadvantage for the second design concept is that the first link of the arm is fixed
vertically but can be rotated about the vertical axis. This arm design would allow a greater
freedom of movement in the xy-plane but under load, the arm would be susceptible to bending
and could cause instability between the chassis and the ground because of the moment arm.
The third design alternative seems to be the most promising because it addresses the flaws of
the other two systems. The drive is a simple tank tread design with tensioners and guide
sprockets for idlers. Additionally, the arm is pivoted low to the chassis, approximately 18 inches
off of the ground, allowing for stable movement and stability while the arm is in operation.
Furthermore, the front of the drivetrain is twice as tall as the average step, ensuring that the robot
will climb the first step and continue.
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3.2. Design Alternate 1
For this design the objective is to maintain a relatively small footprint and a lower center of
gravity with the mobility in mind. The general shape is not to change drastically with similar
cues easy to spot. In this design the robot is to be split into two main components, the base and
the arm. The base will serve as the housing for the drive train and the necessary sensors that the
HAZMAT responders use to investigate the seen.
Figure 1: Proposed Drivetrain
The drive train selected will be an electric tank treads system similar to Figure 1 with
triangular set of wheels. The treads will be driven by two electric brushless motors, as well have
a shape similar to the figure that will allow it to climb stairs. This base is also intended to hold
the batteries and other electrical components such as receivers and controllers incased in its shell.
As stated before the design is to be the smallest of our designs with the intention to make it more
agile in smaller areas. The designed footprint is to roughly be 0.6096 m (24in) wide by 0.6096 m
(24 in) long; this size will ensure the robots ability to fit into almost all legal doorways. The top
of the base will also serve to hold the sensors required to fully analyze the scene of hazardous
material. The sensors are not to be designed but to use existing sensors that information can be
20
relayed back to a controller. This will take into account the first two objectives to climb stairs
and to contain an area to place sensors. To address the non-forced and forced entry a 5 DOF
(degree of freedom) robotic arm will be placed on the top of the base. This arm will allow the
controller to perform accurate movement necessary for non-forced entry tactics. At the end of
this arm will be a cutting/spreader combination end effector similar to the Jaws of Life (figure 2).
This end effector will be powered by and electric motor and be geared to produce the appropriate
power needed for forced entry. Cameras will also be mounted at key positions to relay prevalent
information to the driver to control the robot properly.
Figure 2: Jaws of Life
21
3.3. Design Alternate 2
Figure 3: Complete assembly
22
Figure 4: Exploded Assembly-
Design overview
The displayed figure 3 and figure 4 are the alternative concept designs developed for the
alternative design 2. This concept is not the final design. This design will focus on the overall
look and shown the general frame including the manipulator. There are 5 components of the
robot will have. When designing the robot, one scenarios where considered such as
decontamination of the overall robot. Another design consideration was the compartment which
A B
C
D
E
23
housed the electrical components must pressurized as to not create a spark and create a sealed
area from environment this housing is shown on part e figure 4. The next part is the lid will
fasten on top of the housing shown on part d of figure 4. The next components are estimated
modelling of the end effector which will be mounted on the lid. Overall dimensions of the robot
are shown in figure 3 are in inches and conversion to millimeters is displayed. The complete
dimensions for the robot are 36 inches length, by 24 inches wide (609.6mm), with an overall
height of 68.54 inches (1740.916 mm). The dimensions are subject to adjustments. All
dimensions where evaluated and are less than the required building dimensions for a door which
are less than the minimum size for residential door.
When considered the objectives described in section 2. The assembly is shown in figure 4
following the dotted lines. The design shown will seal the components from the hazmat
environment which is necessary when considering decontamination. The following objective to
climb stairs is shown in part e of figure 4 which will contain rubber tread around the circular
areas of the sides. The length and width provide the required dimensions to move up and down
stairs. Objective 3 will be mounted to part c of the robot. Simple support through a clamp and
recess will ensure a reliable support for the sensors to be mounted. The manipulator is shown in
part b of figure 4. This manipulator will be powered through electricity and will be used to open
doors through force if required or not.
24
3.4. Design Alternate 3
This design features a robust platform that uses tank treads, a four degree of freedom
manipulator, which contains all revolute joints and is fully self-contained. The construction of
the frame will utilize Solid Part and Solid Plate construction. Regardless of the material selected,
choosing to have the overall framework built using these techniques will ensure high durability
and ease of assembly. Although CNC is more expensive than cut and welded frames, there is
more flexibility of design after initial testing if the CNC option is used. Design features, which
can be optimized post initial assembly, include weight balance and reduction as well as the
attachment of accessories in the future. The overall advantages of this platform include the
decreased risk of entanglement, protection for all the internals, and the mobility required for all-
terrain applications and possibly stairs as well. The disadvantages of the design are its overall
size and weight. At just over a meter in length and about 79cm wide, the chassis is very large
when compared with other similar robotics platforms. This size is out of the necessity to house
an array of hydraulic pumps, motors, and batteries onboard the chassis. Additionally, it is
important to note that the overall design differs greatly from other platforms because it sits much
lower to the ground than most. The result is a platform which will be stable and rock less while
moving, which is key for observers and operators at the perimeter of the scene. A steady
platform will provide steady viewing of the environment and stable use of the apparatus. Another
favorable design feature of this platform is that it compartmentalizes every component which
could allow the platform to be made intrinsically safe, much easier than other construction
techniques would allow.
The manipulator will be built like the rest of the chassis, using only solid plates of
material and CNC solid parts. The end-effector of choice is the Jaws of Life, originally designed
25
and manufactured by HURST Hydraulics. These tools are already widely used by fire
departments internationally and are known for their versatility and durability. [16] Normally,
these tools are used for vehicular extrications, as this is typical of a metropolitan area with high
traffic volumes and hence, a higher volume of traffic accidents. The manufacturer, however,
boasts that these tools can be used for forced entry and for pulling heavy loads a short distance.
In fact, firefighters are trained to use these tools for its alternate functions although they usually
have specific equipment designated for certain tasks. [16] The functionality of the Jaws of Life is
certifiable and this tool has seen rigorous testing and many design iterations since its conception
in the 1960’s, making it an ideal tool to be used for the end-effector of this HAZMAT robot.
This design alternative represents a convergence of the advantages of various, existing
robotics platforms, and the attainment of objectives that have not previously been met. It is low
to the ground, fitted with tank treads, and features a hydraulically powered manipulator and end-
effector. All features make it ideal for the purpose it will serve yet, rugged and versatile enough
for HAZMAT teams to use it with confidence.
3.5. Feasibility Assessment
The completion of the project is dependent on several factors. These factors include: Cost
analysis, Manufacturing production, evaluation of objectives, if the project meets all set
objectives.
Furthermore in the area of cost analysis research shows that the fire department does
indeed have the funds $54 million five year capital plan. The projected cost for the unit is to stay
within $20,000 dollars. Giving this projection and the minimum available year funds available to
purchase the hazmat reconnaissance unit. Thus the cost per unit is within the government budget.
[17]
26
In order to implement the manufacturing process funds and correct manufacturing drawings must
be correct and available. The material chosen for the robot is aluminum 6061 T6 not including
the tread. If such actions are completed then the production will be implemented and the
assembly would need to be completed.
Once the manufacturing production and assembly have been completed the following
procedure would be to test and evaluate the robot to further explore if the design follows the
intended objectives. If all the criteria and aforementioned tasks are completed and does not run
into issues, then the feasibility of the assignment will be completely achieved.
3.6. Proposed Design
For the proposed design, the final decision was to create a 35% scale reduction of the original
geometry of the robot, and use a power too weight ratio in order to acquire the same power. As
well our scaled model will weigh approximately 80 lb. and will need to be able to traverse a
range of scaled commercial and residential stairs. To complete this task we have calculated that
we will need motors that can provide 55-60 in-lb. of torque individually. By reducing size of the
robot, the manufacturing costs, as well as electric and mechanical components needed where
readily available. Originally the design would be 40 in by 30 in; the new size is much smaller
14in by 10.5in. The Chassis and platform will be manufactured from aluminum grade 6061,
other accessory mounting hardware will consist of a mixture of 3d printed ABS plastic, on-
corrosive stainless steel hardware and the tread material will consist of acrylic. Communication
will be designed using a combination of Arduino and Vex platforms which pre-exist in the
robotic community. The system will be powered by electricity.
27
3.7. Discussion
There were many factors which affected the final proposed design. Due to cost limitations the
decision was made to rescale the original size. In order to accurately represent the original
model, and use existing tread components which would be compatible with the robot the 35%
was the maximum reduction which would not only present a suitable model, but also facilitate
the mating of components when assembling the robot.
4. Project Management
4.1. Overview
The following Table 1 illustrates the divisions of responsibility for each of the team members.
Table 2 illustrates the timeline for each of the project sections. The timeline is separated by
weeks at the end reaching the 16th week. For the project there are 8 sections: Project
Formulation, Literature Survey, Design / Analysis, Solidworks Model / Cost Analysis,
Prototyping, Construction Testing, Final Design, and Finally Report. Table 3 illustrates the role
and specific responsibilities of each team member. The most difficult aspect of the project was
figuring out how to correctly execute each of the objectives and how to distribute each task.
Once the parameters where calculated the selection process became feasible and the following
sections came together
4.2. Breakdown of Work into Specific Tasks
The following Table 1 illustrates the divisions of responsibility for each of the team
members.
28
Table 1: Breakdown of work into specific tasks
Group
Member
Name
Specific Tasks
Daniel Pico
Evaluate overall project developments, contribution to
component selection, organization presentation, and provided
literature for report sections, collaborated with physical testing.
Oversee entire Project created design for entire project,
Christian
Palomo
Evaluate overall project developments, contribution to
component selection, organization presentation, and provided
literature for report sections, collaborated with physical testing.
Samuel
Caillouette
Evaluate overall project developments such as designing and
presenting an alternative tread option, selection of the battery
and motor, presented alternative methods to reduce the weight
of the chassis, and alternate manufacturing options.
Timeline for work and progress
The following Table 3 illustrates the timeline for work and progress.
29
Table 2: Timeline of Project
4.3. Breakdown of Responsibilities Among Team Members
The following Table 2 illustrates the divisions of responsibility for each of the team
members.
January February March April May June July August September October November December
Project Formulation
Liturature Survay
Research
Design and Analysis
Solidworks Model
Cost Analysis
Prototyping
Constuction
Testing
Final Design
Report
30
Table 3: Breakdown of Responsibilities among Team Members
Group
Member
Name
Role
Description
Daniel Pico
Team Leader /
Project
Designer
Oversee entire Project, create design
Christian
Palomo
Project Analyst
Evaluate overall project developments, contribution to
component selection, organization presentation, and provided
literature for report sections, collaborated with physical testing.
Samuel
Caillouette
Project Analyst
Evaluate overall project developments, contribution to
component selection, organization presentation, and provided
literature for report sections, collaborated with physical testing.
31
4.4. Patent/ Copyright Application
The following HAZMAT ROBOT senior design project purpose is solely designed and used
for academic purposes, all components and manufacturing components will be acknowledged.
There will be no pursuit of commercialization or Copyright application for the HAZMAT
ROBOT.
4.5. Commercialization of the Final Product
There will be no pursuit of commercialization or copyright application for the HAZMAT
ROBOT.
4.6. Discussion
Then most difficult aspect of division of responsibilities was first assessing the areas of the
project that needed attention. For most of the Project the decisions where discussed and agreed
upon, for example: a purchase or design consideration. Using the budget and the chassis
dimensions as a constraint, many design considerations and component selection where selected
using those parameters as a reference.
5. Engineering Design and Analysis
5.1. Overview
The following sections will illustrate the Component analysis and Component selection of
the HAZMAT Robot. The primary systems which are being analyzed are the: power system,
tread system and the structure of the robot. Many Component selections are based off of the
clearance constraints from the original design. Using the building codes as a guide the other
dimensions for the design could be extrapolated and once the chassis was designed both
32
mechanical and electrical components may be selected. Lastly the cost evaluation will be
discussed.
5.2. Kinematic Analysis
Table 4: Nomenclature for Kinematic Diagram and Equations for Static and Dynamic Analysis
Symbol Description SI Units
θ Angle of incline ∘(degree) or radians
Fix
Net force in the horizontal
direction
Lb.(pounds)
Fy
Net force in the vertical
direction
Lb. (pounds)
M Net moment Lbf-in (pound - in)
r Radius of wheel inches
w Weight of robot W= mass x gravity = Lb.
Wb Weight of robot belt Wb= mass x gravity = Lb.
