Computer numerical controlled machine project
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This document describes a student project to build a computer numerical controlled (CNC) machine. The machine uses an AT89C51 microcontroller to receive coordinates from a PC via serial communication and control a servo motor. The microcontroller implements an algorithm to move the motor to the specified coordinates, cutting shapes with straight edges. Hardware components include an H-bridge circuit to drive the stepper motor. The code is written in assembly language and implements functions to rotate the motor in different directions.
![EE332 CONTROL SYSTEMS LAB – CNC MACHINE
SPRING 2013
BIBLIOGRAPHY
Pocketmagic.net (2009) A simple H-Bridge design « PocketMagic. [online] Available at:
http://www.pocketmagic.net/2009/03/a-simple-h-bridge-design/#.UYwLYUrMLuZ [Accessed: 9 May
2013].
Page
17](https://image.slidesharecdn.com/computernumericalcontrolledmachineproject-131025155645-phpapp02/85/Computer-numerical-controlled-machine-project-17-320.jpg)
Computer numerical controlled machine project
- 1. EE332 CONTROL SYSTEMS LAB – CNC MACHINE SPRING 2013 SEMESTER PROJECT “COMPUTER NUMERICAL CONTROLLED MACHINE” SUBMITTED BY : MUHAMMAD ZAIGHUM FAROOQ SUBMITTED TO: ENGG. MEMOON SAJID COURSE: EE341L - CONTROL SYSTEMS LAB Page 1
- 2. EE332 CONTROL SYSTEMS LAB – CNC MACHINE SPRING 2013 ABSTRACT A computer numerical control (CNC) machine is a collection of automated tools controlled by abstractly programmed commands on a storage medium, as opposed to manual control via hand wheels or levers. The machine is operated by stepper motors that move the controls to follow points/co-ordinates fed into the system by a computer. In our work, we have used µ-controller AT89C51 as the storage medium, serially receiving co-ordinates from a pc, processing that data and controlling servo motor accordingly to reach the destination point. Page 2
- 3. EE332 CONTROL SYSTEMS LAB – CNC MACHINE SPRING 2013 Table of Contents ABSTRACT...................................................................................................................................................... 2 INTRODUCTION ............................................................................................................................................. 4 LIST OF HARDWARE USED ......................................................................................................................... 5 LIST OF SOFTWARES .................................................................................................................................. 5 STEPPER MOTOR SPECIFICATION ............................................................................................................. 5 MATLAB CODE FOR SENDING SERIAL DATA ................................................................................................. 5 CIRCUIT DIAGRAMS....................................................................................................................................... 6 H-BRIDGE CIRCUIT......................................................................................................................................... 7 FLOW CHART OF OPERATION ....................................................................................................................... 9 CODING TO IMPLEMENT THE ALGORITHM ................................................................................................ 10 UNIT OF INPUT ........................................................................................................................................ 14 MOTOR STEP SIZE ................................................................................................................................... 14 EFFICIENCY .............................................................................................................................................. 14 IMPROVEMENTS ......................................................................................................................................... 14 INPUT MATRIX & CUTTING DIRECTIONS ..................................................................................... 15 ACKNOWLEDGEMENTS ............................................................................................................................... 16 BIBLIOGRAPHY ............................................................................................................................................ 17 Page 3
