MINISTRY OF EDUCATION AND TRAINING HCMC UNIVERSITY OF TECHNOLOGY AND EDUCATION BACHELOR THESIS MECHATRONIC ENGINEERING TECHNOLOGY STUDY ON INTERPOLATION ALGORITHMS FOR CNC MACHINE ADVISOR: VO LAM CHUONG, MSC STUDENT’S NAME: NGUYEN TAN TAI STUDENT’S ID: 13146280 STUDENT’S NAME: PHUN QUOC VIET STUDENT’S ID: 13146264 STUDENT’S NAME: TRAN DAI NAM STUDENT’S ID: 13146137 SKL 0 0 5 3 6 5 Ho Chi Minh city, July 2017 do an SOCIALIST REPUBLIC OF VIETNAM Independence - Freedom - Happiness ----***---- Ho Chi Minh City, July 15th 2017 MISSION OF THESIS Student’s name: Nguyen Tan Tai Student’s ID: 13146280 Major: Mechatronics Class: 13146CLC Phone number: 0164 6576 793 Student’s name: Phun Quoc Viet Student’s ID: 13146264 Major: Mechatronics Class: 131462B Phone number: 01644960322 Student’s name: Tran Đại Nam Student’s ID: 13146137 Major: Mechatronics Class: 131462A Phone number: 01666323408 Advisor: Vo Lam Chuong, MSc Delivery date: July 15th 2017 Submission date: 1. Title of thesis: Study on interpolation algorithms for CNC machine 2. The original data, documents: Use the embedded beagleboard control 3 axes CNC milling machine 3. Main content: - Setting up the parameters for AC servo drivers - Designing a controller panel, interface boards for AC drivers - Study on the interpolation algorithms based on pulse reference method, concentrating on NURBS algorithms - Simulating and implementing on a real model - Building an experimental lesson for the subject “Practice on Servo Systems” 4.
Product: Milling machines can process Spline curves on materials: mica, plastic, … Dean of Department Advisor i do an SOCIALIST REPUBLIC OF VIETNAM Independence - Freedom - Happiness ----***---- ADVISOR’S COMMENT Student’s name:. Title of thesis:. The content of thesis and the workload:. Project defence approval:.
) Ho Chi Minh City, July 2017 Advisor (Name, signature) ii do an SOCIALIST REPUBLIC OF VIETNAM Independence - Freedom - Happiness ----***---- ADVISOR’S COMMENT Student’s name:. Title of thesis:. The content of thesis and the workload:. Project defence approval:.
) Ho Chi Minh City, July 2017 Advisor (Name, signature) iii do an ACKNOWLEDGEMENT During the working time, we received enthusiastic guidance that help us finish the project successfully. Firstly, we would like to express our sincere gratitude to the School Board of Ho Chi Minh City University of Technology and Education and the Faculty of High Quality Training that create great conditions for successful project. Secondly, we would like to thank Vo Lam Chuong, MSc – our supervisor who gave us a lot of useful guidance and advice that help us to complete the project successfully. From these advice, we know how to apply our knowledge to solve a real problem and feel more confident in our learned skills.
Thank to our group members in Servo Laboratory, who often attend to support each other and cooperate enthusiastically to complete the project. Finally, we would like to thank my family and friends for always supporting, caring and encouraging us during more than four years studying at the universisty. Ho Chi Minh City, July 24th, 2017 Members of group: Phun Quoc Viet Nguyen Tan Tai Tran Dai Nam iv do an ABSTRACT Our country's mechanical engineering has made significant development but the precision engineering industry has not really developed yet to meet the demand for high precision mechanical processes. To achieve the precision and high quality require technology of thriving CAD/CAM/CNC.
Therefore, researching and appling control algorithms are extremely important. This article presents some results in research of interpolation algorithms such as DDA (Digital Differential Analyzer), SA (Stairs Approximation), DS (Direct Search) and NURBS (Non-Uniform Rational B-spline) to improve accuracy for CNC milling machines. We used the strong support softwares to simulate as Matlab, C #, then evaluated the quality and accuracy of the algorithms on the 3-axis CNC milling machine model. v do an TABLE OF CONTENTS MISSION OF THESIS.
ii ADVISOR’S COMMENT .v TABLE OF CONTENTS. vi LIST OF ABBREVIATIONS. ix LIST OF TABLES. ix LIST OF FIGURES AND CHARTS .x CHARTER 1: OVERVIEW PROJECT.
