A REAL TIME VIDEO TRACKING AND WIRELESS SPEED CONTROL FOR MILITARY APPLICATION

SIBAWAIHI MACCIDO

A project report submitted in partial fulfillment of the requirements for the award of degree of Bachelor of Engineering (Hons) in Electrical & Electronics Engineering (Control)

UNIVERSITY OF EAST LONDONDECEMBER 2011

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DECLARATION

I hereby declare that this project entitled A Real Time Video Tracking and Wireless Speed Control for Military Application has been done by me and no portion of the work contained in the report has been submitted in support of any application for any other degree or qualification of this or any other university or institute of higher learning.

Name: ______________________Signature:____________________UEL ID:_____________________Date:________________________

Supervisors Signature:_____________________Supervisors Name:________________________Date:____________________________________

DEDICATION

To my late brother Abdul-Satar Maccido

ACKNOWLEDGEMENTS

Thanks be to Allah (S.W.A) verily,when He intends a thing,Hiscommand is, "be", and it is!I would be very remised if I did not thank the many people who helped me survive the birthing of my project.My parents have been my rock; I dont know how anyone does this without a Dads good advice and a Moms shoulder to cry on.My supervisor, Mdm. Sreeja continues to guide my career with genius and finesse. It is very comforting to know that I am in such good hands.I wont forget Bashir Ibrahim Zwall and Sharavanan my course mates extraordinaire, they made all the difference to my sanity both on and off the road. I am eternally grateful.Thanks to Ms Mary Alvean, first for your unwavering faith in my work, and second for polishing that work until it shines.Thanks to Mr Ery the programming lecturer for being so in tune with my project and helping me find the best ways to express it.Most of all, thank you to all my classmates I firmly believe that you are the most hardworking, intelligent and dedicated mates in the whole world.

ABSTRACT

The aim of this project is to design a real time video tracking, wireless speed and position control system based on PWM control logic using microcontroller for Military application. The project is strictly concerned with; wireless communication and remote control, real time video tracking, speed and position control, and lastly a closed loop model on the receiver section. In order to achieve wireless communication and remote control, RF transmitter and receiver module was designed using microcontroller based technology. To implement a real time video tracking, wireless camera and Bluetooth serial link is used. More also, to achieve closed loop position and speed control of dc motor, PIC microcontroller is used based on its built-in PWM circuitry that generates square wave of different duty cycle. To accomplish a closed loop model, optical disc mounted on the motor shaft is fed back to the microcontroller. To achieve speed measurement, optical encoder is used based on back e.m.f. . The microcontroller is interfaced with Liquid Crystal Display (LCD) for speed display purposes. A laser gun has been installed on the robot so that it can fire an enemy remotely when required. This is not possible until a wireless camera is installed. Wireless camera sends a real time video which could be seen on a remote monitor and action can be taken accordingly. The motor driver (H-bridge) is used to control the direction of the motor. Visual Basic 6.0 is used as a tool to design the Graphical User Interface (GUI) on the PC. At the end of this project, a closed loop speed control is obtained on the receiver section. The speed of the robot is controlled at 10rpm, 8rpm and 5rpm for fast, average and slow respectively. The position of the laser gun is controlled at 15 degrees, 25 degrees and 45 degrees for point down, point medium and point up respectively. A real time video tracking is performed up to 328.083 ft away. Hence, the project has met its main objective.

Table of ContentsDECLARATIONiiDEDICATIONiiiACKNOWLEDGEMENTSivABSTRACTvLIST OF ABBREVIATIONSxvCHAPTER 1: INTRODUCTION11.1 Overview of the Project11.2 Background Study of the Project11.3 Problem statement21.4 Aim of the project21.5 Objectives of the project21.6 Scope of the project31.7 Organization of the report3CHAPTER 2: THEORETICAL BACKGROUND AND LITERATURE REVIEW52.1 Theoretical background52.1.1 Principle of operation of a Direct-Current motor52.1.2 Significance of back Electromotive Force52.1.3 Speed control of Direct-Current Motor62.1.4 Speed control by using tachometer62.1.5 Speed control by using optical encoder72.2 Literature Review92.2.1 Reviews on video tracking and wireless speed control robotics from 1966 to 20089CHAPTER 3: SYSTEM DESIGN143.1 Overview of the design process as block diagram143.1.1 Wireless transmitter and receiver section block diagram and description153.1.1.1 Wireless transmitter section block diagram and description153.1.1.2 Wireless receiver section block diagram and description163.2 Hardware design details183.2.1 Microcontroller183.2.1.1 Choice of microcontroller183.2.1.2 PIC microcontroller for transmitter and receiver193.2.2 Power supply circuit203.2.2.1 Transformer and regulator IC choice203.2.2.2 Power supply simulation and discussion213.2.2.2.1 Decoupling Capacitors and bridge rectifier213.2.2.2.2 Desired output parameters213.2.2.2 Power supply design calculations233.2.2.3 Parameters selection and circuit design calculations263.2.2.3.1 MC oscillator design calculations and simulation263.2.2.3.2 Frequency selection263.2.2.3.3 Justification of results using Multisim 10.0273.2.2.4 Choice of resistors between MC and encoder303.2.2.4.1 Calculated results303.2.2.4.2 Simulated results for pull up resistor313.2.3 DC MOTOR313.2.3.1 DC MOTOR DRIVER CIRCUIT323.2.3.1.1 Motor driver L293D INPUT CIRCUIT323.2.3.1.1.1 Transistor used as an electronic switch323.2.3.1.1.2 Analysis of a transistor switching circuit for cutoff and saturation333.2.3.1.1.2.1 Conditions in cutoff333.2.3.1.1.2.2 Conditions in saturation333.2.3.1.1.3 Design calculations of the L293D driver input circuit343.2.3.1.1.3.1 Condition 1 (transistor in cutoff)343.2.3.1.1.3.1.1 Verification of transistor results in cutoff region by voltage divider rule353.2.3.1.1.3.1.2 Using ohms law to determine the Base Current 353.2.3.1.1.3.1.2 Condition 2 (transistor in saturation)363.2.3.1.1.3.1.2.1 Verification of transistor results in saturation region by Voltage Divider Rule373.2.3.1.1.3.1.2.2 Using Ohms to determine the Base Current 373.2.3.1.1.4 Transistor circuit simulation using ISIS 7 professional software383.2.3.1.1.4.1 Simulation of transistor in cutoff region using Proteus383.2.3.1.1.4.2 Simulation of transistor in saturation using Proteus393.2.4 Design of interfacing circuits403.2.4.1 Interfacing Serial (DB9) with PC403.2.4.2 Interfacing MAX232 with serial (DB9)413.2.4.3 Interfacing MAX232 with PIC16f873A423.2.4.4 Remote control encoder PT2262 and decoder PT2272433.2.4.5 RF transmitter and receiver module443.3 REAL TIME VIDEO TRACKING453.4 MECHANICAL DESIGN453.5 SOFTWARE DESIGN463.5.1 Flow chart of transmitter and receiver section473.5.2 Flow charts description513.5.3 PWM CONTROL LOGIC52CHAPTER 4: HARDWARE AND SOFTWARE DESIGN AND IMPLEMENTATION534.1 Schematic diagram534.1.1 Wireless transmitter schematic diagram534.1.2 Wireless receiver section schematic diagram554.1.2.1 IR sensor schematic574.1.3 Optical encoder574.1.4 DC Motor drive574.2 PCB design rules594.2.1 Working from the Top594.2.2 Tracks594.2.3 Soldering604.2.4 Electrical Testing604.2.5 PCB designs604.3 Software implementation634.3.1 Programming in Mikro C634.3.1.1 Process explanation of main program634.3.1.2 Initialization of the mode of ports634.3.2 PROGRAM DESCRIPTION654.3.2.1 LCD Pin descriptions744.3.2.2 Initialization of PWM764.3.2.3 Initialization of TIMER0 in Timer Mode784.3.2.4 Setup for Serial port794.4 Programming in Visual Basic 6.0814.4.1 Proteus VSM for PIC16824.4.2 Visual basic 6.0 with ISIS 7 professional844.4.2.1 Virtual serial port844.4.2.2 Visual basic 6.0 with Proteus ISIS 7 professional results844.5 Project prototype89CHAPTER 5: RESULTS AND DISCUSSION905.1 Overview of Results905.2 Microcontroller905.3 Motor Driver Circuit915.4 Open loop Speed Control925.5 IR sensor955.5.1 IR sensor designed calculations955.5.2 IR sensor output voltage965.5.3 IR sensor characteristics975.6 Closed loop Speed Control985.7 PWM outputs1015.8 Message and Received Signals1035.9 Real time video tracking outdoor testing results1055.10 PROBLEMS ENCOUNTERED1065.10.1 Mechanical1065.10.2 Hardware1065.10.3 Software107CHAPTER 6: CONCLUSION AND FUTURE RECOMMENDATION1086.1 Conclusion1086.2 Future Recommendations108REFERENCES110APPENDIX: AGANTT CHART113APPENDIX B: RECEIVER SECTION C PROGRAM114APPENDIX C: MECHANICAL DESIGN USING SOLID WORKS120APPENDIX D: VISUAL BASIC PROGRAM121APPENDIX E: HARDWARE TESTING RESULTS124

