UNIVERSITI TEKNOLOGI MALAYSIA
Contents
1. pattern 2 43 second byte is the third byte is the lower fourth byte is the2. 12 13 14 15 16 18 19 20 21 22 29 24 24 26 28 4 2 4 3 Complete circuit Pick and place routine 29 31 xi xii LIST OF ABBREVIATIONS SCARA Selective Compliance Automatic Robotic Arm PCA Printed circuit assembly RIOS Robotic arm Interactive Operating System SSC Serial Servo Controller GUI Graphical user interface RC Servo Radio DC Direct current PIC Printed Integrated Circuit Approx Approximately xiii LIST OF APPENDICES APPENDIX TITLE PAGE Al Gantt Chart for Semester 1 36 A2 Gantt Chart for Semester 2 37 B Programming Source Code 38 CHAPTER 1 INTRODUCTION 1 1 Background In manufacturing and assembling industries human labour is largely employed to do repetitive task which usually requires precision and accuracy It is unavoidable that humans will make mistakes while performing a task Moreover productivity will be lower as human have limited working hours and work slower To overcome the human inefficiency more and more industrial robots are designed and built to accommodate the increasing demands for better productivity product quality and precision in performing task Industrial robots come in various types and designs depending on the function and purpose it is build for These robots reduce labour cost and will become the solution for shortage of workers in future by directly replacing human workers in performing task in industries and other fields of work
3. Cytron Technologies Inc PIC 16F87XA Data Sheet 2003 Microchip Technology Inc CYTRON http www cytron com my viewProduct php pcode S K40C CYTRON http www cytron com my viewProduct php pcode S K40B WIKIPEDIA http en wikipedia org wiki Universal asynchronous receiver transmitter SOCIETY OF ROBOTS http www societyofrobots com microcontroller_ uart shtml 12 13 35 EXTREME CIRCUITS http www extremecircuits net 2009 08 ampere or current boostercircuit htmi Mohamad S A S Robotic Arm Functioning Using Image Processing Universiti Teknologi Malaysia 2011 36 APPENDIX A1 Gantt Chart for Semester I 2011 2012 Bunjim poday JEUILUAS apijs uonequasaid asedaid Buns 1i1o10uu 0135 Sunumyesodod paford youeas Ju3uodwo uBisap waysAs uBis p aJEMPJEH el Buyaug WSd APPENDIX A2 Gantt Chart for Semester II 2011 2012 owap pue uonjejuasalj PE apijs uonelu s id asedaig i aw Ge PE KE Da oatorra pes PN pue alemjjos 3JEMPJEY le18 lu W3JS S j01 u09 pue Sujuuuue180 d a1emyos dojanag APPENDIX B Programming Source Code include include lt pic h gt configuration __ CONFIG 0x3F32 define define SW1 RBO define SW2 RB1 define LED1 RB6 define LED2 RB7 define SER RB2 function prototype void init void void init_servo_position unsigned char channel unsigned int position void on off cmd unsigned char channel uns
4. Thus it is actually not suitable to be chosen for this project However due to lower cost many students chose to use this type of motor For future projects more advance motors like digital servo and stepper motor is advice to be used to provide more flexible accurate and precise movements iii Controller Better and more advance controller like PID controller can be implemented in the project iv Sensor A sensor can be place at the fingers of the gripper to detect whether the gripper is gripping the item or not This can be a safety function to stop the robot arm function if the item that is supposed to be gripped is dropped V Image processing Image processing can be included to enable the robot arm to detect and change the orientation of the item to the wanted orientation by itself A more advance pick and place robot arm can be developed though this 10 11 RERERENCE CELESTICA http www celestica com Careers Careers aspx id 916 HOBBYTRON http www hobbytron com lynx arm html M W Sam Robotic Arm with Image Processing Bachelor Thesis Universiti Teknologi Malaysia 2009 Ashraf E Eduardo Y Karen B and Ricardo S Design and Development of a Competitive Low Cost Robot Arm with Four Degrees of Freedom Modern Mechanical Engineering 2011 1 47 45 CYTRON http www cytron com my viewProduct php pcode RGO2A amp name Small 20Robot 20Gripper RC Servo C36R C40R C55R User s Manual V1 0 Apr 2009
5. 1 Robotic Arm Design 3 3 2 Two Finger Gripper 3 3 2 Radio Control Servo Motor 3 4 Circuit Development 3 4 1 Microcontroller 3 4 2 Enhanced 40 Pins PIC Start Up Kit 3 4 3 8 Channels Servo Controller 3 4 4 UART 3 4 5 Current Booster and Voltage Regulating Circuit 3 4 6 Power Source 3 5 Software Programming 3 5 1 Flow Chart for Programming RESULTS AND DISCUSSIONS 4 1 Introduction 4 2 Actual Robotic Arm Structure 4 3 Complete Circuitry Design 4 4 Complete Programming Source Code 4 5 Pick and Place Routines CONCLUSION 5 1 Conclusion 5 2 Recommendations 11 12 13 14 15 16 17 18 20 21 22 23 24 25 25 27 27 29 30 30 32 33 34 viii Appendix A Appendix B 36 37 38 43 FIGURE NO 2 1 22 2 3 2 4 3 1 3 2 3 3 3 4 3 5 3 6 3 7 3 8 3 9 3 10 3 11 3 12 3 13 3 14 4 1 LIST OF FIGURES TITLE Lynx 5 Programmable Robotic Arm Completed robotic arm hardware structure by Sam Men Wee Free body diagram of robot arm Actual hardware structure of robot arm Complete system design Simplified project flow chart Preliminary robotic arm design in different angle views Image of 2 finger gripper C55R RC servo motor from Cytron PIC 16F877A Schematic diagram of PIC 16F877A SK40C SCO8A Schematic diagram of UART interface Schematic diagram of current booster and voltage regulating circuit 12V 0 5A AC DC adapter 12V 2A AC DC adapter Programming flow chart Programming flow chart PAGE