N
Net Normal force acting on
the robot
Lb. (pounds)
33
Figure 5: Drive is stopped, free body diagram of robot static situation
∑ 𝐹𝑥 = 𝑓 − 𝑤 sin 𝜃 (Equation 1 (force in the x-direction) Static Situation)
∑ 𝐹𝑦 = 𝑁 − 𝑤 cos 𝜃 (Equation 2 (force in the y-direction) Static Situation)
∑ 𝑀 = 0 (Equation 3 (Net moment) Static Situation)
∑ 𝑇 = 𝐹𝑟 × 𝑟 (Equation 4 (Net Torque) Static Situation)
Figure 6: Net weight of 1/3 scale robot and corresponding static torque
Loads Location From Center Angle Radians Resistance Norm Resultant Force
Torque applied to Drive
due to gravity(in-lbf)
Available
Torque Residual
Chassis 30 0 0 0 0 12.000 60.000 12.000 21.00 2428 2449
Batteries(Drive) 20 0 0 10 0.174533 11.818 59.088 1.399 2.45 2428 2430.448
Batteries(Hydraulics) 10 10 0 20 0.349066 11.276 56.382 -9.245 -16.18 2428 2411.821
Arm 0 25 10 30 0.523599 10.392 51.962 -19.608 -34.31 2428 2393.687
Motors 0 -10 0 40 0.698132 9.193 45.963 -29.375 -51.41 2428 2376.594
Pumps 0 -15 0 50 0.872665 7.713 38.567 -38.249 -66.94 2428 2361.064
Total Projected Weight 60 60 1.047198 6.000 30.000 -45.962 -80.43 2428 2347.567
34
Figure 7: Dynamic model, drive is in motion climbing
∑ 𝐹𝑥 = 𝑚𝑎𝑥 = 𝑤 sin 𝜃 − 𝑓 + 𝑤𝑏 sin 𝜃 = −𝑤𝑏
𝑔𝑎𝑏
(Equation 5 (force in the x-direction) dynamic Situation)
∑ 𝐹𝑦 = 0
(Equation 6 (force in the y-direction) dynamic Situation)
Using principles of trigonometry one could extrapolate the force necessary to overcome the
friction and weight of the robot. By estimating the force the next step would be to be to calculate
the torque. Using a diameter of 2.111 inches we could find the estimate the necessary variables
shown in table 4.
35
5.3. Stress Analysis
For this analysis the tread chain will be analysis under a tension load. Since the force of
the tread chain will be distributed across each tread link in order to achieve an idea of the shear
across the pin and link. Another stress analysis dealt with the thickness of the side panels under
load, with pockets and without pockets there was a significant difference in the behavior of the
part under stress as shown in section 5.10.
5.4. Mechanical Analysis
Gear analysis of system
The gear analysis is first conducted using eq. shown below which takes into account the
diameters of the driving gear to the driven gear to establish a gear ratio which can then be used to
find the rpm of each gear. Since gear 1 and 2 are the same diameter, there is a 1:1 gear ratio.
Gears 3, 4, and 6 are also the same diameter which means that they have the same gear ratio. A
representation of the gear system is shown below in figure 8. The Rpm of the motor is 38 rpm
(revolution per min), this will be the initial speed of the first gear.
Figure 8: Gear System
36
𝑛𝐿 =𝑁𝐹
𝑁𝐿× (𝑛𝐹) (𝐸𝑞. 7 𝐺𝑒𝑛𝑒𝑟𝑎𝑙 𝐸𝑞𝑢𝑎𝑡𝑖𝑜𝑛)
𝑛1 = 𝑛2 = 2.110
2.110× (38) = 38 𝑅𝑃𝑀 (𝑔𝑒𝑎𝑟 𝑟𝑎𝑡𝑖𝑜 𝑓𝑟𝑜𝑚 𝑔𝑒𝑎𝑟 1 𝑡𝑜 𝑔𝑒𝑎𝑟 2)
𝑛3 =𝑁2
𝑁3× (𝑛2) =
2.110
1.130× (38) = 70.96 𝑅𝑃𝑀 (𝑔𝑒𝑎𝑟 𝑟𝑎𝑡𝑖𝑜 𝑓𝑟𝑜𝑚 𝑔𝑒𝑎𝑟 2 𝑡𝑜 𝑔𝑒𝑎𝑟 1)
𝑛3 = 𝑛4 = 1.130
1.130× (70.96) = 70.96 𝑅𝑃𝑀 (𝑔𝑒𝑎𝑟 𝑟𝑎𝑡𝑖𝑜 𝑓𝑟𝑜𝑚 𝑔𝑒𝑎𝑟 3 𝑡𝑜 𝑔𝑒𝑎𝑟 4)
𝑛5 =𝑁4
𝑁5× (𝑛4) =
1.130
4.99× (70.96) = 16.09 𝑅𝑃𝑀(𝑔𝑒𝑎𝑟 𝑟𝑎𝑡𝑖𝑜 𝑓𝑟𝑜𝑚 𝑔𝑒𝑎𝑟 4 𝑡𝑜 𝑔𝑒𝑎𝑟 5)
𝑛6 =𝑁5
𝑁6× (𝑛5) =
4.99
1.130× (16.09) = 70.96 𝑅𝑃𝑀 (𝑔𝑒𝑎𝑟 𝑟𝑎𝑡𝑖𝑜 𝑓𝑟𝑜𝑚 𝑔𝑒𝑎𝑟 5 𝑡𝑜 𝑔𝑒𝑎𝑟 6)
Bearing Analysis
The bearing analysis consists of each of the shafts which will rotate freely. In order to
correctly determine if the Bearing will operate under the required conditions, for each shaft
requiring a bearing the catalog rating was calculated using an overestimation of force parameters
and standard Weibull parameters for ball bearings the result showed a high catalog rating. Using
the Catalog rating, the bearings chosen for the application will need to have either an equal or
greater load rating compared to the Catalog rating. Below figure 9. Catalog rating for the
bearing. For a simple analysis the thrust force is taken to be negligible. The example shown
below was repeated for the other shafts following. The Weibull parameters are shown on table 5.
For the catalog rating of 763 lb. the bearing is shown the dynamic capacity for a double shielded
bearing will provide a dynamic load of 1,200 at $12.02. [18]
37
Figure 9: Bearing Free Body Diagram
Figure 10: Related nomenclature and application conversion factor
38
Table 5: Weibull Parameters
Weibull parameters
X0 0.02
b 1.483
a 3
(theta-x0) 4.439
Application factor 2
𝑥𝑑 =𝐿𝑑
𝐿10 (𝐸𝑞. 2 𝐺𝑒𝑛𝑒𝑟𝑎𝑙 𝐸𝑞𝑢𝑎𝑡𝑖𝑜𝑛 𝑓𝑜𝑟 𝑑𝑖𝑚𝑒𝑛𝑠𝑖𝑜𝑛𝑙𝑒𝑠𝑠 𝑑𝑒𝑠𝑖𝑔𝑛 𝑙𝑖𝑓𝑒)
𝐿𝑑 = 60 × (10000) × 𝑛𝐷 (𝐸𝑞. 3 𝐺𝑒𝑛𝑒𝑟𝑎𝑙 𝐸𝑞𝑢𝑎𝑡𝑖𝑜𝑛 𝑓𝑜𝑟 𝑑𝑖𝑠𝑖𝑟𝑒𝑑 𝑑𝑒𝑠𝑖𝑔𝑛 𝑙𝑖𝑓𝑒)
𝐿10 = 10 6 𝑟𝑒𝑣𝑜𝑙𝑢𝑡𝑖𝑜𝑛𝑠 (𝐸𝑞. 4 𝑟𝑎𝑡𝑖𝑛𝑔 𝑙𝑖𝑓𝑒)
𝐶10 = 𝑎𝑓𝐹𝑑 [𝑋𝐷
𝑥0 + (𝜃 − 𝑥0)(1 − 𝑅𝑑)1
𝑏⁄]
1𝑎⁄
(𝐸𝑞. 5 𝐺𝑒𝑛𝑒𝑟𝑎𝑙 𝐸𝑞𝑢𝑎𝑡𝑖𝑜𝑛 𝑓𝑜𝑟 𝑐𝑎𝑡𝑎𝑙𝑜𝑔 𝑙𝑜𝑎𝑑)
Example:
𝐹𝑟 = √502 + 502 = 70.71 𝑙𝑏𝑓 (𝐸𝑞. 6 𝐺𝑒𝑛𝑒𝑟𝑎𝑙 𝐸𝑞𝑢𝑎𝑡𝑖𝑜𝑛 𝑓𝑜𝑟 𝐸𝑞𝑢𝑖𝑣𝑎𝑙𝑒𝑛𝑡 𝑙𝑜𝑎𝑑)
39
𝑥𝑑 =60(10000)(38)
106 = 22.8 (𝐸𝑞. 7 𝐺𝑒𝑛𝑒𝑟𝑎𝑙 𝐸𝑞𝑢𝑎𝑡𝑖𝑜𝑛 𝑓𝑜𝑟 𝐸𝑞𝑢𝑖𝑣𝑎𝑙𝑒𝑛𝑡 𝑙𝑜𝑎𝑑)
𝐶10 = 2(70.71) [22.8
0.02+(4.439)(1−0.99)1
1.483⁄]
13⁄
= 765.56 lbs. (eq.8 catalog rating)
5.5. Material Selections
There are several materials that where considered for the construction and fabrication of the
robot. Material being used on the robot will consist of metal alloys and plastics along with fluids
used for lubrication. Chemical batteries will be discussed in the power section 5.7.When
considering the materials being used for Hazmat reconnaissance there are several factors which
must be considered. The factors that must be considered for material selection are: machinability,
strength, cost, and feasibility of being decontaminated. The following table 6 illustrates the
various materials and the corresponding factors used for construction of the platform.
40
Table 6: Material Selection Properties for common metal grades
Each of the columns represent a property of the material. The first column is Machinability.
In order to calculate machinability there are many aspects and conclusions that must be taking
into account some of the aspects may be surface finish Brinell hardness, and how much power
would be required to cut into the metal for example in the case of the experiment a material was
turned on the lathe and then cut into. [19]The following column illustrates the Brinell hardness
number for each of the materials. For the purposes of the application we decided to use the
highlighted materials, Aluminum, Stainless, and Plain Machine able. The next column displays
the cost per pound of the metal. Depending on the supplier the cost could vary depending on how
much material to purchase. The smaller the quantity the more expensive and with the higher
quantity the lower cost. An average cost was tabulated to in order to achieve a more practical and
true value for the materials. [20] The final column shows the level of decontamination. The
Metal
Machinability
(power
required for
turning hp.
Per cu in per
min)
Hardness
(Brinell)
cost per
lb
feasibility of bieng
decontaminated
Aluminum 5005
0.1-0.2 28 0.66 low
Aluminum 60610.1-0.2 65 0.66 low
Stainless 316
0.5-1 149 0.79 high
plain
machinable
steel 1045 or
0.5-1 163 0.09 low
Titanium 6AL-
4V Eli Titanium n/a 379 1.97 high
pharmaceutical processing equipment, marine
exterior trim, surgical implants, and industrial
equipment that handles the corrosive process
chemicals used to produce inks, rayons,
photographic chemicals, paper, textiles, bleaches,
and rubber.
used for axels, bolts, forged connecting rods,
crankshafts, torsion bars, light gears, guide rods
biomaterials, biomedical implants,
biocompatibility
Applications
Factors considered
Material Selection Properties for common metal grades
Cooking utensils, decorative trim, awnings, siding,
storage tanks, chemical equipment
truck bodies and structural components
41
standard in order to classify the feasibility of decontamination of a metal uses DF or
(Decontamination Factor). The Decontamination factor measures the effectiveness of a
decontamination process. Mathematically the DF is a ratio of the change in state of the
radioactivity of the material. The final column of the material properties table illustrates the
various applications used for each of the metals. [15] The Primary metal alloy that will be used
in the construction of the robot will be aluminum 6061, Stainless 316 and plain Machine able
steel. These alloys where chosen do to the cost per pound and the function needed for the
application. Ideally if cost was not an issue and the method of manufacture was not an issue
Titanium would be the choice for construction of the robot do to the high strength and the
decontamination level. This alloy will be used due to the corrosive resistant properties, and the
density of aluminum is much less than other alternative metals. Another reason is that the cost of
Aluminum is much lower than other metals. Aluminum 6061 is primary used to construct the
chassis of the Robot, other alloys are metals used in ball bearings and steel alloys are used for the
bolts.
The primary Plastics will be PLA or (Polylactic Acid). PLA is used because it is a bio-
degradable type of plastic. PLA will be used to construct the shelf used to house the sensors and
other fastening supports. [15]
42
5.6. Finite Element Analysis
Figure 11: Simulation of tread track using POM Acetyl Copolymer
Figure 12: Stainless Steel Chain link
The following figures 11 and 12 illustrate the alternative solutions to implement the tread
system. Figure 12 has an Ultimate tensile strength (UTS) of 90 ksi (kilo pounds per square inch)
which the simulation proved the load is below the UTS by a factor of 10. Figure 11 displays a
maximum stress of 29 ksi (kilo pounds per square inch), which would be under the yield stress
43
for POM Acetyl Copolymer of 17 KSI providing a factor less than 1. Using this tool as an
estimation, the decision was made to use the stainless steel links.
Figure 13: Panel without Pocket
Figure 14: example of panel with pocket
The following figures above illustrate a side panel. For this problem the goal was to
investigate which panel would yield a higher stress. By reducing weight shown in figure 14 using
44
the same material, one may observe figure 13 to show a lower stress. By examining the points
the conclusion was to consider the minimal use of pockets when necessary.