List Of Figures

Figure 2.1.4.1: Direct Current motor coupled with tachometer in block form6Figure 2.1.5.1: Optical encoder rotating disk showing a ray of light from light source pointing at the photo detector7Figure 3.1.1.1.1: Wireless transmitter section block diagram15Figure 3.1.1.2.1: Wireless Receiver Section block diagram17Figure 3.2.2.1.1: Battery powered power supply20Figure 3.2.2.1.1: Transformer powered power supply21Figure 3.2.2.1.1: Power supply simulation using 12 V DC as source voltage23Figure 3.2.2.1.2: Power supply simulation using 230 V, 50Hz as source voltage23Figure 3.2.2.1.3: Oscilloscope output ac to dc level voltage23Figure 3.2.2.3.3.1: MC oscillator28Figure 3.2.2.3.3.2: Frequency counter displaying 4MHz crystal28Figure 3.2.2.3.3.3: Frequency counter displaying Period of 250 nsec29Figure 3.2.2.4.2.1 simulated result for pull up resistor31Figure 3.2.3.1.1.1.1: Ideal switching action of a transistor schematic32Figure 3.2.3.1.1.3.1.1: Transistor in cutoff region schematic34Figure 3.2.3.1.1.3.4.1: Transistor in saturation region schematic36Figure 3.2.3.1.1.4.1.1: Proteus simulation showing transistor in cutoff region38Figure 3.2.3.1.1.4.1.1: Proteus simulation showing transistor in saturation region39Figure 3.2.4.2.1: RS23 Interface with Max23242Figure 3.2.4.3.1: MAX232 interface with PIC16F873A42Figure 3.5.1.1: Flow chart of program in Visual basic 6.048Figure 3.5.1.2: Flow chart of transmitter section in Microsoft Visio software49Figure 3.5.1.3: Flow chart of receiver section in Microsoft Visio Software50Figure 3.5.1.3: Receiver section flow chart interrupts process51Figure 4.1.1.1: Wireless transmitter schematic diagram54Figure 4.1.2.1: Wireless receiver schematic diagram56Figure 4.1.2.1.1 IR sensor schematic57Figure 4.2.1.1: Transmitter section PCB61Figure 4.2.1.2: Receiver section PCB62Figure 4.2.1.3: IR sensor section PCB62Figure 4.3.1.2.1: Configure input and output port64Figure 4.3.1.2.2: Define motor output pins65Figure 4.3.2.1: Define motor output pins66Figure 4.3.2.2: Off interuppt process66Figure 4.3.2.3: Setting baud rate at 9600bps67Figure 4.3.2.4: Read input port67Figure 4.3.2.5: Program to send 1000 if F is given as the input68Figure 4.3.2.6: Program to send 0100 if Bis given as the input69Figure 4.3.2.7: Program to send 0010 if L is given as the input69Figure 4.3.2.8: Program to send 0001 if R is given as the input70Figure 4.3.2.9: Program to send 1000 if F is given as the input71Figure 4.3.2.10: Program to send 1100 if 1 is given as the input71Figure 4.3.2.11: Program to send 1010 if 2 is given as the input72Figure 4.3.2.12: Program to send 1001 if 3 is given as the input72Figure 4.3.2.13: Program to send 1110 if 4 is given as the input73Figure 4.3.2.14: Program to send 0111 if 5 is given as the input73Figure 4.3.2.15: Program to send 1101 if 6 is given as the input74Figure 4.3.2.16: Program to send 1011 if 7 is given as the input75Figure 4.3.2.17: Program to send 0101 if 8 is given as the input75Figure 4.3.2.12: Configure LCD77Figure 4.3.2.2.1: PWM output78Figure 4.3.2.2.2: Simplified PWM block diagram78Figure 4.3.2.3.1: Timer1 block diagram80Figure 4.3.2.4.1: USART transmit block diagram81Figure 4.3.2.4.2: USART received block diagram82Figure 4.3.2.4.3: Setting the baud rate82Figure 4.4.1: Visual basic GUI83Figure 4.4.1.1: Transmitter and receiver circuit simulation using ISIS 7 professional85Figure 4.4.2.1.1: Virtual Terminal for data display86Figure 4.4.2.2.1: Forward button is pressed hence the motor moves in clockwise direction (1010)88Figure 4.4.2.2.2: Reverse button is pressed hence the motor moves counterclockwise direction (0101)89Figure 4.4.2.2.3: Left button is pressed hence the motor moves in leftward direction (1000)90Figure 4.4.2.2.4: Right button is pressed hence the motor moves in right direction (0010)90Figure 5.4.1: Fast (speed at 10 RPM)94Figure 5.4.2: Average speed at (8 RPM)95Figure 5.4.3: Slow (speed at 5 RPM)96Figure 5.5.1.1: IR sensor to determine R197Figure 5.5.1.2 IR sensor simulation output at black time98Figure 5.5.1.3 IR sensor simulation output at white time98Figure 5.5.2.1: Sensor characteristics99Figure 5.6.1: Closed loop response graph with speed maintained at 10 rpm100Figure 5.6.2: Closed loop response graph with speed maintained at 8 rpm101Figure 5.6.3: Closed loop Response graph with speed maintained at 5 rpm102Figure 5.7.1: PWM output showing the graph of motors running at slow speed 5 rpm103Figure 5.7.2: PWM output showing the graph of motors running at average speed 8 rpm104Figure 5.7.3: PWM output showing the graph of motors running at Fast speed 10 rpm104Figure 5.8.1: Message signal [Voltage Vs time]105Figure 5.8.2: Received signal [Voltage Vs time]105Figure 5.9.1: Real time image captured at CH1106Figure 5.9.2: Real time image captured at CH1106

List of TablesTable 3.2.2.3.3.1: Frequency and period output parameters29Table 3.2.4.1.1: RS232 pin assignments (DB9 PC signal set)40Table 3.2.4.2.1: RS232 Line Type and Logic Level41Table 4.2.2.1: Motor driver data inputs58Table 5.2.1 Voltage regulator LM780592Table 5.3.1 Voltage regulator LM781293Table 5.4.1 Open loop speed Measurements obtained when the reference input was set at fast speed94Table 5.4.2 Measurements obtained when the reference input was set at Average speed94Table 5.4.3 Open loop speed measurements obtained when the reference input was set at fast speed95Table 5.5.1.1 Sensor outputs represented in tabular form98Table 5.6.1 Closed loop speed measurements obtained when the reference input was set at fast speed100Table 5.6.2 Closed loop speed measurements obtained when the reference input was set at fast speed100Table 5.6.3 Closed loop speed measurements obtained when the reference input was set at fast speed101

LIST OF ABBREVIATIONS

PC -Personal ComputerPCB -Printed Circuit BoardDC -Direct CurrentPIC -Peripheral Interface Controller NASA -National Aeronautics and Space AdministrationEEMO -Extreme Environment Mission OperationRS232 -Recommended Standard 232IC - Integrated CircuitMC - MicrocontrollerI/O -Input / OutputTTL -Transistor-Transistor LogicIR -Infra RedOSC -OscillatorRX -ReceiverTX -TransmitterLCD -Liquid Crystal DisplayPWM -Pulse Width ModulationAC -Alternating currentRF -Radio-FrequencyUSB -Universal Serial BusRx -ReceiverRAD -Rapid Application DevelopmentEMF -Electro Motive ForceVB -Visual BasicGUI -Graphical User InterfacePID -Proportional Integral ControllerRPM -Revolutions Per MinuteUSART -Universal Synchronous Asynchronous Receiver Transmitter

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CHAPTER 1

INTRODUCTION

1.1 Overview of the Project

This chapter gives an overview of the whole project, starting with the project background, problem statement, project objectives, and scope.

1.2 Background Study of the Project

As robotics technology is rapidly advancing, removing humans from the battlefield may change a societys understanding of war and how it may be conceptualized. Unmanned robotic systems replacing humans in acts of conflict conveniently suits a nation intolerance of casualties during violent conflict because robotic systems are capable of solving repeated problems more efficiently and effectively than human beings. In addition, further removing humans from the process of war may give the appearance that war is an impersonal activity that does not physically or emotionally burden the populace (McDaniel 2008). Robotics is a wide technology area that also encompasses a subset of valuable enabling technologies. Teleported mobile robotic systems are remotely operated vehicles designed to perform tasks in coordination with human operators. However, teleportation can be realistically enhanced by a level of automation removing challenges such as constant monitoring (Dastur, 2009). The aim of this proposal is to develop a video tracking and wireless speed control using microcontroller for military application. Teleoperating the robot from the remote location will allow a user to have complete command and control over the robot via visual aids which keeps the operator aware of the remote environment, thus enabling him to witness the accomplishment of task. 1.3 Problem statement

Nowadays, in military application, one of the long standing challenging aspect in mobile robotics is the ability to maintain a real time video tracking and wireless speed control, avoiding obstacles especially in battlefield and unknown environment. The requirement to get rid of delay to obtain a real-time location of an object would reduce the number of military personnel injured or killed in combat situations. To overcome these issues, a real time video tracking and wireless speed control for military application is introduced (Ogata, 2002). The features of combat robot and wireless camera are proposed here in this project. The accuracy and tracking performance of the robot can be improved using closed loop feedback (complex structure that can compensate all disturbances). The variation and accuracy of the speed can be improved using PWM controller.

1.4 Aim of the project

The aim of this project is to design a real time video tracking and wireless speed control robot using microcontroller for military application.

1.5 Objectives of the project

Specifically, the objectives are:1. To design a transmitter and receiver module using microcontroller.2. To perform video tracking using wireless camera, and3. To perform wireless speed, position, and firing options control based on PWM. Lastly, closed loop model on the receiver section.