6. Celestica Inc is a multinational electronics manufacturing services company The headquarters of this company is situated in Toronto Canada One of the branches in Malaysia is located at the Tampoi Industrial Estate in Johor Bahru The Johor Bahru team provides its customers with printed circuit assembly PCA box build repair services systems assembly and test 1 In Celestica Inc some of the workers are assigned to manually pick up hard drive circuit boards one by one and place the circuit boards in trays following the correct arrangement and orientation Due to slow productivity and human error Celestica Inc decided to request for an automatic pick and place robotic arm which can replace human workers in performing the previous task mentioned An automatic robotic arm can perform repetitive task faster with higher precision without stopping robotic arm is a mechanism that is designed and built to resemble and imitate the movement of a human arm The design and structure of a robotic arm depends on the function and complexity of the task to be performed Usually robotic arms are more widely used in manufacturing industries that deals with small electronic components where pick and place task is essential Lynx 5 Type I SCARA and Type II SCARA are some of the robotic arms that were already developed and sold in the market 12 Objectives The objective of this project is to design and build a four degree of freedom robotic arm wi
7. SCO8A 22 3 44 UART Universal Asynchronous Receive Transmit abbreviated UART is known as a piece a piece of computer hardware that translates data between parallel and serial forms 10 However in the context of robotics it is better known as a useful device for communicating serial data between microcontroller and computer UART changes incoming parallel information to serial data which can be sent on a communication line 11 For this project UART is use to send data between the microcontroller and the servo controller The data sent each time is the size of one byte A minimum of 5volts supply is required for microcontroller to interface with SKO8A Figure 3 10 shows the schematic diagram of the connection between SK40C to servo controller using UART interface SCOSA UICOOA Faj ss 8 2 SK40C Figure 3 10 Schematic diagram of UART interface 23 3 45 Current Booster and Voltage Regulating Circuit This circuit plays a major role in supplying a constant 6 09V and approximately 2 67A to the servo motors The povver source for this circuit is from a 12V and 2A adapter source In this circuit LM7806 provides a constant and regulated output of 6 09 volts As for the power transistor TIP 2955 it is used to boost the extra needed current above the maximum allowable current provided via the regulator Current up to 1 5A will flow through the regulator anything above that makes the reg
8. each robotic arm joint position and dynamics deals with its movement that takes into consideration of mass and inertia Path planning is also used in interpolating robotic arm movement from one point to another point Moreover a camera is attached to the robotic arm and image processing is employed to extract image data and features that can eventually help the robotic arm recognize the object in its presence 3 Windows graphical user interface GUI is important for the simulation of the robotic arm and the result is displayed in 3D where the current arm position and movement will be shown GUI is also used to monitor the robotic arm status The remote control interface via Bluetooth device is an extra feature for the robotic arm The idea of using image processing to help the robot recognize object targets enables the robot arm to pick up a specific item with better efficiency and higher accuracy However the high degree of freedom complicates the mechanical structure The 6 degrees of freedom used in this project increases the complexity of the control algorithm and kinematic control Complexity in inverse kinematics leads to the inaccuracy of link angle position given by the mechanism 2 2 3 Competitive Low Cost Robot Arm This low cost robot arm was developed by a group of researchers from different countries and universities The objective of this work is to design develop and implement a competitive low budget robot arm with e
9. the sponge At this point the back view of the sponge representing the back view of the PCB will be flipped to the top view Figure 4 3 shows the complete pick and place routine Figure 4 3 1 shows the random position of the robot arm before start up In Figure 4 3 2 the robot arm moves to the preset initial position at start up After start up as shown in Figure 4 3 3 the robotic arm will move to the first position where the sponge with the white marking surface is located to pick up the sponge The gripper will open slightly and then gripped the sponge After the sponge is picked the robotic arm proceeds and moves to the second position While moving to the second position to place the sponge the wrist actuator will rotate the gripper at 180 degrees to change the orientation of the sponge This is shown in Figure 4 3 4 In Figure 4 3 5 the sponge with the altered orientation is placed at the second location At this point the 31 gripper will release grip to drop and place the sponge at the second location This routine will continue until the reset button on SK40C is pressed When the reset button is pressed the pick and place robot arm will stop functioning and return to initial position Figure 4 3 Pick and place routine CHAPTER 5 CONCLUSION 5 1 Conclusion In conclusion the objectives of this project are accomplished A four degrees of freedom automated robotic arm with a 2 finger gripper for pick and place p
