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School of Computing, Engineering and Physical Sciences Sergio Zapatel Interactive Ultrasonic Guided System (EL3990) Submitted in partial satisfaction of the requirements for the degree of Bachelor of Engineering (with Honours) in Electronic Engineering April 2011 I declare that all material contained in this report, including ideas described in the text, computer programs and drawings, is my own work except where explicitly and individually acknowledged. Signed......................... Date ........................... Interactive Ultrasonic Guided System 2 Abstract This project is about developing software capable of controlling a prebuilt robot with an added system for measuring distances using ultrasonic waves. The software will handle the ultrasonic sensor for detecting obstacles that stand in the way of the robot and after that it will be capable of deciding which path the mobile should follow. The system is controlled using a simple keypad and the user has to follow the instructions showed in an LCD display. Interactive Ultrasonic Guided System 3 i. List of Figures Figure 2–1 Overview schematic of the RP6 Robot System[1]................................................13! Figure 2–2 ATMEGA32 Block Diagram [2]...........................................................................14! Figure 2–3 Mosfet H-bridge [1]...............................................................................................15! Figure 2–4 PWM regulation [1]...............................................................................................15! Figure 2–5 Expansion bus connector[1] ..................................................................................16! Figure 3–1 About of Programmer's Notepad 2........................................................................19! Figure 3–2 RP6 Loader Screenshot .........................................................................................20! Figure 3–3 I2C logo[3].............................................................................................................21! Figure 3–4 Typical Configuration of an I2C link [6]...............................................................22! Figure 3–5 Board of the serial bus cable .................................................................................24! Figure 4–1 Learning phase[8]..................................................................................................26! Figure 4–2 Goal seeking[8] .....................................................................................................26! Figure 4–3 SRF02 Beam Pattern .............................................................................................28! Figure 4–4 SRF08 Beam Pattern .............................................................................................28! Figure 4–5 SRF08 Front side...................................................................................................29! Figure 4–6 SRF08 back side view and connections [4]...........................................................30! Figure 4–7 Objects Avoidance Strategy ..................................................................................31! Figure 4–8 Escape angle calculation .......................................................................................32! Figure 4–9 Escape angle calculation 2 ....................................................................................32! Figure 5–1 Seven-segment and dot matrix display [9]............................................................34! Figure 5–2 Passive and active matrix displays [9] ..................................................................34! Interactive Ultrasonic Guided System 4 Figure 6–1 Hardware connections ...........................................................................................39! Figure 6–2 Motion system distance test ..................................................................................48! Figure 6–3 PWM waves before adjustment.............................................................................49! Figure 6–4 PWM waves after adjustment................................................................................50! Figure 6–5 Angle deviation with rotate movement .................................................................51! Figure 7–1 Future work ...........................................................................................................53! Figure C–1 Take measure function..........................................................................................60! Figure C–2 Function explore block diagram ...........................................................................61! Figure C–3 Auto escape function block diagram ....................................................................62! Figure C–4 Manual escape function ........................................................................................62! Figure C–5 Start exploring block diagram ..............................................................................63! Figure C–6 Select parameters function....................................................................................64! Figure C–7 Backlight function block diagram ........................................................................65! Figure C–8 Main menu block diagram....................................................................................65! Figure C–9 Main loop block diagram......................................................................................66! Interactive Ultrasonic Guided System 5 ii. List of Tables Table 1 Communication Speed Values of the I2C bus[3] .......................................................22! Table 2 Commands for the SRF08 [4].....................................................................................30! Table 3 Registers of the LCD display [5]................................................................................35! Table 4 Commands for the LCD display [5] ...........................................................................36! Table 5 Matrix keypad values..................................................................................................37! Table 6 Registers used by the matrix keypad [5].....................................................................37! Table 7 Ultrasonic sensor test of measured distances..............................................................47! Table 8 Ultrasonic sensor test depending on the reflection surface ........................................47! Table 9 Deviation test..............................................................................................................49! Table 10 Rotational movement test .........................................................................................52! Interactive Ultrasonic Guided System 6 iii. List of Abbreviations ATMEL....................... Advanced Technology Memory and Logic EEPROM .................... Electrically Erasable Programmable Read Only Memory FIFO............................ First Input First Output FTDI............................ Future Technology Devices International Ltd. GNU............................ GNU is Not Unix GCC ............................ GNU Compiler Collection IC ................................ Integrated Circuit IR ................................ Infrared IIC or I2C .................... Inter –Integrated Circuit LCD ............................ Liquid Crystal Display MDI............................. Multiple Document Interface MOSFET..................... Metal-Oxide Semiconductor Field-Effect Transistor NiMh........................... Nickel Metal Hydride PCB............................. Printed Circuit Board PFM ............................ Potential Field Method PWM........................... Pulsed Wave Modulation SRAM ......................... Static Random Access Memory ROM ........................... Read Only Memory RP6.............................. Robot Project 6 SCL ............................. Serial Clock SDA ............................ Serial Data SRF ............................. Sonic Range Finder TOF............................. Time Of Flight TWI............................. Two-Wire Interface (it is a synonym of I2C) UART.......................... Universal Asynchronous Receiver / Transmitter USB............................. Universal Serial Bus Interactive Ultrasonic Guided System 7 Contents ABSTRACT..............................................................................................................................2 I. LIST OF FIGURES .............................................................................................................3 II. LIST OF TABLES..............................................................................................................5 III. LIST OF ABBREVIATIONS...........................................................................................6 1. OVERALL DESIGN AND PRELIMINARY RESEARCH.......................................9 1.1 INTRODUCTION .................................................................................................................9 1.2 EVOLUTION OF THE PROJECT.............................................................................................9 2. THE RP6 ROBOT........................................................................................................11 2.1 INTRODUCTION ...............................................................................................................11 2.2 MAIN CHARACTERISTICS.................................................................................................11 2.3 DETAILED FEATURES: .....................................................................................................13 2.3.1 Microcontroller.......................................................................................................13 2.3.2 Motion system .........................................................................................................15 2.3.3 Expansion system....................................................................................................16 2.3.4 Power supply...........................................................................................................17 3. THE WORKING ENVIRONMENT..........................................................................18 3.1 SOFTWARE......................................................................................................................18 3.1.1 GCC: GNU Compiler Collection............................................................................18 3.1.2 Programmer’s notepad...........................................................................................19 3.1.3 RP6 Loader.............................................................................................................19 3.2 HARDWARE.....................................................................................................................21 3.2.1 The I2C Bus .............................................................................................................21 3.2.2 Serial Communication ............................................................................................24 4. THE ULTRASONIC OBJECT AVOIDANCE SYSTEM........................................25 4.1 CURRENT RESEARCH ON OBJECT AVOIDANCE STRATEGIES..............................................25 4.2 TIME OF FLIGHT ..............................................................................................................26 4.3 ULTRASONIC SENSOR CHOICE .........................................................................................28 4.4 THE SRF08 ULTRASONIC SENSOR...................................................................................29 4.5 STRATEGY FOR THE OBJECT AVOIDANCE.........................................................................31 Interactive Ultrasonic Guided System 8 5. THE INTERACTIVE DISPLAY SYSTEM ..............................................................34 5.1 LCD DISPLAY BASICS .....................................................................................................34 5.2 LCD DISPLAY ................................................................................................................35 5.3 MATRIX KEYPAD.............................................................................................................37 6. RESULTS......................................................................................................................38 6.1 FINAL RESULT.................................................................................................................38 6.2 HARDWARE.....................................................................................................................39 6.3 SOFTWARE ......................................................................................................................40 6.3.1 Libraries..................................................................................................................41 6.3.2 LCD display and Matrix keypad functions .............................................................43 6.3.3 Ultrasonic system....................................................................................................44 6.3.4 Menu Functions ......................................................................................................46 6.3.5 Main program.........................................................................................................46 6.4 TEST RESULTS.................................................................................................................47 6.4.1 Measuring distances with the ultrasonic sensor.....................................................47 6.4.2 The motion system...................................................................................................48 6.4.3 The object avoidance system...................................................................................51 6.4.4 The LCD Display ....................................................................................................52 7. FUTURE WORK .........................................................................................................53 8. CONCLUSION.............................................................................................................54 A. BIBLIOGRAPHY ........................................................................................................55 B. STATEMENT OF WORK ..........................................................................................56 C. SOFTWARE BLOCK DIAGRAMS ..........................................................................59 D. SOFTWARE CODE.....................................................................................................67 E. DATASHEETS .............................................................................................................79 F. CD-ROM CONTENTS ................................................................................................80 Interactive Ultrasonic Guided System 9 1. Overall design and preliminary research 1.1 Introduction The idea for this project came from my supervisor, Phil Tranter. From a list of possible topics I chose the three most interesting for me. The aim of the project is to develop an ultrasonic guided system, applied in a mobile robot in order to avoid objects. Furthermore the project will provide a total remote control for the robot, via a radio communication system of 434 MHz1. All the systems must be included in a single PCB2 that fits in the robot bodywork. In addition to this a remote control must be constructed. 1.2 Evolution of the project The development of the project has had three main structural changes. At the beginning the project consisted of the creation of the motion system for the platform, the design of the ultrasonic avoidance object system and the implementation of the wireless remote control. At the end of November my supervisor offered me a complete robot system called RP63 which improved my project possibilities because it has an integrated motion system that I can use instead of designing my own system. The robot system also includes an I2C4 interface, which was another topic of the proposal projects. The characteristics of the robot system are explained in the Chapter 2. At this point the decision was taken to pursue a new direction of the project and to start focusing more on software rather than hardware. 