Automated Loading and Unloading System for Getinge USA Corporation

Preliminary Design Review Report

November 14, 2003 Thanasis Gkourlias

Derek Arnold Lawrence Derdzinski

Amber Mescher Chris Sangster

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Executive Summary This Preliminary Design Review Report defines the design of the Automated Loading and Unloading System for Getinge Corporation. The Automated Loading and Unloading System will be a self-guided, fully automated, robot type product that is capable of loading and unloading medical carts of various sizes into Getinge's washing machines. This system will be a stand-alone product to be offered as an option to, and interface with, the Getinge Model 7800 Floor Loading Cart Washer. The robotic device will transport the carts to a washing machine, mainly used in hospitals. The goal of this project is to design, fabricate, debug, demonstrate, and potentially field test this automated system (robot) to prove its ability to load and unload medical carts. The Automated Loading and Unloading Team designed all aspects of the robotic solution. This includes the robot frame (housing), wiring, controls, integration and operator interface, drive system, docking and latching, tracking and charging system. The product will safely operate within a hospital central supply environment. The existing automated systems, which this system will face, require digging on the floor and installing big components to lead the cart into the washing machine. In opposition to the existing systems, the new Automated Loading and Unloading System is going to be compact, flexible, safe, easy to move, and reprogrammable. The team implemented the Engineering Design Planner methodology to design the robot. There are five design stages of the process. The first stage of the report, recognizing and quantifying the need, discusses the goals, motivation, and background of the project. The second stage presents an overview of four concepts the team has developed. The next stage presents the feasibility assessment the team conducted for each of the four concepts. The fourth stage presents a detailed description of the goals of the project as well as specifications of the design. The fifth stage, describes the analysis that has been done to design the automated system. Finally, the description of the experiments that will be performed next quarter, and a presentation of the plan for finishing the project on schedule and within budget will be performed. Technical data is also included, along with the summary of the current status of the project. The robot design continued to refine as multiple and often parallel activities occurred. That is, as brainstorming, customer requirements, feasibility studies, and technology searches continued to be refined, the design solidified. The initial design did not turn out to be the final design The final design of the robot is shown in the drawings included in the technical data package. The package has both assembly drawings as well as part drawings. The robot will be tested next quarter to validate that the robot meets the design objectives and specifications.

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Table of Contents Executive Summary ..........................................................................................................2 Table of Contents..............................................................................................................3 List of Illustrations............................................................................................................5 1.0 Recognize and Quantify the Need ..............................................................................6

1.1 Project Mission Statement ...................................................................................6 1.2 Product Description .............................................................................................6 1.3 Scope Limitations ................................................................................................8 1.4 Stake Holders.......................................................................................................9 1.5 Key Business Goals ...........................................................................................10 1.6 Top Level Critical Financial Parameters ...........................................................10 1.7 Financial Analysis .............................................................................................10 1.8 Primary Market..................................................................................................11 1.9 Secondary Market..............................................................................................11 1.10 Order Qualifiers .................................................................................................11 1.11 Order Winners ...................................................................................................11 1.12 Innovation Opportunities ...................................................................................12 1.13 Background Research ........................................................................................12

2.0 Concept Development...............................................................................................15 2.1 Building vs. Buying ...........................................................................................15 2.2 Cart Towing Concept.........................................................................................16 2.3 Power System Concept ......................................................................................16 2.4 Control System Concept ....................................................................................17 2.5 Drive System Concept .......................................................................................17 2.6 Navigation System Concept ..............................................................................17 2.7 Communication System Concept ......................................................................18 2.8 Cart Detection System Concept.........................................................................18 2.9 Retro Fit Concept...............................................................................................18 2.10 Concept Development Conclusion ....................................................................19

3.0 Feasibility Assessment..............................................................................................20 3.1 Building vs. Buying ...........................................................................................20 3.2 Cart Towing Feasibility .....................................................................................21 3.3 Power System Feasibility ..................................................................................21 3.4 Control System Feasibility ................................................................................22 3.5 Drive System Feasibility....................................................................................22 3.6 Navigation System Feasibility...........................................................................22 3.7 Communication System Feasibility...................................................................23 3.8 Cart Detection System Feasibility .....................................................................23 3.9 Retro Fit Feasibility ...........................................................................................23 3.10 Feasibility Conclusion .......................................................................................24

4.0 Performance Objectives and Specifications..............................................................25 4.1 Design Objectives..............................................................................................25 4.2 Performance Specifications ...............................................................................26 4.3 Design Practices Used by the Team ..................................................................29 4.4 Safety Issues ......................................................................................................29

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5.0 Analysis of Problem and Synthesis of Design .........................................................31 5.1 Cover Design .....................................................................................................31 5.2 Mounting............................................................................................................31 5.3 Control System ..................................................................................................32 5.4 Drive System .....................................................................................................32 5.5 Navigation System.............................................................................................35 5.6 Retro Fit ............................................................................................................36 5.7 Power Supply Selection.....................................................................................36 5.8 Charging System................................................................................................37 5.9 Cart Towing .......................................................................................................37 5.10 Cart Recognition................................................................................................39 5.11 Analysis Conclusion ..........................................................................................40

6.0 Future Plans ..............................................................................................................41 6.1 Experimentation.................................................................................................41 6.2 Schedule.............................................................................................................42 6.3 Budget................................................................................................................42

7.0 Conclusion ................................................................................................................43 References ......................................................................................................................45 Appendix.........................................................................................................................47

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List of Illustrations

Figure 1.1: Belimed Automated Loading and Unloading System ........................................12 Figure 1.2: Tug in Action.......................................................................................................13 Figure 2.1: Two-pin Robot Design ........................................................................................16 Figure 5.1: Top and Bottom Frame Views ...........................................................................31 Figure 5.2: Drive System of Robot ......................................................................................32 Figure 5.3: Calculations for Weight Distribution ..................................................................33 Figure 5.4: Calculation of Drive Motor Torque and Power...................................................34 Figure 5.5: Calculation of Current Drawn from the Motors..................................................35 Figure 5.6: Cubic Screw Jack Sizing .....................................................................................38 Figure 5.7: Screw Jack Motor Current Drawn.......................................................................39 Figure 5.8: Overall Design of Robot......................................................................................40 Figure 6.1: Spring Quarter Schedule .....................................................................................42

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1.0 Recognize and Quantify the Need 1.1 Project Mission Statement The Automated Loading and Unloading System Senior Design Team is to design and

fabricate a working prototype in conjunction with Getinge USA. This prototype will be

used to help hospitals manage their personnel. This will allow the hospital washing area

to be more efficient, leaving more personnel for other needs. A secondary goal of the

project is to release the system in conjunction with the new Getinge 7800 series washer,

which will be released in October 2004.