1.6 Scope of the project

The general aim of the study is to design a video tracking and wireless speed control of military robot. This robot is radio operated; self powered, and has all the controls like a normal car. It has got gun and camera mechanism installed on it. The laser provides options for firing an enemy remotely when required; this is not possible until a wireless camera is installed. The camera sends real time video which could be seen on a remote monitor so that action can be taken accordingly. The robot can silently enter into enemy area and send all the information through its tiny camera eyes. It is designed for fighting as well as suicide attack.Furthermore, we will then focus on elaborating and designing a suitable transmitter and receiver module using microcontroller-based circuit. A PIC microcontroller was selected for this project but there are other microcontrollers like the 8051 series, Motorola, Hitachi, Texas and Arm which can be equally useful. Finally, priority will be given to the software design and implementation in order to develop a suitable algorithm that will prompt interaction with the military robot.

1.7 Organization of the report

The work presented in this thesis has been covered in six Chapters.

Chapter 1 provides some introduction through background study, aim, objectives and scope of the project.

Chapter 2 discusses the literature review carried out by analyzing similar works done in the past and some recent relevant research in the field.

Chapter 3 begins with relevant theories and simulation of various circuits. It also includes concise PWM control logic and its application on the current system.

Chapter 4 includes detailed information on circuit schematic, PCB design and microcontroller source codes.

Chapter 5 lists all of the hardware and software testing results and concludes with a detailed analysis on each of them.

Chapter 6 concludes the work done throughout the project and provides few recommendations on improving efficiency for systems to be designed in the future.

CHAPTER 2

THEORETICAL BACKGROUND AND LITERATURE REVIEW

2.1 Theoretical background

In order to familiarize myself with the project, some theoretical background research on the topic was carried out. This research included relevant theories on Direct Current motor, its principle of operation, significance of its back e.m.f, its speed measurement, model of separately excited Direct Current motor, last but not the least Direct Current motor controller.

2.1.1 Principle of operation of a Direct-Current motor

Based on the research it was understood that a motor is a device that converts an electrical energy to mechanical energy. According to Faradays law, whenever a current carrying conductor is placed in a magnetic field; it experiences a mechanical force. Hence, when a supply is given, the interaction between the flux produced by the current carrying conductor and the flux produced by the permanent magnet called the main flux, magnetic repulsion and attraction takes place, this exerts a magnetic force on the conductor which causes the rotation on the system.

2.1.2 Significance of back Electromotive Force

The speed of the motor can be measured based on the concept of back e.m.f induced in the motor when it is running. At normal running condition, the difference between back e.m.f and supply voltage is very small. Back e.m.f regulates the flow of armature current and it automatically alters the armature current to meet the load requirement. According to Faradays law of electromagnetic induction whenever a conductor cuts the lines of flux, e.m.f will be induced in the conductor. This induced e.m.f in the armature always acts in the opposite direction of the supply voltage. According to Lenzs law, the direction of induced e.m.f is always opposite with the main cause producing it.

2.1.3 Speed control of Direct-Current Motor

To start with this project, a device that will measure the speed to enable closed loop control of the motor shaft is needed. Currently, there are several methods which can be used to measure the speed. However, we will discuss speed measurement by using optical encoder and tachometer.

2.1.4 Speed control by using tachometer

The speed measurement using tachometer is based on the concept of back e.m.f induced in the motor at running condition. The direction of induced e.m.f is always opposite with the main cause producing it.

Figure 2.1.4.1: Direct Current motor coupled with tachometer in block form

The magnitude of the e.m.f is given by;

where; Electromotive force Constant based on motor rotation Magnetic flux Speed rotation in revolution per minuteHence, the actual relationship between motor speed and back E.M.F is given as:

Thus, the motor speed is directly proportional to the E.M.F voltage and inversely proportional to the field flux.

2.1.5 Speed control by using optical encoder

The optical encoder type is one of the best methods to measure speed of dc motor. This contains an optical disc, which has slots cut into it, that shines a beam of light from a transmitter across a small space and detects it with a receiver the other end. The signal is picked up when a slot is between the transmitter and receiver. Figure 2.1.5.1: Optical encoder rotating disk showing a ray of light from light source pointing at the photo detector

This will have an output that switch to +5V when the light is blocked, and about +0.5V when the lights is allowed to pass through the slots in the disc. The frequency of the output waveform is given by;

where; Frequency of output waveform Speed of the motor in revolution per minute Number of slots at the disc

Hence, from the frequency equation, the speed of dc motor in rpm is given by;

At the end of this study, the operation of dc motor is understood. Also, different types of speed measurement techniques have been discussed. Lastly, IR sensor will be used for the speed measurement in this project as it was recommended one of the best techniques for speed detection.

2.2 Literature Review

2.2.1 Reviews on video tracking and wireless speed control robotics from 1966 to 2008

Researchers have pioneered the art and science of robotics technology over the past 66 years. Mobile robotics research has played a key role in the application of robots in our world. A mobile robot is a mechanical device that can perform preprogrammed physical task; it may act under the control of a human or under the control of preprogrammed software (Li, 2001). Teleoperated mobile robotics is remotely operated vehicles designed to perform tasks in coordination with human operators (Dastor, 2009). Teleoperated mobile robotics can be realistically enhanced by a level automation removing challenges such as constant monitoring. Nils Nilsson developed the first mobile robot SHAKEY at Stanford University from 1966 to 1972. It was the first mobile robot with the ability to reason and react to its environment. This robot possessed a visual range finder, a camera and binary tactile sensors. It was the first mobile robot to use artificial intelligence to control its actions. Its main objective was to navigate through highly structured environments. Shakey has had a substantial influence on present-day artificial intelligence and robotics. Using a TV camera, a triangulating range finder, and bump sensors, Shakey was connected to DEC PDP-10 and PDP-15 computers via radio and video links. Interoperating programs with varying levels of sophistication provided Shakey with the ability to combine simple movements and environmental perception into robust, complex tasks, enabling it to achieve goals given by a user. The system also generalized and saved these plans for possible future use. Inducted into the Robot Hall of Fame in 2004, Shakey is today on display at the Computer History Museum in Mountain View, California (Nilsson, 1984).Lunar rover, developed in the 1970s at the Jet Propulsion Laboratory, was designed for planetary exploration. Using a TV camera, laser range finder and tactile sensors, the robot categorized its environment as traversable, not traversable and unknown. Alunar roverorMoon roveris aspace explorationvehicle designed to move across the surface of theMoon. Some rovers have been designed to transport members of ahuman spaceflightcrew, such as theApollo Lunar Roving Vehicle; others have been partially or fullyautonomous robots, such asLunokhod 1 (Weisbin, et al., 2008).Flakey was developed between 1982 1995; fully functional in 1985. It was a mature custom-built mobile robot platform, approximately one meter high and 0.6 meter in diameter. The hardware has remained stable with relatively minor additions to the sensing and communications capabilities since 1985. There are two independently-driven wheels, one on each side, providing a maximum linear velocity of about 500mm/sec and turning velocity of 100 deg/sec. Flakeys sensors included a ring of 12 sonar range finders, wheel encoders, and a video camera used in combination with a laser to provide dense depth information over a small area in front of the vehicle. Flakeys onboard computers included a workstation and other processors dedicated to sensor interpretation, motor control, and radio communications (Saffioti, 1993).Hans Moravec developed CART in the Artificial Intelligence laboratory at Stanford. Cart is a card-table sized mobile robot controlled remotely through a radio link, and equipped with a TV camera and transmitter. A computer has been programmed to drive the cart through cluttered indoor and outdoor spaces, gaining its knowledge about the world entirely from images broadcast by the onboard TV system and performed obstacle avoidance by gauging the distance between CART and obstacles in its path. The system is moderately reliable, but very slow. The cart moves about one meter every ten to fifteen minutes, in lurches. After rolling a meter, it stops, takes some pictures and thinks about them for a long time. Then it plans a new path, and executes a little of it, and pauses again. Moreover, In 1964-71The cart evidently sat unused in an ME laboratory until 1966 when Les Earnest, a senior research scientist who had recently joined the Stanford Artificial Intelligence Lab (SAIL), found it and talked its creator, James Adams, into letting SAIL use it to try navigating on the road around SAIL under computer control using visual references. However the radio links and other electronics that had existed earlier had vanished, so he recruited Electrical Engineering PhD student Rodney Schmidt to built a low power television transmitter and radio control link and undertake the visual guidance project (Moravec, 1983).From 1993 to 2001 LURCH (for Large, Useful Robot Controlling Hazards) was designed for control of robot functions in realistic outdoor terrain and is operated using high-level directives from a remote station connected via a packet-switched radio network. LURCH was created by modifying an Andros Mark V-A robot from Remotec, Inc. to incorporate SRIs planning and control system. Enhancements include onboard control of the mobile base and a manipulator arm based on a ruggedized PC system. Onboard sensors include stereoscopic vision, 16 ultrasonic sensors, and encoders for all robot, manipulator, and camera motions.ERRATIC and Pioneer 1994present, is a smaller version of flakey with the same differential drive and sonar sensors, but without vision capabilities. Addressing the need for an easy-to-construct, low-cost robot development platform, SRI designed ERRATIC to run as a robot server from a host computer over a remote serial connection. It provides basic functions of forward/back velocity and angular position integration stall sensing, and sonar ranging. Pioneer I is a production version of the ERRATIC platform. The real-time controller for ERRATIC (Saphira) is based on software developed at SRI on the Flakey project; it was a commercial version by Erratic made by real world. The software runs a reactive planning system with a fuzzy controller, behavior sequencer, and deliberative planner with integrated routines for sonar sensor interpretation, map building, and navigation (Ericson, 2003).From 1995-present robotic systems are becoming smaller, lower power, and cheaper, enabling their application in areas not previously considered. This is true of vision systems as well. SRIs Small Vision Module (SVM) is a compact, inexpensive real-time device for computing dense stereo range images, which are a fundamental measurement supporting a wide range of computer vision applications. We describe hardware and software issues in the construction of the SVM, and survey implemented systems that use a similar area correlation algorithm on a variety of hardware. The hardware consists of two CMOS 320x240 grayscale imagers and lenses, low-power A/D converters, a digital signal processor and a small flash memory for program storage. All of these components are commercially available. The SVM is packaged on a single circuit board measuring 2" x 3" (Figure 1). Communication with a host PC for display and control is through the parallel port. During operation, the DSP and imaging system consume approximately 600mW. SRI is developing the next generation of this device, which will feature nearly a 600-percent performance improvement (Konolige, 1995).The Centibots were developed from 2002 to 2004, they are mobile coordinated robots that can autonomously and effectively explore map and survey the interior of unknown building structures. The Centibots marked a milestone in robotics, representing the largest collection (more than 100) to date of coordinated autonomous mobile robots. These autonomous team robots were designed to augment the situational awareness of human teams such as crisis response teams in situations that could pose a threat to people. Centibots improve upon current robot architectures, which rely on large, power-hungry subsystems for mobility, communication and control, and are limited to only individual or small teams of robots (Konolige, et al, 2003).LAGR was developed 2005 present, Real-time vision and learning technologies are at the core ofthe DARPA Learning Applied to Ground Robotics (LAGR) program to develop autonomous off-road navigation. The goal is to develop sensing- and-camera-based techniques for learning the mobility properties of objects in a new environment and planning and control techniques for using this information to avoid such difficulties as loose sand, bushes, and cul-de-sacs.SRI developed color-and-texture-based techniques for learning and recognizing paths and obstacles; a real-time, stereo-based visual odometry technique for precisely locating the robot as it moved through complex outdoor environments; mapping of features for later runs; and very efficient, low-level control techniques so the robot could rapidly traverse planned paths and quickly free itself (Erkan, et al, 2007).Trauma Pod and Medical Automation Robots was developed 2005 present. SRI is the lead integrator on a collaborative DARPA program to develop a futuristic battlefield-based, unmanned medical treatment system dubbed the Trauma Pod. This system could stabilize injured soldiers within minutes of a trauma and administer life-saving medical and surgical care prior to evacuation and during transport. Related developments are under way: dexterous robotic tools to improve patient outcomes and enable new procedures through development of nimble, smaller endoscopic tools; additional automation tools for the operating room; and remote delivery of trauma care. SRIs M7 surgical robot conducted the first-ever acceleration compensated medical procedure in zero gravity flight for NASA. The M7 was also the first surgical robot to be successfully deployed to an undersea habitat simulating the rigors of outer space in NASAs Extreme Environment Mission Operation (NEEMO), demonstrating remote surgery over 1,200 miles of public Internet. One year later, the M7 demonstrated the first autonomous ultrasound guided medical procedure in the same undersea laboratory. Last but not the least, telerobotics Assistance for the Elderly and Disabled was presented in 2008 by SRIs multidisciplinary approach to solving major global challenges has prompted researchers to invent robot-based solutions that would help manage assistance and care of the elderly and the disabled. Robots built on SRIs telepresence technology could provide real-time remote monitoring, physical support, therapeutic advice, and communication between patient and caregiver, and among the patient, family members, and clinical personnel (Lanuzzi, 2008).From the above journals reviewed, it is concluded that the topic of research is an advanced area of control engineering which is commonly being explored by control engineers. The application of real time video tracking and wireless speed control robot to solve complex problems is rapidly increasing.