5.7. Motor analysis and selection:
The following discussion is going to discuss the different aspects of the motor selection. The
factors which contribute to the selection of the motor involve: Power Requirement, Weight of
robot, current draw, Torque required, and duty profile. When considering the factors the initial
decision was to use the full scale robot however do to budgeting complications the design of the
robot was too use the same system and scale down the weight to the 35% scale reduction. With
the reduction incorporated the following table 7 illustrates the total projected weight and required
torque for the system.
Table 7: Projected Weight Analysis and Torque by considering varying degrees of incline
Loads weight (lb) Angle of incline Radians
Resistance
(lb)
Resultant Force
(lb)
Torque applied to
Drive due to
gravity(in-lbf)
Chassis 150 0 0 16 16 17.84
Batteries(Drive) 110 10 0.17 15.76 1.87 2.08
Batteries(Hydraulics) 0 20 0.35 15.04 -12.33 -13.74
Arm 80 30 0.52 13.86 -26.14 -29.15
Motors 60 40 0.7 12.26 -39.17 -43.67
Pumps 0 50 0.87 10.28 -51 -56.86
Total Projected Weight 80 60 1.05 8 -61.28 -68.33
70 1.22 5.47 -69.7 -77.72
Assumed coefficient of friction *0.2 is half of 0.4, the suggested coefficent of STATIC friction for rubber against slick surfaces
45
Table 8: Power Requirement when submitted to a 70 degree incline
Table 8 illustrates the duty profile weight projection and the maximum current draw for
each motor. These approximations take into account a power to weight ratio of 1.6, which can
also be taken as the safety factor. The original projected weight for the full scale robot is 400lbs.
with the power to weight ratio the adjusted weight taking 400 and dividing by the 1.6 should be
80 lbs. again this value is an overestimation of the power requirements and torque requirements
assuming the robot will continuously climb a 70 degree incline. Note the Duty profile classified
for the system will undergo periodic drive and stop motions with electric braking. The first motor
considered for the system is shown in figure 15 shows the MMP-TM57 Geared Motor. Figure 16
illustrates a similar almost exact motor however the difference between the TM57 and the TM55
is that the Torque output is less. The following table 9 illustrates the specifications for each of
the motors considered for selection of the Hazmat robot.
Less then Power
Requirement =
VI (watts)
WIEGHT INCLINE voltage (V)current
(amperes)Torque (in-lbs)
720 80 LBS 70 DEG 12 less then 60 60
Torque (in-lbs) Torque (oz-in) Torque (Nm)
60 960 6.78
Duty Profile
S7 - Continuous
operation periodic duty with electric
braking
35% Scaled down model-Current Robot
46
Figure 15: MMP-TM57 Geared Motor [21]
Figure 16: MMP-TM55 Geared Motor
47
Figure 17: Amp flow E30-400 Motor [22]
Table 9: Motors considered for selection
5.8. Battery Selection
For the battery selection, we will be basing the size on two important factors. These
factors are runtime as well as weight. The runtime is the amount of time that the robot will be
able to operate before the batteries are depleted and the robot can no longer perform its
functions. For this we are have defined based on information that a runtime of 30 min will be
adequate for the robots tasks. Due to price reasons the batteries that will be used will only be led
acid batteries therefore not much can be done in consideration for the weight. In the future other
battery technology can be considered to improve on this aspect, such as Lithium Iron Phosphate
(LiOP4) that has a higher energy density.
model Gear Reduction Rpm at load rated Continous Torque (in-lbs) rated peak Torque (in-lbs)
MMP-TM57-100 100 44 109 443
AmpFlow E30-
400 Motor n/a 5700 n/a 93.75
MMP-TM55-100 99:50:01 44 100 348
48
For led acid batteries we can uses equations based one Peukert’s law and be able to
determine the capacity needed to run the robot for our 30 min time period. These batteries will
only be powering the drivetrain of the robot, which is made up of two Midwest Motion motors.
These two motors as seen in the figure will produce a max draw of 7.2 Amps each totaling 14.4
Amps. This is what we will use to determine the worst-case scenario to power the motors at max
load.
Figure 18: Drive Motor Current Draw
With a continuous draw of 14.4 Amps we can gage the capacity required for the batteries. Due to
the fact that we are using sealed led acid batteries we can use Peukerts’s equations.
𝑇 = 𝐻 (𝐶
𝐼𝐻)
𝐾
T= Time (hr)
H= Amp Hour rating (AH)
C= Amp Hour capacity (AH)
I= Load Applied (Amp)
K= Peukert’s Exponent
Solving for the capacity:
𝐶 = 𝐼𝐻 ∗ (𝑇
𝐻)
1𝐾
49
However, Peukert’s exponent is still needed for this calculation. Peukert’s exponent
depends on the type of battery used for our purpose we are using an Absorbent Glass Mat
(AGM) led acid battery which has a K value between 1.05 to 1.15 (closer to 1 is better). Using a
conservative value of 1.15 we have a theoretical capacity of 11.65 Amp Hours (AH). This is not
however this would imply depleting the batteries completely, which degrades the battery. It is
normally recommended to maintain a 50% charge to keep batteries healthy. Ultimately a battery
with 24 AH capacity will be ideal for hour needs, however dude to our size constraints for testing
16 AH (combination of 2 8 AH batteries) will be used. This still gives a estimated run time of
21.6 minutes which is adequate for testing.
50
The batteries that were chosen for the prototype testing were Power Sonic PSH-1280 8
AH batteries. The reason these batteries were chosen was due to its many good qualities. From
research these batteries had the best capacity to weight ratio about 1.33 lb. per AH. As well this
kind of sealed led acid battery boast being flame retardant as being AGM.
As eluded by the calculations the battery configuration that was chosen was to run two of
these in parallel configuration. Being in a parallel configuration the motors will have access to
twice the amount of amps. Whereas a series configuration would allow only the amount of amps
equals to one battery with double the voltage, which is outside of the recommended range of the
motors the illustration in figure 18 explains these properties. This is something that is usually
done in order to meet the current demands of the mothers under load. However with the selection
of the PSH-1280F2 each individual battery can supply a constant of a 20 amps and a max of 25.5
amps for a duration of 7 min, illustrated through figure 21. This decision was made to both allow
for maximum allowance of amps to be supplied to the motors and other accessories as well to
simplify the circuit and allow for a single “kill” switch in an emergency situation.
Figure 19: Parallel vs. Series configurations [23]
51
Figure 20: Power Sonic PSH-1280f2 [24]
52
Figure 21: Performance Specifications for PSH-1280F2 Battery [25]
53
5.9. Communication system
With all robotic platforms there is a need for a translator to transfer the input commands
from the user to the robot machine code. The complexity of this device follows the inputs and
outputs that are required for its tasks. For the prototype design many different communication
systems were considered with for this design all with their own positive and negatives.
Arduino
The Arduino is very common micro controller; it finds itself used in many small DIY (do
it yourself) projects. This is the first controller that was considered. It has many advantages being
relatively inexpensive due to the fact that it is an open platform with many different
manufactures. As well-being open platform this board also has many different accessories and
support for a large community.
Figure 22: Arduino Mega [26]
54
However the one major downside with this platform for when considering the full scale
design was with the consideration of having multiple video streams that would be processed and
sent from the Arduino board. Although being very adaptable the Arduino platform is not a very
powerful one. With this system it was not recommended to used due to lack of processing power
from multiple online forums. The other option that was universally recommended was the
raspberry pi microcontroller.
Raspberry Pi
The Raspberry Pi is a microcontroller much like the Arduino in its basic operations and is
open source. One of the main differences that distinguish the Raspberry Pi from the Arduino is
its processor it use s and ARM processor. This Processor is much more powerfull and can there
for process more instructions. The diffrence is much more noticebale with he second itteration of
the Raspberry Pi 2 which stouts a quad core processor allowing to handle more streams which
would be needed handle multiple videos streams along with basic motor instructions to a motor
controller. This however does have some cons, the type of programing required for this system is
much more difficult when compared to the Arduino and has a much steeper learning curve even
with other programing experience and many helpful communities. With all considerations the
Raspberry Pi 2 would be the optimal choice for the full-scale design.
55
Figure 23: Raspberry Pi [27]
However with the need to downscale the design and only focusing on prototyping the
design a microcontroller with the capabilities of the Raspberry Pi 2 and Arduino were neither
necessary nor available within the budget. Exploring other options the choice became clear when
considering the Vex Platform of which we have experience with using and coding with.
Vex
Vex is an organization that holds robotic completions for both high school and college
level participants. Similar to the Lego Mindstorms vex tries to appeal to young students and
encourages them to design and build robots for the use in their competitions. The consideration
with using this platform starts with the ease of use as stated prior experience will medicate any
learning curve as well the vex components fit within the needs of the design. This system also
natively is ready to work with a physical controller natively. This is greatly simplifies the process
when compared to the pervious platforms where a controller would need to be sourced and coded
56
into the microcenter. The one major drawback to the vex system is video recording is not
supported with the microcontroller meaning video really would need to be transferred by another
system. Lastly we were able to borrow a unit like the system seen in the figure below for testing
purposes.
Figure 24: Vex microcontroller brain, Controller, Receiver [28]
Coding the Vex brain is a very simple process do to the fact that the system is used to
teach younger students how to program. The basis of the coding is C++ in a program rightfully
called EazyC. The Code listed below shows the simple code used in order to control the motors
through the use of the motor controllers.
57
Figure 25: Code applied for tank drive onto robot
5.10. Speed Controllers
The speed controllers also known as a motor controller is a device that allows for the
control of the amount of amps to be supplied to a given electric motor. Essentially the motor
controller can be seen as a valve controlling the amount of current and therefor the power of the
motor. These devices are needed in most robotic application where the microcontroller cannot
supply the motor with the required voltage or amps. Similarly with our use case the vex
microcontroller cannot supply the necessary voltage or current the motors supplied for this
design (12 Volts 7.2 AMP). For our case the speed controller selected would need to fall in the
58
dimensions of the specifications of the motors. It is important in the selection process that the
speed controllers do not just meet the requirements of the motor they are known to overheat
when reaching their limitations. Other considerations into the size of the speed controller and the
method of communication to the microcontroller are taken into count for proper fitment into the
overall system. For these reasons the decisions was to go with the Victor SP motor controller, a
Vex motor controller that can more than handle the needed throughput of the MMP motors.
Figure 26: Comparison of Vex Motor Controllers [29]
59
From the figure above it can be seen the Victor SP motor controller has a nominal voltage of 12
volts and a rated continuous current of 60 Amps well above the condition that are planed to be
run. As well this speed controller when compared to others has a relative small form factor
which works well with the scaled down prototype.
Figure 27: Victor SP Interface Dimensions [28]
60
5.11. Camera
As previously noted the camera that is to be mounted on the prototype will not be directly
linked to the microcontroller operating the robot. This was do to the lack of video support on the
vex platform. However video relay does not need transmitted from the microcontroller. The
other option is to a self-contained system, one that can transmit the video wirelessly on its own.
As well due to the constraints to build a prototype rather than full scale the camera selected
would not need to stand to conditions that would be expecting in a full size unit. This testing
exception allowed for a more relaxed selection in the specifications for the camera. This is where
a single ip camera is used in order to test basic surveillance and field of view testing.
Figure 28: D-Link 931L ip Camera [30]
Shown in the figure above the ip(internet protocal) camera selected is a D-Link 931L ip
camera. This product was chosen due to its small size and wireless capabilities. Being an ip
camera it only requires a router to connect to and as long as there is a connection to the router the
video feed can be remotely accessed by anyone able to connect to the network. However as
61
illustrated in the diagram above the camera does require a direct feed of current in the form of a
DC connection.
In order to maintain the supply needed for the camera and to continue to have the system
untethered. A system had to be devised to convert the power going out of the batteries (12 Volt)
to a usable voltage for the camera, which requires 5 Volts at 1 Amp. The use of a voltage
regulator was connected into the circuit in order to perform this task. A voltage regulator is a
device with converts the input voltage from high voltage to low. There are many different kinds
of regulator that work for different inputs and output voltages. For the needs of this system the
use of a L7805, which works for 12v to 5v. It is also very important to use a heat sink with these
devices depending on the use. The heat skink is needed in order to expel the power loss through
the regulating process.
𝑃 = (𝑉𝑖 − 𝑉𝑜) × 𝐼
𝑖. 𝑒. (12 𝑉𝑜𝑙𝑡𝑠 − 5 𝑉𝑜𝑙𝑡) × 1 𝐴𝑚𝑝 = 7 𝑊𝑎𝑡𝑡𝑠
For the case of this design the heat sink would require to dissipate 7 watts of heat from
the device.
62
Figure 29: Example Circuit Diagram for Voltage Regulator [31]
The figure above shows an example circuit diagram for the voltage regulator. As well, not
specified in the diagram there are two capacitors connecting the positive leads to the ground
connection. This is done to mitigate the noise that is created by the voltage altering process.
5.12. Electrical Circuit
The electrical circuit servers as an important part in any robotic design. Due to the
relatively small nature of the prototype being constructed, the design of its circuit follows a
similar trend. The circuit of this robot contains only a few components as listed in the table
below.