10. very much appreciated Special thanks go to my course mates and friends for their continuous encouragement and valuable advice I am also appreciative of the suggestions and solutions they gave to help me solve any problem that arises Lastly I will like to thank my parents for their never ending support and encouragement throughout my studies Thank you for believing in me ABSTRACT Robotic arm is widely used in manufacturing and assembling industries to replace human labour and overcome human inefficiency in performing job tasks Automated robotic arms are proven to be able to perform well especially in repetitive pick and place task In this project a four degree of freedom automated robotic arm with a two finger gripper is developed and built This robotic arm serve as a solution to replace workers who are assigned to manually pick up hard drive circuit boards one by one and place the circuit boards in trays following the correct arrangement and orientation in manufacturing industry The hardware software programming and a simple circuitry were designed built and later integrated to produce a fully automated pick and place robotic arm This project will serve as a future reference to students who are interested and also for any further development by industries vi ABSTRAK Lengan robot diguna secara luas dalam industri pembuatan dan pemasangan untuk mengganti buruh manusia dan mengatasi ketidakcekapan manusia dalam menjalan
11. C 21 3 4 3 8 Channels Servo Controller SCOSA This servo controller can control up to 8 channels of servo motors simultaneously and independently Each servo signal pin can generate 0 5ms to 2 5ms servo pulses Thus servo motors can have an angle of rotation from 0 to 180 degrees In addition this servo controller has a resolution of 8000 steps which is equivalent to 0 25ms servo pulse The servo pulse is controlled by simply manipulating the resolutions while writing the program to control the servo motor movement Besides this user can activate or deactivate any servo channel of choice Moreover users are free to set the initial position of any servo channel for the next start up This feature is very useful in this project since each servo motor has different initial position at start up Another function of this servo controller allows user to request the position of an individual servo The UART here has a 9600 baud rate On the other hand the small design of this board is very useful This board has the dimension of 49mm x 46mm It is also possible to extend up to 16 channels by linking together two 8 channel servo controller Figure 3 9 shows an image of SCO8A SI to S8 are the 8 channels where the servo motors will be connected SCO8A has a separated power source for the PIC operation and for powering the servo motors The pins RX TX GND and 5V are used for UART connections to the SK40C SCO8A www cytron com m y Figure 3 9
12. PSZ 19 16 Pind 1 07 UNIVERSITI TEKNOLOGI MALAYSIA DECLARATION OF THESIS UNDERGRADUATE PROJECT PAPER AND COPYRIGHT Author s full name KUAN PEI WEN Date of birth 25 SEPTEMBER 1988 Title PICK AND PLACE ROBOTIC ARM Academic Session 2011 2012 I declare that this thesis is classified as CONFIDENTIAL Contains confidential information under the Official Secret Act 1972 RESTRICTED Contains restricted information as specified by the organization where research was done OPEN ACCESS agree that my thesis to be published as online open access full text acknowledged that Universiti Teknologi Malaysia reserves the right as follows The thesis is the property of Universiti Teknologi Malaysia The Library of Universiti Teknologi Malaysia has the right to make copies for the purpose of research only The Library has the right to make copies of the thesis for academic exchange Certified by AA Mb SIGNATURE SIGNATURE OF SUPERVISOR 880925 07 5142 DR KUMERESAN A L DANAPALASINGAM NEW IC NO PASSPORT NO NAME OF SUPERVISOR Date 25 June 2012 Date 25 June 2012 NOTES If the thesis is CONFIDENTAL or RESTRICTED please attach with the letter from the organization with period and reasons for confidentiality or restriction T hereby declare that I have read this thesis and in my opinion this thesis is sufficient in terms of scope and quality for the award of the degree of Bachelor