CHAPTER 3

SYSTEM DESIGN

3.1 Overview of the design process as block diagram

The block diagram represented in Figure 3.1.1 gives an intuitive description of the various stages involved in order to achieve real time video tracking and wireless speed control. As seen below, the project consists of two parts, transmitter section and receiver section.

Figure 3.1.1: Overview of the design shown as a block diagram

3.1.1 Wireless transmitter and receiver section block diagram and description

3.1.1.1 Wireless transmitter section block diagram and description

The Transmitter section consists of RS232, PIC16F873A microcontroller, encoder, RF TX Module. This section is based on computer control. The visual basic program downloaded into the PC enables the rapid application development (RDP) of graphical user interface which will allow the user to control the speed and positioning of the robot from the computer. This is made possible by interfacing the microcontroller with the computer using MAX232 through RS232 serial communication. RS232 (recommended standard 232) support both synchronous and asynchronous transmissions and its user data is send as a time series of bits. Max232 is an integrated circuit that converts signals from an RS-232 serial port to signals suitable for use in TTL compatible digital logic circuits such as the microcontroller. The serial data sends from the PC through RS232 gets converted to parallel data and is fed to the PIC microcontroller and vice versa. The microcontroller PIC converts the received data to pulses which undergo modulation by the encoder. RF TX transmits the modulated signals to the RF Rx section.

Figure 3.1.1.1.1: Wireless transmitter section block diagram

3.1.1.2 Wireless receiver section block diagram and description

The Receiver section consists of RF receiver module, decoder, Micro controller, motor driver, transistor, and dc motors. RF_RX_315MHz receives the transmitted signals. This signal undergoes demodulation to suppress the carrier and decode back the original data. The output is finally fed to the Micro controller (PIC), which gives the directives to three major circuits respectively. These include the motor-driver circuit, and the firing control and lastly the LCD circuit depending on the user input. Output from the microcontroller is fed to C1815 transistors before going to the L293D motor driver circuit. This is because the motors attached to the output of the driver needs high current to activate. The signals received by the motor-driver circuit will enable the motor to choose the direction that it is supposing to be running in and also to come to a complete stop if that is what the user instructed. Furthermore, one of the signals received from user inputs will be a control reference. The control reference inputted will be fed into the PIC in-built PWM circuit to generate an appropriate duty ratio that will be sent to the wheels of the motor, these PWM control signals will directly control the speed and direction of the dc motor with the aid of the motor driver. The variation of the PWM is directly proportional to the increase and decrease of the motor speed. Notice that, although the voltage has fixed amplitude, it has a variable duty cycle which means the wider the pulse, the higher the speed and vice versa. The signals received by the transistor will turn the laser gun on/off. And lastly, to accomplish a closed loop model, infra red (IR) sensor mounted on the motor shaft is fed back to the microcontroller. Infra red detectors convert incoming infra red light into electric current. The microcontroller is interfaced with Liquid Crystal Display (LCD) for speed display purposes.

Figure 3.1.1.2.1: Wireless Receiver Section block diagram

3.2 Hardware design details

3.2.1 Microcontroller

3.2.1.1 Choice of microcontrollerThere are many types of microcontroller available in the market for example Motorola, Atmel and PIC microcontroller. Although main specifications are a little bit different; however the concepts are similar with each other. Basically, microcontrollers must contain at least two primary components random access memory (RAM), and an instruction set (Hill, 2000). RAM is a type of internal logic unit that stores information temporarily. RAM contents disappear when the power is turned off. While RAM is used to hold any kind of data, some RAM is specialized, referred to as registers. The instruction set is a list of all commands and their corresponding functions. During operation, the microcontroller will step through a program (the firmware). Each valid instruction set and the matching internal hardware that differentiate one microcontroller from another.Most of the microcontrollers also contain read-only memory (ROM), programmable read-only memory (PROM) or erasable programmable read-only memory (EPROM) (Hill, 2000). All of these memories are permanent: they retain what is programmed into them even during loss of power. They are used to store permanent lookup tables. Often these memories do not reside in the microcontroller; instead, they are contained in external ICs, and the instructions are fetched as the microcontroller runs. This enables quick and low-cost updates to the firmware by replacing the ROM. After going through number of journals and books the microcontroller type chosen for this project is a PIC microcontroller. PIC MC is a family of Harvard architecture that has separate storage (program or data memories can have different bits depth) and signal pathways for instruction and data. A microcontroller with Harvard architecture can both read an instruction and perform a data memory access at the same time, even without a cache. It can thus be faster for a given circuit complexity because instruction fetches and data access do not contend for a single memory pathway. 3.2.1.2 PIC microcontroller for transmitter and receiver

In transmitter section, PIC16F873A micro controller is chosen to be used as the control system of the robot. This is due its low power consumption (wide operating voltage range from 2.0 to 5.5 V) high speed Flash/EEPROM technology, easy to program (only 35 single-word instructions execution) and its pin out compatibility to other 28/40pin like PIC16F877A microcontrollers. Furthermore, the PIC 16F873A microcontroller has the ability to withstand both commercial and industrial temperature ranges. However, the most important reason for selecting this chip is because of its built-in PWM Generator module. Pulse Width Modulation is critical to modern digital motor controls. By adjusting the pulse width, the speed of a motor can be efficiently controlled without larger linear power stages. These modules are built into the Capture/Compare/PWM (CCP) peripheral. As previously mentioned PIC16F873A has two CCP modules. Each CCP module is software programmable to operate in one of three modes: 1) A Capture input, 2) A Compare output and 3) A Pulse Width Modulation (PWM) output. For the CCP module to function, Timer resources must be used in conjunction with the CCP module. The desired CCP mode of operation determines which timer resources are required.While in receiver section, PIC 16F877A microcontroller has been selected for the purpose of controlling the speed of the dc motor on the receiver section. It is a simple but powerful controller only 35 single word instructions to program the chip. This controller chip has been selected based on several reasons these are; its portable and consumes less current. Small in size and equipped with sufficient output ports more also, it has built-in PWM module which allow us to vary the duty cycle of the motor drive. And lastly, it provides an ease of programming and reprogramming (up to 10,000,000 cycles). MC communicates with the outside world through the input and output (I/O) port pins. The number of I/O pins per controllers varies greatly, plus each I/O pin can be programmed as an input or output (or switch during the running program). The load (current draw) that each pin can drive is usually low. If the output is expected to be a heavy load, then it is essential to use a driver chip or transistor buffer. The entire pins have multiple functions, depending on the operating mode and data control registers.