63
Table 10: Items in circuit
# Item Quantity
1 12 volt battery 2
2 7.2 Volt Battery 1
3 Switch 1
4 Power Distribution 1
5 Voltage Regulator 1
6 10 μF Capacitor 2
7 2 Amp Fuse 1
8 10 Amp Fuse 2
9 Camera 1
10 Speed Controller 2
11 12 Volt Motor 2
12 Vex Microcontroller 1
These items bring together both the circuit for the Vex micro controller as well as the
circuit for the motors, which are serrated in terms of power source. This can be seen clearer in
figure 30 which shows the layout of the entire circuit. In the illustration of this circuit it can be
64
seen the source of energy for the motors comes from a pair of 12 Volt Led Acid batteries that are
configured in parallel. Immediately introduced is the use of a “kill” switch where the robot can
be disconnected from the power source in an emergency situation. This power is then distributed
out to the two speed controllers and camera through the use of a distribution board. Here other
safety measures are taken with fuses leading out for each component in the case where it could
be over loaded. As shown the circuit for the microcontroller is on a separate circuit with its own
power supply. This is due to the proprietary nature of the Vex components that a separate batter
was used for it. Ideally the entire system would be run purely off the two 12 Volt led acid
batteries in parallel with its appropriate fuse feeding off the power distribution board. The
advantage of this would require less space for the batteries. Also unifying the circuit would allow
the microcontroller to be safer position with a fuse for over loading and immediate shutdown
with the use of the “kill” switch.
Figure 30: Circuit Diagram of Prototype Robot
65
5.13. Proposed Drive Train Cost Summery
The following table 11, will illustrate the purchases and the part cost break down. The initial
section will include the readily available parts which were able to be purchased either online or
at a local vendor. The corresponding section projects the manufactured parts and costs associated
with each section such as the chassis, mounting parts, and assembly hardware.
Table 11: Cost Breakdown
Robotics Cost Sheet
# Description Quantit
y Total Price
Date of Purchase
Location of Purchase
1 Drive Motors 2 $522.00 9/21/15 Midwest Motion
Products
2 Batteries 4 $71.69 9/22/15 AtBatt.com
3 Battery Charger 2 $20.26 9/22/15 Amazon.com
4 Camera 1 $40.00 9/22/15 Tiger Direct
5 Bearing 36 $89.90 10/9/15 Blair Bearings
6 Sprockets 18 $113.70 10/9/15 BBManufactureing
7 Water Jet 1/2 4 $156.00 10/9/15 Nautic Waterjet Fabrications,Inc
8 Water Jet 1/2 4 $150.00 10/9/15 Nautic Waterjet Fabrications,Inc
9 Reamers 4 $194.79 10/21/15 Shars Tooling Company
10
Raw material Several $66.59 10/22/15 Simons Stainless Surplus
11
Victor SP 2 $127.18 10/26/15 Robot Market Place
12
Dewitt tools Several $43.00 10/26/15
Dewitt tools
13
Dewitt tools Several $43.00 10/26/15
Dewitt tools
14
McMaster tools Several $335.00 11/1/15
McMaster Tools
15
Dewitt tools 2
$9.00 11/2/15
Dewitt tools
1 Electronics Several $11.00 11/2/15 Alpha Electronics
66
6
17
Sprockets 16
$193.00 11/2/15
Blair Bearings
18
Suspension Several $16.00 11/7/15 CEWater Jet
19
Panels/ Motor Receivers 4
$250.00 11/23/15
Zicarelli
20
Electronics 2
$45.99 10/27/15
B&F Marina
21
Tools 7
$30.00 11/7/15
Tools and equipmetnt sales corp
22
Bushings 6
$40.00 11/8/15
Ace
Complete Estimated cost: $2,568.10
6. Prototype Construction
6.1. Overview
The following sections will illustrate the prototype model. The prototype model will
consist of description, design section, construction section, parts list, and cost analysis. The idea
of the prototype is to facilitate the same objectives as a full scale representation of the robot
through all the same challenges as a smaller scale. Before reconstruction of the full scale model
the prototype will require a lower cost to construct and will facilitate all testing requirements
before being applicable to full scale.
6.2. Description of Prototype
The HAZMAT ROBOT prototype will be a one-third scale representation of the actual
scale robot. The geometry will be scaled down one third of the original size and the power to
67
weight ratio will maintain the same. In order for machinability purposes and cost limitations the
material of the robot prototype will be aluminum 6061, however as stated earlier the optimal
material would be a grade of titanium or easily decontaminate materials used for the medical
application. The motors will deliver 100 in-lbs. of continuous torque the batteries will be 12v 7.2
amperes. For the prototype a flight of stairs will be constructed and will follow the residential
building code regulations. The tread system will use number 35 chain as the belt and the number
25 chain as the driving chain.
6.3. Prototype Design
The following figure illustrates the prototype of the robot. The overall chassis of the
robot consists of 4 panels: 2 outer panels, and 2 inner panels. The space in the center of the robot
houses the battery compartment and the motors. The motors are mounted parallel side by side
from each other. The outer space on each side will contain the sprockets and drive train of the
system. Each side will have an independent motor allowing for reverse, full range of planer
motion. The tread system will comprise of a belt covering the chain links which will sit on the
sprockets. By designing the robot with a high torque and low center of gravity the robot will be
able to quickly traverse up and down inclines.
68
Figure 31: Prototype Model of the HAZMAT ROBOT
When designing the prototype many factors needed to be considered and implemented in the
modeling stage before beginning the manufacture the parts. The budget for the build was first
determined then after the budget was calculated design components for the robot could be made.
Ultimately much of the support structure was machined using a 3-axis CNC (computer numerical
control) milling machine or using a drill press. With collaboration the panels were able to be
water jetted. Another difficulty was the tread system. The decision was made to create a tread
system using existing links and a universal pulley belt, which would be able to purchase at any
online hardware store. The build is currently in progress however the expected completion of the
assembly will be November 6, 2015.
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6.4. Parts List
The following table will illustrate all components being assembled on the hazmat robot.
There will be parts which are being manufactured and already manufactured parts which are
reflected on the table.
Table 12: Part List for Robot
Parts List Qty Description Function
1 Outer Right Panel support structure
1 Outer Left Panel support structure
1 Inner Right Panel support structure
1 Inner Left Panel support structure
1 top support Panel support structure
2 vertical panels store electrical components
2 horizontal panels store electrical components
2 diagonal compartment plates store electrical components
4 suspension part house the sprockets and support sprockets
2 suspension part housing create a joint between the chassis and suspension
2 motor housing part support the motor
2 rubber housing used to dampen vibration support and reduce vibration
2 Electrically Driven Motors Drive Robot
2 12 volt batteries Power Robot
6 1.130 inch diameter idler sprockets Tread system
2 4.99 inch diameter guide sprockets Tread system
6 2.11 inch diameter drive sprockets Tread system / drive train
2 1/2 inch shaft axel for robot
6 3/8 inch shaft used for idler sprockets
12 10-24 machine screws to join the vertical and horizontal panels, and motor housing to the motor
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6.5. Construction
Table 13: Nomenclature used for construction
Nomenclature
Symbol Description SI Units
AS Surface area ft2
DIA
Nominal Diameter of
drill(inches)
in
d Depth of Cut (inches) in
Length Length of part (inches) in
Width Width of part (inches) in
Depth Depth of part (inches) in
FPT Feed per Tooth n/a
FPR Feed per Revolution n/a
IPM Inches per minute in/ min
RPM Revolution per minute n/a
SFM Surface Feed per minute Surface feet/min.
TPI Threads Per inch n/s
Initial considerations for construction was based on a full sized prototype of the robotics
system. With full sized model in mind the construction process was planned to commence with
the manufacturing of the larger plates of the robot, reducing cuts to allow for minor alterations.
Given the new size of our design being a 35% scale of the original design the initial construction
plan needed to be altered in order to conform to our new needs. Ideally our construction would
begin similar before with the construction of the chaise however due to the smaller form factor
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the available hardware did not exactly conform to our prototype scale and the new chaise would
need to be modified first. Our initial construction process begins with the compiling of essential
materials and components. The initial components that were purchased where the battery, motor
and speed controllers. While the components where being ordered the first step of construction
was the obstacle which consisted of climbing a stair case and being able to traverse across
alteration surfaces. As shown in figure 32 building the stair case first consisted of creating a
template and figuring out what dimensions to use. As stated in the earlier paragraph since the
robot was scaled to a reduction of 35% the stairs needed to be scaled down as well. Using the
building codes for a residential stair case the average height is 7.75 in, depth of 10 in width of
37.8 in of each step the team was able to find the scaled value of 3.5 in depth, and a height of
2.715 in and width of 12.6 in. The angle is 39.032 degrees for the overall angle of the stair case.
In figure 34 and figure 35 illustrate the fabricated and completed stair case with an overall length
of 42 in and an overall height of 34.05 in. The overall area of the table is 3ft2.
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.
Figure 32: Installing each of the support blocks for each side
Figure 33: Setting up each of the steps
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Figure 34: Completed stairs and assembly not including table
Figure 35: Completed stairs and table front view
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Figure 36: Completed stairs Isometric view
While the stair case was being built the drawings of the outer and inner panels where
under review by the Engineering Center machine shop and a Water Jet vendor. The cost to
process the panels through a CNC machine was an estimated $1750.00. This CNC cost included
the material, setup and tooling cost. The cost to water jet the panels leaving out features which
required Machining do to the step profile was an estimated $300 for all the panels. Additionally
the motor receivers and the additional required machining estimated $250. The net savings for
first water jetting provided a net savings of $1200.
Figure 37 illustrate the water Jet facility. Water jet works by placing the sheet material from
0.125 in to 6in on a bed and allowing water at a high pressure to cut through the material
providing the required 2-dimensional profile. Figure 38 illustrates the appearance of the panels
after a post process from the water jet.
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Figure 37: Water Jetting Facility
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Figure 38: Inner and outer plate’s appearance after Water Jetting
Once the panels had been processed by the water Jet, the panels where processed by the
engineering manufacturing center. This was a necessary CNC construction to create a housing
for the motors and slots for the supporting members of the robot. All CNC manufacturing was
done on the Fadel Vertical CNC machine as shown in figure 39. The panels are shown in figure
40, notice the step down and the flanges around the motor receiving area. The Ideal method used
for manufacturing is by initially using a large flat end mill to remove a majority of the feature
then once the material has been removed a smaller flat end mill would be used as a final sweep
along the profile to remove and create a final finish. The battery and all slots where created using
a high speed steel flat end mill. The flat end mill tool is shown in figure 40. Note the preferred
method to construct the panels and other mating components would be a combination of CNC
and Water Jet.
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Figure 39 (Fadel CNC Milling Machine [32]
Figure 40: Flat end mill used for CNC manufacturing [33]
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Figure 41: Appearance of Inner and Outer Panels after CNC operation
Figure 42: Appearance of Motor Receivers after CNC operation
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Once the panels where completely finished and all CNC required features were
manufactured the following components of the Robot could be fabricated: Sprocket and bearing
press fit, drop plates, top plate, bottom plate, suspension, and tread. Primary manufacturing
equipment used to fabricate the additional pieces where the knee mill or manual mill, drill press,
lathe, vertical band saw, horizontal band saw, and a bench grinder. A manual mill unlike a CNC
mill which can be operated through a program requires the operator to calibrate the part on the
table of the equipment and adjust the position relative to the drill using the 3 axis table feed hand
wheel. Since the material being used was aluminum the spindle speed RPM of the tool would
need to be rotating at 2200 RPM. The SFM unlike the CNC was controlled by the lever arm and
would be operated using a line of sight method. For aluminum it is best to set the spindle speed
to above 2000 Rpm and for steel from 700 to 1000 rpms. [34] The Manual mill Bridgeport is
shown in in figure 43 and the drill press is shown in figure 43 as well. The lathe and reamers are
shown on figure 45 and figure 46 respectfully. The reamers used for the drill press are based off
the measured Outer Diameters of the Bearings, the standard rule is that for any press fit
application the part fit needs to be -.001 or -.0005 smaller than the part being pressed in the
housing. In the case of a press fit bearing into the sprocket, the sprocket inside diameter needs to
be -.001 or -.0005 smaller than the outer diameter of the bearing. In order to achieve this the
sprockets need to be drilled using a standard drill and then the feature needs to be reamed to
achieve the -.001 or -.0005 smaller than the bearing. For the idler sprockets and smaller
sprockets the reaming sizes are .6220 and .6225 inches for an outer diameter bearing of .623 and
the drill is 19/32 inch. For the larger sprocket the reamer is .7470 and .7475 for an outer diameter
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bearing of .748 and the drill is 23/32. The tread system was constructed using timing belts and
K-1 tabs which allow the belt and chain to move together around the sprockets. The timing belt
and K-1 tabs are joined using rivets which can be shown in figure 50. In order to keep all the
holes aligned with the timing belt the team created a fixture which held the belt in place while
providing drilling locations allowing for precise placement of the rivets once the holes had been
drilled.