1.2 Product Description

One of the most significant problems in designing a competitive Automated Loading and

Unloading System for hospital medical cart washers is their bulk. This bulk takes up

valuable room in a hospital cleaning area. Based on customer feedback, Getinge USA

needed an Automated Loading and Unloading System that will be a self-guided, fully

automated, non-invasive, robot type product. The system should also be capable of

loading and unloading large, floor mounted, washing machines with medical carts of

various sizes and weights. The system is intended to be a stand-alone product to be

offered as an option to, and interface with, the Getinge 7800 Floor Loading Cart Washer.

There must be two robots, one for loading the medical carts on the soiled side of the

washer, and another for unloading the medical carts on the clean side of the washer. This

is needed because the robot cannot go between the two areas without causing

contamination.

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The advantage of a robot type loading and unloading system is that it takes up much less

of the valuable hospital floor space than the other systems available today. It can also

take the place of a staff member of the hospital so that they can be doing something more

valuable then just loading a medical cart washer.

The Senior Design team used this idea to design a mobile robot. This design includes

concepts of the robot frame and covering, wiring, controls, drive system, docking and

latching systems, tracking system, safety system, charging system, integration, and

operator interface. The robot was designed to be small enough to fit underneath the

medical carts, to be powerful enough to pull the heavy medical carts, and be able to adapt

to latch on to medical carts of different heights.

The smallest medical cart has five and a half inches of clearance between the bottom of

the medical cart and the ground. The robot was designed to be fully functional and able

to traverse underneath even the smallest cart. The product specifications that Getinge

provided state that the robot needs to produce about fifty pounds of linear force besides

the force needed to pull its own weight. In order accomplish this and still fit under the

medical cart, the robot’s components, including batteries, motors, and the pin used to

connect to the medical cart needed to be very powerful and still less than four inches in

height. A pin will be raised from the robot into a universal locking mechanism on the

medical cart.

Since this is a mobile robot, the only power source available is battery power. We want

to be able to reuse the batteries, so each system will include a charging station where the

robot can charge during the wash cycle.

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A recognition system will be needed to differentiate the medical carts. An array of color

blocks attached to the bottom of each cart will take care of this. The robot will have

sensors to read the color code, and decipher which type of medical cart it is connecting

to. It will then decide which washing cycle to perform and transfer this information to

the washer.

RF communications cannot be used in hospitals. Due to this constraint, infrared

communication system will be used to communicate wirelessly between the robot and the

washer.

An array of infrared sensors will be in front and back of the robot for obstacle avoidance

and distance measurement. There will be two types of infrared sensors, long range and

short range.

The navigation system will determine the location of the robot in the room with respect to

the washer and the charger. The robot will also follow a guidance line throughout the

room to ensure that the cart is loaded straight. In order for the robot to know its position

with respect to the washer or charger, an encoder will be used in conjunction with each

motor.

The microcontroller will be the brain of the operation. It will contain enough input and

output ports to address each device in the robot. The microcontroller needs to be fast

enough to process all information coming from all different components while making

decisions at the same time.

1.3 Scope Limitations

The prototyped Automated Loading and Unloading System shall be fully designed by the

end of RIT’s Fall Quarter, and assembled by the end of RIT’s Spring Quarter.

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At the end of the Fall Quarter, the senior design team will hold a Preliminary Design

Review. At this review the team will be responsible for:

• Complete design of the system

• Drawing Package

• Software flow charts

• Bill of Materials

• Quotes for Vendors

• Budget

At the end of the Spring Quarter, the senior design team will present the debugged and

tested prototype. At this presentation they will be responsible for:

• Working prototype

• Final Report / Binder

• Initial testing done using a medical cart and washer

The senior design team will not be responsible for the following:

• Washer Design

• Microcontroller Design

• PLC Integration

• Hospital Installation

1.4 Stake Holders

The main stakeholders are the students working on the design and the Getinge USA

Corporation. Other stakeholders are the hospitals and staff in which these system will be

integrated, and the future of Automated Loading and Unloading Systems.

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1.5 Key Business Goals

The team will be successful when they have designed a working Automated Loading and

Unloading System that requires very little human interaction. If this has been done:

• The students on the team will have learned how to work on a multidisciplinary

team.

• A proof of concept will have been completed and further can be requested for

future prototypes.

• Getinge with have an advantage on the other medical cart washer production

companies, and could profit immensely.

1.6 Top Level Critical Financial Parameters

• Given the decision to have the robot travel under the medical carts, will cause a

need for smaller components at higher prices. The components that will cause the

most concern are the batteries, motors, and screw jack.

• The scope of the project will require our robot to be very robust, which can be

costly. It will need to have reliable parts and certain aspects to withstand the

environment of the hospital, which may not have been considered in other

environments.

1.7 Financial Analysis

A $10,000 budget has been appropriated for the cost of producing one robot. This budget

shall include:

• Motors, Gearboxes, and Encoders

• Electronics

• Wheels

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• Attachment System

• Batteries and Battery Charger

• Sensors

• Chassis, and Body

• Wires, Bolts, and Hardware

1.8 Primary Market

The primary market of the Automated Loading and Unloading System is hospitals with

Getinge 7800 Floor Loading Washing Machines.

1.9 Secondary Market

The Automated Loading and Unloading System could very easily be adapted to other

environments where a cart needs to be moved.

1.10 Order Qualifiers

The Automated Loading and Unloading Team shall fabricate, assemble, and program a

prototype that will load a medical cart into the Getinge 7800 Series washer. The team

will also do experimentation to verify the power and efficiency of the robot.

1.11 Order Winners

The following are the goals of the project if time and budget permit:

• Be small enough to fit underneath the smallest of the medical carts.

• Be sufficiently powerful to pull the heaviest medical cart that is specified.

• Be sufficiently reliable as defined in the specifications.

• Meet safety requirements as defined in the specifications.

• Have the need for very little human interaction.

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• Be able to sense the location and type of medical cart.