3.2.2 Power supply circuit

3.2.2.1 Transformer and regulator IC choice

PIC16F873A microcontroller requires a stable 5V TTL input to activate. Also, the encoder PT 2262 and RF_Tx_315MHz requires stable 9 V TTL input to operates. Power supply circuit is designed for this purpose because dc lead-batteries do not provide consistently stable output voltage. An LM7805 and LM7809 are used to regulate the input voltage. LM78** series has three legs; the input line voltage, the output regulated voltage and common ground. According to the datasheets, the reference voltage should be slightly higher than the desired output voltage hence the source in this circuit is 12 V - 1 A lead acid battery. To avoid the excess energy dissipated on the regulator IC, a heat sink is introduced. A backup circuit is designed using, 230 V ac source, bridge rectifier, filter, regulator and centre tapped step down transformer. From the requirement stated above 5 V dc and 9 V dc level voltages are required to activate the ICs. Therefore, LM7805 and 7809 are needed to regulate the voltage in order to fulfill the requirement. Block diagram for the arrangement is given below.

12 V, DCDiodeFilter LM78**Figure 3.2.2.1.1: Battery powered power supply

In Figure 3.2.2.1.1, the transformer is used to step down the 240 AC supply voltage. A bridge rectifier coupled with filter circuit convert the AC current to DC current and suppresses all the remaining AC levels. The regulator received and regulates the DC voltage to the required level.

230 V, 50 Hz AcTransformer 25:1Bridge Rectifier Filter Regulator LM78**Figure 3.2.2.1.1: Transformer powered power supply

3.2.2.2 Power supply simulation and discussion

3.2.2.2.1 Decoupling Capacitors and bridge rectifier

The bridge rectifier converts AC to DC, the output of the bridge rectifier is fed to the stabilizing capacitors. The decoupling capacitors C1 and C2 are used to stabilize the output in order to maintain a consistently stable output. From Figure 3.2.2.2.3 we can see that the line in blue represents the voltage after been filtered by capacitor C1, the voltage at this stage is 12.245 V. This 12.245 V is regulated to 5 V by LM7805. The remaining ac component is filtered out by capacitor C2 in order to maintain a consistently stable output. Lastly, the desired output has been determined and it represents the voltage level in red.

230 Vrms, 50 Hz AC supply25:1 centre-tapped step down transformerBridge rectifier 1B4B42Filter 2.2 mF and 48 uF capacitor C1 and C2 respectively.Voltage regulator LM7805 Digital voltmeter and Oscilloscope

3.2.2.2.2 Desired output parametersAs stated earlier PIC16F873A microcontroller requires a stable 5 V TTL input to activate. Also, the encoder PT 2262 and RF_Tx_315MHz requires stable 9 V TTL input to operates. Power supply circuit is simulated and it provides consistently stable output voltage using LM7805 and LM7809 to regulate voltage. Most MC operates under a recommended current, 5 mA. If the microcontroller is driving several circuits therefore the current will be set to exceed 5 mA. As seen from Figure 3.2.2.1.1 the desired output current and voltage have been determined. Also, LM7809 regulator was used to determine the dc level voltage that will activate the encoder PT 2262 and RF_Tx_315MHz. From the components prepared, power supply circuit connections were made using Multisim 11.0 software as shown in Figure 3.2.2.1.1 and Figure 3.2.2.1.2. Figure 3.2.2.1.1: Power supply simulation using 12 V DC as source voltage Figure 3.2.2.1.2: Power supply simulation using 230 V, 50Hz as source voltage

Figure 3.2.2.1.3: Oscilloscope output ac to dc level voltage

3.2.2.2 Power supply design calculations

It is of importance to check if the power supply simulation agrees with our calculated values. Referring to figure 3.2.2.1.2 the calculations can be obtained using mathematical equations given below;

The solution given above is for the power supply design calculations, it is based on the design the power supply will be developed. Analysis will be made to see if the design calculations correspond with the hardware implementation. Hence, the objective of this task is accomplished. Also from the power supply simulation the output was regulated to 5 V, 9 V and 12 V which serves as the input supply to the microcontroller circuit, motor driver circuit, and the laser gun circuit.

3.2.2.3 Parameters selection and circuit design calculations

3.2.2.3.1 MC oscillator design calculations and simulation

Microcontroller operates functionally if a clock signal is supplied to it. Availability of different oscillator frequencies makes it necessary to review on past and present works this will lead you towards understanding various types of oscillator frequencies and their respective applications. Therefore, it is required to make the selection depending upon the requirements and specifications, such as; Clock speed (high speed) RC oscillator Low power crystals Internal RC mode

3.2.2.3.2 Frequency selection

In this project it is required to use a high performance crystal with a high speed in order to get rid of delay and speedup wireless transmission of data (bytes). An important notice is stated in the RF module RX_PT 2272 datasheet, say, if the module is used with microcontroller, the frequency should be under 4 MHz. With respect to this a 4 MHz frequency oscillator is selected. This entails that with a clock frequency of 4 MHz, the processor utilized in this project can process data 4 million times in every seconds for every clock cycle. Another reason for its selection is that ceramic oscillator provide more stable frequency signal that other oscillators like RC oscillator although are cheaper and consume less power but produce inaccurate frequency which is not suitable for timing applications. Accordingly, after conducting numerous literatures a consensus is reached and a 4 MHz clock is selected based on energy efficiency (consume less power) and operational speed (stable frequency). Two 22 pF capacitors were use to filter out external noise from interfering the crystal frequency. Aside from the oscillator, another essential circuit for this microcontroller is the Master Reset circuit. Once a low input is given to the pin 1 (MCLR/THV), the microcontroller will be reset and start to execute the very first instruction which is already been programmed into it. Therefore, in the circuit, a pull-up resistor is connected to the pin. Once the pull-up resistor is omitted, the microcontroller will be reset. Now, the period can be obtained by substituting 4 MHz for the clock source. So:Let,The instruction cycle frequency = The instruction cycle time = Now,

(3.2.2.3.2.1)

Therefore the instruction cycle time i.e. the period can be returned as, (3.2.2.3.2.1)

3.2.2.3.3 Justification of results using Multisim 10.0 In this project, Multisim 11.0 software was used in order to justify our calculated results.

Figure 3.2.2.3.3.1: MC oscillator

Frequency Counter was used to verify the amount of frequency fed into the MC as the frequency is the rate at which the periodic waveform repeats itself and is measured in Hz.

Figure 3.2.2.3.3.2: Frequency counter displaying 4MHz crystal

We know that, period (T) is the reciprocal of frequency (), and referred to the time it takes a periodic pulse waveform ( ) to repeats itself at a fixed interval and is measured in sec. Hence, by simulation, the period can be returned as;

Figure 3.2.2.3.3.3: Frequency counter displaying Period of 250 nsec

Table 3.2.2.3.3.1: Frequency and period output parameters

ParametersCalculated valuesSimulated values

Frequency4MHz4MHz

Period250ns250ns

From the results obtained, the simulation results have solemnly justified the calculated results this entails that our design is correct. Therefore, the objectives are achieved.

3.2.2.4 Choice of resistors between MC and encoder

The output from the MC has a limited supply of current which is not enough to transmit data to the encoder. To solve this problem, pull up resistors were connected in series with the MC output pins in order to boost up the current to a mA level that can enable the transmission.

3.2.2.4.1 Calculated results

Design parameters;

;

(3.2.2.4.1.1)

(3.2.2.4.1.2)

(3.2.2.4.1.3)

3.2.2.4.2 Simulated results for pull up resistor

From the result obtained using MULTISIM 11.0 we may say that, the simulation results have justified the calculation results.

Figure 3.2.2.4.2.1 Simulated result for pull up resistor

It should be noted that are selected as. Therefore, the current flowing through each of the above mentioned resistors to activate the encoder is 5.000 mA.

3.2.3 DC MOTOR

This project required the design of a 4 wheel car as it is for military application therefore two motors are required to control the movement of the robot in all direction. However the control is the back wheel type whiles the front wheels moves freely. DC geared motors were selected over the stepper motors because dc motor can deliver high torque at higher speed than steppers, a feedback using IR can be used which can report back to microcontroller the actual operating speed for error correction and lastly, the requirement of the project was that the movement of the robot should be smooth in correspondence with reference input speed which can be realized practically only through dc motors as stepper motors moves in steps upon receiving input signals.

3.2.3.1 DC MOTOR DRIVER CIRCUIT

DC motors draw a relatively higher current in comparison to servo motors. The PIC 16F877A microcontroller can only provide a maximum of 25 mA current from its I/O pins which is insufficient for motor operation. Therefore, an L293D motor driver was used which can provide a maximum of 2.0 A current to dc motors. Also, this IC has an equivalent circuit of a dual H-bridge which implies that one IC is used for bidirectional control of two motors simultaneously.