Figure 43: Knee Mill on the left side Drill press on the right Side
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Figure 44: Knee Mill Machining features on sprocket
Figure 45: Lathe used to create holes and create press fit
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Figure 46: Reamer tools used to create press fit
Figure 47: Vertical Band Saw [35]
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Figure 48: Horizontal Band Saw [36]
Figure 49: Bench Grinder [37]
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Once the additional components were fabricated the next step was assembly of the
hardware and other components the boxed aluminum was constructed by first bieng cut by the
vertical band saw then bieng smoothed out by the bench grinder. E clips where mounted to the
shafts to prevent the axles from displacing themselves from the initial position. saw then bieng
smoothed.out by the bench grinder. E clips where mounted to the shafts to prevent the axles from
displacing themselves from the initial position. Another way of joining members to each other
was by using threading hardware the threads used for the robot are 10-32, 4-40, and 5-40. The
convention of the hardware is that the first number represents the size of hole and the second
number signifies the number of threads per inch. All of the hardware bieng used on the robot
uses english units however there are similar metric hardware that can be on the robot. The thread
sizes were chosen and based off of the geometrical clearances for the tensioner and the mounting
slots. Note all threads are engaged with a maximum 0.5 inches. The components that required
threads are the tensioner shaft, the inner panels, the vertical and horizontal panels, and the top
and bottom plate. An additional emergency switch panel was installed and used 10-32 threads.
The following figures 52 through 54 illustrate the progress from initial chassis up to the final
assembly of the figure.
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Figure 50: Tread Jig
Figure 51: Tread Chain K-1 Tabs
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Figure 52: Chassis of Robot not including bottom and battery housing plates
Figure 53: Chassis of robot including bottom battery housing plates
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Figure 54: Final assembly with batteries and additional components except the suspension
Figure 55: Assembly without motors and tread system)
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Figure 56: Final side assembly without outer panel
Figure 57: Complete assembly of Hazmat Reconnaissance Robot
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7. Testing and Evaluation
7.1. Testing and Evaluation
Overview
The following sections will evaluate the performance of the HAZMAT ROBOT through the
objectives and develop experiments that will validate the theoretical analysis. Each of the
objectives to be under review will be Robotic system that can operate under hazardous
conditions such as if the robot is able to complete the tasks and how efficiently. The speed test
will compare the robot time against the time it takes for a member of the fire department to
complete the similar task whether it be preparation, stair climbing testing, towing capability, and
battery capacity. For evaluation of the equipment personal must successfully be able to assess the
situation based solely on the visual feedback. The sections being discussed will be: Design of
Experiments, Test Results and Data, Evaluation of Experimental Results, and Improvement of
the design, followed by Discussion.
7.2. Design of Experiments – Description of Experiments
The following section will provide each of the Experiments conducted for the Robot and
will include a description and will evaluate the objective of each experiment. Each of the
experiments reflect the overall behavior and performance of the robot. When conducting the tests
shown below the robot provided the highest difficulty when attempting the stair climbing test.
We through various configurations and reexamination of the geometrical assembly of the robot
the team was able to find a solution and will be further discussed in the stair climbing test
section.
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7.3. Towing Test
This test will evaluate towing capacities of the robot. For this test the robot was submitted to
an extreme condition which is when the surface of the plane is wetted. When discussing the
towing capabilities of the robot it is important to note the placement of the connecting member
and note the terrain where the towing took place. For testing purposes there are 2 surfaces that
where explored. The surfaces are a grass surface and a wetted concrete surface. These surfaces
where chosen for the test because the surfaces represent a low coefficient of friction, specifically
Rubber on grass is roughly 0.35 for car tire on grass. [38] For rubber on wetted Concrete the
coefficient is roughly .45. [39] The following table 14 illustrates the Experimental maximum
towing capacity of the robot when travelling on grass and wetted concrete surface. As expected
the when a lower coefficient of friction the robot would only be able to tow roughly 39% less
than when the robot is on a concrete surface. Theoretical values where based off of the nominal
motor specifications and through the torque and radius of the drive sprocket along with
approximate friction coefficients mentioned earlier the theoretical max weight can be calculated.
The error shown reflects the inaccuracies of the friction coefficient. The motors are not geared
and have continuous torque of 100 in-lbs. per motor giving both motors 200 in-lbs.
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Table 14: Towing Test Results
Towing Test Results
Surface Experimental Max Weight
(lbs.)
Theoretical Max
Weight of both
motors (lbs.)
Error %
Wetted Concrete 60.5 100.35 40
%
Grass 36.5 78.05 53
%
Testing Weights
Weight of Robot (lbs.) 47.5
Weight of Net Blocks(lbs.) 60.5
Weight of Individual cinder Block (lbs.) 36.5
Weight of half of cinder Block (lbs.) 24.0
Figure 58: 60.5lb. Cinder block on Concrete
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Figure 59: 36.5 lb. Cinder Block on Concrete
7.4. Battery Consumption Test
When considering the Battery Consumption test there are several significant factors to
consider and too compare against. The test will not only compare to the theoretical value of the
battery life but will also compare again the required time necessary for the fire department.
Through testimony of the firefighter personal the necessary time of preparation before entering
the hazmat scene is 30 minutes. In order to meet the requirements of the firefighting personnel a
safety factor of 2 was applied to allow an additional 30 minutes for the Hazmat response team to
deploy the robot and gather data of the scene. The following table 15 illustrates the experimental
run time of the robot. The run time gathered included variable loading and simultaneously
included traversing over all terrain surface. Theoretical run time used the analysis from section 5
including the use of one battery which would provide a run time of 21.3 min. The use of 2
batteries would provide a run time of 42.6 minutes which is very conservative value. The
associated errors shown may be caused by not considering the time load acting on the battery.
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Ultimately the robot will have periods of loading and unloading of current which would depend
on the operator and the environment. The robot successfully was able to operate within the 60
minute time frame and would continue past the hour requirement.
Table 15: Battery Consumption Test
Battery Consumption Test
Path of travel Experimental
time Theoretical
time
Required Time to
meet objective
Factor of Safety
all terrain travel(with weight along with variable loading) > 60 min 21.3 60 min 3
7.5. Speed Test
The purpose of this test was to find out how far the robot could travel once deployed in the
field. As shown on table 16 the test was conducted on a wetted concrete surface with no
additional weight being applied. As the table shows the Experimental speed is 0.33ft/s. This
value was calculated by timing the robot travel 10 ft. The Theoretical value was 0.29 ft/s. The
theoretical value is calculated through the different sprockets and using the different ratios of
teeth as a factor to reduce the initial speed of the motor. The analysis for this relationship is
shown in section 5. The following columns illustrate the percent error and net distances for 30
minutes and 60 minutes respectively. The reasoning behind the error can be caused by various
issues first by human error because a team member would initiate the timer while another team
member was moving the robot. Another issue this would be due to the surface of travel if the
surface provided a lower coefficient of friction the speed value acquired may have been closer to
the theoretical value. The usefulness of the net distance travelled would be in the case were the
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square footage of a facility is known the Hazmat unit would be able to determine whether the
Hazmat Robot could be utilized. The average person can walk 4 feet per second however the
robot with equipment and proper safety equipment this value may vary. [40]
Table 16: Speed Test Results
Speed Test Results
Surface Experimental Speed (ft./s)
Theoretical Speed (ft/s)
Error %
net distance in Feet to travel in 30 min
net distance to travel in 60 min
Wetted Concrete no weight 0.33 0.29 14% 521.43 1042.86
7.6. Stair Climbing Test
Upon final assembly of the robot the robot was not able to traverse the stairs in the original
configured position. This issue was mitigated using counter weights. The counterweights acted to
level the robot from the front and ensure the robot does not tip over. The method of setting up the
test was by mounting rails and placing the various weights on the rails. The robot was able to
ascend the stairs with a 12lb weight with difficulty. Through observation a design change would
be to adjust the rear arm and elongate it in order to span the robot over 3 steps instead of 2 steps.
Other suggestions were made to redesign the tread system in order to achieve more traction. The
final suggestion was to elongate the overall chassis to allow for the robot to pivot on the step.
The following table 17 illustrates the various configurations and whether or not the configuration
was able to traverse the stairs. The following figures: 61-63 shows the configuration of the
weights placed 12.11 inches from the center of mass in the positive x-direction and 2.50 inches
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in the positive y-axis. Using the formula, center of mass the center of mass for the various
weights can be calculated.
Figure 60: Distance of weight relative to center of Mass
(𝑋𝑖𝑛) =𝑚1𝑥1+𝑚2𝑥2+𝑚𝑛𝑥𝑛
𝑚1+𝑚2+𝑚𝑛 (Equation 1 Center of Mass equation)
Table 17: Stair Climbing Test
x y z
no wieght mounted at top -0.03 -0.13 0.53 no
5lb wieght mounted at top 1.15 0.192 0.53 no
10 lb weight mounted at top 2.105 0.351 0.53 Yes
12 lb weight mounted at top 2.441 0.407 0.53 Yes
Stair Climbing Test
Ability to climb
Yes or no
Center of Mass Relative to geometrical
originConfiguration
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Figure 61: 5lb. counter weight
Figure 62: 10lb. counter weight
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Figure 63: 12 lb. counter weight
7.7. Improvement of Design:
Through testing of the system and evaluating the various components of the design there are
several adjustments which may be made to increase the performance. With the regards to the
power system the batteries would be ideal for the system and provided a run time which satisfied
the required time. The motors aside from the torque which meets all necessary requirements. The
motor however may be geared in order to increase the speed to meet the average walking speed
of a person. The design may be modified in order to shift the center of mass further toward the
front to allow for smoother stair climbing. Other Ideas which may be able to allow for the robot
to stair climb would be by elongating the rear leg and extending the tread. Making these
modifications would shift the pivot point of the system and allow for the thread to pass over all
of the steps.
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7.8. Discussion:
The following sections illustrated testing done to evaluate the robot. The robot did pass the
battery consumption test, towing test, and speed test. The robot in the original configuration did
not meet the stair climbing test. In order to meet the stair climbing test the center of mass of the
robot needs to be adjusted towards the front. The tread motors and other components
successfully perform and the robot can be deployed through a variety of industrial areas which
contain minimal debris environment.
8. Design considerations
8.1. Health and Safety
With the final state of the completed prototype there is much to be considered for the
environment that its full-scale counterpart is designed to endure (water, heat, and hazardous
chemicals). This does not mean the concept did not take these into consideration, but were not
implemented for cost and time reasons. The main health and safety concerns with this robot
brake down into two categories, the platform and the operator.
For the operators the main concerns involve the maintenance also the hazards and
contaminants that come with the robot has completed its objectives. The robot as designed is
believed to make to allow for relatively easy maintenance for the battery, tread, and for most
components that have possibilities for breaking down. However, many of the operations would
require many tools and the assistance of at least one other individual, adding to that the final
design considers a robot that weighs close to 90 kg (200lb). It is important that further research
can go into this aspect of the design as to make it more accessible to smaller hazmat crews the
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ones who may find the most utility of this robot. With the prototype design some of these
features were implemented for our use and to improve the testing operations, including the tread
and batteries. The biological hazards were not considered with the prototype design this was a
decision made due to the lack of ability to test these parameters and the dangers that could come
along with it. However it is a concern that has been considered, the use of materials that are
resistive to hazardous chemicals or materials with high decontamination properties in order to
avoid the spread to the operator when in contact with the unit. Furthermore the design also shows
the use of compartmentalizing key components with specialized filters to avoid internal
contamination.
For the prototype it does emote a fair amount of safety features that were desired for the
full-scale design. These features include a strong build quality which can handle large loads and
emergency electrical fuses and switches this can be seen the figure 64. The fuses allow for the
maximum amperage to be limited in the event that an excess of current is being drawn. The fuse
will pop and disconnect itself from the circuit avoiding any harm to the motors and the speed
controllers. As well the batteries that were selected for this prototype design are fire retardant
AGM led acid batteries the safest and most efficient of the led acid batteries. Although these do
serve as important safety functions others such as waterproofing, thermal resistance, as well as
making it to hazardous chemicals, which could fatigue or damage key structural components.
Some of these features as stated were not implemented into the prototype design in order to
reduce cost and manufacturing time.
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Figure 64: Left Fuse that has been popped, Right Fuse in good condition [41]
The obvious safety concerns with having this as an emergency tool for HAZMAT
firefighters is the many conditions that this system can be placed in. It is not unreasonable to
assume a situation where this unit is in a scene where it can be raining heavily. The design would
require a waterproof seal in order to prove useful in all scenarios of a HAZMAT firefighter. This
quality was considered similarly to the resisting contaminates to the robot with isolating the key
components to the outside environment. This system allows the units to avoid any contact with
any harmful material effecting the operations of the internal components.
Thermal resistance for robot is an objective that did not take much concern however
could definitely improve the usability of the robot. At the current time the robot can handle a
limited thermal range based on the environments where testing occurred; however was not tested
to work in a condition similar to one in a burning building or frigid environment. Although, it is
reasonable to suspect that our current prototype could handle large amounts of heat from the
choices of aluminum panels and tread built from timing belts only limited really to the plastic
components and the cooling of the electrical components.