13. bow motion 5 Wrist one servo motor for rotational wrist motion 6 Two finger gripper one servo motor to grip and release grip operation 28 29 4 3 Complete Circuitry Design The finalized circuitry design will be presented here The complete circuit consist of one SK40C with one PIC 16F877A one servo controller board one current booster and voltage regulating circuit and a UART connection Figure 4 2 shows the complete circuit for this project Figure 4 2 Complete circuit 1 SK40C with PIC 16F877A 2 Current booster and voltage regulating circuit 3 Servo controller 4 UART interface 5 Three pin terminals to connect servo motor to servo controller 30 4 4 Complete Programming Source Code The written programming source code for the robotic arm movements is included at Appendix B Please refer to Appendix B for more details and explanations 4 5 Pick and Place Routines After completing the hardware software and circuitry the final procedure is integrating all of them into one complete working system that can perform a pick and place routine The item to be picked and placed is a blue sponge with the dimension of 4cm x 3cm x 3cm The blue sponge surface with the white marking represents the initial orientation of a PCB from the top view Aside from being able to do the pick and place routine the wrist of the robot arm can rotate the sponge 180 degrees to change to orientation of
14. ce by Microchip Technology Inc is selected to be used in this project 7 This microcontroller is cheap and easy available in the stores It has suitable functions and enough output pins for a robotic arm with 5 servo motors The 8 channels of 10 bit analogue to digital converter is an important function for converting the analogue output voltage received from potentiometer to a digital signal Figure 3 6 shows the image of a PIC 16F877A and Figure 3 7 shows the schematic diagram of the PIC Figure 3 6 PIC 16F877A 19 40 Pin PDIP MCLR VPP 1 40 RB7 PGD RAO ANO e 2 39 J s r RB6 PGC RAT AN1 lI13 38 RB5 RA2 AN2 VREF CVREF 4 37 RB4 RA3 AN3 VREF 5 36 RB3 PGM RA4 TOCKI C1OUT lt 6 35 RB2 RAS AN4 SS C20UT lt 7 lt 34 lt RBI REO RD ANS lt 8 f 33 RB0 INT RE1 WRIANG6 lt 9 lt 30 v RE2 CS AN7 31 vss VDD gt bo 30 lt RD7 PSP7 Vss gt 7 1 u 29 7 RD6 PSP6 OSC1 CLKI 4 287 RD5 PSP5 OSC2 CLKO lt r 2 27 HH RD4 PSP4 RCOITIOSO TICKI e r 4 26 H RCTIRXIDT RC1 T10SI CCP2 1 25 J RC6 TX CK RC2 CCP1 lt 1 24 J RCSISDO RC3 SCK SCL lt 23 J RC4 SDI SDA RDO PSPO lt L 1 22 J RD3 PSP3 RD1 PSP1 lt L 20 21 I RD2 PSP2 Figu
15. down to 60 delay 300000 position speed 1 900 30 grip open delay 200000 position speed 1 2100 30 grip close smaller d number bigger delay 200000 position speed 3 3750 20 2nd link go up to 90 delay 200000 position speed 5 3125 15 up first link o up 42 position speed 6 3750 15 delay 400000 void on off cmd unsigned char channel unsigned char on off unsigned char first_byte 0 first_byte 0b11000000 channel uart_send first_byte uart_send on_off void delay unsigned long time for time gt 0 time unsigned char uart_rec void unsigned char rec_data while RCIF 0 wait for data rec_data RCREG return rec_data return the data received void uart_send unsigned char data while TXIF 0 only send the new data after TXREG data the previous data finish sent void position_speed unsigned char channel unsigned int position unsigned char speed unsigned char first_byte 0 higher_byte 0 lower_byte 0 first_byte 0b11100000 channel higher_byte position gt gt 6 amp 0b01111111 position value from 0 8000 are greater than a byte lower byte position amp 0b00111111 uart sendffirst byte uart send higher byte higher byte of position ObOxxxxxxx uart send lower byte byte of position ObOOxxxxxx uart send speed speed value from 0 100 void patternrec if SW1 0 pattern 1 else if SW2 0
16. he development of embedded applications employing Microchip s PIC 13 MPLAB IDE supports both assembly and C programming languages 3 5 1 Flow Chart for Programming Figure 3 14 shows the flow chart to program the pick and place robotic arm movements to pick an item from the first position and release the item at the second position 26 Motors move to initialize position Switch I pressed Actuator motion brings arm to first position Gripped pick item Actuator motion brings arm to second position Release Grip Place item Press Reset Button Yes Figure 3 14 Programming flow chart CHAPTER 4 RESULTS AND DISCUSSIONS 4 1 Introduction In this section the overall results for the project will be presented and explained The results include the actual structure circuitry and programming source code The pick and place process done by the robotic arm will also be shown step by step 4 2 Actual Robotic Arm Structure Figure 4 1 illustrates the Actual structure of the robotic arm The robotic arm is build from aluminium bars and uses PCB stands to raise up the base E Figure 4 1 Actual robotic arm structure 1 Rotating base one servo motor for base rotational motion 2 Left panel for the first link one servo motor for up down shoulder motion 3 Right panel for the first link one servo motor for up down shoulder motion 4 Second link one servo motor for up down el
17. igned char on off void delay unsigned long time unsigned char uart rec void void uart send unsigned char data void position speed unsigned char channel unsigned int position unsigned char speed void patternrec int pattern 0 initialization void init 38 39 HI set I O port for switchs and LEDs TRISB 0b00000011 1 for input 0 for output TRISD 0b00000000 uart initialization SPBRG 129 baud rate set as 9600 for crystal with 20Mhz BRGH 1 high speed option for baud rate SYNC 0 asynchronous mode CREN 1 enable reception SPEN 1 enable serial port TXEN 1 enable transmission TX9 0 HI 8 bit transmission RX9 0 HI 8 bit reception LED1 LED2 1 delay 80000 LED1 LED2 0 delay 80000 on off cmd 0 1 void init_servo_position unsigned char channel unsigned int position LED1 1 LED2 0 unsigned char first byte 0 higher byte 0 lower byte 0 first_byte 0b10000000 channel higher_byte position gt gt 6 amp 0b01111111 position value from 0 8000 are greater than a byte lower_byte position amp 0b00111111 uart sendffirst byte uart send higher byte second byte is the higher byte of position ObOxxxxxxx uart send lower byte while uart rec 0x04 wait the 0x04 value from SCO8A RB2 1 void main doing init 40 delay 2 RB2 0 delay 18 initial position of all the servo mot