3.2.3.1.1 Motor driver L293D INPUT CIRCUIT

The output from the microcontroller is approximately a 3.3 mA current and the motor driver L293D needs high current in order to drive the motor, to solve this problem transistor is used as a switch. Transistor, when used as an electronic switch is normally operated alternately in cutoff and in saturation. Digital circuits make use of the switching characteristics of transistors.

3.2.3.1.1.1 Transistor used as an electronic switch

The basic operation of transistor as a switching device is illustrated in Figure 3.2.3.1.1.1.1. In the first part, the transistor is in cutoff region because the base-emitter junction is not forward-biased. In this condition, there is, ideally, an open between collector and emitter, as indicated by the switch equivalent. While in the second part, the transistor is in the saturation region because the base-emitter junction and the base-collector junction are forward-biased and the base current is made large enough to cause the collector current to reach its saturation value. In this condition, there is, ideally, a short between collector and emitter, as indicated by the switch equivalent. Actually, a voltage drop of up to a few tenths of a volt normally occurs, which is the saturation voltage,

Figure 3.2.3.1.1.1.1: Ideal switching action of a transistor schematic

3.2.3.1.1.2 Analysis of a transistor switching circuit for cutoff and saturation

3.2.3.1.1.2.1 Conditions in cutoff

As mentioned earlier, a transistor is in the cutoff region when the base emitter junction is not forward-biased. Neglecting leakage current, all of the currents are zero, and is equal to,

(3.2.3.1.1.2.1.1)

3.2.3.1.1.2.2 Conditions in saturation

When the base-emitter junction is forward-biased and there is enough base current to produce a maximum collector current, the transistor is saturated. The formula for collector saturation current is,

(3.2.3.1.1.2.2.1)

Since is very small compared to, it can usually be neglected. The minimum value of base current needed to produce saturation is;

(3.2.3.1.1.2.2.2)

should be significantly greater than to keep the transistor well into saturation.

3.2.3.1.1.3 Design calculations of the L293D driver input circuit

3.2.3.1.1.3.1 Condition 1 (transistor in cutoff)

The criterion used to analytically determine the output voltage () when the transistor is in cutoff i.e. the Square wave fed to the transistor (C1815) is at 0V can be returned as;*Note: - All resistors chosen are 1 K each

1.0KV+ = 12V1.0K1.0KV+ = 12VFigure 3.2.3.1.1.3.1.1: Transistor in cutoff region schematic

From above diagram it is seen that when the input, the transistor is in cutoff (i.e., it act as an Open switch) and hence 3.2.3.1.1.3.1.1 Verification of transistor results in cutoff region by voltage divider rule

According to the rule, the voltage across an element is equal to the resistance of the element divided by the total resistance of the series circuit and multiplied by the total impressed voltage:Now;

(3.2.3.1.1.3.2.1)

Hence, the output voltage is equal to 12V and is fed to the driver chip L293

3.2.3.1.1.3.1.2 Using ohms law to determine the Base Current

(3.2.3.1.1.3.3)

3.2.3.1.1.3.1.2 Condition 2 (transistor in saturation)

The criterion used to analytically determine the output voltage () when the transistor is in cutoff i.e. the Square wave fed to the transistor (C1815) is at 0 V can be returned as;*Note: - All resistors chosen are 1 K each 1.0KV+ = 12V1.0K1.0KV+ = 12VFigure 3.2.3.1.1.3.4.1: Transistor in saturation region schematic

From above diagram it is seen that when the input, the transistor is in saturation (i.e., it act as an closed switch) and hence

3.2.3.1.1.3.1.2.1 Verification of transistor results in saturation region by Voltage Divider Rule

According to the rule, it states that the voltage across an element is equal to the resistance of the element divided by the total resistance of the series circuit and multiplied by the total impressed voltage:Now;

Hence the output voltage is equal to 0V

3.2.3.1.1.3.1.2.2 Using Ohms to determine the Base Current

Hence, the base current is 0 ATherefore , the design calculations shows that if a 0 V input is fed as an input to a transistor in cutoff region the corresponding output will be the voltage supplied at the collector junction likewise if a 5 V input is fed to a transistor in saturation region the corresponding output will be 0 V. To generate high current the four outputs pins of the PIC microcontroller goes through a transistor to the L293D driver.3.2.3.1.1.4 Transistor circuit simulation using ISIS 7 professional software

Simulation of L293D driver input circuit was performed using ISIS 7 professional software based the above calculated design parameters. The simulation results are shown below.

3.2.3.1.1.4.1 Simulation of transistor in cutoff region using ProteusFrom the aforementioned components, connection were made successfully using ISIS 7 professional as shown in figure 3.2.3.1.1.4.1.1

Figure 3.2.3.1.1.4.1.1: Proteus simulation showing transistor in cutoff region

As explained earlier, the transistor is in cutoff only when the base emitter junction is not forward-biased. Neglecting leakage current, all of the currents are zero. From the diagram above we can see that when the reference voltage V1 = 0 V, its results to a negative current -1.943 pA. According to ohms law, at constant temperature voltage is directly proportional to current. Due to the fact that the circuit is now acting as an open circuit, voltage V2 directly flow through the output. Indicators were used to at the reference and output stage to indicate when the voltage is either high or low. At this condition, the reference stage indicator is low while the output stage indicator is high. This proved to us that the calculated results were correct and can activate the motors. Therefore, the dc output 12 V is fed as an input to the driver IC L293D.

3.2.3.1.1.4.2 Simulation of transistor in saturation using Proteus

The transistor is in saturation only when the base-emitter junction is forward-biased and there is enough base current to produce a maximum collector current. According to ohms law, at constant temperature, voltage is directly proportional to current. From the diagram above we can see that when the reference voltage V1 = 5 V, its results to a positive current 4.277 mA Due to the fact that the circuit is now acting as a closed circuit, voltage V2 does not flow through the output directly. Indicators were used at the reference and output stage to indicate when the voltage is either high or low. At this condition, the reference stage indicator is high while the output stage indicator is low. This proved and justified our calculated results

Figure 3.2.3.1.1.4.1.1: Proteus simulation showing transistor in saturation region

This proved to us that our calculated results were correct and can activate our motors. Hence, the dc output 12 V is fed as an input to the Motor Driver IC L293.3.2.4 Design of interfacing circuits

Since the circuit design and components selection is being achieved successfully, design and discussions on how to provide interaction to enable transmission and reception of signals between selected components is given below.

3.2.4.1 Interfacing Serial (DB9) with PC

Presently, most PCs has a 9 pin connector on either the side or back of the computer. From Table 3.3.1.1 it is seen that the PC can send data (bytes) to the transmit pin (i.e. pin 2) and receive data (bytes) from the receive pin (i.e. pin 3. The Serial port (DB9) rs232 (recommended Standard 232) is much more than just a connector to PC because it converts data from parallel to serial and changes the electrical representation of the data. If the connector on the PC has female pins, therefore the mating cable needs to have a male pin connector to terminate in a DB9 connector and conversely. Data bits flow in parallel from the PC because it uses many wires at the same time to transmit whereas serial flow in a stream of bits from the serial connector because it transmit or receive over a single wire. The serial port create such a flow by converting the parallel data to serial on the transmit pin (i.e. pin 2) and conversely. The serial port has a built-in computer chip called UART used in translating data between parallel and serial forms. Table 3.2.4.1.1: RS232 pin assignments (DB9 PC signal set)

Pin 1Input DCDData Carrier Detect

Pin 2InputRXDReceived Data

Pin 3OutputTXDTransmitted Data

Pin 4Output DTRData Terminal Ready

Pin 5NilNilSignal ground

Pin 6InputDSRData Set Ready

Pin 7 Output RTSRequest To Send

Pin 8InputCTSClear To Send

Pin 9InputRIRing Indicator

3.2.4.2 Interfacing MAX232 with serial (DB9)

Max232 is an integrated circuit that has a dual driver/receiver and typically converts signals from an RS-232 serial port to signals suitable for use in TTL compatible digital logic circuits such as the microcontroller. The serial data sends from the PC through RS232 gets converted to parallel data and is fed to the PIC microcontroller and conversely. When a TTL level is fed to Max232 IC, it converts TTL logic 1 to between -3 V and -15 V, and converts TTL logic 0 to between +3 V to +15 V and conversely when converting from RS232 to TTL. The table below clarifies the RS232 transmission voltages at a certain logic state are opposite from RS232 control line voltages at the same logic state.

Table 3.2.4.2.1: RS232 Line Type and Logic Level

Rs232 line type and logic levelRs232 voltageTTL voltage to/from MAX 232

Data transmission (Rx/Tx) logic 0+3V to +15V0V

Data transmission (Rx/Tx) logic 1-3V to -15V5V

Control signals (RTS/CTS/DTR) logic 0-3V to -15V5V

Control signals (RTS/CTS/DTR) logic 1+3V to +15V0V

Figure 3.2.4.2.1: RS23 Interface with Max232

3.2.4.3 Interfacing MAX232 with PIC16f873A

To enable communication between the PC and the Microcontroller the MAX232 IC circuit serves as a tool of interface. As stated earlier, MAX232 converts parallel data (bytes) transmitted from the PC to serial bits stream because most digital devices require TTL or CMOs logic levels. The first step to consider when connecting the device to RS232 serial port is transformation of RS232 voltage levels into 0 and 5 volts. This is not possible without the RS232 level converters such as MAX232. In this project, MAX232 is one of the most important circuits used in order to interface PIC16F873A or modem of the computer. From Figure 3.2.4.3.1 it is seen that the output pin 10 of CMOS or TTL is fed to pin 17 of PIC16F873A and the output pin 18 of PIC16F873A is fed to CMOS or TTL. Hence, this is how the microcontroller communicates with the MAX232 IC.