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8.2. Assembly and Disassembly
As discussed before in the previous sections the assembly and disassembly is a major
concern with the prototype and the final full-scale design. As for the design aircraft frames
inspired the design of the chasse where the exterior contains the shell and the supporting
structure for the system. This allows for minimum material to be needed and allows for a strong
rigid frame. For the Assembly process of our design is quite simple with 4 major panels with
branch together with a few interlocking panels. Do the limit of our time to design and
manufacture the robot most of the sections connect through the use of 10-32 screws instead of
mechanisms that do not require the use of a tool. It is ideal that the assembly as well as the
disassembly of the robot could be built in this manor for ease of maintenance as mentioned.
For disassembly of the robot the following procedure displays the steps required to obtain
accesses to sprockets and tread.
Figure 65: Illustration of removal of side panel for tread maintenance
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As seen in the figure above the process of getting access to the inner components are
simple. By first unpensioning the tensioner at the yellow circle and by removing the screws in
red the side panel can be removed. Once the panel is removed access to the tread, sprockets and
suspension. This is seen from the figure 66 where the tread has already been removed and other
internal components can be seen.
Figure 66: result of removing side panel and tread system
As seen minimal effort is needed with prototype design, which was intended to allow for
our different testing needs. The full size version of the design however would not be as straight
forward with the implementation of waterproofing. All though implementation of simple/tool
less would be greatly utilized, some examples of these systems are wing nuts, secure latches, and
cotter pins as seen in the figures.
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Figure 67: Wing Nut [42]
Figure 68: Latch [43]
Figure 69: Hairpin Cotter Pin [44]
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8.3. Manufacturability
The robot was designed have a generally simple design. The prototype was constructed
using some basic manufacturing techniques, as well as some more complex. For manufacturing
the processes of water jetting, knee mill, lathe and a CNC for the more complex work. Overall
the design does have a high manufacturability with the proper machinist. To help with the
manufacturability the design also does not call for a low tolerance that can be seen within the
engineering drawings.
8.4. Maintenance of the System
Regular Maintenance
Do to the fact that this device would be in place with an emergency unit of the firefighter
division proper maintenance serves an important protocol to ensure functionality in a hazardous
environment. The general systems that would require regular maintenance in day-to-day
operations would be the batteries, treads, and communications systems. The batteries due to the
large capacity will more than likely be replaced rather than being charged for reduced down
time. As well, depending on different battery technology used in the system may need inspection
after a given amount of cycles. For the prototype design the batteries used are Absorbent Glass
Mat Sealed led acid, which degrades close to 20% of its maximum capacity in a six-month
period seen in figure 70, an extremely important aspect that will affect its usability. The tread
system is another system that can see regular maintenance, this one depends more on the use
case of the system depending tasks that are being asked to perform. Similarly to tiers on a care
the treads of the robot are designed for a limited amount of uses before they begin to ware out.
The final regular maintenance would be under the communication systems this is important
process in order to ensure communications do not fail or effect the task assigned to the robot.
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Figure 70: Shelf life of Selected Battery Power Sonic PSH-1280 [25]
Major Maintenance
As for major maintenance of the system there is only two sources that could be
considered major maintenance which are motor and structural failure. These are both
possibilities that are very detrimental to the system. In these cases the system will be under
severe down time and not usable. In this highly unlikely case the robot would require a complete
tear down in order to obtain access to the effected components. In the case of the motors besides
the replacement of the motor, diagnostics are also required to determine the root cause of the
issue in order to take the appreciate actions. In the other case scenarios with structural damage is
taken on the system more steps will have to be taken do to the range of possibilities that can take
this definition. This kind of maintenance requires a close inspection of the effected components.
Following this inspection the process of remanufacturing certain panels and the replacement of
components damaged.
8.5. Risk Assessment
Do to the nature of the tasks of the Robotic system that is being designed there are many
risk factors that need to be taken into account. Not only do these risks apply to the robot itself but
in extension any person coming into contact with it after performing a HAZMAT task.
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Depending on the situation at hand the risks can be moderate to severe exposer to different
contaminants. It is important that Further research can go into the design of the material that will
be in direct contact with the contaminants in order to prevent expositor outside of a given hazmat
sight.
Aside from threat of unwanted contamination being unknowing transported with the
robot, there are risks specific to the robot in the environment. From questioning HAZMAT
fighter fighters “You can never be certain of the situation you are entering”, it is important to
expect the unexpected. The conditions for the robot can very and without extensive testing with
different materials and contaminants the reaction between the two is unknown. Certain measures
can be accounted for, in the case for flammable gas where only a spark is needed to ignite a
flame all electrical components need to be isolated and protected. The terms used for these kinds
of devices are intrinsically safe. Without the validation of testing it should be labeled as a risk for
all participants.
9. Design Experience
9.1. Overview
The following section will discuss several areas of the design. The areas of the design will
involve: standards being used, Contemporary Issues, Impact of Design in a Global and Societal
Context, Professional and Ethical Responsibility, Life-Long Learning Experience, and
Discussion. Some the standards being used are building codes, OSHA standards which will
incorporate various chemical preventative codes, and health safety regulations. The robot will be
able to function locally and globally which will require different maintenance ability depending
on the country. A contemporary issue which may be relevant to designing a robot is how the
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robot is being used however the current application the robot will not be used in defense. The
Impact of the design in a Global and Societal Context may be considered to be an instrument
used to aid in the fire departments or other associated department in order to facilitate the data
gathering by involving the SI units and meeting relatable installation requirements. The Robot
would need to meet and abide by all professional and ethical responsibilities. Through the design
of the robot experiences with team work collaboration and time management have been gained
and can be applied to future projects.
9.2. Standards used on the project
Codes followed by OSHA standards, international building codes, and Department of
Transportation codes. Chemical safety codes from GSA or (General Services Administration)
agency. The following codes that need to be followed are shown below:
DOT - Department of Transportation; Hazardous Materials Regulations 49 CFR 100-180;
Occupational Safety & Health Administration (OSHA) in 29 CFR 1910.1200
GSA in FED-STD-313;
Other codes are mentioned earlier in the report are shown in section 1.4 of the report.
The first code 49 CFR 100-180 mentioned classifies Occupational safety & Health protocols and
Procedures. The code 29 CFR 1910.1200 involves Hazard communication and to guarantee the
labeling and classifications of chemicals and storage. The last standard being discussed is FED-
STD-313. This code is the Material safety Data, Transportation Data, and Disposal Data, for
hazardous materials [45]
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9.3. The contemporary issues
Contemporary which may arise from the construction of the hazmat robot would be the
concern of a robot to completely replace a human hazmat personnel when in a hazmat situation
arises. This issue has been very prominent in media and there much controversy to which
limitations and constraints need to be put in place. However for this construction and build our
intentions are clear that the robot will be solely used as an instrument for the hazmat personal to
facilitate data gathering and enter areas which are not suitable for the fire department personnel.
Do to the unpredictability of the scene it would be of greater benefit to allow for user control to
operate in the scene. Another reason would be lack of decontamination which would be used for
certain environmental scenarios. Some important aspects to consider from Robots taking the
place of humans would be from an economic and political stand point. When discussing the issue
of the economic stand point with the use of automation researchers have not seen the product
increase which would go against the intuition. The reason for this is due to the fact that since the
employees are the driving force behind production through purchasing power. The increase in
automation will decrease the amount of personal holding jobs and will ultimately decrease the
amount of supply by the companies. From a political stand point this issue the new policies
would need to reflect how the robotic inventions are utilized and determine how much of an
influence this should make on society including schools and other municipal agencies. [46]
Another Contemporary issue which may arise may be controversy when the robot is being
utilized for defense purposes. Do to the modularity of the robot, the robot would be very feasible
to attach weapons or reconnaissance equipment to the platform. The objective of the robot
however is to only be used in public health and safety and should not be used for the purposes of
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defense or warfare. All requirements of the robot are for the Hazmat Robot are to meet the
Hazmat branch of the fire department and are to meet there needs. [47]
9.4. The Impact of the design in a global and societal context
The Impact of the design in a global society would impact various countries in a positive way
and provide additional safety measures for the fire department and other related departments
involved and acting on the hazmat scenarios. One way of facilitating the various countries would
be by following the international building codes. Another way would be to convert and use both
units which can be utilized in the manufacture of the robot for manufacturing purposes. In
different areas of the world different countries may be limited by manufacturing methods and
practices. The maintained will be universal in the protocol and all tools necessary for assembly
and disassembly will be included. [47]
9.5. Professional and Ethical Responsibility
The following ASME (American society of mechanical engineers) code of ethics of
engineers and the National Society of Professional Engineers Code of Ethics for Engineers will
be used to illustrate the ethical responsibilities of the Hazmat Robot. In regards to the robot some
of the ethical responsibilities will be to ensure the welfare and public health are takin paramount
and held in the highest regard. This responsibilities is explained as the first fundamental principal
of the code of ethics of engineers. Another responsibility of the engineer is to consider the
environment. By considering the environment one can ensure the safety of the land and animals
associated are not harmed. In the case of the robot the robot is powered using electricity and seal
lead acid batteries as power source which will be exposed of using environmentally safe protocol
and the metal and rubber will be able to be renewable assuming there is no contamination from
the hazmat scene. [48] If the robot is contaminated then the material must be decontaminated
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using a third party company with the resources to decontaminate panels and various components
.From NSPE (National Society of Professional Engineers) we will not falsify or permit
misrepresentation of the project and robot. The Robot will abide by the functions and regulations
set forth by the fire department. [49]
9.6. Life-Long Learning Experience
Experiences gained from the project include manufacturing practices, design
management, and logistic and communication skills. Manufacturing practices gained through the
project are water jetting application and cost which would be associated with the size of the
design. Additionally another aspect of water jetting would be whether to purchase the material
through a third party or directly through the water jetting company. By comparing the cost of
CNC (Computer numerical Controlled) manufacturing too water jetting the cost will show that
for 2 dimensional cutting water jetting would be a lower cost than to CNC the part. Along with
the cost to outsource manufacturing another factor of manufacturing would be fitment of the
parts. Through the experience the team has learned tolerance and fitment practice for aluminum
and steel. Another very important component of the design was compatibility of components
relative to other components. For example if the motor shaft was in millimeters the gear being
put on the shaft needed to be in SI units and this convection would have to be consistent for the
chain riding on the gears. Logistics was important in organizing the shipping and lead time for
the completion of the parts and other miscellaneous components. One logistical dilemma was
when the team was looking for the chain in a number 25 tabs and there was no available vendor
to which the manufacturing needed to be adjusted to accommodate the bigger size tab links. In
order to meet the deadlines, the electrical components where purchased before hand and while
the project was awaiting one part the team was working on another component of the project.
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Finally Communication was a vital and learned experience throughout the project.
Communication was necessary in developing solutions and led to meeting deadlines and
exploring each other’s strengths and weakness as to build from that and work to complete the
project.
9.7. Discussion
The following aforementioned sections discussed the overall importance and impact the
design has made upon the team. The robot when utilized in the application of hazmat
reconnaissance will serve to facilitate the personal in data gathering and will be able to relay the
information to the personal. The team has gained significant growth of communication and
related engineering disciplines such as additional manufacturing practices which could be further
utilized for future projects and applications to come.
10. Conclusion
10.1. Conclusion and Discussion
The current prototype has many inefficiencies, however, that does not bar the platform
from continued research and testing, which will improve the overall concept. The apparatus did
not successfully climb the stairs without modification to the raw concept. At first, we were under
the impression that the toppling action could be prevented by applying counter weight to the
front of the chassis. To test this theory, we constructed a frame of L-Bracket steel and mounted it
to the top of the apparatus. We then marked 1-inch increments on the frame so that the position
of the weight would be known. The goal of the experimentation with the frame and counter
weight, was to determine the required torque about the geometric center, which would enable the
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apparatus to climb the stairs. When it finally did climb up the stairs, it was very laborious and
progress was slow. Furthermore, the additional bracket and counter weight required for climbing
made descending the stairs a precarious task and once again, the apparatus would attempt to
summersault down the stairs. After researching stair-climbing apparatus further, it was noted that
what all similar platforms have in common is the ability to always touch at least two steps for
any single instant in time.
The apparatus does bridge the gap between two steps but while it drives over the nosing
of the steps, there is an instant in time just before it reaches the third step where the apparatus
loses contact with the initial step. The result is that the robot then teeters on the nose of one step,
which shifts its balance to the rear. Now as the robot continues to drive forward with its balance
shifted to the rear, the reaction is that it climbs nearly vertically on the third step and begins to
roll backward on its self.
After recoding this behavior numerous times and slowing down the footage for analysis,
coupled with the knowledge of other similar concepts, it is clear that this current design needs an
increase in the length of the contact area . The current length is 7.5” while the distance along the
hypotenuse of 3 steps is 8.75”. If the rear arm is extended sufficiently such that the contact
length is stretched to 9”, the robot will climb without hesitations and slippage will be minimal if
at all. In addition to the inadequacies of some of the design parameters, some of the components
were manufactured using less than desirable methods. In the case of the suspension arms, either
CNC or water-jet pieces where to be cut and then assembled and welded together. This would
have resulted in strong symmetric components. Such components would have reduced any
deviations of fitment between the halves of the apparatus. Secondly, such components also allow
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for an appropriate knowledge of the spacing requirements prior to their construction. The
necessity for foresight when working with such components cannot be overstated.