18. ires good planning before implementing any part of the project Project flow is the tasks arranged in sequence planned for the project Here the project started with literature review whereby articles journals and research papers were read to obtain necessary information before carrying out the project After getting sufficient background knowledge on theories and concept hardware and circuit design will be develop Designs will be drawn using software like Google SketchUp 8 The designs will be based on the requirements and functions stated in previous chapters Based on the designs developed construction of the hardware and circuit will be executed Then the project will proceed to the hardware and software integration This will be the hardest part and more time will be required here After successfully combining and integrating all the necessary parts the robot arm will be tested and tuned If the robotic arm functions as desired 13 the project is successful and work will stop here However if it has errors or complications software and hardware integration have to be carried out all over again Figure 3 2 shows the simplified project flow chart Literature Hardware and review Circuit Design Software and Hardware and Hardware Circuit Integration Construction En Fine Tuning and Testing Functioning 7 TT Yes Figure 3 2 Simplified project flow chart 3 3 Mechanical Hardware Mechanical hardware includes the
19. is because they are DC motors with built in gearing and feedback control loop circuitry where no motor driver is needed Degree of rotation for a servo motor is controlled by Pulse Width Modulation Figure 3 5 illustrates the selected type of RC servo motor Figure 3 5 C55R RC servo motor from Cytron 17 Specification for CSSR RC servo motor i Full Metal Gears ii Suitable for heavy duty application iii 2 Ball Bearings iv Speed sec 60deg 0 22 4 8V 0 20 6 0V 0 17 7 2V v Torque Kg cm 9 0 4 8V 11 0 6 0V 13 0 7 2V maximum 7 2V vi Size mm 40 8x20 18x36 5 vii Weight g 55 viii Rotation angle 180 degree ix Pulse width range 0 582ms to 2 5ms estimation In this project a total of 5 servo motors are used A servo motor is attached to the base elbow and wrist for rotational or link movements For the shoulder joint two servo motors are used because more torque is needed to support the heavy frame of the robotic arm at that joint 3 4 Circuit Development In this section mainly the microcontroller and position sensor used will be discussed 18 3 4 1 Microcontroller Microcontrollers are like mini computers that can be fit into robots Fora robotic arm microcontroller is the master brain that controls all the joint movements and determines the next step to be executed PIC 16F877A a powerful 200 nanosecond instruction execution yet easy to program CMOS FLASH based 8 bit microcontroller produ
20. kan tugas pekerjaan Lengan robot automatik telah dibukti boleh memberi prestasi yang baik terutamanya dalam tugas ambil dan letak berulang Dalam projek ini lengan robotik berautomatik yang mempunyai empat darjah kebebasan dengan penggenggam dua jari direka dan dibina Lengan robot ini menjadi penyelesaian untuk mengganti pekerja yang ditugaskan untuk mengambil papan litar tercetak satu demi satu dan meletak papan litar dalam dulang mengikut susunan dan orientasi yang betul secara manual dalam industri pembuatan Perkakasan perisian pengaturcaraan dan sebuah litar yang mudah telah direka dibina dan kemudiannya disepadukan untuk menghasilkan sebuah lengan robot ambil dan letak berautomatik Projek ini akan berfungsi sebagai rujukan kepada pelajar pelajar yang berminat dan juga untuk penyelidikan dan pembangunan lanjut pada masa depan CHAPTER TABLE OF CONTENTS TITLE DECLARATION DEDICATION ACKNOWLEDGEMENT ABSTRACT ABSTRAK TABLE OF CONTENTS LIST OF FIGURES LIST OF ABBREVATIONS LIST OF APPENDICES INTRODUCTION 1 1 Background 1 2 Objectives 1 3 Scopes 1 4 Problem Statements LITERATURE REVIEW 2 1 Introduction 2 2 Previous Projects 2 2 1 Lynx 5 Programmable Robot Arm Kit 2 2 2 Robot Arm with Image Processing PAGE il ili iv vi vii xii xiii Q Q N N U A vii REFERENCES 2 2 3 Competitive Low Cost Robot Arm METHODOLOGY 3 1 Introduction 3 2 Project Flow 3 3 Mechanical Hardware 3 3
21. nhanced control The robot arm is develop to handle or pick and place light material which can later be used as an assistant for industrial workforce According to their research a basic structured robot arm should be limited to 4 degrees of freedom because such a design allows most of the necessary movements and at the same time keeping the costs and the complexity of the robot competitively low Thus this project implements the idea of a 4 degrees of freedom robotic arm where all the joints are revolute Acrylic material was used to build the robot arm and servo motors were used to execute arm movements Controllers were replaced by servo motors with encoders in this project Hextronik HX12K servo motors are responsible for joint movements at the shoulder elbow wrist and base A two finger commercially available gripper was chosen as the end effector Figure 2 3 shows the free body diagram of the robot arm whereas Figure 2 4 illustrates the actual hardware structure Wrist Shoulder Effector Figure 2 4 Actual hardware structure of robot arm 10 To control the robot arm an Atmega 368 with an Arduino development programming board microcontroller a six channel Micro Maestro servo controller board driver and a computer based user interface vvas integrated to form a vvorking system for robot arm movement Moreover Labvievv performs inverse kinematic calculations and communicates the proper angles serially to a mic