- 4. EE332 CONTROL SYSTEMS LAB – CNC MACHINE SPRING 2013 INTRODUCTION Computer numerical machines are very commonly used the days . They have high tendency to replace the manual cutting machines as they are extremely user friendly . They give user enough free time to be able to control more than 5 machines very easily . This ease combined with a much greater degree of precision and accuracy sets their scope . Our main aim of the project was to cut any shape by controlling the machine numerically but as it was our semester project so we succeeded in cutting all the shapes that have straight edges . This project does not cut any round shape. A motor with rotating round cutter was turned on during the cutting process then commands are given for specific coordinates by matlab . Machine reaches that coordinates by cutting the object in a line with any slope depending on the coordinates at present . After that again coordinates are given to the controller through matlab and machine repeats its process . It carries on this way and cuts a closed shape with great degree of accuracy and precision . Page 4
- 5. EE332 CONTROL SYSTEMS LAB – CNC MACHINE SPRING 2013 LIST OF HARDWARE USED Following table shows the hardware used : CONTENT 1. µ-controller trainer with serial cable 2. H-bridge circuit1 3. 12V&5V power supply SPECIFICATION QUANTITY 1 2 1,1 LIST OF SOFTWARES Following table shows the softwares used : SOFTWARE 1. MATLAB 2. MCU 8051 IDE PURPOSE For entering co-ordinates and serially communicate them For programming the µ-controller STEPPER MOTOR SPECIFICATION Sequence of bits to rotate stepper motor through each consecutive step: D1 D2 D3 D4 1 0 0 1 1 1 0 0 0 1 1 0 0 0 1 1 Moving from top to bottom will move the motor in clockwise steps. While taking the opposite sequence will move the motor in anti-clockwise direction. MATLAB CODE FOR SENDING SERIAL DATA ss=serial('COM3'); ss.baudrate=9600; fopen(ss); ss.Terminator = 'CR'; tx =1; fprintf(ss,'%s',tx1); pause(1); Page 5
- 6. EE332 CONTROL SYSTEMS LAB – CNC MACHINE SPRING 2013 CIRCUIT DIAGRAMS Page 6
- 7. EE332 CONTROL SYSTEMS LAB – CNC MACHINE SPRING 2013 H-BRIDGE CIRCUIT To operate the stepper motor, we need a motor driving circuit that gives enough current to move the stepper motor in loaded conditions as present on the real CNC machine. We used the above H-bridge ic named L298 . You can also use any other H bridge circuit, commonly of transistors “Tip 122”. Page 7
- 8. EE332 CONTROL SYSTEMS LAB – CNC MACHINE SPRING 2013 STEPPER MOTOR CONTROL CIRCUITRY (REPEATED TWICE) The circuit shown below in the diadram is the main controlling circuitry for controlling the stepper motors. Page 8
- 9. EE332 CONTROL SYSTEMS LAB – CNC MACHINE SPRING 2013 FLOW CHART OF OPERATION Data Input Data sending by serial communication MATLAB Data received to µcontroller serial communication Interpreting data Giving instruction to motors Control Unit R U D L Page 9 L U R D
- 10. EE332 CONTROL SYSTEMS LAB – CNC MACHINE SPRING 2013 Computer interfaced with µ-controller using MATLAB. 1. Registers R₆ and R₇ to store the co-ordinate lengths entered through pc. Magnitude of R₆ and R₇ decides the no. of steps the stepper motor will move. 2. Register R₅ to hold the bit to give the direction in which the stepper motors will rotate. There are four cases which decide the motion of stepper motor as shown in the direction. 3. For 1 unit entered stepper motor will rotate 0.5cm. 4. Each step of stepper motor covers 20µm of length. A loop of 125 cycles, whereby each cycle consists of 2 steps is used to cover 0.5cm of length. CODING TO IMPLEMENT THE ALGORITHM org 00H mov tmod,#20H mov th1,#-3 mov scon,#50H setb tr1 main:nop her3: jnb ri,her3 lcall delay mov a,sbuf lcall delay dec a mov r7,a mov p0,a clr ri lcall delay here4: jnb ri,here4 lcall delay mov a,sbuf lcall delay dec a mov r6,a mov p0,a clr ri lcall delay here5: jnb ri,here5 lcall delay mov a,sbuf lcall delay mov r5,a mov p0,a clr ri Page 10