These inefficient mechanisms include the suspension, rotating assembly component
selection, and the addition of improved locks and retainers for the rotating assemblies. These
inefficiencies were present due to sizing constraints and the resulting limited availability of
components for the size bracket applied to this concept. If this prototype had been built to at least
50% the size of the real apparatus, a more broad selection of components would have been
available for use. It is also important to note that the budget was a great limitation. In one
instance, one option was selected over the other because it would chop the price in half. Over
time, the less expensive components proved themselves to be of such low quality that it added
difficulty to certain procedures and they eventually broke down.
Despite the difficulties encountered with some of the components and features of the
design, there is still much promise in the concept. The main goal of this scaled construction is to
prove that an apparatus of the size and proportions required for the HAZMAT application would
be able to perform the maneuvers on various surfaces and climb stairs. Although stairclimbing
requires further research, the data acquired, empirical or otherwise, suggests that with proper
modification, the existing prototype will be able to climb stairs. Additionally, climbing stairs is
not the only maneuvering challenge present when operating in a HAZMAT environment. Being
able to transition across different surfaces, perform maneuvers on uneven terrain, and maintain
traction on slick surfaces, are equally important to the task.
The testing conducted with this platform included driving in dense vegetation, rock and
rubble, dirt and mud, concrete (damp/mossy), and most importantly, driving across from one
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zone to another. Transitional driving is important because it demonstrates the ability of the
platform or vehicle to maintain control even though the coefficients of friction on one point of
contact may vary from the other. This condition may be present when driving from the outside of
the active HAZMAT scene to the “Hot Zone” where the contaminants are, and may affect the
traction of the apparatus. This platform performed excellently in these challenges and was
virtually unimpeded by the change in terrain. The torque provided by the motors allowed the
apparatus to drive without being slowed and this makes for a more manageable driving condition
for the operator.
Another important design consideration is that of towing and plowing. From the
researcher’s point of view, it is difficult to state how crucial the ability to move other objects is
to the overall goal of maneuvering in a HAZMAT environment. While interviewing real
HAZMAT Firefighters from the City of Hialeah Fire Department, they were asked how
necessary it would be to know the “towing capacity” of such an apparatus if they had one for
their department. The response was that “it would be a benefit”. The firefighters went on to
describe the difficulty posed to them if they discover an injured civilian which cannot leave the
scene on their own or if one of their Firefighters is compromised and needs to be evacuated
quickly. Such an apparatus would be able to tow a “down” individual using a modified rescue
sled and evacuate them to safety. Additionally, other obstructions may be present which might
impede the progress of the apparatus into the scene, essentially rendering it useless to the
purpose for which it was created: to survey the scene and assist thereafter. The ability to tow and
push other objects out of the path, also allows the apparatus to be used for clearing the path to the
target of the scene so that the human counterparts can reach it with minimal resistance. This
apparatus performed outstandingly in the push and pull testing. In a “worst case” test, the scaled
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apparatus, weighing 47lbs, towed a maximum of 60lbs while driving on a slick concrete surface.
That means that even when traction is compromised, the platform can pull 1.27 times its own
weight.
The platform performed outstandingly in maneuvering, transitioning, towing, and with
slight modifications, will be able to climb stairs as intended. Thus, this design is promising and
further research and development will yield an even better apparatus.
10.2. Evaluation of Integrated Global Design Aspects
From the outset of this project it was understood that a full sized, fully developed,
apparatus could be used around the globe for HAZMAT scenes and environmental cleanup
operations. As more and more countries around the world continue to develop and become more
sophisticated, their reliance on plastics and inorganic materials will increase. As such demand
grows, the likelihood of spillage or mismanagement of such materials will also grow and
necessitate the institution of HAZMAT-Fire Service or other similar organizations. Whatever the
chosen method is, any team which will be dealing with dangerous chemicals and scenes could
benefit from the use of such an apparatus.
This leads to the conclusion that if such an apparatus could be used around the world, it
would be appropriate and even necessary in some cases, to have an alternate version which
utilizes the metric system for all of its geometry and component selection. These components
should have been made using metric units in their prints and design. The purpose for having
components which were already made with these considerations is to make maintenance and
repair of the apparatus much easier in those countries which do not use the English system and in
which procurement of such components, which utilize the English system, will be difficult.
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Another crucial aspect of the overall design is the selection of a power source. Once
again, this component should be of a type which is readily available around the world and is easy
to service. The optimal choice for this component is Sealed Lead Acid. These batteries are made
of solid cells inside of a layered matrix which is then enclosed by the plastic shroud which makes
up the exterior of the battery. This type of battery is very common and is available in a broad
variety of shapes and sizes which makes it an excellent choice for this apparatus. Additionally,
this type of battery is the least expensive when compared to other batteries which utilize more
charge-dense materials. Examples of batteries which would be desirable but would raise the price
of the apparatus substantially include Lithium Polymer (LiPoly), Nickle Cadmium (NiCd) and
Iron Phosphate (FePO4). In the case of the scaled prototype which was built for this project, it
utilizes SLAs with dimensions which are common to most backup battery-surge protectors.
Furthermore, this battery requires no maintenance and only requires the proper charging and
discharging in order to exact the maximum life of the part. Sealed Lead Acid is a great choice for
this application because it uses a sealed construction which leaves only the terminal leads
exposed. These leads can easily be covered and sealed from the environment by using the proper
equipment on the circuit and ensuring that the wires are completely insulated and shielded.
The previous considerations are ample enough that the apparatus is usable by any
Rescue/HAZMAT personnel from any country around the world.
10.3. Evaluation of Intangible Experiences
Throughout the course of this project there were many defining moments which give an
“added value” to the experience thereof. Lobbying for sponsorship support, adaptation of designs
to meet manufacturing methods and flexible design are a few keynotes which made this project
experience unique and fulfilling for the team.
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An integral part of this project which has increased the experience of the team was the
interactions with real world vendors. Many companies were approached for possible sponsorship
of the project. No approaches were made for funding but request was always made from the
position that the donation of components or services would be preferred to financial help. The
companies approached include, Tesla, NPC, Horizon, and Ballard. Tesla was approached for the
possibility of help with regards to the power supply. Either advice for the selection of a power
source or assistance in implementing a circuit which could improve such a power source would
have been helpful. Tesla declined.
National Power Chair (NPC) was approached with the hopes that they might donate the
motors required for the Full-Scale apparatus. Each motor costs approximately $360 and with a
total of 4 on board the apparatus, that represents a sizeable investment; large enough for a sticker
to be placed on the Robot. NPC said they would consider it and sent a sponsorship application
which was filled out and returned. Subsequently, they never responded.
Horizon and Ballard were both approached. Both companies are in the business of
making Hydrogen-Cell Power Supplies. Because the initial goal was to create the full scale
apparatus which had considerable power needs, these companies were solicited with the aim of
using their power supplies for the robot. Based on the four drive motors alone, a maximum draw
scenario could require up to 650 amperes, 162 amperes per motor. Although that number
represents a peak current scenario, the power requirement is still substantial for a 24 volt circuit.
Ballard declined immediately because their units were reportedly too large for use in our
apparatus. Horizon, on the other hand, seemed very keen to the idea but after communicating
over the course of a month, they determined that their units could not be used for this project
because they were unsure if it would work.
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After so many failed attempts of gaining sponsors and after so much time lost, we
resolved to build a scaled prototype and we would now utilize our own funds. From this
experience one truth emerged and the lesson learned is that when you are launching a concept,
potential sponsors will not always view the project in the same light as you, the designer, will.
Despite the difficulty that sponsorship can pose, it is still up to the team to press forward and
continue to try. In our case we decided to back the project ourselves.
Another Valuable lesson learned is that when events outside of your control begin to
affect the project, do not abandon the concept. Instead, seek out other methods for accomplishing
the objectives. Out team experienced such an occurrence with the manufacture of the suspension
components. We had planned to make the suspension arms from flat bar aluminum which could
be either CNC or Water-Jet into the required shape. After waiting two weeks for four different
vendors to return a quote and possibly execute the job, we contacted all of them and none of the
four had even glanced at the prints. Being short for time and requiring the suspension
components that week in order to commence testing, we resolved to use rectangular aluminum
tubing and fabricate the desired shape from various lengths. Within two days, we had fabricated
the necessary components and moved on to fitment of the track.
A very important facet of our experience gained from this project was the realization of
how important it is to make a design modular, especially if it is the first prototype. Our design
had the ability to be adjusted fairly easily. This feature was particularly useful when it came time
to run the robot on the stairs. Because most of the components could be repositioned or locked
by placing a screw, it was very easy to reconfigure the suspension and attempt to climb the stairs
again and again. In addition, most of the springs had similar dimensions, or there was only a
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maximum size which must be considered. This gave us the ability to swap any spring to any
position on the suspension system.
Although many aspects of the project went well, it can be said that there was oversight
with regards to the suspension overall. The system required analysis from different points of
reference and the use of more methods than were applied. For instance, the springs were
determined based on static and dynamic calculations. While the springs did behave in the manner
predicted by the calculations, there was one consideration which was overlooked: the track and
sprockets behave in a manner that more closely simulates a cable and pulley system. Because it
was not framed in this manner, we did not realize that the strength of the motors would pull the
tread to the point that it bottomed-out the suspension. Had the suspension been considered in this
manner, we would have realized that there would need to be additional sprockets to isolate the
drive sprocket from the rest of the system and thereby prevent the direct transfer of force to the
suspension components. To overcome this difficulty, we instead limited the travel of the
suspension arms since they are responsible for the large travel of the suspension. By leaving the
smaller appendages (the feet) free, the apparatus still had some suspension travel.
The most important wisdom gained from this experience is that some processes are long
and require repeated testing and repeated failure in order to achieve success in the future. The
process of design was rigorous though we discovered that it still needs further work and study.
The manufacturing process was laborious but after completing the first prototype it is apparent
where the deficiencies are and solutions are attainable. With all things considered, perseverance
is key.
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10.4. Commercialization Prospects of the Product
In the real world, the difference between ideas that are built and the ideas that are
scrapped is often a combination of market assessment and development cost versus selling price.
In the case of this project, there is a relatively large market for robotic reconnaissance devices.
The key for our project is that it targets a very precise niche in the market. There are a few
platforms on the market which claim to be useable for HAZMAT scenarios but these are all a
retrofit. They were not purpose built for the HAZMAT environment.
Of the apparatuses which are purpose built and have been completed, price is the limiting
factor. The target market does not want to pay $200,000 dollars or more per apparatus. [50] This
is one of the strengths of the apparatus which we have designed; it reduces overall costs on the
initial and production side. Many of the existing apparatus use exotic materials such as titanium
and carbon-fiber while the HRU design utilizes 6061 aluminum and stainless steel. While other
platforms employ special, in-house sensory, the full-scale of our apparatus would allow the
HAZMAT teams to equip and unequip their existing sensors to the apparatus. Furthermore, the
design we have created has virtually zero dangling or extending appendages which may cause
entanglement on the scene. The result is a platform with smooth, easy to clean surfaces that is
robust yet maneuverable, which is what is needed for this field.
There are a few negatives to the design, however, further research is needed to determine
the feasibility of the overall concept. One such attribute is that the suspension needs to be
analyzed and redesigned to perform the full function of climbing as intended. Additionally,
further research into material treatments and coatings must be conducted in order to select the
proper treatment for aluminum and steel in order to prevent contamination, reactivity and
corrosion of the apparatus as it enters a volatile environment.
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Another positive of the design is that once it does reach a developed and marketable state,
the base is an excellent candidate for performing a myriad of other tasks. These alternate roles
include military, law enforcement, large-scale leak or cleanup assistance, mining reconnaissance,
and exploration. Because of the strenuous demands placed on an apparatus by the HAZMAT
environment/problem, it stands to reason that a platform which can function in such a harsh
environment could be retrofitted and used in less demanding environments with even greater
reliability.
10.5. Future Work
As this project draws to a close, it is understood that this was a first attempt to create a
platform which addresses the mobility requirements for entering the HAZMAT environment.
These criteria include the following; perform maneuvers in various terrain, perform maneuvers
on reduced traction surfaces, and to climb stairs with ease. Although not all of these objectives
were accomplished, achievement of these goals and overall improvements to the system are
within reach, even for this prototype. Apart from the mobility aspects, there was a lot of
information gathered about existing technology which may be applied to the full-scale apparatus
and improve its alternate functions.
The most crucial feature, and often a limiting factor for any apparatus, is the power
supply. Scientists and engineers continue to develop new machines and apply technology in
ways never conceived before yet they remain tethered to the laboratory. It is quite evident that
what is needed for the ultimate success and implementation of this and other apparatuses, is a
major breakthrough in power-generation. There are apparatuses that boast relatively high runtime
and standby time but these numbers do not represent actual work in the designated field. In order
for robotics to grow and be applied in their fields, more power is necessary. Some possible
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methods include enhancing circuits so that current draw is regulated, and improving alternative
energy methods by making them more applicable to mobile platforms.