1 434 MHz band 2 PCB: Printed Circuit Board 3 RP6: Robot project 6 4 I2C: Inter-integrated circuit Interactive Ultrasonic Guided System 16 2.3.3 Expansion system 2.3.2.1 The I2C bus The main expansion system of the robot is the I2C bus. It allows connecting up to 127 peripherals using only a two-wire interface. This data communications bus is explained in depth in chapter 3.2.1 2.3.2.2 Expansion connectors The robot has two expansion buses or XBUS that permit the power lines and some other useful lines to be available in other places of the robot, such as the upper platform. The pinout of the connector is: - SDA10 and SCL11 are the connections of the I2C bus. - INT1, INT2 and INT3 are the interrupt inputs of the µC. - +UB is the battery voltage. - VDD is the +5V power supply. - MRESET is the Master Reset Signal of the µC. - GND is the ground connection. It also has another two expansion connectors called USRBUS1/2 that allow the user to make connections between expansion modules. They just provide a connection between two boards and they do not have any specific pinout. Information obtained from [1] 10 SDA: Serial DAta line 11 SCL: Serial CLock line Figure 2–5 Expansion bus connector[1] Interactive Ultrasonic Guided System 17 2.3.4 Power supply The power supply is obtained from six AA-type batteries. They provide a total voltage of 7.2V since each one of them has a 1.2V voltage. Due to the characteristic of rechargeable batteries, if they are completely charged they can offer up to 9V. This is the cause of the voltage variations in the signal +UB and the fluctuation depends on the charge level of the batteries [1]. The robot system is equipped with a +5V regulator capable of supplying a maximum current of 1.5A, but it is recommended not to use more than 800mA without using an additional heat sink [1]. Some rechargeable batteries were studied1213 as well as chargers1415 but in the end some batteries were borrowed from the lab. Their performance was not as expected, so finally traditional alkaline power cells have been used for all the tests made for this project. Only three packs of six batteries have been spent since the power consumption of the robot has not been too high. 12 http://uk.farnell.com/ansmann/5035201/battery-rechargeable-nimh-aa/dp/1453781?Ntt=5035201 13 GP 2700mAh AA rechargeable batteries from Rapid electronics, now they are discontinued 14 http://www2.conrad-uk.com/goto.php?artikel=250125 15 http://www2.conrad-uk.com/goto.php?artikel=235703 Interactive Ultrasonic Guided System 18 3. The working environment 3.1 Software The main objective of the project is to develop the necessary software to manage the robot. This chapter explains all the software resources used for creating the robot software and the subsequent process of programming the microcontroller. All the programs are running under Windows XP Professional Version 2002 SP3 3.1.1 GCC: GNU Compiler Collection The abbreviation GCC stands for GNU16 C Compiler. When it was created, it only entailed C language but nowadays some other languages like Ada, Java or Fortran have been added to the compiler. The GNU Project17 is an operative system created by users and its main characteristic is that it is completely free. It was launched in 1984 by Richard Stallman and today it is still being developed. The GCC is the compiler created for this operative system. The first version of the compiler was released on the 22 of March of 1987 and the most recent is from the 25 of March of the current year18. The GCC compiler is distributed by Free Software Foundation (FSF)19. The complete libraries and archives of the compiler and the manuals can be found at http://gcc.gnu.org/ 16 GNU: GNU is Not Unix 17 more info in http://www.gnu.org/ 18 http://gcc.gnu.org/releases.html 19 http://www.fsf.org/ 3.1.2 Programmer’s notepad Programmer’s notepad is a free license code editor20. It supports C language with syntax highlighting and it has a very useful tabbed MDI interface. The main features of the program can be found in the developer website21. The election of this text code editor was made because it is easy to use and at the same time it is a powerful tool for software development. It is also the programme recommended by the manufacturer of the robot. Figure 3–1 About of Programmer's Notepad 2 The version of the program was 2.0.8 and it can be downloaded at: http://www.pnotepad.org/download/ 3.1.3 RP6 Loader It is a program developed by Arexx Engineering and it is used to upload the .hex files generated with the code editor to the microcontroller on the RP6. It is not necessary to install 20 http://www.pnotepad.org/licensing/ 21 http://www.pnotepad.org/features/ Interactive Ultrasonic Guided System 20 it on the PC since it is written in Java. The program includes a terminal for monitoring the data received from the robot. It has an option that allows the user check the memory status and the value of each byte in the ROM. Figure 3–2 RP6 Loader Screenshot Figure 3–2 shows a screenshot of the RP6 Loader. The main parts of the program are: 1- Selection box for choosing the connection method to the robot. In this case the serial connection detailed in chapter 3.2.2 appears. 2- Selection of the .hex file that is going to be sent to the robot. 3- Upload the selected file. 4- It is possible to start and stop the robot remotely. 5- This box shows the status of the robot. It includes the firmware version and the updated battery voltage. 6- Tabs for selecting the terminal and the memory viewer (HexViewer). Interactive Ultrasonic Guided System 21 3.2 Hardware The implementation of this project does not require complex hardware since all the external components needed are connected via the I2C bus. These components are the LCD display, the keypad matrix and the ultrasonic sensor. The robot is connected to the PC using a UART to USB22 interface, which is used for programming the microcontroller and for receiving data from the robot. All the physical connections are explained in detail in chapter 6.2 3.2.1 The I2C Bus The I2C bus is a serial communication protocol designed by Philips at the beginning of the 1980s. In the late seventies, the use of microprocessors in consumer electronics was increasing and Philips started to think about one new solution to save some space in the PCBs. The reason was that the data communications as well as the addresses used for interconnect integrated circuits and microcontrollers occupied a large space of the board, since they used the parallel communication system with a wide eight bits bus. Philips researched for a low cost system that interconnects the data and address lines of the microcontroller and the integrated circuits. This inter-IC bus was called IIC or I2C bus and it started to be implemented in systems where size and cost were compulsory and the data speed was not much important23. 