- 11. EE332 CONTROL SYSTEMS LAB – CNC MACHINE SPRING 2013 lcall delay tri: mov a,r5 cjne a,#0,over sjmp $ mov a,r5 over:cjne a,#1,over1 mov r4,#125 back6:mov a,r7 mov r1,a mov a,r6 mov r0,a back5:djnz r4,here2 sjmp main mov a,r5 over1:cjne a,#2,over2 mov r4,#125 back67:mov a,r7 mov r1,a mov a,r6 mov r0,a back57:djnz r4,here27 sjmp main mov a,r5 over2:cjne a,#3,over3 mov r4,#125 back68:mov a,r7 mov r1,a mov a,r6 mov r0,a back58:djnz r4,here28 sjmp main mov a,r5 over3:cjne a,#4,over4 mov r4,#125 back69:mov a,r7 mov r1,a mov a,r6 mov r0,a back59:djnz r4,here29 over4:sjmp main Page 11
- 12. EE332 CONTROL SYSTEMS LAB – CNC MACHINE SPRING 2013 here2:mov a,r1 jz too loo:acall down acall delay djnz r1,loo too:mov a,r0 jz back6 acall left acall delay djnz r0,too sjmp back6 here27:mov a,r1 jz tooo looo:acall up acall delay djnz r1,looo tooo:mov a,r0 jz back67 acall right acall delay djnz r0,tooo sjmp back67 here28:mov a,r1 jz toooo loooo:acall up acall delay djnz r1,loooo toooo:mov a,r0 jz back68 acall left acall delay djnz r0,toooo sjmp back68 here29:mov a,r1 jz to lo:acall down acall delay djnz r1,lo to:mov a,r0 jz back69 acall right acall delaysjmp back69 Page 12
- 13. EE332 CONTROL SYSTEMS LAB – CNC MACHINE SPRING 2013 down: mov a,30h jz soo mov p1,#99H lcall delay mov p1,#0ccH lcall delay mov 30h,#0 sjmp haha soo:mov p1,#66H lcall delay mov p1,#33H lcall delay mov 30h,#1 haha: ret up: mov a,31h jz soo1 mov p1,#33H lcall delay mov p1,#66H lcall delay mov 31h,#0 sjmp haha soo1:mov p1,#0ccH lcall delay mov p1,#99H lcall delay mov 31h,#1 haha1: ret left: mov a,32h jz soo2 mov p2,#99H lcall delay mov p2,#0ccH lcall delay mov 32h,#0 sjmp haha soo2:mov p2,#66H lcall delay mov p2,#33H Page 13
- 14. EE332 CONTROL SYSTEMS LAB – CNC MACHINE SPRING 2013 lcall delay mov 32h,#1 haha2: ret right: mov a,33h jz soo3 mov p2,#33H lcall delay mov p2,#66H lcall delay mov 33h,#0 sjmp haha soo3:mov p2,#0ccH lcall delay mov p2,#99H lcall delay mov 33h,#1 haha3: ret delay: mov r2,#40 h1:mov r3,#255 h2:djnz r3,H2 djnz r2,h1 ret end UNIT OF INPUT Unit of input is 0.5 cm in the above program and can be changed by changing the number 125 in the program. For example, if you change the number from 125 to 63 then unit of input will be 0.25cm. MOTOR STEP SIZE Motor step size is 500 steps/cm. EFFICIENCY In the above program it depends on the inputs. IMPROVEMENTS 1: Efficiency of the above program can be improved by making more precise sub-control units. 2: Efficiency of the above program can be increased by two folds if we change the motor rotating units. Page 14
- 15. EE332 CONTROL SYSTEMS LAB – CNC MACHINE SPRING 2013 In the above program every time the motor rotate is called motor takes two steps , by changing it to take one step efficiency will double as well as program length will decrease . Its very easy. Just take a rom location save the 66H in it retrieve it in motor rotate routine , rotate left or right according to routine and then save it back in the same location . 3: Currently we input from matlab the directions and lengths of coordinates, we should improve it to entering the +,- coordinates and let the computer calculate lengths and direction . 4: Data should be received as ascii characters. 5: It should also be improved to cut the curves of different types . 6: It should also be programed to three directional cutting . INPUT MATRIX 1 7 7 3 5 3 1 5 3 3 5 3 4 7 1 4 7 1 CUTTING DIRECTIONS 4 1 & 3 Third number in input matrix represents the direction. First two numbers are lengths. Many others possible, they also depend on connections of motors. Moreover above lines arrows are not according to scale. Page 15
- 16. EE332 CONTROL SYSTEMS LAB – CNC MACHINE SPRING 2013 ACKNOWLEDGEMENTS For this project, we owe our gratitude to Mr. Memoon Sajid who assigned us this project and was a source of constant help throughout both morally and practically. We would also like to thank our teacher Mr. Kashif Riaz who with his marvelous teaching skills made assembly language almost innate for us. We would also like to thank Mr. Nayyar Abbas who diligently taught us the use and programming of µ-controller. Last but not the least we would like to thank our honorable Dean (FEE) Dr. Nisar who had been very supportive in the requisition of hardware without which this project would never have seen the light of day. Page 16
- 17. EE332 CONTROL SYSTEMS LAB – CNC MACHINE SPRING 2013 BIBLIOGRAPHY Pocketmagic.net (2009) A simple H-Bridge design « PocketMagic. [online] Available at: http://www.pocketmagic.net/2009/03/a-simple-h-bridge-design/#.UYwLYUrMLuZ [Accessed: 9 May 2013]. Page 17