Figure 3.2.4.3.1: MAX232 interface with PIC16F873A

3.2.4.4 Remote control encoder PT2262 and decoder PT2272

The circuit is made up of digital encoding chips PT 2262 for high power transmitter modulation signal paired with high sensitivity decoding chip matching circuit PT 2272 for long distance and wireless control (speed and position). Both chips have 12 bits of maximum tri-state address pins providing up to 531,441 (or 3^12) address codes; by that means, it drastically reduce any code interference and unauthorized code scanning possibilities. Both chips encode data and address pins into a serial waveform suitable for RF modulation. Furthermore, when PT 2262 encodes the code address and data set at A0 ~ A5 and A6/D5 ~ A11/D0 the output is fed to DOUT (pin 17) only if TE (pin 14) is pulled to 0 (low state). This waveform is fed to RF modulator for transmission. The modulated radio frequency is received by the RF demodulator at the receiver section and reshaped it back to its original waveform. The decoder PT 2272 is then used to decode the waveform and set the corresponding output pins. It has a built-in oscillator circuitry that allows a precision oscillator to be constructed by connecting a resistor between OSC1 (pin 15) and OSC2 (pin 16) which determines the fundamental frequency of the encoder PT 2262. Therefore, for PT2272 to decode correctly the received waveform, the oscillator frequency PT 2272 must be 2.5 ~ 8 times that of transmitting PT 2262. In this project, 4.7 Mohm and its correspondence oscillator resistance 820 K* is selected for PT 2262 and PT 2272 respectively. Note that, 820 K* operates when PT 2272s Vcc = 5 V to 15 V. This entails that if the supply is lower than 5 V, a lower oscillator resistor value for both PT 2262 and PT 2272 should be used.

3.2.4.5 RF transmitter and receiver module

One of the main objectives of this project is to achieve wireless communication between the transmitter and receiver section this is made possible using RF_TX_315 MHz transmitter and RF-Rx_315 MHz receiver module. In this project, a low cost transmitter and receiver module is used to transmit signals up to 100 meters at specified frequencies and hence the antenna design, Linton college working environment and supply voltage will seriously impact the effective distance. It short distance, and battery power device development fits our requirement as we are to demonstrate only within the college premises. RF_TX_315 have wide operating voltage range (3 V 12 V), current range, transfer rate of , transmitting power of and lastly antenna length of 24 cm. While RF-Rx_315 operating voltage range starts from , operating current range , bandwidth of 2 MHz, its sensitivity is , and a transfer rate of and lastly data output is TTL. They both have the same modulation technique (ASK/OOK), the same frequency (315 MHz). The encoded waveform from DOUT (pin 14) of PT 2262 is fed to RF_Tx_315 MHz modulator for transmission. The modulated radio frequency is received by the RF demodulator at the receiver section and reshaped it back to its original waveform. It is important to note that since the module is used with microcontroller, the clock frequency should be less than or equal to 4 MHz. More also, keep distance between oscillator and the RF modules to avoid the disturbance from oscillator.

3.3 REAL TIME VIDEO TRACKING

Another important objective of this project is to obtain real time video tracking. To achieve that Digital Surveillance camera was selected among other wireless camera. This camera is selected based on its transmission range and high resolution. It enables the transmission and reception of real time video up to 328.083 ft with a very high resolution. The camera transmitter and receiver need 9 V and a current of 200 500 mA to power on. Screws were used to install the camera on the robot, and then a 9 V battery is used to power the transmitter. The wireless receiver is connected to USB-enabled which enables the wireless receiver to be plugged into the USB port of the PC. Another advantage of selecting this camera is because of it size. It portability definitely will reduce complexity of the mechanical design.

3.4 MECHANICAL DESIGN The mechanical design of this robot consists of the chasis of the main structure of the military robot. The entire model was designed in Solidworks software. This was done in order to reduce make the real fabrication easier, faster and less expensive (due to exact dimensions of the parts). Individual mechanical components were designed separately and then assembled together to check if they fit with each other. During the design process, wireless camera slots, later gun stand, sensor slots, wiring, DC and servo motor positions were put into considerations. All chassis was design was made of hard plastic. The entire set of designs is attached in Appendix C.

3.5 SOFTWARE DESIGN The software design serves as a vital role in the operation of the whole system, the system will not operate without the software. An algorithm needs to be established to enable the PIC controllers read the input and respond accordingly. The programming language selected for this project is the C program. The C program will enable communication between the user and the system, and many different interfaces in the system. With the software downloaded into it, microcontroller acts as brain of the whole video tracking and wireless speed control system. It will receive the desired speed from user through PC via the RS232 serial port. The actual speed will be compared with the desired speed and the correction will be done by microcontroller in order to maintain the desired speed of the motor. The flow chart diagram developed will give an intuitive description of the system software. The programs are divided into two parts which are main program and interrupt program. The microcontroller will always loop the main program until an interrupt occurred. When the controller receives an interrupt flag, then it will jump to interrupt the process.

3.5.1 Flow chart of transmitter and receiver sectionThe system flowcharts were designed as follows:

Figure 3.5.1.1: Flow chart of program in Visual basic 6.0

Figure 3.5.1.2: Flow chart of transmitter section in Visual studio

Figure 3.5.1.3: Flow chart of receiver section in Microsoft Visio Software

CLEAR INTERRUPTION FLAGGET VALUE OF SPEEDGAIN = GAIN -1?ERROR=REF DETECTED SPEEDREF=DETECTED SPEED?NOCLEAR COUNTERRESET TIMERRETURN FROM INTERRUPTIONSEND SPEED IN RPM TO LCD

YESNO

NO

YES

Figure 3.5.1.4: Receiver section flow chart interrupts process

3.5.2 Flow charts description

At the beginning of the program, the visual basic interface serves as the user input to the system as the project requires the control of the military robot using PC. The transmitter section gets it reference input from the PC via RS232 serial communication. This condition is satisfied only if the reference input is received else it will wait until it gets the reference input. If the condition is satisfied a corresponding output will be transmitted on to the receiver section. On the receiver section, interrupt occurs after every 0.5 sec. The microcontroller will execute the interrupt program instead of the main program when it gets the interrupt flag. At first, the microcontroller reads the reference speed. Then it compares the reference speed with the detected speed to compute the error speed. When the detected speed is greater than the reference speed, a speed down process takes place i.e., the error voltage generated will speed down the process until it track the reference input. Likewise, when the reference input is greater than the detected speed, a speed up process takes place i.e., the error voltage generated will speed up the process until it track the detected speed. Since the system is intended to work continuously; therefore after reaching the end of subroutine, the microcontroller starts reading signal voltages again as indicated in the feedback loop.

3.5.3 PWM CONTROL LOGIC

Pulse width modulation is a very good technique used in the microcontroller to control the speed and position of the motor. Power supplied to the motor has constant amplitude but varying pulse-width or duty cycle. Duty cycle refers to the ratio of pulse width to period (time taken to complete one cycle). The duty cycle of PWM is determined by the pulse width since the frequency is held constant while the on-off time is varied. Thus, the power increases duty cycle in PWM. Duty cycle is returned mathematically as;

Basically, the speed of a DC motor is a function of the input power and the drive characteristics. While an area under an input pulse width train is a measure of average power available from such an input. Two processes of PWM are used in this project to ensure that the speed is maintained at a given input. These are; the speed down and the speed up process. The program execute the speed down process whenever the detected speed of the motor is higher than the reference speed, in such condition error signal is generated to ensure that the detected speed maintains the input. Whereas the speed up process is executed whenever the reference input is less than the detected speed, error signal is generated in order to speed up the process to ensure that the reference completely maintain the output.

CHAPTER 4

HARDWARE AND SOFTWARE DESIGN AND IMPLEMENTATION

4.1 Schematic diagram

4.1.1 Wireless transmitter schematic diagramAs designed in chapter 3, the Transmitter section contains RS232, PIC microcontroller, and wireless Module. This section is based on computer control. The visual basic program downloaded into the PC enables the rapid application development (RDP) of graphical user interface which will allow the user to control the speed and positioning of the system from the computer. This is made possible by interfacing the microcontroller with the computer using MAX232 through RS232 serial communication. RS232 (recommended standard 232) support both synchronous and asynchronous transmissions and its user data is send as a time series of bits. Max232 is an integrated circuit that converts signals from an RS-232 serial port to signals suitable for use in TTL compatible digital logic circuits such as the microcontroller. The serial data sends from the PC through RS232 gets converted to parallel data and is fed to the PIC microcontroller and vice versa. The microcontroller PIC converts the received data to pulses which undergo modulation by the encoder. Wireless module transmits the modulated signals to the RF Rx section.