22 USB: Universal Serial Bus 23 The historical information has been taken from http://www.lammertbies.nl/comm/info/I2C-bus.html Figure 3–3 I2C logo[3] Interactive Ultrasonic Guided System 22 The I2C is a bidirectional serial communication system and the transmission can be done with only two lines called SDA and SCL. SDA is used for transmitting the data bits and SCL is a clock signal. The data sent through the SDA line include the address of the device required and also the data requested. Depending on the specification adopted, the communication speed is: Standard mode (Sm) 100 kbits per second Fast mode (Fm) 400 kbits per second Fast-mode plus (Fm+) 1 Mbit per second High speed mode (Hs mode) 3.4 Mbit per second Table 1 Communication Speed Values of the I2C bus[3] The main characteristics of the I2C bus are [6]: - Simplicity and flexibility - TWI: Two wire interface, only two bus lines are required - No strict baud rate required - Simple master/slave relationships between all components This is the typical hardware configuration for an I2C link: Figure 3–4 Typical Configuration of an I2C link [6] Interactive Ultrasonic Guided System 23 The elements of Figure 3–4 are: – VCC: Supply voltage – GND: Common ground – SDA: Serial Data line – SDL: Serial Clock line – Rp: Pull-up resistance – Rs: Serial Resistance – Cp Wire capacitance – Cc: Cross-channel capacitance As shown in Figure 3–4 a pull-up resistor is connected from each line of the bus to the positive rail. These resistors are necessary because when the bus is free both lines have to be in high state. Interactive Ultrasonic Guided System 24 3.2.2 Serial Communication The robot is connected to the PC via serial communication. It uses the FT232R24 chip from the manufacturer FTDI25 that converts the UART signal to USB. The circuit includes a LED that lights up when there is some activity. The usual transfer speed between the computer and the robot is 500kBaud [1]. Figure 3–5 Board of the serial bus cable 24 datasheet is included in the CD. More info in http://www.ftdichip.com/Products/ICs/FT232R.htm 25 FTDI: Future Technology Devices International Ltd; http://www.ftdichip.com/ Interactive Ultrasonic Guided System 25 4. The Ultrasonic Object Avoidance System There are many documented ideas and strategies for avoiding objects and walls26. Most of the contemporary robots with that objective employ at least 3 different sensors in order to get data from all sides of the robot27 and decide what to do. There are also projects that mount a single ultrasonic sensor, but they include a servomotor for making the sensor work as a radar system. The budget of this project is restricted and installing more than one sensor or servomotors would exceed the budget. The solution adopted is to use a fixed high precision ultrasonic sensor with a wide beam pattern that takes measures in different positions in order to calculate the right path to follow. This process is explained in more detail in the chapter 4.5. 4.1 Current research on object avoidance strategies In the recent years one of the most popular techniques used in the object avoidance systems is called potential field method or PFM28 that models the robot and its environment behaviour using field arrows. It is a technique that was developed in the eighties but it is still in use although there are some researches that expose its limitations.29 Another popular technique is working with fuzzy logic, which consists in considering more than two possible states, introducing values between the logic 0 and 1. In this specific example taken from the paper referenced in [8], the robot is using a ring of 24 ultrasonic sensors for taking measures. The method is based on having a learning period in which the 26 For example, http://letsmakerobots.com/node/5305 27http://ieeexplore.ieee.org/Xplore/login.jsp?url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F10831%2F3 4146%2F01626586.pdf%3Farnumber%3D1626586&authDecision=-203 28 A complete tutorial written by Michael A. Goodrich is included in the CD 29 The paper containing that information is included in the attached CD. It is called “Potential field methods and they inherent limitations for mobile robot navigation”, written by Y.Koren and J. Borestein. Interactive Ultrasonic Guided System 32 The triangles are shown in Figure 4–8 and the angles in Figure 4–7 Figure 4–8 Escape angle calculation The first triangle is formed by the wall, the left measure and the right measure. The α angle of Figure 4–9 can be calculated by applying the following formula: [1] so the angle is obtained from [1]: [2] Figure 4–9 Escape angle calculation 2 Interactive Ultrasonic Guided System 33 From the right angle and the value of α in [2], the angle β can be incurred: β = 90º - α [3] With the data obtained in [3] it is possible to get the value of ϕ (the angle the robot should rotate in order to follow a parallel path respect to the wall) as shown in the Figure 4–7: ϕ = 45 + β [4] Combining [2], [3] and [4] the complete equation that obtain the escape angle is37: 37 Note that if the robot approximates to the wall in a different angle that the shown in the example, the values for calculating the function arctan can change. The numerator always has to be the longer one of both measures. Interactive Ultrasonic Guided System 34 5. The Interactive Display System 5.1 LCD display basics The purpose of a display is to convert electric signals into visual information. A display is composed by small areas called pixels. The different pixels of the display are switched on and off and all of them together create the desired image to show. There are two basic types of displays depending on the shape of their pixels:” seven-segment displays” and “dot-matrix displays” [9]. Their structure is shown in the next figure. Figure 5–1 Seven-segment and dot matrix display [9] Depending on the way the pixels are activated it is possible to differentiate between active and passive matrix. The active matrix displays have one semiconductor device in each pixel for turning it on and off. Normally it is a transistor that acts as a switch. In the passive matrix display the columns and the rows of the matrix are the electrodes [9]. Both methods are shown in the next figure: Figure 5–2 Passive and active matrix displays [9] Interactive Ultrasonic Guided System 35 5.2 LCD Display It is a passive dot matrix display with twenty characters per row and four rows (20 x 4) so it can display eighty characters at the same time. Each character is composed of a 5 by 7 matrix. It requires a power supply of 5 V. It includes a driver circuit that gives the possibility of controlling it via I2C or via serial mode. The module has a mode selection jumper for choosing between the I2C and the serial mode. This choice must be done before switching on the device since the driver check that jumper in the starting routine. The I2C mode is selected when the jumper is open. In this mode, the data communications system is faster than the LCD can accept data so it is included a FIFO buffer of 64 bytes that stores the data the LCD cannot show until it is displayed. The address of the display when it is connected to the I2C bus is 0xC6. The LCD has four registers, detailed in the next table: Register Read Write 0 Number of free bits in FIFO buffer Command Register 1 Keypad state low byte Not available 2 Keypad state High byte Not available 3 Version Not available Table 3 Registers of the LCD display [5] The register number 0 is the only one that has a double purpose since it can be read or written. In written mode this register takes the commands for the LCD display. When it is read it shows the number of free bits that rest in the FIFO buffer. Register one and two show the status of the matrix keypad and register three shows the current version of the LCD software. Interactive Ultrasonic Guided System 36 These are the commands that can be set to the command register: Decimal Command Description 0 Null (ignored) Ignored as a no operation 1 Cursor Home Sets the cursor to the home position (top left) 2 Set cursor (1-80) Cursor to a position specified by the next byte, where 1 is the top left and 80 is the bottom right 3 Set cursor (line, column) Sets cursor using two bytes, where first byte is the line and the second byte is the column 4 Hide cursor Stops the position cursor from appearing on the display 5 Show underline cursor Changes the cursor to the underline type 6 Show blinking cursor Changes the cursor to the blinking type 8 Backspace Deletes the preceding character from the current position on the display 9 Horizontal tab (by tab set) Moves the current position across by the tab space set by command18 (default tab space 4) 10 Smart line feed Moves the cursor down one line to the position beneath in the same column 11 Vertical tab Moves the cursor up one line to the position above in the same column 12 Clear screen Clears the screen and sets cursor to the home position 13 Carriage Return Moves the cursor to the start of the next line 17 Clear Column Clears the contents of the current column and moves cursor right by one column 18 Tab set Sets the required tab size, the following byte can be a size of between 1 and 10 19 Backlight on Turns the backlight of the LCD03 on 20 Backlight off (default) Turns the backlight of the LCD03 off 27 Custom char generator Allows 8 custom chars to be built. 