• Verify that Engineering Design Models agree with prototype.

1.12 Innovation Opportunities

Potentially the Automated Loading and Unloading System could be used with a new

Getinge 7800 Series washer. Eventually, the Automated Loading and Unloading System

will be integrated into any hospital that uses a Getinge washing machine.

1.13 Background Research

The research completed by the Automated Loading and Unloading team consisted of

exploring systems in existence, robots on the market, and components.

Figure 1.1 - Belimed Automated System

Belimed makes a system where there is a track in front of the washer that pulls the

medical cart into and out of the washer. Steris also makes a system similar to this. The

problem with both of these systems is that they take up too much room in a hospital.

They also require a large amount of construction on the floor to install the system and

still require an operator. Getinge desired a solution that will not require a fulltime

operator or invasive floor construction.

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There is also an automated robot available in production today, Tug by Aethon, which

pulls carts from one end of the hospital to the other using a built in map and by tracing

the walls. A disadvantage of Tug is that the carts have only two wheels, which make

them mobile only when Tug is attached. For the Automated Loading and Unloading

System desired by Getinge, the robot has to adapt to the medical carts, instead of the carts

adapting to the robot. Also, Tug costs about $35,000 to buy, which is out of the range of

the $10,000 budget provided by Getinge. Below is a picture of Tug in action.

Figure 1.2 – Tug in Action

ActivMedia creates some other robots that are available and on the market today. They

have three robots that were considered for use by the team as base robots. These robots

would already work, but still need some modifications to achieve the application at hand.

One of their robots, called the PowerBot, can carry up to 220 pounds, map a room, follow

a path autonomously, maneuver in tight areas, and avoid obstacles. It has a lot of things

that we are looking for except for the fact that it is too big to fit under our medical carts

and would still need modification to work in the hospital environment. This robot also

cost roughly $20,000, which is way out of our cost range considering we would still have

to modify it. Another robot made by ActivMedia was the Pioneer 3-AT. It can only

carry a payload of 30 kg, and is also too tall to fit under a medical cart. It carries a base

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price $5995, which is not totally out of our price range, but it would still require a lot of

modifications. The third robot that was considered from ActivMedia was the Pioneer 3-

DX. It’s not as powerful as the P3-AT, as it can only have a payload of 23 kg. This

carries a base price of $3695, and would also require a lot of modifications.

Angelus Research Corporations makes a robot called Whiskers the Intelligent robot. It

only costs $895, and is small enough to fit under a medical cart, but not strong enough to

pull it. It would also require a lot of major modifications to be able to meet the required

specifications.

Finally we found two robots made by Applied AI Systems, INC. called the LABO-2, and

the LABO-4. The LABO-4 costs $19,200 and has a payload of 90 kg. The LABO-2

costs $20,400 and has a payload of about 135 kg. Both of these robots have the type of

power that we are looking for, but both don’t fit in the size constraints that we need.

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2.0 Concept Development

The Automated Loading and Unloading System team developed a large list of possible

ways of loading and unloading a medical cart into and out of the washer. This list can be

seen in the concept development part of the Engineering Design Planner binder. The list

of ideas originally contained 30 items. These ideas were discussed and voted on to create

a base of four ideas. The four most favorable ideas were: to design a robot with arms that

would surround the medical cart, to design a robot with a hook which would pull the

medical cart, to design a robot which would accept the pins from the medical cart, and to

design a robot which would lift the medical cart while accepting a pin. Group drawings

were formed and the ideas started the development stage.

2.1 Building vs. Buying

The main driving point of this project was being able to design the robot in ten weeks,

and being able to mass produce it after prototype. Getinge and the Automated Loading

and Unloading System design team discussed various options, which included, building

the robot from components, buying a robot base and adding components, and buying an

existent robot.

It was desirable to stay at a cost below $10,000 which devalued buying a complete robot.

Building the robot from components and building on top of an existing robot base were

both considered. The decision to build from components came about due to the available

bases not meeting the constraints of the project.

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2.2 Cart Towing Concept

A major aspect of the design was determining how to move the medical cart. The team

decided that the most favorable way to move the medical cart would be by having the

robot attach to two pins dropping down from the medical cart.

Figure 2.1 Two-pin Robot Design

As this idea grew, so did the size of the robot. The robot changed from fitting entirely

under the medical cart to fitting partially under the medical cart to make enough room for

a camera, Ultrasonic sensors, motors, and various other parts. This idea was developed

and presented to the customer. For various reasons to be discussed in the feasibility

section, the customer suggested a different design. This design was a robot that fit under

the medical cart and shot a pin into a hole on the mounting bracket attached to the

medical cart. The robot would lift the medical cart and pull it by this pin.

2.3 Power System Concept

One constraint was that the robot must be a mobile robot. This led to the robot being

powered by batteries with a charging station. There will be multiple batteries to provide

enough power to drive the motors, run sensors continuously, and keep the microcontroller

working. The robot will return to the charging area during each wash cycle. The

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charging area will be mounted on the wall to avoid obstruction and to provide a safe

environment.

2.4 Control System Concept

The initial plan for the control system was to modify one that already existed. The

control system desired was the Whisker board available from Angelus research. This

board was going to be used as the base control and another microcontroller was to be

piggybacked on top of it to provide ample inputs and outputs. The microcontroller was to

handle the inputs and outputs of all sensors along with motor encoders. As the quarter

progressed, experiments were done with the whisker robot, and it was found to be not as

reliable as desired. The company was researched further and considered to not be a

reliable company. The control design was then changed to one microcontroller with

ample inputs and outputs.

2.5 Drive System Concept

The four-wheeled robot will need to be directed as it travels throughout the hospital. The

drive systems considered were 4 drive wheels, 2 drive wheels and 2 casters, and 2 drive

wheels 2 stationary wheels. Each system was considered and simulated.

2.6 Navigation System Concept

The robot will “see” as it navigates throughout the room. The camera will be the primary

controller for navigation of the robot. It will recognize certain objects that have been

preprogrammed into it. There will also be arrays of infrared sensors for obstacle

avoidance and distance determination. The robot will follow a certain array of lines on

the floor to travel throughout the room and to ensure that it enters the washer straight.

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There will be an array of IR sensors on the top of the robot, which detect the proper

position for the pin to enter the cart.