Figure 4.1.1.1: Wireless transmitter schematic diagram

4.1.2 Wireless receiver section schematic diagramThe receiver section contains wireless receiver module, PIC16F877A microcontroller, L293D motor driver, LCD and DC motor. The RF Rx receives the transmitted signals. This signal undergoes demodulation to suppress the carrier and decode back the original data. Depending upon the input given by the user a corresponding output will be outputted by the microcontroller. From the circuit it is clearly seen that Port B, C and D are defined as the microcontroller outputs. Where Port B of the microcontroller controls the LCD circuit, Port C controls the servo motor and laser gun and port D controls the motor driver circuit. Port D & C (RD7, RD6, RD5, RD4 and RC7) are fed to their respective circuit through C1815 transistors to ensure high current and high speed. The signals received by the motor-driver circuit will enable the motor to choose the direction that it is supposing to be running in and also to come to a complete stop if that is what the user instructed. Furthermore, one of the received signals received from user inputs will be a control reference. The control reference inputted will be fed into the PIC in-built PWM circuit to generate an appropriate duty ratio that will be sent to the wheels of the motor, these PWM control signals will directly control the speed and direction of the dc motor with the aid of the motor driver. The variation of the PWM is directly proportional to the increase and decrease of the motor speed. Notice that, although the voltage has fixed amplitude, it has a variable duty cycle which means the wider the pulse, the higher the speed and vice versa. Furthermore, the receiver section is interfaced with an IR sensor for detecting the speed. Detected speed is sent to the microcontroller through pin 8 for computation. The circuit for IR sensor is given in figure

Figure 4.1.2.1: Wireless receiver schematic diagram

4.1.2.1 IR sensor schematic Figure 4.1.2.1.1 IR sensor schematic

4.1.3 Optical encoderThis is a simple wheel encoder based on the idea that white stripes will reflect IR light, while black ones will absorb it. This will result in a series of electrical pulses as the wheel is rotating, providing the microcontroller with precious information that can be used to calculate displacement, velocity or even acceleration. It is now clear that this kind of sensor has to be Always ON, to detect every single white stripe passing in front of it, to achieve accurate results. IR detector consists of two characteristics 1). High light illuminate low resistance and low voltage drop 2). Low light illuminate high resistance and high voltage drop.

4.1.4 DC Motor driveThe Device is a monolithic integrated high voltage, high current four channel driver designed to accept standard DTL or TTL logic levels and drive inductive loads (such as relays solenoids, DC and stepping motors) and switching power transistors. To simplify use as two bridges each pair of channels is equipped with an enable input. A separate supply input is provided for the logic, allowing operation at a lower voltage and internal clamp diodes are included. This device is suitable for use in switching applications at frequencies up to 5 kHz.A minimum of three pins are required for each motor namely: The Enable (E) (Pin1 & 9) the input A (pin 2 and 10) and input B (pin 7 and 15). In this project, the motor driver section was tested independently with an external supply to verify the working operation of the driver. After I have tested and verified that the logic (i.e., forward, reverse, left, right and stop) works correctly, the inputs are then given to the output (port D4, D5, D6, and D7) of PIC16F877A microcontroller. The idea behind testing the motor driver circuit independently is for ease of trouble shooting. The motor rotates in either direction depending on the input pin value it receives from the microcontroller. Its operation is summarized in Table 4.2.2.1.

Table 4.2.2.1: Motor driver data inputsNoEnableInput AInput BRotation

Pin2Pin7Pin10Pin15

111010Forward

210101Reverse

311000Left

410010Right

510000Stop

4.2 PCB design rules

4.2.1 Working from the TopPCB design is always done looking from the top of your board, looking through the various layers as if they were transparent. This is how all the PCB packages work. The only time you will look at the work from the bottom is for manufacturing or checking purposes. This through the board method means that you will have to get used to reading text on the bottom layers as a mirror image.

4.2.2 TracksThere is no recommended standard tracks size. What track size you use will depend upon (in order of importance) the electrical requirement of the design, the routing space and clearance you have available, and your personal reference. Every design will have a different set of electrical requirements which can vary between tracks on the board. All but basic non electrical device will require a mixture of track sizes. As a general rule though, the bigger the track width, the better. Bigger tracks have lower dc resistance, lower inductance, can be easier and cheaper for the manufacturer to etch, and are easier to inspect and rework. Changing tracks from large to small and then back to large again is known as necking or necking down. This is often required when you have to go between IC or component pads. This allows you to have a big low impedance tracks, but still have the flexibility to route between tight spots.In practice, the track width will be dictated by the current flowing through it, and the maximum temperature rise of the track you are willing to tolerate. Note that every track will have a certain amount of resistance, so the tracks will dissipate heat just like a resistor. It should be noted that the wider the track, the lower the resistance. The thickness of the copper on your PCB also plays a part, as will any solder coating finish. The thickness is normally specified in ounces per square foot with 1oz copper being the most common. Other thicknesses can be order like 0.5oz, 2oz and 40oz. The thicker copper layers are useful for high current, high reliability designs.

4.2.3 SolderingSoldering considerations need to be taken into account when laying out the board. There are three basic soldering techniques hand, wave and reflow. Hand soldering is the traditional method typically used for prototypes and small production runs. Major impacts when laying out the board include suitable access for the iron, and thermal relief for pads. Non-plated through double sided boards should allow for ample room to get the soldering iron onto the top side pads.

4.2.4 Electrical TestingFinished PCB undergo checked for electrical continuity and shorts at time of manufacture. This is done with an automated flying probe or bed of nails test machine. It checks that the continuity of the tracks matches the PCB file. Based on rules and conditions transmitter and receiver PCB layouts was developed. 4.2.5 PCB designs

Before proceeding to PCB implementation, testing on breadboard was done and the working operation of the circuit was properly tested errors were checked and rectified. Hence, it is time to turn it into a nice Printed Circuit Board (PCB). The PCB design is a manufactured version of the schematic and a natural and easy extension of the design process. Eagle 4.09r2 software was used to position the transmitter and receiver components linked with thousands of tracks into an intricate design that meets a whole host of physical and electrical requirements. This software is chosen because it has a very neat layout and proper PCB layout is very often an integral part of the design.

Figure 4.2.1.1: Transmitter section PCB

Figure 4.2.1.2: Receiver section PCB

Figure 4.2.1.3: IR sensor section PCB

The PCB layout schematics were printed out on glossy paper. Glossy, is the PCB layout transfer paper. The layouts were printed with a Laser printer. Copper clad laminates were cut using hack saw into three sizes in accordance with the layouts for the transmitter, receiver and sensor circuit. To avoid shrinking, a paper was placed over the glossy to help distribute pressure through surface irregularities. Pressing iron was used to iron the already arranged PCB thoroughly for about 15minutes. The copper clad were allowed to cool off and the glossy paper was nicely peeled off to reveal the transferred image. In order to replace missing parts before transferring into etchant a permanent marker was used. Etchant (HCL acid) was poured into an electric etching tank. A hole was drilled on the circuit board, tied and hung inside a potable small tank for about 15 minutes. Once the unwanted copper was etched away until only a toner image remaining, it was removed and rinsed it under lots of running water. After it dried up thinner was used to clean it and made it ready for drilling.

4.3 Software implementation

4.3.1 Programming in Mikro CMicrocontroller acts as the brain of the whole wireless speed control system. It receives the desired speed from the user PC through RS232 serial port. The actual speed is then compared with the desired speed and correction will be done accordingly by microcontroller so that it will always maintain the DC motor speed at the speed set by the user. An algorithm has been developed which makes the microcontroller to read the input and respond accordingly. These algorithms are represented by the flow chart in chapter three. These flowcharts are then translated into C language and compiled using Mikro C, the PIC16F873A and PIC16F877A development tool. Refer to appendix B for complete C program.

4.3.1.1 Process explanation of main programThere are six parts of main program in microcontroller. Which are initialization of ports, PWM, Timer1, setup for serial port, get reference speed and check noise function.

4.3.1.2 Initialization of the mode of portsGeneral purpose I/O pins can be considered the simplest of peripherals. They allow the PICmicro to monitor and control other devices. In general, when a peripheral is functioning, that pin may not be used as a general purpose I/O pin. For most ports, the I/O pins direction (input or output) is controlled by the data direction register, called the TRIS register. TRIS controls the direction of PORT. A 1 in the TRIS bit corresponds11111111 to that pin being an input, while a 0 corresponds to that pin being an output. An easy way to remember is that a 1 looks like an I (input) and a 0 looks like an O (output). The PORT register is the latch for the data to be output. In this project, we use port A and E as digital input where it receives input (H/L) from PT2272 decoder and speed detector respectively while port B, C and D were used as output ports. To configure port A and E as input port, it must be programmed by writing 1 to all its 8 pins. Conversely, to configure port B, C and D as output port, it must be programmed by writing 0 to all its 8 pins. The following codes were therefore used for input and output ports configurations: //main routinevoid main(void){ ADCON1=0x06; //configure as digital I/O TRISA=0b11111111; //configure port A as input TRISB=0b00000000; //configure port B as output TRISC=0b00000001; //all port C as input except pin 1 TRISD=0b00000000; //configure port D as output TRISE=0b00000011; //all port E as input except pin 1&2Figure 4.3.1.2.1: Configure input and output port

When the PIC powers up, the default ADCON1 sets all the analog ports ON to use the ports as digital I/O you must appropriately configure by means of loading 0x06 to ADCON1 register. //define pin used#define sec_flag flag.F0 //count every second#define ir PORTC.F0 //PORTC.PIN0 = infrared input//define motor output pins#define motor1_fwd PORTD.F4 //PORTD.PIN4 = motor1_Forward#define motor1_rwd PORTD.F5 //PORTD.PIN5 = motor1_Reverse#define motor2_fwd PORTD.F6 //PORTD.PIN6 = motor2_Forword#define motor2_rwd PORTD.F7 //PORTD.PIN4 = motor2_Reverse#define servo1 PORTC.F7 //PORTC.PIN7 = define Servo1#define laser PORTC.F1 //PORTC.PIN1 = define laserFigure 4.3.1.2.2: Define motor output