32-255 ASCII chars Writes ASCII chars straight to the display Table 4 Commands for the LCD display [5] The information of this chapter has been obtained from the manufacturer’s Technical Documentation [5]. The complete technical documentation including detailed connections and measures is included in the CD-ROM. Interactive Ultrasonic Guided System 37 5.3 Matrix keypad It is a four rows and three columns matrix keypad and in each intersection it has a switch associated to a push-button. The keypad is connected to the LCD module using a seven-line bus. Three of these lines are input signals introduced in the keypad and the other four are the outputs of each row. The module sends a signal to the first column and checks if any of the switches is on. If this happens, a signal is sent in the corresponding output. COL 1 COL 2 COL 3 ROW 1 1 2 3 ROW 2 4 5 6 ROW 3 7 8 9 ROW 4 * 0 # Table 5 Matrix keypad values The module is constantly scanning the keypad to detect changes in the keys and it reflects the changes in two registers. These registers are located in the addresses one and two of the LCD module. In the next table both registers are represented. They indicate the key that has been pressed sorted by its position in the keypad (Row/Column). High byte Low byte 0 0 0 0 4/3 4/2 4/1 3/3 3/2 3/1 2/3 2/2 2/1 1/3 1/2 1/1 0 0 0 0 # 0 * 9 8 7 6 5 4 3 2 1 Table 6 Registers used by the matrix keypad [5] When one key is pressed the corresponding bit in the register will be in high state. This information is included in the Technical Documentation [5]. Interactive Ultrasonic Guided System 38 6. Results This chapter explains all the work done in the project. It includes the hardware built, the developed software and the tests done. 6.1 Final results The result obtained is a system that avoids objects with two different strategies. A menu is showed in the LCD display and the user can choose which strategy prefers to use with the help of a keypad. The first strategy is called “Automatic mode”. In this case, the robot stops at a predetermined distance from the object. After that it takes two distance measures and mathematically calculates the required angle to get away from the object following a parallel path respect to it. The detailed explanation of the operation is in chapter 4.5. The second strategy is called “Manual mode”. The user is asked to introduce the desired values with the keypad. These values are: explore degrees, escape degrees, stop distance and robot speed. After that the object avoidance routine will start using the specified parameters. The robot is supposed to be automatic and autonomous so once the program is started it will not stop until the reset button is pressed38. 38 The reset button of the robot is next to the serial bus connector, it is the same as the start button. Interactive Ultrasonic Guided System 39 6.2 Hardware The LCD display and the ultrasonic sensor are both connected using a four-line ribbon cable to the power supply and I2C lines of the robot. The keypad matrix is connected with a sevenline bus to the LCD display, which has the integrated circuit that manages the keypad. Chapter 3.2 explains the characteristics of the hardware in more detail. Figure 6–1 Hardware connections Note that the pull-up resistors needed for the proper working of the I2C bus are already implemented in the RP6 robot. Interactive Ultrasonic Guided System 40 6.3 Software The robot microcontroller is programmed in C language. The developed program has been divided in several parts depending on the system the code is referring to. This separation helps to test specific sections of the code without compromising the rest of the program. It is also based on a large number of functions since this way the code is neat and more efficient. There are three groups of function declarations. The first two have the purpose of controlling the hardware system: one is composed by the functions that control the ultrasonic sensor and the other one is in charge of the LCD display and the keyboard matrix. The third group is responsible for the software of the functions that appear in the main menu. After that the main program is declared which includes an infinite loop with the main menu included. Therefore the basic structure of the software is the following: - Include libraries - Variables and constants declaration - Declaration of LCD display and keypad functions - Declaration of ultrasonic sensing functions - Declaration of main menu functions - Main loop In the following chapters the purpose of each function will be explained. Appendix C includes some block diagrams designed for better comprehension of the code, which is included in appendix D. Their location is referenced next to the name of each function. Interactive Ultrasonic Guided System 41 6.3.1 Libraries The program needs to have a number of libraries. Most of them are included in the GCC compiler but there is a group of libraries that have been specifically developed by Arexx Engineering for controlling this robot. These libraries include some necessary functions for the proper operation of the RP6. Below is a short explanation about each library and the functions taken from them. 6.3.1.1 RP6RobotBaseLib.h This library includes the basic operations of the robot. The following functions are used: - mSleep(x): this routine introduces a delay of x milliseconds in the code. It blocks the normal flow of the program until the delay time is finished. - startStopwatch(): this function initializes a counter that runs regardless of the normal program flow. - setStopwatch(t):sets the counter to a specific t initial value. - getStopwatch() take the instant value of the counter. - rotate(uint8_t desired_speed, uint8_t dir, uint16_t angle, uint8_t blocking): makes the robot turn with the selected parameters: rotating speed, direction of turning, rotating angle and an option for blocking the program flow while the robot is rotating. - changeDirection(uint8_t dir): sets the turning direction of each motor to move the robot in the required direction. The possibilities are FWD, BWD, LEFT or RIGHT. - moveAtSpeed(uint8_t desired_speed_left, uint8_t desired_speed_right): this routine sets the speed value for each motor. - task_RP6System: this function is in charge of updating all the systems of the robot. It checks and updates the changes in the motion system and other systems not relevant for the project like the analogue to digital converter or the bumpers status. Interactive Ultrasonic Guided System 48 6.4.2 The motion system The accuracy of the robot’s movements is not very high. There are two different motors, one for each caterpillar and they cannot be calibrated separately. Both encoders are using the same conversion factor but due to mechanical issues they are not providing the same movement to each one of the caterpillar wheels. The function moveAtSpeed (speedLeft, speedRight) is used to perform the tests. It requires two input parameters and each one of them represent the speed of each motor. By observing the robot moving across a theoretically straight line it can be deduced that the left motor runs slower that the right one, which ends in a deviation movement towards the left. The objective of the tests is to get the values that compensate the difference between the two motors by correcting the left one. Figure 6–2 Motion system distance test The correction has been introduced as follows: moveAtSpeed (speedLeft + balance value, speedRight). The chart below shows the deviation of the robot respect a straight line. The surface material has not too much influence in this test since both wheels have the same grip and the conditions for each motor are the same. The tests were done using various correction values in the left motor and with different speed values. Interactive Ultrasonic Guided System 49 Speed Correction