22. nologies Sdn Bhd This gripper is made from metal and can pick up some relatively heavy objects The claws open to about 2 inches depending on the servo motor used Since the two fingers move parallel to each other a better grip is acquired However this gripper set is not assembled It has to be assembled by the user The components that come with the set are not a perfect fit Thus a few modifications have to be made so that the gripper can function nicely This gripper will be attached to the actuator at the wrist of the robot arm Figure 3 4 shows how the gripper looks like Figure 3 4 Image of 2 finger gripper The medium size metal gear servo has the following features 5 16 1 180 degree rotation ii Operating Voltage 4 8V 6 0V 111 Operating Speed 0 18sec 60degree 6V iv Output torque 3 2kg cm 6V v Dimensions 28 8 x 13 8 x 30 2mm 3 3 3 Radio Control Servo Motor RC hobby servos are compact low cost and great actuators for robots The popularity in using RC servo motors in the robotics field is due to its ability to rotate and maintain at certain location position or angle according to control pulses from a single wire 6 A RC servo motor comes with a gearbox and small motor to enable motion The electronic circuit embedded in the RC servo motor controls the motor so that the output gear vvill move to the desired position In short the main reason for choosing RC servo motors as actuators for joint movements
23. of Engineering Electrical Mechatronics Signature aa Supervisor DR KUMERESAN A L DANAPALASINGAM Date 25 JUNE 2012 PICK AND PLACE ROBOTIC ARM KUAN PEI WEN A thesis submitted in partial fulfillment of the requirements for the award of the degree of Bachelor of Engineering Electrical Mechatronics Faculty of Electrical Engineering Universiti Teknologi Malaysia JUNE 2012 DECLARATION I declare that this thesis entitled Pick and Place Robotic Arm is the result of my own research except as cited in the references The thesis has not been accepted for any degree and is not concurrently submitted in candidature of any other degree 1 2 Signature Call Name KUAN PEI WEN Date 25 JUNE 2012 DEDICATION This thesis is dedicated with respect and love to my parents who never stop believing in me and for their eternal encouragement and strong support throughout my journey of education ACKNOWLEDGEMENT In preparing this thesis I received numerous guidance from many people A number of them made significant contributions to this thesis Their insights advice suggestions and guidance helped me greatly in completing my final year project First of all I would like to thank my helpful supervisor Dr Kumeresan a l Danapalasingam The supervision and support that he gave truly help the progression and smoothness in completing this thesis His cooperation and top notch guidance are
24. ors at start up init_servo_position 8 3750 rotating base init_servo_position 6 1875 right panel for first link init_servo_position 5 5000 left panel for first link init_servo_position 3 3750 2nd link init_servo_position 2 3750 wrist rotation init_servo_position 1 1500 gripper while 1 patternrec while pattern 1 LED1 0 LED to show which part of the program the robot arm is LED2 1 1st position position_speed 8 1875 50 channel 8 base rotate to 45 delay 250000 position speed 5 1250 15 down first link go down position_speed 6 5625 15 delay 250000 position speed 2 0 30 wrist move to 0 delay 450000 position_speed 3 2500 20 2nd link go down to 60 delay 300000 the gap the gap 41 position speed 1 900 30 grip open delay 200000 position speed 1 2100 40 grip close smaller d number bigger delay 200000 position speed 3 3750 20 2nd link go up to 90 delay 200000 position speed 5 3125 15 up first link o up position speed 6 3750 15 delay 400000 2nd position position speed 8 5625 50 channel 8 base rotate to 135 delay 250000 position speed 5 1250 15 down first link go down position speed 6 5625 15 delay 250000 position speed 2 7100 40 wrist move to 180 delay 450000 position speed 3 2500 20 2nd link go