2.7 Communication System Concept

Since there is no RF communication allowed in the hospital, the communication will

occur with infrared transceivers along with a wired connection. The wired connection

will communicate between the washing machine and the charging station. The infrared

transceivers will communicate between the robot-washing machine and robot-charging

station. The transceivers will inform the washer when the medical carts are loaded and

tell the washer what cycle to perform. The charging station will tell the robot when there

is a certain amount of time left in the washing cycle. From this communication, the robot

will know when to get a cart and when to load it into the washing machine.

2.8 Cart Detection System Concept

The medical cart will be detected in multiple stages. The initial detection of the medical

cart will come from the camera, so that the robot knows to retrieve that medical cart. The

second line of detection will be a series of infrared sensors on the top of the robot that

will read what type of medical cart it is and what washer cycle to perform.

2.9 Retro Fit Concept

One major constraint of the robot was that there had to be a universal kit to go on every

medical cart. This retro fit concept developed into a plate across the front wheels with a

hole for the pin, along with the black and white blocks for the infrared sensors to read to

determine the cart type. On the rear wheels, there will be spacers to ensure that the

medical cart stays level. This module will mount directly to the case medical carts and

will mount on a lowering bracket of the wire medical carts. There will be different black

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and white block schemes for different cart types to distinguish between the medical carts

and laundry cycles.

2.10 Concept Development Conclusion

The preliminary design concept is a robot that will travel under the medical cart, raise a

pin into the medical cart and pull the medical cart into the washer. The robot will be

powered by batteries and built from components stated previously. The drive system will

consist of two motors with encoders to drive each wheel separately in a skid/steer design.

There will be one microcontroller to control the robot. This microcontroller will handle

both the input and the output of the sensors and motor encoders. The navigation system

of the robot will consist of a camera and infrared sensors for distance measurement and

object avoidance. Communication will be provided to and from the robot by infrared

transceivers and between the charging station and washing machine by a hardwire

connection. The robot will detect types of medical carts by an array of infrared sensors.

Each medical cart will have a harness to which the robot will mount. This will make for

a complete system.

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3.0 Feasibility Assessment

Feasibility was assessed using two methods. One method was the Pugh’s method where

four designs are compared against the base design. This method produces results that are

not always accurate because no aspect of the design is weighted more than the others.

The second method used for feasibility assessment was a weighted method. This method

proved to be much more accurate as it weighted the most important factors over the less

important factors.

3.1 Building vs. Buying

The way the robot was produced was a great factor in the design of the robot. The three

choices that were considered were building the robot from scratch, buying a robot base

and adding components, and buying an existing robot. The first case considered was

buying an existing robot. While this was by far the quickest solution to the company’s

desires, it did not meet the requirements in cost. The lowest priced robot was found to be

$35,000, while the robot budget was $10,000. It also did not leave any room for

adaptations to this specific project.

The second idea considered was buying a robot base, and adding components to it. This

idea was entertained for a bit, as it would make programming and testing much easier,

since there was a guarantee that the robot would work. This idea however, began to fall

through when no bases were found that were suitable for the application. The price was

also a factor as the robot bases that were found were around $10,000, which would not

leave much room for any additions.

The last idea considered was building the robot from components. This strategy will

require more work and time to create a working model, but it does give the flexibility

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needed. This is also the only option that has a chance of being under the $10,000 budget

provided.

3.2 Cart Towing Feasibility

Four options were initially considered to tow a medical cart. These options were pulling

and lifting with one pin, pulling with two pins, hooking onto the medical cart, and

grabbing the medical cart from the side. As the ideas developed, grabbing the medical

cart from the side was voted out due to the massive amount of fragile material that would

be present in the arms. The hook idea was seriously considered due to the fact that a

retrofit kit would not be needed, but it was unsure how a medical cart could be moved

backward easily with a hook. The one pin and two-pin design were seriously considered

and designed. The two-pin design won over the one pin design because of the

controllability in turning. The two-pin design was presented to the customer who

expressed doubts in the ability to produce the amount of torque necessary to turn the

medical cart. The customer favored a design much like the one pin design, except that

they wanted the pin to come up from the robot instead of down from the medical cart.

Although this would make steering a bit tricky, it was worth the cost of being able to

travel completely under any medical cart.

3.3 Power System Feasibility

The most beneficial power source was determined to be batteries. These batteries could

either be lead acid, or Nickel-Lithium. Lead acid batteries were selected due to their

weight and ability to short cycle. Nickel-Lithium batteries required a very long amount

of charging time, and became unpredictable when not charged completely. They were

also very hard to find at large voltages and larger currents needed for the motors. Lead

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acid batteries were available in many voltages and many currents. They can be charged

for a short amount of time and also add weight to the robot for traction.

3.4 Control System Feasibility

The microcontroller for the desired robot required as many inputs and outputs as possible.

The initial microcontroller to be used was the whisker robot controller. This was found

to be inadequate because it did not have enough input or output pins for all of the sensors.

It was also found that the company was not very reliable and the software was not

sufficient. The microcontroller that was chosen was had more than enough input and

output lines and could control everything necessary. It also has a development board and

sufficient software and support.

3.5 Drive System Feasibility

The drive systems considered for the robot were four separate drive wheels, two sets of

two drive wheels, and two drive wheels - two caster wheels. The four separate wheel

drive was deemed to be too hard to control and not needed in this application. The

scheme of two sets of two drive wheels was considered, but it was decided that it was not

necessary in this application. The drive system that was decided upon was two drive

wheels and two caster wheels. This system made turning at any radius easy, while the

caster wheels support the weight of the robot and the medical cart.

3.6 Navigation System Feasibility

The navigation system of the robot was one of the most important parts of the robot. The

choices for navigation were a camera, ultrasonic sensors, and infrared sensors. The

camera was initially going to be used for medical cart detection. It was later realized that

the camera could do navigation along with object detection. The ultrasonic sensors were

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going to be used as object avoidance, however in the new design of the robot, there was

no room and no need for the ultrasonic sensors. The infrared sensors were the hardest

sensors to place on the robot. These sensors are very limited in the amount of space that

they can see. The infrared sensors are going to be used to find the end of the washer

along with close obstacle avoidance and reading medical cart types.

3.7 Communication System Feasibility

The three types of communication systems considered were RF transmission, infrared

transmission, and wired transmission. RF transmission was ineligible, as it is not allowed

in the hospital. The Infrared transmission was used to communicate between the robot

and the washer and the robot and the charging station in place of the RF communication.