in the left motor Deviation (cms) 0 6 +6 4 60 +12 0 0 10 +6 5 90 +12 1 0 18 +6 10 120 +12 1 Table 9 Deviation test Considering the results of the test, the left motor has been software-adjusted using the exemplary value of +12 every time the function moveAtSpeed is called. With this value the robot has an acceptable straight movement when it is required. However, there is another method that can help to improve the behaviour of the motors. In both motor drivers there are two potentiometers that control the duty cycle of the PWM wave. The RP6 Loader can show the waveform of the PWM signal if the self-test program is running. If is not properly calibrated you have the possibility of adjusting the PWM duty cycle. These are the waves before adjusting the PWM: Figure 6–3 PWM waves before adjustment As shown in the Figure 6-3 the square wave does not have a 50:50 duty cycle and it needs calibration. Interactive Ultrasonic Guided System 50 It is a delicate operation that must be done in a dark environment since the direct light can damage the optical sensors that read the encoders of the gearbox. The only information about this process is obtained from the English-speaking forum of Arexx Engineering41, but it is only available in a pdf-document written in German[10], which is included in the CD-ROM. The manufacturer documentation says that an adjustment of 60:40 or vice versa is correct. These are the waves after the adjustment: Figure 6–4 PWM waves after adjustment After executing this process the robot is capable of moving in a straight line without needing the software compensation calculated in the previous test. 41 http://www.arexx.com/forum/viewtopic.php?t=580 Interactive Ultrasonic Guided System 51 6.4.3 The object avoidance system As mentioned in the previous section, the motion system has a remarkable influence on the object avoidance function. This task needs the robot to turn 45º degrees to the right and then come back to its initial position and turn 45º left. The difference between the two motors is again decisive for achieving the appropriate angles. The executed tests show that the rotate function is not accurate and the robot does not stop at the proper angles. The calculation of the escape angle is not correct because of this. Figure 6–5 Angle deviation with rotate movement As seen in Figure 6–5, the robot’s initial position is the coloured in grey. After the rotational movement the robot should be in the green position, but due to the mentioned inaccuracies the robot may rotate more degrees until the red position. This deviation will cause a wrong escape angle calculation. Interactive Ultrasonic Guided System 52 The floor surface is also an important influence in the rotation angle. The grip of the caterpillar wheels decreases on tiled or plastic floors and the measures are not correct. Surface Requested degrees Real degrees 45º to the left 48 Carpet 45º to the right 42 45º to the left 44 Varnish wood 45º to the right 40 45º to the left 43 Plastic 45º to the right 40 Table 10 Rotational movement test This problem can be solved implementing and additional position sensor to the robot, like a compass or a gyroscope to make the rotation angle more accurate. 6.4.4 The LCD Display All the commands of the LCD were tested to verify their proper operation. Interactive Ultrasonic Guided System 53 7. Future work The most important improvement can be the implementation of a compass or gyroscope in order to have a proper feedback about the real position of the robot. With that information the rotate movement would have a high accuracy, which means that the obtained measures for the calculation of the escape angle will be really precise. That way the escape angle will be perfectly know. The gyroscope will also check that the robot has rotate the exactly escape angle. Another form of expansion can be to add more ultrasonic sensors since the I2C bus has the capability of managing up to 127 devices. With three sensors the same algorithm for avoiding objects can be used. The two new sensors can be installed in the robot in a position of 45 degrees respect to the middle sensor (Figure 7–1), so the rotate movement for taking measures is not necessary anymore. The measures are done faster and they are more reliable since the possible rotate errors are eliminated. Figure 7–1 Future work Interactive Ultrasonic Guided System 54 8. Conclusion The work of the whole year has paid off and the project has accomplished its main objective of avoiding objects using an ultrasonic sensor. The software developed meets the requirements of control an ultrasonic sensor and manage the results obtained. The algorithm designed for avoiding objects is mathematically justified and is really simple to implement. However, there are some problems that do not allow the system to work with a high accuracy. Regarding to the motion system, the motors cannot be calibrated with a high precision. This is problematic because the robot is not able to move forward in a completely straight line. That is also the cause of the mistakes in calculating the new robot path since the rotation movements are not accurate and the measures are not taken in the correct place. The LCD display system works well and does what it is required to do. The amount of memory needed to fill the entire display is considerable high and at the beginning was a problem since there are several different screens. The amount of RAM is limited and store the char arrays in the ROM is imperative. In order to reach this objective and save the variables in the program memory, it requires the use of the PROGMEM attribute, the operation of which was difficult to understand. Interactive Ultrasonic Guided System 55 A. Bibliography [1] Arexx Engineering. (2007). RP6 Robot System Manual. Zwolle, The Netherlands: Arexx Engineering. [2] Atmel Corporation. (March 2005). Datasheet: 8-bit AVR Microcontroller with 32K Bytes In-System Programmable Flash. San Jose, CA, USA. [3] NXP. (2007, Junio 19). I2C-bus specification and user manual. [4] Devantech LTD. SRF08 Ultrasonic range finder technical specification [5] Devantech LTD. LCD03 I2C Display module technical documentation [6] telos EDV Systementwicklung GmbH. (1997). i2c bus. Retrieved January 15, 2011 from i2c bus: http://www.i2c-bus.org/ [7] Everett, H. R. (1995). Sensors for mobile robots. Natick, MA, USA: A K Peters. [8] H. Boubertakha, M. T.-Y. (2010). A new mobile robot navigation method using fuzzy logic and a modified Q-learning algorithm. Journal of Intelligent & Fuzzy Systems 21 , 113-119. [9] Fisch, M. R. (2004). Liquid crystals, laptops and life. World Scientific Publishing Company, Incorporated . [10] Arexx Engineering. (2007). Drehgeber richtig einstellen. Zwolle, The Netherlands: Arexx Engineering. (The translated title is “Set encoders correctly”) Interactive Ultrasonic Guided System 56 B. Statement of Work EL3990 Statement of Work Interactive Ultrasonic Guided System B.Eng. (Hons.) Electronic Engineering Issue 1, 29 October 2010 S. Zapatel 1- Aim The aim of the project is to develop an ultrasonic guided system, applied in a mobile robot in order to avoid objects. Furthermore a LCD display with a matrix keypad will be added to monitor the activity of the robot and interact with the robot. All of these peripherals will be connected using the I2C data communication bus. 2- Background There are many existing robot applications which require the robot to be able to avoid obstacles without human supervision. A very recommendable way of providing that characteristic is using ultrasonic sensors to detect obstacles (Bishop, 2008). In order to do so, these sensors must be supported by a microcontroller, which will determine the new path of the robot, depending on the programmed strategy. A prebuilt robot will be used to achieve this objective. The included microcontroller will be programmed with an algorithm that takes data from an ultrasonic sensor and after analyzing them allows the robot to decide which way it should move to. At the same time it is required to monitor and control the system results without the use of a computer, in order to let the robot have the mobility necessary. To solve this problem, a LCD display will connect the robot with the environment and a matrix keypad will contribute to interact with the robot. 