Another aspect of our apparatus which still requires research is the suspension. The
design of this apparatus was approached with the end-goal in mind and this severely limited the
amount of time spent researching the suspension. There are many robotics platforms which
employ tank treads but there is an even greater variety of stairclimbing apparatuses. Among
these, the suspension is often the defining characteristic. Some mechanisms use a type of
“walking” action while others use tank tread and moveable pivot points. This apparatus does not
utilize any appendages nor does it have any independently controlled links within the suspension.
After conducting the testing of the scaled prototype, it became apparent that some type of
independent control would greatly enhance the performance of the drive system. In the case of
the target field for our apparatus however, a simpler system is a better system. Fewer moving
parts translates into fewer crevices where contaminants may cling and fewer possible points of
failure. For those reasons, this apparatus must be designed such that it will climb stairs without
difficulty and without the addition of any cumbersome appendages or addition moving parts.
In order to properly design such a suspension system, a proper kinematic and phase study
must be conducted. This means analyzing the motion of the suspension as a reaction to the
overall movement of the system. The tread system will be considered as a cable and the
sprockets, as pulleys. The points of contact between the steps and the tread will then behave as
pressure points, which alter the tension in the belt up to that point. Apart from changing the
method of analysis prior to the redesign of this vital component, the different scenarios, which
may occur while climbing, will also be brought into consideration.
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A lot of time and effort was spent researching the equipment, which may be needed for
such an apparatus to function in the HAZMAT environment yet none of this information was
applied to this prototype because it was beyond the scope of this project. In the future, even more
research must be conducted with regards to door-opening devices and methods, and forced entry
methods. Only then will we be able to create an arm, which has the right tools for forced, and
non-forced entry. These components should be rested separate of the apparatus and then applied
to the apparatus to test for drivability and end-user functionality.
Lastly, the treads will also need special research and testing in order to ensure that this
component will survive the punishment of a heavy load and exposure to corrosives and other
concentrated chemicals. After material testing confirms the best candidates for coating the
exterior of the tread, further research must be conducted to determine whether or not these
materials can be used to coat a metallic sub structure. This same manufacturing technique is used
in construction equipment and snowmobiles. The result is a rigid structure for bearing the loads
and connecting to the drive sprockets and cogs that still has the grip and flexibility on the
exterior, which is pivotal to the tasks of maneuvering and stair climbing. Overall, there is still
much work needed in order to complete this apparatus but all technology already exists and is
only being reapplied to this unique field.
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11. References
[1] U. Auckland, "Robotics History Timeline," 2015. [Online]. Available:
http://robotics.ece.auckland.ac.nz/index.php?option=com_content&view=article&id=31:rob
otics-history-timeline&catid=8:fun-robotics-stuff&Itemid=43. [Accessed 23 11 2015].
[2] "Tactical Robots," 1990. [Online]. Available: http://www.sdrtactical.com/About.aspx.
[3] "Qinetiq North America," 2001. [Online]. Available: https://www.qinetiq-
na.com/company/history/.
[4] "BOZ ROBOTICS," 2006-2015. [Online]. Available:
http://www.bozrobot.com/BOZ_XL.html.
[5] D. V. Welch, "APPLYING ROBOTICS TO HAZMAT," Pasadena, 1990.
[6] "Wikepedia," 28 November 2011. [Online]. Available:
http://en.wikibooks.org/wiki/Robotics/Components/Power_Sources.
[7] R. J. Linster.United States of America Patent US4973028A, 1989.
[8] P. J. Owsen.United States of America Patent US4671774A, 1985.
[9] "ASME," 2015. [Online]. Available: https://www.asme.org/about-asme/standards.
[Accessed 23 11 2015].
[10] "ISO," 2015. [Online]. Available: http://www.iso.org/iso/home/store/catalogue_ics.htm.
[Accessed 23 11 2015].
[11] "Energy," 2015. [Online]. Available: http://energy.gov/ehss/services/nuclear-
safety/department-energy-technical-standards-program/doe-technical-standard. [Accessed
23 11 2015].
[12] "ASTM," 2015. [Online]. Available:
http://compass.astm.org/CUSTOMERS/search/search.html?query=astm&dltype=allstd&bos
section=03. [Accessed 23 11 2015].
[13] "UNITED STATES DEPARTMENT OF LABOR," 26 3 2012. [Online]. Available:
https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id
=10651. [Accessed 23 11 2015].
[14] I. B. CODE, "INTERNATIONAL BUILDING CODE," CHAPTER 10 MEANS OF
DEGREES SECTION 1008.1.1 IBC INTERPRETATION NO. 05-05, pp. 1-2, 2003.
125
[15] "Matweb," 5 aril 1996-2015. [Online]. Available: www.matweb.com.
[16] B. William, Interviewee, Hazmat Firefighting Conditions. [Interview]. 2015.
[17] "Miami Dade County," 2015. [Online]. Available: http://www.miamidade.gov/fire/about.a.
[Accessed 23 11 2015].
[18] "McMaster-Carr," McMaster-Carr, 2015. [Online]. Available: http://mcmaster.com.
[Accessed 23 11 2015].
[19] D. W., G. Soloway and B. Duffin, "Comparative Machinability of Brasses," Steels and
Aluminum Alloys, pp. 1-10.
[20] 19 11 2015. [Online]. Available: http://www.infomine.com/investment/metal-prices.
[21] "Midwest Motion Products," 2015. [Online].
[22] "Robot MarketPlace," Robot MarketPlace, 2015. [Online]. Available:
http://www.robotmarketplace.com/products/0-E30-400.html. [Accessed 23 11 2015].
[23] "12 Volt Battery Information & Resources," 12voltbattery, 2015. [Online]. Available:
http://www.12voltbattery.info/index.php?page=batteries_parallel_vs_series. [Accessed 23
11 2015].
[24] "atbatt.com," Atbatt, 2014. [Online]. Available: http://www.atbatt.com/power-sonic-12v-
8ah-sealed-lead-acid-battery-with-f2-terminal-fire-
retardant.asp?gclid=CJHym7aBoskCFUMXHwodk-8Oiw. [Accessed 23 11 2015].
[25] "Power Sonic," 2013. [Online]. Available: http://www.power-
sonic.com/images/powersonic/sla_batteries/psh_series/PSH-1280FR.pdf. [Accessed 23 11
2015].
[26] "Simon Fraser University," Simon Fraser University, 3 7 2015. [Online]. Available:
http://www.lib.sfu.ca/borrow/borrow-materials/laptops-equipment/arduino-mega-2560.
[Accessed 23 11 2015].
[27] Wiki, 20 10 2015. [Online]. Available:
https://wiki.openwrt.org/toh/raspberry_pi_foundation/raspberry_pi. [Accessed 23 11 2015].
[28] "Vex Robotics," Vex Robotics, 2015. [Online]. Available:
http://www.vexrobotics.com/news/2010/09/vex-robotics-upgrade-incentive-programs-
announced/. [Accessed 23 11 2015].
[29] "vex robotics," 2014. [Online]. Available:
http://content.vexrobotics.com/vexpro/pdf/Victor-SP-Talon-SRX-Info-Sheet-20140819.pdf.
[Accessed 23 11 2015].
126
[30] "recursos-tecnologicos," recursos-tecnologicos, 2015. [Online]. Available:
http://www.recursos-tecnologicos.com/mercado/camara%20dlink%20931l/. [Accessed 23
11 2015].
[31] M. Brain, "How Electronic Gates Work," HowStuffworks, 1 4 2000. [Online]. Available:
http://electronics.howstuffworks.com/digital-electronics4.htm. [Accessed 23 11 2015].
[32] Fadel VMC 6030 CNC VERTICAL MACHINING CENTER, Gaec, 2015.
[33] "antiqueradios," antiqueradios, 2015. [Online]. Available:
http://www.antiqueradios.com/forums/viewtopic.php?f=2&t=267964. [Accessed 23 11
2015].
[34] "Curious Inventor," 21 11 2015. [Online]. Available:
http://store.curiousinventor.com/guides/drill_speed.
[35] "Gallery Hip," 21 11 2015. [Online]. Available: http://galleryhip.com/vertical-metal-
cutting-band-saw.html.
[36] "Baileigh," 21 11 2015. [Online]. Available: http://www.baileigh.com/band-saw-bs-
916m?utm_source=bing&utm_medium=cpc&utm_campaign=Bing_Shopping&utm_term=
{Keyword}.
[37] "Tool Box," 25 11 2013. [Online]. Available: http://www.tlbox.com/power-hand-tools/5-
best-bench-grinders-not-only-durable/.
[38] G. Elert, "THE PHYSICS HYPERTEXTBOOK," 2015. [Online]. [Accessed 22 11 2015].
[39] "The Engineering Toolbox," 2015. [Online]. [Accessed 22 11 2015].
[40] E. A. B. J. A. H. R. K. Raymond C. Browning, "Effects of obesity and sex on the energetic
cost and prefferred speed of walking," Journal of Applied Physiology, pp. 390-398, 2006.
[41] "m3forum," 2015. [Online]. Available:
http://www.m3forum.net/m3forum/archive/index.php/t-398646.html. [Accessed 23 11
2015].
[42] "gtc-direct," gtc-direct, 2015. [Online]. Available: http://www.gtc-
direct.com/products/productImages/64.gif. [Accessed 23 11 2015].
[43] directindustry, 2015. [Online]. Available: http://www.directindustry.com/prod/bene-
inox/product-8514-963239.html. [Accessed 23 11 2015].
[44] "Amazon," Amazon, 2015. [Online]. Available: http://www.amazon.com/MK-MK-16-
Hairpin-Cotter-Hitch-Pins/dp/B002GPJRP6. [Accessed 23 11 2015].
127
[45] "Electronic Code of Federal Regulations," 19 November 2015. [Online]. [Accessed 21
November 2015].
[46] C. Hollander, "Are Robots About to Take Our Jobs?," National Journal, p. 2, 2014.
[47] J. Kaplan, "Robot Weapons: What's the Harm?," The New York Times, p. 2, 2015.
[48] "CODE OF ETHICS OF ENGINEERS," ETHICS, p. 1, 9 10 2007.
[49] N. S. o. P. Engineers, "Code of Ethics for Engineers," Code of Ethics for Engineers, p. 2,
July 2007.
[50] G. Helen, "Where humans fear to tread:," pp. 1-4, 2 1998.
[51] U. o. Auckland, "Robotics History Timeline," 2015. [Online]. Available:
http://robotics.ece.auckland.ac.nz/index.php?option=com_content&view=article&id=31:rob
otics-history-timeline&catid=8:fun-robotics-stuff&Itemid=43.
[52] miamidaede.gov, "miamidade.gov," 8 aril 2015. [Online]. Available:
http://www.miamidade.gov/fire/about.asp.
128
Appendices
A. Detailed Engineering Drawings of All Parts, Subsystems and Assemblies
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
B. Multilingual User’s Manuals in English, Spanish and French
English Manuel:
148
149
Spanish Manuel:
150
151
152
French Manuel:
153
154
C. Excerpts of Guidelines Used in the Project: Standards, Codes, Specifications and
Technical Regulations
"ASME," 2015. [Online]. Available: https://www.asme.org/about-asme/standards. [Accessed 23
11 2015].
"ISO," 2015. [Online]. Available: http://www.iso.org/iso/home/store/catalogue_ics.htm.
[Accessed 23 11 2015].
"Energy," 2015. [Online]. Available: http://energy.gov/ehss/services/nuclear-safety/department-
energy-technical-standards-program/doe-technical-standard. [Accessed 23 11 2015].
"ASTM," 2015. [Online]. Available:
http://compass.astm.org/CUSTOMERS/search/search.html?query=astm&dltype=allstd&bossecti
on=03. [Accessed 23 11 2015].
I. B. CODE, "INTERNATIONAL BUILDING CODE," CHAPTER 10 MEANS OF DEGREES
SECTION 1008.1.1 IBC INTERPRETATION NO. 05-05, pp. 1-2, 2003.
155
"CODE OF ETHICS OF ENGINEERS," ETHICS, p. 1, 9 10 2007.
N. S. o. P. Engineers, "Code of Ethics for Engineers," Code of Ethics for Engineers, p. 2, July
2007.
D. Copies of Used Commercial Machine Element Catalogs (Scanned Material)
156
157
158
159
160
161
162
163
164
165
166
E. Detailed Raw Design Calculations and Analysis (Scanned Material)
Figure 71: Force hand calculation page 1
Figure 72: Force hand Calculation Page 2
167
Figure 73: Force hand Calculation Page 3
Figure 74: Suspension designs
168
Figure 75: Suspension Hand Calculation Page 1
Figure 76: Static Suspension Hand Calculation Page
169
Figure 77: Bearing Free Body Diagram
170
Figure 78: Static analysis of robot on incline
171
Figure 79: Dynamic analysis of robot on incline
172
Figure 80: Analysis of robot climbing stairs
173
Figure 81: Minimum power requirement for stair climbing
174
Figure 82: Motor comparison for full size design
175
Figure 83: Battery and stair sample hand calculations
176
Figure 84: Stair Construction Calculations
177
Figure 85: component dimensions Page 1
178
Figure 86: Component Dimensions Page 2
179
Figure 87: Component Dimensions Page 3
180
Figure 88: Machinability component Mach set up
181
Figure 89: component suspension dimensions
182
F. Project Photo Album