The charging station will also be able to communicate with the washer through a hard-

wired connection.

3.8 Cart Detection System Feasibility

Detecting a medical cart may be one of the most challenging aspects of the design. The

object attributes of the medical carts are its existence and its type. The initial medical

cart detection was to be camera technology. With the new design where the robotic

device must fit under the medical cart, the camera does not have the scope to detect the

medical cart. As an added detection infrared sensors will determine what the type of

medical cart, which in turn determines which wash cycle to perform.

3.9 Retro Fit Feasibility

Retro fitting the medical carts was something that was very important to the customer.

They have many medical carts in hospitals unable to be replaced. The most efficient

solution was to add a bracket to the medical cart for the robot to attach to, instead of

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changing the way the medical carts are made. This allows for all medical carts to be

accessed by the robot and by a human. The kit will be attached between the front wheels.

This simplifies the robotic controls as well as cut down on the number of modifications

necessary to the medical cart.

3.10 Feasibility Conclusion

The feasibility analysis was defined, refined, and validated by weekly meetings with

Getinge management. Their knowledge of the hospital environment and our constant

brainstorming helped shape the final feasibility model.

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4.0 Performance Objectives and Specifications

The objectives and specifications define “what is needed” and “how well” the solution

will perform. The performance objectives and specifications were customer defined to

meet their market place needs.

4.1 Design Objective

There are a number of design objectives that must be met.

• This product shall be self-guided and fully automated.

• This product shall be capable of loading floor-mounted washing machines with

medical carts of various sizes.

• There will be two robots per system. RIT will design and prototype the loading

side robot and if time permits, the unloading side robot.

• The system must be a stand-alone product that will interface with the Getinge

Model 7800 Floor Loading Cart Washer.

• The system must have the capability of detecting the presence of a medical cart in

the load and unload staging areas.

• The system must have the capability of detecting the presence of the washer.

• The product must identify medical cart type.

• The system must have a manual override. (This is important in the case of an

emergency and service.)

• This system must be rechargeable.

• There must be a charging/docking station mounted in the area where the robot can

be recharged.

• The robot must also be able to detect the amount of energy left in its fuel cells.

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• The robot must also be able to charge itself automatically

• The medical carts that the robot will be loading into the washer must be modified

so that the robot can safely attach to and navigate them throughout the hospital.

• The system will be configurable to three 7800 Cart Washer models based on load

length.

• The robot will be protected (i.e. circuit breakers) to minimize any chance of fire

or smoke generation.

4.2 Performance Specifications

There are certain performance specifications that must be met in order for the project to

be successful. The system was designed around these specifications. They are listed

below:

A. NO PIT REQUIREMENTS

The design will not require any pits or holes that must be dug into the floor of the

hospital.

B. EXTERIOR SURACFE-304 STAINLESS STEEL

The exposed exterior surfaces of the robot is to be type 304 stainless steel with a

standard #3 finish. This will match the surface of the medical cart washers and will

be able to withstand the heat and hot water that will be inside of the washer. The

exterior surface must also be smooth and free of snag points to facilitate wipe-down

cleaning.

C. 50 POUNDS OF LINEAR FORCE

The robot must provide 50 pounds of linear force in order to move the medical carts.

D. 100 POUND LOAD

27

The robot must be designed to operate with a 100-pound load on top.

E. EASILY REMOVABLE COVER

The cover of the robot must be easily removable so that maintenance and service can

easily de done to the robot.

F. SIZE

The robot must be sized for compatibility with healthcare industry standard case and

surgical medical carts. The robot must be able to travel underneath a medical cart.

G. SERVICE SPACE

No service space is to be required from within or behind the wall mounted

components or from below floor mounted components (no pit).

H. CYCLE TIME

The automated system is to be capable of loading or unloading one medical cart in

one minute or less. Time measured from the robot leaving till it’s return to a charging

station located no more that three feet (914 mm) from the washer door opening.

I. SUPPLY VOLTAGE

The system must be capable to operate on 120 V, single phase, 50/60 Hz.

J. OPERATED BY GE VERSA-MAX PLC

The automated system is to be operated by a GE Versa-Max Programmable Logic

Controller. The operator interface is a 6” TCP color touch panel display. Using this

touch panel the operator will be able to accomplish the following:

• Start the automated processing cycle

• Monitor the process status of automated operations

• Stop automated process

28

• Start washer processing with partially loaded chamber

K. OPERATING AMBIENT CONDITIONS

The system must be able to operate under these conditions:

• Temperature: 10°C (50°) to 40°C (104°F)

• Pressure: Atmospheric from 0 to 2000 m (6500ft)

• Relative Humidity: 10 to 90 % non condensing

• Pollution degree: 2

L. STORAGE AND SHIPPPING

The system must be able to be packed and shipped in the following conditions:

• Temperature: -18°C (0°F) to 60°C (140°F)

• Pressure: Atmospheric from 0 to 3690 m (12000 ft)

• Relative Humidity: 10 to 90 % non condensing

• Package robot is to survive conditions experienced in the shipping process

without damage.

M. REGULATORY & CODE COMPLIANCE

The product is to be designed to meet requirements of the latest edition of the

following standards:

• UL-3101-1, Certified by ETL Testing Laboratories

• CSA C22-2 No. 1010.1, Certified by ETL Testing Laboratories

• FCC

• Seismic requirements per California Administrative Code

N. RELIABILITY AND LIFE EXPECTANCY

29

With utilities within specified limits and factory recommended maintenance

schedules, the system shall be designed to function properly without failure or need

for repair for a minimum of 12 months from the date of installation. (3 cycles/hr. x

12 hrs./day x 6 days/week x 50 weeks/yr. = 10,800 cycles considered 12 month

usage)

4.3 Design Practices Used by the Team

There were many design practices that were considered by the team. A list of these

practices are listed below:

• Design for Manufacturability- The system was designed so that all needed parts

are readily available and the system shall be easily manufactured.

• Design for Safety- The product was designed to comply with all the safety codes

and specifications.

• Design for Efficiency- The team designed the system to be as efficient as possible

and output as many cycles as possible.

• Design for Reliability- The system was designed to be reliable and not to need

constant maintenance and service. It was also designed to meet the 12-month

failure requirement.