3- Activities 3.1- Work breakdown structure 1. Research for general information 1.1. Choosing main topic of the project 1.2. Choosing specifications 2. Progress report preparation 3. RP6 Robot System 3.1. Literature review and researching 3.2. Research about its motion system 3.3. Programming robot microcontroller 3.4. Test of motion system 4. Ultrasonic guided system 4.1. Literature review and researching Interactive Ultrasonic Guided System 57 4.2. Choosing kind and number of sensors and object avoiding strategy. 4.3. Designing electronic circuit 4.4. Programming robot microcontroller 4.5. Test of ultrasonic guided system 5. LCD display system. 5.1. Research about LCD displays 5.2. Choose LCD display 5.3. Programming robot microcontroller 5.4. Test the LCD display 6. Overall general test 7. Building prototype 7.1. Add sensor and display to the robot 7.2. Check the connections 8. Final test of the prototype 9. Final report preparation 10. Preparation viva/poster presentation. 3.2- Task descriptions First, a research on the Internet will be done to choose the main topic of the project and its specifications (WBS 1.1, WBS 1.2). The first one of the reports will be a Progress Report that includes the aim of the project, the initial steps done for its development and the planning for finishing the project successfully (WBS 2). Then the RP6 robot system will be studied (WBS 3), beginning with a research on its instruction manual and datasheets (WBS 3.1). The research will focus in its motion system (WBS 3.2) and the code necessary for achieve the proper movements will be designed (WBS 3.3). A test of the robot and the programming will check the proper working of the motion system (WBS 3.4). After that a research on the Internet will be done (WBS 4.1) in order to find the best solution regarding the ultrasonic sensors, i.e. which kind of sensor and which strategy is going to be used in the project (WBS 4.2). The electronic circuit for the ultrasonic sensors will be designed (WBS 4.3) and the programming will be done (WBS 4.4). A test will be done to check the ultrasonic sensors system (WBS 4.5). The next step will be designing the LCD display system (WBS 5). A research on that kind of displays will be done (WBS 5.1) and the necessary LCD will be chosen (WBS 5.2). The robot microcontroller will be programmed for showing the appropriate messages in the display (WBS 5.3). The LCD display system will be tested (WBS 5.4) exploring all the possibilities of the display. Then a general test of the entire system will be done (WBS 6). Once checked that all the systems are working properly, all the external elements will be added to the robot (WBS 7.1), and all the connections will be checked (WBS 7.2). The final test of the complete prototype will be done (WBS 8). The final report will be written which includes all the work done and the final conclusions (WBS 9). Finally, the viva voice and poster presentation will be prepared (WBS 10). Interactive Ultrasonic Guided System 64 2. Menu functions 2.1. Select parameters Figure C–6 Select parameters function Interactive Ultrasonic Guided System 65 2.2. Backlight Figure C–7 Backlight function block diagram 2.3. Main menu Figure C–8 Main menu block diagram Interactive Ultrasonic Guided System 66 3. Main program Figure C–9 Main loop block diagram Interactive Ultrasonic Guided System 67 D. Software code 1. LIBRARIES AND DEFINITIONS.............................................................................68 2. DEFINITION OF DISPLAY FUNCTIONS ..............................................................68 2.1. BLINKING..................................................................................................................68 2.2. INITIALIZE CURSOR ...................................................................................................68 2.3. WRITE LCD..............................................................................................................69 2.4. READ KEYPAD...........................................................................................................69 2.5. WAIT HASH ...............................................................................................................70 2.6. READ VALUE.............................................................................................................70 3. DEFINITION OF OBJECT AVOIDANCE FUNCTIONS......................................71 3.1. TAKE MEASURE.........................................................................................................71 3.2. EXPLORE...................................................................................................................72 3.3. AUTO ESCAPE ...........................................................................................................72 3.4. MANUAL ESCAPE ......................................................................................................73 3.5. START EXPLORING....................................................................................................74 4. DEFINITION OF MENU FUNCTIONS ...................................................................75 4.1. PREDEFINED VALUES ................................................................................................75 4.2. SELECT VALUES ........................................................................................................75 4.3. BACKLIGHT...............................................................................................................77 4.4. MENU .......................................................................................................................77 5. MAIN PROGRAM.......................................................................................................78 5.1. MAIN PROGRAM........................................................................................................78 Interactive Ultrasonic Guided System 68 1. Libraries and definitions #include "RP6RobotBaseLib.h" #include "RP6I2CmasterTWI.c" #include <avr/pgmspace.h> #include <math.h> #define SRF_ADR 0xE0 // address for the ultrasonic sensor in the I2C bus #define LCD_ADR 0xC6 // address for the LCD display in the I2C bus int correction = 0; //value for the correction of the motor deviation int degrees_explore; //degrees the robot rotate when it is taking measures int degrees_escape; //degrees the robot rotate to avoid the object int stop_distance; //distance to an object that makes the robot stop int speed ; //explore speed int escapetype; //defines auto or manual escape char StartScreen[80] PROGMEM =" PRESS # TO START "; 2. Definition of display functions 2.1. Blinking void blinking(void) { int i; //counter for the times the screen blinks for (i=0;i<10;i++) { I2CTWI_transmit2Bytes(LCD_ADR, 0, 20); //switch backlight on mSleep(50); I2CTWI_transmit2Bytes(LCD_ADR, 0, 19); //switch backlight off mSleep(50); } } 2.2. Initialize cursor void init_cursor (void) { I2CTWI_transmit2Bytes(LCD_ADR, 0, 12); //clear screen and set cursor at home I2CTWI_transmit2Bytes(LCD_ADR, 0, 4); //hide the cursor } Interactive Ultrasonic Guided System 69 2.3. Write LCD void write_LCD (char data[80]) { init_cursor(); //initialize screen for (unsigned char i=0; i<80;i++) //send 80 chars { I2CTWI_transmit2Bytes(LCD_ADR, 0, pgm_read_byte(&(data[i]))); //send to the register 0 of LCD address the byte that corresponds to the address of the parameter received } } 2.4. Read keypad int key ; //value of the key pressed uint8_t keychar; //char of the key pressed, used for printing void read_keypad(void) { uint16_t key_pressed = 0; //represents the register of the keypad key = 13; while (key > 11) { //the keypad register is composed by two bytes uint8_t keypad_high_byte; uint8_t keypad_low_byte; //asking and reading the value of the high byte of the register I2CTWI_transmitByte(LCD_ADR, 2); keypad_high_byte = I2CTWI_readByte(LCD_ADR); //asking and reading the value of the low byte of the register