25. ot The software used is a DOS software written in Quick BASIC version 4 5 This robotic arm has an interesting structural design which can serve as a reference The design is simple and not too bulky for a robotic arm with four degrees of freedom On the other hand Mini SSC II servo controller can be replaced by microcontroller for easier implementation and better actuator control Figure 2 1 Lynx 5 Programmable Robotic Arm 2 2 2 Robotic Arm with Image Processing This is a robotic arm done by Sam Men Wee a student from Universiti Teknologi Malaysia in year 2009 The core idea of this project is to construct a 6 degree of freedom robotic arm that can emulate the movements of a human arm successfully with the assistance of image processing application The wanted outcome is to use the robot arm to help human in daily chores Since the robotic arm is built to emulate as closely as possible the motion of a human arm all joints constructed are revolute joints The shoulder part has three degrees of freedom with three joints constructed in revolute configuration for the positioning of robot wrist Another three revolute joints are designed for yam pitch and roll movement at the wrist two finger gripper is attached as the end effector Figure 2 2 illustrates the complete hardware structure of the robot arm Figure 2 2 Completed robotic arm hardware structure by Sam Men Wee In this project robot kinematics is used to compute
26. ously by students and researchers will be discussed here 2 2 Previous Projects For the past years many have attempted to design create and construct robotic arms using different approaches Below are some of the projects which are closely related to the concept of a pick and place robotic arm 2 2 1 Lynx 5 Programmable Robotic Arm Kit Lynx 5 is one of the successful robot arm build by Lynxmotion which is already sold in the market with popular demands It is build for repeated fast and accurate movements This robotic arm has 4 degrees of freedom that allows rotation at the base and motion at the shoulder elbow and wrist The kit comes along with a two finger gripper The structure of the robotic arm is made from ultra tough laser cut Lexan structural components black anodized aluminium servo brackets and custom injection moulded components 2 For motion at each joint of the arm servo motors are used Hitec HS 422 servo motor is used for all the joints except the gripper where HS 81 is used Figure 2 1 shows the structure of the Lynx 5 robotic arm A pre assembled Mini SSC II servo controller controls the motion of the servo motors by providing control pulses to servos after receiving position commands from a computer The robotic arm can be taught to have a sequence of movements using RIOS Robotic arm Interactive Operating System with a mouse or joystick For better arm positioning inverse kinematic is applied in this rob
27. re 3 7 Schematic diagram of PIC 16F877A Below are the important features of PIC 16F877A i Pin Count 40 pin PDIP ii Program Memory 14KB or 8K 14 bit Flash iii Max Crystal Speed 20MHz iv RAM Bytes 368 v EEPROM Bytes 256 vi Timers 2 x 8 bit 1 x 16 bit vii Digital Communication 1x A E USART 1 x MSSP SPI I2C viii Capture Compare PWM 2 x CCP ix ADC 8ch 10 bit x Comparators 2 20 3 42 Enhanced 40 Pins PIC Start Up Kit SK40C This start up kit is designed to offer an easy to use starter board for PIC microcontroller users It comes with basic element for users to begin project development and offers plug and use features 8 No extra components are required for the PIC to function thus saving development and soldering time 9 A 12volts 0 5ampere adapter will be use to power this board Only the UART pins will be used to connect to the servo controller board Figure 3 8 illustrates an image of SK40C Below are some of the important features that this start up kit offers i ICSP connector for UICOOA simple and fast method to load program ii Perfectly fit for 40 pins 16F and PIC18F PIC iii 2 x programmable switch iv 2 x LED indicator v 20MHz crystal oscillator vi UART connection to interface with other controller or even computer vii Users are able to utilize the function of PIC by directly plugging in the YO components in whatever way that is convenient to user Figure 3 8 SK40
28. rocontroller that drives the servo motors vvith the capability of modifying position speed and acceleration 4 As an addition feature this robot arm can function fully in manual mode Users can switch to manual mode when the inverse kinematics calculations become too complicated This research paper suggests the use of 4 degrees of freedom for simple robotic arm It is a good suggestion as the complexity of the structure kinematics calculation and algorithm will be lower Using lower degree of freedom can reduce the cost of developing a robotic arm as well CHAPTER 3 METHODOLOGY 3 1 Introduction Methodology is about the entire flow and methods implemented to complete the project It includes information and explanation on the basic mechanical structure to the final stage where testing and tuning takes place The project is divided into three parts which are mainly the hardware construction circuit development and software programming Main components used will also be elaborated here Figure 3 1 shows the complete system design 12 Electronic Circuit Microcontroller P16F877A SCOSA Servo controller 8 channels Current booster and voltage regulator circuit Aluminium bars C language 2 Finger gripper MPLAB IDE v8 46 6 RC Servo Motor PIC kit 2 v2 61 Mechanical hardware Software Programming Integration Figure 3 1 Complete system design 3 2 Project Flow A successful project requ