• Design for Cost- The team designed the robot to be competitive with the pricing

of robots that are already available. It was also designed to have a manufacturing

cost of $10,000.

4.4 Safety Issues

Since this system is made for use in a hospital, there are many safety measurements that

must be met. They are listed below:

30

• Any floor mounted locating and detection devices to be such as to not be trip

hazards to operators.

• Audible and visual alarms during any movement of the robot.

• System to be capable of detecting obstructions and subsequently stopping

motions. Manual restart is required to resume operation.

• Emergency stop switch located on robot and control console.

• Automated system to deactivate when 7800 Cart Washer is in “fault mode”.

• In the event of a power failure, the control system shall retain current cycle

information for a minimum of 30 days.

• Upon power restoration, the controller will revert to standby status. If power loss

occurs during a cycle, a cycle not completed message will also be displayed.

• If a detectable system failure or malfunction occurs, the controls will go into a

known safe state.

• Failure and malfunction messages shall be displayed in order of occurrence and

printed.

• An audible warning shall sound whenever a failure message is displayed.

• In the event of an automatic abort resulting in am incomplete cycle, the operator

must restart the system. The unit will not start automatically if a fault is cleared.

31

5.0 Analysis of Problem and Synthesis of Design Final designs were created for each component of the robot. After these designs were

made, specific parts were selected to ensure proper assembly. Specific calculations were

performed to determine the requirements of components chosen. The robot drawings

started taking shape as the components were placed inside.

5.1 Cover Design The cover consists of four pieces of type 304 stainless steel with a #3 finish. The top

piece shall be connected to the top of the frame with a hinged back and two screws in the

front for easy, yet controlled access. The lower portion of the cover will consist of the

bottom and sides. The front and back will remain attached to the frame and will support

the sensors and charging receptors.

Figure 5.1 – Top and Bottom Frame Views

5.2 Mounting

The mounting system will consist of screws and standoffs for the circuit boards. Pan head

bolts recessed into the mounting bracket will secure the motors. The batteries will be

secured to the frame by straps wrapped around the top of the batteries.

32

5.3 Control System

The Control system is the C805F120 made by Cygnal (www.cygnal.com). The selection

of this control system was based on the requirements of the video and infrared navigation

systems, which will require these features. This controller meets or exceeds memory

requirements (i.e. 128k flash and 8.25K RAM). Robotic performance will be support by a

100 MHz processor. The other selection factor for the control system was the number of

I/O ports required to accommodate the quantity of proximity sensors required for obstacle

avoidance. The control system comes with the microcontroller, a development board,

and development software. This enables integration of the electronic parts into the robot.

5.4 Drive System

The drive system will consist of two DC servomotors with encoders. The gearbox was

selected based on its axial load carrying capacity. The concept was to provide mechanical

drive power as simply and efficiently as possible.

Figure 5.2 – Drive System of Robot

The robot has an estimated weight of 85 lbs. Furthermore, the robot will have to support

150 lbs from the medical cart that it is moving. The total weight distribution is 60% on

33

the drive wheels and 30% on the caster wheels. This translates to 50 lbs on the drive

system from the robot and 150 lbs from the medical cart for a total of 200 lbs. Since the

weight will be equally distributed between the two drive wheels, each wheel will have to

support 100 lbs. The motor will need an output of 75 watts to move the robot at the

desired speed of one half mile per hour. The motor selected is the Maxon EC45, which

has a sufficiently good power to weight ratio. This motor also mates to the smallest

gearbox capable of withstanding the 100lbs that will be applied to the bearings in axial

load. The calculations for the weight distribution can be viewed in figure 5.3 below.

Description Weight

Distence From Caster percent

Drive Wheel

Caster Wheel

Battery 30 6 37.5 11.25 18.75Microcontroller 1 18 112.5 1.125 -0.125Drive Wheels 5 16 100 5 0Caster Wheels 1 0 0 0 1Pin Assembly 8 16 100 8 0Motor Controler 1 17 106.25 1.0625 -0.0625IR sensors 0.5 17 106.25 0.53125 -0.03125Camera 0.25 17 106.25 0.265625 -0.01563IR Comunacation 0.25 14 87.5 0.21875 0.03125Frame 10 10 62.5 6.25 3.75Cover Top 0.5 10 62.5 0.3125 0.1875Cover Frount 0.5 20 125 0.625 -0.125Cover Bottom 1.5 10 62.5 0.9375 0.5625Cover Back 0.5 -2 -12.5 -0.0625 0.5625Motor 15 16 100 15 0Total 75 NA 67.35417 50.51563 24.48438

Figure 5.3 - Calculations for Weight Distribution

Calculations were also performed for the motor torque and power. It was specified that

the force to push the medical cart was 50 lbs. It was estimated that the force to push the

robot was 15 lbs. The derivations and calculations for motor torque and power can be

seen in figure 5.4 below.

34

Force to push medical cart: 50 lb Force to push robot: 15 lb Total Force (F): 75 lb Safety (Sf): 1 We will be using the fact that this motor will be only used interminably as a safety. Total Force (Fd) : F*Sf = 75 lb Outer Diameter of the wheel (D): 3

Fd

D

Torque (τ)= ( ) inozlbinFD−=−=

== 18005.11275*

23*

2τ

Max Designed Speed (v): MinFeet

hourMile 445.0 =

Circumference = ftinr 785.042.923**22 === ππ

Rotational Velocity (ω):min

02.56785.0

min44 rev

ft

ft

Cv

===ω

Power (P): wattshp

rev

ftin

lbin

P 6.741.05250

min02.56*

12

5.112

5250*

==

−

==τω

Torque constant of motor (Km): Amps

inoz *71.16

Gear ratio estimated (G): 30:1

Torque at the motor (τmotor): inozinozG

*78.6530

*1800==

τ

Figure 5.4 – Calculation of Drive Motor Torque and Power

The derivations and calculations for Current drawn from the motor can be seen in figure

5.5 below.

35

No-load speed of motor (no): 1916 RPM No load amperage (Io): 0.508 Amps. Armature resistance (R): 0.7 Ω

Amperage draw of one motor while turning (Il): AmpsIK o

m

motor 45.4508.71.1678.65

=+=+τ

Actual motor speed: RPM

Ampsinoz

AmpsRPMK

RInm

o 1786*71.16

45.4*13501916**1350 1 =−=−

Figure 5.5 – Calculations of Current Drawn From the Motors

The speed as a percent of no-load speed is 87.90%, which does not fully utilize the

motor, but we sized the motor because of the gearbox requirements. The percent of

torque compared to the stall torque is 13.66%, which is appropriate for this motor.