I2CTWI_transmitByte(LCD_ADR, 1); keypad_low_byte = I2CTWI_readByte(LCD_ADR); //now the two register are joined in one variable key_pressed = keypad_low_byte + (keypad_high_byte << 8); switch(key_pressed) //to each key is assigned its numerical value and the ascii code that corresponds. The value used in the switch structure is the value of the complete register { case 0: key = 12; break; // no pulsation = 12 case 1: key = 1; keychar ='1'; break; // 1 case 2: key = 2; keychar ='2'; break; // 2 case 4: key = 3; keychar ='3'; break; // 3 case 8: key = 4; keychar ='4'; break; // 4 case 16: key = 5; keychar ='5'; break; // 5 case 32: key = 6; keychar ='6'; break; // 6 case 64: key = 7; keychar ='7'; break; // 7 case 128: key = 8; keychar ='8'; break; // 8 case 256: key = 9; keychar ='9'; break; // 9 Interactive Ultrasonic Guided System 70 case 512: key = 10; keychar ='*'; break; // * = 10 case 1024: key = 0; keychar ='0'; break; // 0 case 2048: key = 11; keychar ='#'; break; // # = 11 } } while (key_pressed > 0) //this loop detects when the key has been released.It goes out of the loop when the value of the register of the keypad is 0 { key_pressed = 0; uint8_t keypad_high_byte; uint8_t keypad_low_byte; I2CTWI_transmitByte(LCD_ADR, 2); // keypad register high byte keypad_high_byte = I2CTWI_readByte(LCD_ADR); I2CTWI_transmitByte(LCD_ADR, 1); // keypad register low byte keypad_low_byte = I2CTWI_readByte(LCD_ADR); key_pressed = keypad_low_byte + (keypad_high_byte << 8); } } 2.5. Wait hash void wait_hash (void) { int cont = 0; //is only the variable for controlling the loop while (!cont) //keeps reading the keypad until the # is pressed { read_keypad(); if (key == 11) //11 is the value assigned for the key “#” { cont = 1; mSleep(500); } } } 2.6. Read value uint8_t value; //stores the value introduced with the keypad void read_value (char screen[80]) { value = 0; write_LCD(screen); I2CTWI_transmit2Bytes(LCD_ADR, 0, 2); //set cursor to a position I2CTWI_transmit2Bytes(LCD_ADR, 0, 50); //position 50, in the middle of the third line I2CTWI_transmit2Bytes(LCD_ADR, 0, 6); //blinking cursor read_keypad(); //read tents Interactive Ultrasonic Guided System 71 value = key; //store tents I2CTWI_transmit2Bytes(LCD_ADR, 0, keychar);//show key pressed in the screen read_keypad(); //read units value = (value*10) + key; //store units and add the tents I2CTWI_transmit2Bytes(LCD_ADR, 0, keychar); //show key pressed in the screen I2CTWI_transmit2Bytes(LCD_ADR, 0, 4); //Hide cursor mSleep(1000); } 3. Definition of object avoidance functions 3.1. Take measure uint16_t distance; //distance of the measurement void takeMeasure(void) { static uint8_t measureInProgress = false; static uint8_t dist_high_byte; static uint8_t dist_low_byte; int end = 1; while (end) { if(!measureInProgress) //loop for starting the measure process { the command 81 orders the SRF08 to get the measure result in centimetres I2CTWI_transmit2Bytes(SRF_ADR, 0, 81); measureInProgress = true; setStopwatch1(0); //start the counter from 0 } else if(getStopwatch1() > 70) //after 70 ms the wave has returned to the sensor and the result can be measured { measureInProgress = false; //request and receive of the high byte range register I2CTWI_transmitByte(SRF_ADR, 2); dist_high_byte = I2CTWI_readByte(SRF_ADR); //request and receive of the high byte range register I2CTWI_transmitByte(SRF_ADR, 3); // dist_low_byte = I2CTWI_readByte(SRF_ADR); /join the two registers in one value distance = dist_low_byte + (dist_high_byte << 8); end = 0; } } } Interactive Ultrasonic Guided System 72 3.2. Explore uint16_t distanceRight = 0; // distance measured in the right point uint16_t distanceLeft = 0; // distance measured in the left point void explore (void) { // turn right the value of degrees_explore for obtaining the measure on the right side rotate(40, RIGHT, degrees_explore, BLOCKING); takeMeasure(); //take a measure distanceRight= distance; //store the read distance //this lines are for showing the result in the terminal of the RP6 Loader writeString_P("\nDistance Right: "); writeInteger(distanceRight, DEC); writeString_P(" cm\n "); // turn left for obtaining the measure of the left side. The degrees are multiplied by two because the robot has to rotate to the initial position and then continue to the final position. rotate(40, LEFT, 2*degrees_explore, BLOCKING); takeMeasure(); //take a measure distanceLeft = distance; //this lines are for showing the result in the terminal of the RP6 Loader writeString_P("\nDistance Left: "); writeInteger(distanceLeft, DEC); writeString_P(" cm\n "); // return to initial position rotate(40, RIGHT, degrees_explore, BLOCKING); } 3.3. Auto escape void escape (void) //escape auto { int result_in_degrees = 0; double radians; if (distanceRight > distanceLeft) { //calculate alpha angle (result in radians) radians=atan2(distanceRight, distanceLeft); //convert from radians to degrees result_in_degrees = radians*180*M_1_PI; //calculate the escape angle degrees_escape = 135 - result_in_degrees; //rotate the desired angle for escape rotate(40, RIGHT, degrees_escape, BLOCKING); //move forward and with the selected speed changeDirection(FWD); moveAtSpeed(speed +correction,speed); writeString_P("TURN RIGHT!!\n"); //show in terminal distance = stop_distance+1; } Interactive Ultrasonic Guided System 73 elsif (distanceRight < distanceLeft) { //this is the same as the previous loop but it is used when the left distance is larger than the right one radians=atan2(distanceLeft, distanceRight); result_in_degrees = radians*180*M_1_PI; degrees_escape = 135 - result_in_degrees; rotate(40, LEFT, degrees_escape, BLOCKING); changeDirection(FWD); moveAtSpeed(speed +correction,speed); writeString_P("TURN LEFT!!\n"); distance = stop_distance+1; } else { //if the distances left and right are equals it means that the robot is perpendicular to the wall, so for escaping in parallel to the wall a 90 degrees turn is required. This turn is towards the right but it perfectly could be on the left rotate(40, RIGHT, 90, BLOCKING); changeDirection(FWD); moveAtSpeed(speed +correction,speed); distance = stop_distance+1; } } 3.4. Manual escape void escapeman(void) { if (distanceLeft < distanceRight) { //the robot rotate the degrees selected by the user rotate(40, RIGHT, degrees_escape, BLOCKING); //and move forward changeDirection(FWD); moveAtSpeed(speed +correction,speed); writeString_P("TURN RIGHT!!\n"); //show in terminal distance = stop_distance+1; } elsif (distanceLeft > distanceRight) {//this is the same as the previous loop but it is used when theleft distance is larger than the right one rotate(40, LEFT, degrees_escape, BLOCKING); changeDirection(FWD); moveAtSpeed(speed +correction,speed); writeString_P("TURN LEFT!!\n"); //show in terminal distance = stop_distance+1; } else {//if the distance left is equal to the right distance the robot turn 180 degrees rotate(40, LEFT, 180, BLOCKING); changeDirection(FWD); moveAtSpeed(speed +correction,speed); writeString_P("TURN 180 DEGREES!!\n"); //show in terminal distance = stop_distance+1; } } Interactive Ultrasonic Guided System 80 F. CD-ROM contents At the end of the report a CD-ROM is attached including all the additional data that due its extension or features have not been included in the report. The software developed during the project is also included. Below are listed the contents of the CD-ROM: – Results: - Files of the software developed - Final Report in pdf format – RP6 Robot System: - User’s Manual - Datasheets of the components (included the microcontroller) - “Set encoders correctly” (German) – Object Avoidance background: - Tutorial of potential field method - Paper about limitations of the potential field method - Example papers of Potential Field method - Example papers of fuzzy logic systems – Ultrasonic Sensor: - Technical documentation - Schematic – LCD display - Technical documentation – Communications Systems: - I2C bus specification and user’s manual - Datasheet of serial communication chip FT232R - Serial communication schematics – Software: - RP6 Loader - RP6 libraries - Programmer’s notepad - Tutorial on PROGMEM attribute – Components and robot pictures