29. structure of the robot arm from the base links to the 2 finger gripper as the end effector The materials used to build the main frame of the robot arm are aluminium links and bars The choice of materials is due to the availability lower cost and weight 14 3 3 1 Robotic Arm Design The robotic arm is designed for simple pick and place purposes The robotic arm will pick an item from a fix point and place it at another fix point Thus a simple structure vvith four degrees of freedom is sufficient This design has four revolute joints which is located at the base shoulder elbow and wrist These four joints emulate the motion of a human arm In this project only two links will be used A tyvo finger gripper vvill serve as the end effecter Due to time constrain and the complexity to build a gripper a commercially available gripper was used for this project For motion and movements of the joins actuators like servo motors are considered A radio control servo motor is attached to every joint of robotic arm Figure 3 3 shows the preliminary sketch of the robotic arm design using Google SketchUp 8 Side view 45 degrees 45 degrees view solid view x ray Figure 3 3 Preliminary robotic arm design in different angle views 15 3 3 2 Two Finger Gripper A two finger gripper will serve as the end effector for this project gripper set that comes with a medium size metal gear servo was purchase from Cytron Tech
30. th a gripper for pick and place purposes Besides that a hardware and software system that can be integrated to support the application system of the pick and place robotic arm will be developed 1 3 Scopes The scope of the project is to construct a robotic arm with 4 revolute joints to pick a rectangular item with the dimension of 4cm x 3cm x 3cm from a fix position A to another designated position B The item to be picked will resemble a hard drive circuit board but in a smaller and lighter version 1 4 Problem Statement Below are the problems encountered while designing and constructing the robotic arm 1 Unable to pick up a real hard drive circuit board due to the limited torque of the robotic arm motors 11 The actuator used has limited torque A robot arm structure that is bulky and heavy will wear out the actuators due to overloading iii Constraints in the robotic arm design due to limited rated torque of the actuators iv Difficulty in programming the RC servomotors to the desired position as each of the motors has a slightly different angle or rotation with the same given input CHAPTER 2 LITERATURE REVIEW 2 1 Introduction The research conducted on previous theses journals articles research papers and other sources will be presented in this chapter The main idea of literature review is to obtain enough relevant information and knowledge on similar projects done by others A few projects done previ
31. ulator conduct and adding the extra needed current to the output load 12 Due to the high current drawn by servo motors components such as regulator and power transistor will be very hot Thus to reduce the heat generated these components must be mounted on heat sinks Figure 3 11 shows the schematic diagram of the current booster and voltage regulating circuit LM 7806 Regulated Output Unregulated Input Power supply of Power source from 6 09V 2 67A Approx 12V 2A DC adapter A 35V 470uF 35V 470uF pe Figure 3 11 Schematic diagram of current booster and voltage regulating circuit 24 3 4 6 Power Source Two AC DC adapters are used to power this project A 12V 0 5A adapter is used to supply power to the SK40C A 5Vsupply will be supplied from the SK40C to servo controller for PIC operation through UART interface Another adapter which supplies the 12V 2A will be connected to the current booster and voltage regulating circuit The regulated output power supply from this circuit will then be fed into the servo controller to power the servo motors Figure 3 12 illustrates the 12V 0 5A AC DC adapter while Figure 3 13 shows the 12V 2A AC DC adapter Figure 3 12 12V 0 5A AC DC adapter Figure 3 13 12V 2A AC DC adapter 25 3 5 Software Programming MPLAB IDE software is used to write programs to control the movement of the joints MPLAB Integrated Development Environment IDE is a free integrated Gcc based toolset for t
32. urpose was successfully developed and built Throughout this project problem solving skills were put to use to overcome any hardware software or circuitry problems that arise This project provides analytical skills training hardware assembly training program writing training and circuitry design training The hands on experiences acquired from this project are valuable and will definitely be useful in future Generally this project gives students a chance to incorporate robotic theories and application into their projects Future developments on projects related to the robotic studies are a must to further enhance the robotic field in our country and bring the robotic field to a whole new level internationally 33 5 2 Recommendations Even though the project is a success there are a few limitations that can be further improved to develop a better and more robust automated pick and place robotic arm 1 Hardware Usually students opt to handmade their mechanical hardware by themselves to safe cost However the structure build by students are mostly based on assumptions without solid test and research This results in the lack of accuracy in the dimension and structure of the robot arm Students can try to incorporate off the shelf hardware structure into their own design for a more solid and accurate hardware design ii Actuator The actuator used in this project is the RC servo motor This servo motor is limited to certain torque
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