5.5 Navigation System

The navigation system will consist of a video camera and a select amount of infrared

sensors. The video camera will serve as the main component of both the navigation

system and the medical cart detection system. The camera will be capable of detecting

both color and shape of objects. There will also be a series of proximity sensors for

obstacle avoidance. The first sensor series will be an array of long-range infrared sensors.

This will be placed on the front and back of the robot. The second type of sensor will be a

short-range infrared sensor. These sensors will allow the robot to stop before colliding

with any potential obstacles and will only be used in crash potential situations. Refer to

the following figure for the location configuration that we will be using.

36

5.6 Retro Fit Kit

There will be a number of different Retro Fit Kits necessary for the varying medical cart

designs available. There will be some design characteristics that will be consistent

thought the versions. The piece that the robot will see will be the same on every cart.

This piece will consist of a hole in the center of the bracket. This hole will receive the pin

from the robot.

The mounting system will attach to the top of the caster wheels through the existing holes

for the wheel bolts. The wheels will be removed; then the bracket will be added and the

wheels will be reinstalled. In the case of the wire frame cart, this method will not work.

In this case we will have a bent piece of metal over the support bars to secure the bracket

to the medical cart. This will allow the bracket to be at the same height for all carts.

5.7 Power Supply Selection

The power supply system will consist of four 12-volt lead acid batteries. The advantage

of lead acid batteries is that the battery can be recharged when the robot has a time and

does not require a complete cycle for continued battery performance. The voltage

required to power the motors is 24 volts therefore the batteries will be grouped with two

sets of parallel linked batteries wired in series giving the necessary voltage and current.

Due to size constraints, grouping the 12-volt batteries created the 24-volts necessary.

The current capacity of theses batteries is 12AH since we will be using 4 of them at 24

volts we will have a total of 24AH with an estimated 7Amp power drain we will have 3.4

hours of continuous operation. The robot will operate for an estimate of 2 minutes out of

every ten minutes or 20% of the time. This should allow the robot to operate for a 16-18

hour day without the need for recharging, which is much more than the specifications call

37

for.

5.8 The Charging System

The Charging system will consist of a standard 24V battery charger, communications

chip and a plug system. The battery charger will need to have the circuits to properly

charge and maintain the batteries. The plug will consist of two posts that will stick out

from the charger; this is where the robot will connect to the charger. The plugs will have

springs on them to keep them tight against the robot. The robot will have receptors

consisting of isolated plats of metal that will receive the power.

5.9 Cart Towing

Hitching to the front of the medical cart and then pulling the medical cart into position

will accomplish the towing. The biggest concern will be for the radius of turning. The

medical cart wheels can be as close as fourteen inches between inside edges. The robot is

12 inches wide, which means that the robot can only rotate 36 degrees off of center.

After the medical cart is positioned in the washer, the robot will detach and drive out

from under the medical cart. Upon departure of the washer, the robot will signal the

washer to commence with the wash cycle or retrieve the second medical cart. The system

to lift the cart will consist of a cubic screw jack combined with a DC motor. We chose

the cubic screw jack due to its size and large lifting capacity. The calculations to size the

cubic screw jack can be see in figure 5.6 below.

38

Actual Force (Feff): 150 lbs=0.667kN

Transmission Ratio: revmm

iP 25.=

Efficiency: η=25%

Idle Torque (MO): .03 N*m

Required Drive Torque (MT):

mNmNmkNMiPFeffM OT ==+=+= 4.19*136.0*03.25.*

14.3*25.*2*667.*

**2 ηπ

Power (P): wattshp

rev

ftininlb

P 6.3045.05250

min60*

12982.3

5250*

==

−

==τω

Figure 5.6 – Cubic Screw Jack Sizing

This screw jack will require it’s own motor. The calculations of current draw from the

screw jack motor can be see in figure 5.7 below.

39

No-load speed of motor (no): 3759 RPM No load amperage (Io): 0.345 Amps. Armature resistance (R): 3.1 Ω

Torque constant of motor (Km): Amps

inoz *21.8

Amperage draw of one motor while turning (Il):

Amps

AmpsinozinozI

K om

motor 71.2345.*21.8

4.19=+

−=+

τ

Actual motor speed: RPM

AmpsinozAmpsRPM

KRIn

mo 2381*21.8

71.2*13503759**1350 1 =−=−

Figure 5.7 – Screw jack motor current drawn The speed as a percent of no-load speed is 90.36%, which does not fully utilize the motor

but we sized the motor because of the gearbox requirements. The percent of torque

compared to the stall torque is 4.41%, which is low utilization, however this motor seems

to be the most appropriate in other aspects.

5.10 Cart Recognition

The recognition system will consist of the before mentioned video camera as well as

three infrared sensors. The video camera will use its abilities of object edge recognition

and color sensing to track down and hitch up to the medical cart. The infrared sensors

will read three patches on the medical cart that can either be black or white. This will

give eight different combinations. This will be enough to differentiate the various

medical cart sizes and cycles. The downfall of this system will depend on the robot

latching onto the medical cart prior to the recognition system identifying the medical cart.

40

This will not be a concern for the most part however if the robot has to sort a lot of

medical carts to match two for the same cycle, it will become a concern.

5.11 Overall design/Analysis Conclusion

The overall concept for our robot is a four-wheel design. The front wheels will drive the

medical cart while the back wheels will allow motion in any direction. The turning will

be accomplished by the speed differentiation in the drive wheels. The medical cart will be

lifted by the cubic screw jack. This design can be seen in figure 5.8 below.

Figure 5.8 – Overall Design of Robot

41

6.0 Future Plans

At this point, the team has completed the first six steps required to finish the project. The

team is ready to start the assembly of chosen components and then begin testing the

robot. Changes are expected on the robot housing and on components used. This is due

to future changes on medical cart requirements for safety, motor, and battery sizes.

The team will start performing tests on the robot to acquire knowledge of the problems

that can come up and check for the best way of task completion. This can be done and

learned by:

• Taking the needed measurements by completing tasks one after the other.

• Comparing the team results with the manufacturer component data, so the team

will be able to validate their experiments.

• Software simulation results.

The experimentation will prove that the concept will work and will act as a starting point

for improvement from future teams. The team is going to use AutoDesk Inventor for

mechanical design and C programming for microcontroller design.

6.1 Experimentation

Several experiments must be done to the robot. First, the team must validate that the

performance objectives and specifications have been met. Then, the team will build a

specification table to show the relationship between space, safety, working time and

charging time.

In order for the team to validate the performance objectives and specifications, the speed,

power, torque, and pulling force of the robot will need to be determined. The team will

also need to find the efficiency of the robot. This will be done by continuous testing on

42

various combinations of robot-required tasks, along with precision, power management,

and communication and timing performance.

6.2 Schedule A schedule has been developed for the spring quarter that will keep the team on track to

finish the project on time. The schedule, shown below, has been designed to give the

team an idea of which activities it should be working on and when they should be

completed rather then to describe the day-to-day work of the team.

March April May Task Name 3/12 3/19 3/26 4/2 4/9 4/16 4/23 4/30 5/7 5/14Delivery of components Assembly of Robot Develop Software Testing Program in Microcontroller Test each component with microcontroller Test tasks Test final design Final report Final presentation Critical design review

Figure 6.1 – Spring Quarter Schedule 6.3 Budget The team’s budget is $10,000 provided by Getinge. This money is to be used for building

and testing of the robot. According to the Bill of Materials, the amount spent is less than

$5000. This is a good projection that the entire system can be manufactured for under

$10,000.

43

7.0 Conclusion

The senior design team has completed the first six design processes this quarter. These

include the needs assessment, project objectives, project specifications, concept

development, feasibility assessment, the analysis and synthesis of design and the

preliminary design documents.

The robot designed is the first step toward a working robot. The present design is a proof

of concept, which in the future can be used to take the robot to market. The goal of the

team is to develop, fabricate, and test a robot capable of loading and unloading a washing

machine in a variety of locations.

The team developed four concepts and assessed their feasibility. The concepts include

different sizes, attachment methodology and communication. Although each concept

compared well with the baseline design, the team decided to proceed with the specified

design discussed. This decision was based upon the results of the feasibility analysis, the

constraints, and the company’s requirements. The team will justify the components used

upon testing the robot.

An analysis of several aspects of the robot was completed. A variety of calculations were

done to determine the pulling strength due to frictional effects and weight. Two flow

charts were developed showing the robot’s steps on every move and communication.

Finally, an analysis was done to select the microcontroller that will be used to control the

movements of the robot.

By the end of the spring quarter, the team will have fabricated a robot capable of

completing the tasks required. The team will conduct several experiments designed to

44

analyze the performance of the robot. The experimental results will also be used to

validate the software for future use.

45

References: Product Specification: Model 2040 Automated Loading and Unloading System, Specification Number: 360246, Getinge Sourcing. LLC. Hazard Analysis, Series 7800/7900 Health Care Washers, Specification Number: 360231, Getinge Sourcing. LLC. Design Control Procedure, 8/04/03, QSP # 110, Rev. E, Getinge Sourcing. LLC. Data and Specifications, Model 7800 Series Floor Loading Cart Washer, Getinge USA. http://www.motioncontrol.com http://www.maxonmotorusa.com/ http://www.micromo.com/ http://www.superdroidrobots.com/trekker_drive.htm http://www.oopic.com http://www.robotcombat.com/marketplace_motors.html http://www.lynxmotion.com http://www.robotics.com http://www.mobilerobots.com http://www.activrobots.com/ http://www.engr.iupui.edu/me/courses/fproject.shtml http://www.atmel.com/dyn/resources/prod_documents/doc1253.pdf http://microcontrollershop.ucpros.com/product_info.php?products_id=154 http://www.keil.com/mcb517/ http://eet.etec.wwu.edu/CPU12/PODInstrs.pdf http://www.post-gazette.com/businessnews/20011025aethon1025bnp2.asp http://www.irobot.com

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http://www.aai.ca/robots/index.html http://www.robotbooks.com http://www.medtronic.com/semi/products/microcontrollers.html http://microcontroller.com/default.asp http://www.samsung.com/Products/Semiconductor/common/product_list.jsp?family_cd=LSI060101 http://www.robotstorehk.com/sensor.html http://www.aethon.com/ http://www.angelusresearch.com

47

List of Appendices

Appendix A: Software Flowcharts Appendix B: Sample Storage Layout Appendix C: Circuit Block Diagram Appendix D: Bill of Materials Appendix E: Order Forms Appendix F: Design Drawings Appendix G: Technical Drawings Appendix H: Calculations

Appendix B: Sample Storage Layout

Appendix A: Software Flowcharts

Appendix C: Circuit Block Diagram

Appendix D: Bill of Materials

Appendix E: Order Forms

Appendix F Design Drawings

Appendix G: Technical Drawings

Appendix H: Calculations

Apply Charge

battery full

standby

Yes

No

Charge

5 min tillfinish wash

charge to cart

Yes

No

Charging Load Side

Charge

1 min tillfinish wash

charge to washer

Yes

No

Unload Side

follow parking line

obstacelaviodance

follow line toparking area #2

at parking area #1

Cart Available

Hook to Cart

Charger to Parking

Yes

No

Search for Carts

Yes

No

obstacelaviodance

at parking area #2

Cart Available

Yes

No

Search for Carts

No

Hook to Cart

Yes

Wait

Battery LowNo

Yes

Charge

Hook onto Cart

Detect cart

Rotate ifnecessary

go under cart

find barcode

Yes

No

Read Cart TypeLift Pin

Cart to Washer

go around left

obstacle

obstacle

obstacle avoidance

Yes

No

stop wait3 seconds

Yes

left clear right clearNo

continue

No

go around right

Yes

call for help

No

Yes

follow parking line

obstacelaviodance

backup

at washer

end of washer

Remove Pin

parking to washer

Yes

No

enter washer

Yes

cart #1 Cart #2possible

No

Get cart

No

start washer cycle

Yes

return tocharging area

No

Yes

check area 2

empty

wait

check area 1

Yes

battery low

No

Yes

No

empty

battery low

Yes

charge

No

return

Washing Machine

charging area

Parking AreaSMALL CARTS

Parking AreaLARGE CARTS