The urgency of the project. The scientific and practical significance of the project. Research objectives of the project. Object and scope of the study.
Research scope of the project. Research subjects of the project. Specific research methods .2 CHAPTER 2: OVERVIEW TECHNOLOGY CNC. CNC technology overview.
CNC machine structure .6 vi do an 2. CNC control loop. Semi-closed Loop.15 CHAPTER 3: MECHANICAL SECTION. CNC milling machine.
CNC milling machine introduction. CNC milling technology. CNC milling machine design. Method of moving workpiece.
Selecting the optimum solution. Selecting structure of motion. Selecting guiding method. Calculating, engines selection.
General CNC machine model .35 CHAPTER 4: ELECTRIC DESIGN. Buffer circuit overview. Introduction common protocol .42 vii do an 4.44 CHAPTER 5: INTERPOLATION ALGORITHMS. Interpolation algorithms introduction.
Reference pulse method. Software DDA Interpolator. Stairs Approximation Interpolator. Direct Search algorithm.
Theory of NURBS curve. Survey the NURBS curve characteristics. NURBS interpolation algorithm design .55 Calculating the parameters value .55 Calculating the knots vector .56 Calculating base function Spline.56 Calculating control points .56 Finding the equation for curve.56 Calculating the points of the NURBS curve .58 Interpolate the NURBS curve using DDA algorithm. Building diagram of NURBS interpolation algorithm.
Simulating NURBS interpolation. General algorithm interpolation of system .62 CHAPTER 6 : EXPERIMENTAL RESULTS .63 viii do an 6.71 LIST OF ABBREVIATIONS NURBS Non-Uniform Rational Basis Spline CNC Computer Numerical Controlled RPM Revolution Per Minute NC Numerical Control LED Light Emitting Diode SCR Silicon-Controlled Rectifier PLC Programmable Logic Controller MCU Micro Controller Unit CAD Computer Aided Design CAM Computer-Aided Manufacturing MMI Multi Media Interface PIC Programmable Intelligent Computer ARM Advanced RISC Machine DDA Digital Differential Analyzer SA Stairs Approximation DS Direct Search LIST OF TABLES Table 3.1: Parameters of shafts.1: Parameters of STM32F407VET6 .37 ix do an LIST OF FIGURES AND CHARTS Figure 2.1: Milwaukee Magic CNC machining center .2: CNC Router machine .3: CNC Laser Cutter machine .5: CNC Lathe machine .6: CNC milling machine .11: Dovetail way system .12: AC and DC servo motor .14: Semi-closed Loop control [3] .15: Closed loop control [3] .17: Open loop control [3] .18: Opto-isolator schematic .19: (a) PLC of Omron Corporation .1: Vertical milling machine .2: Horizontal milling machine .3:CNC milling machine .4: The cutting process .5: Type of cutter .6: Fix workpiece method .7: Workpiece moves on Y axis .8: Workpiece moves on X and Y axes .9: Ball screw for CNC machine .10: Timing belt and timing pulley .11: Parameters of timing belt .12: Type of profile (timing belt) .26 x do an Figure 3.13: Parameters of timing pulley .14: Timing belt and pulley on model.15: Linear guide on model .16: Dovetail ways on model .17: Transmiter on X, Y axes .18: Transmiter of Z axis .20: Motor of X, Y axes .21: SGDA AC Servopack driver .22: Servo motor MSMA082A1A .23: MSDA083A1A AC Servo driver .24: Modeling model on Solidworks .1: Block diagram of the circuit STM32F40xxx [5] .2: Command Pulse input circuit [6] .5: Argument Isolator circuit driver design .6: Opto-isolator PC 817 .8: Communicate between slaves by RS 485 [17] .9: Main interface design .2: Flowchart of reference pulse method [3] .3: Flowchart of sampling method [3] .4: DDA interpolation algorithm [3].5: DDA linear algorithm simulation .6: DDA circle algorithm simulation .7: Stairs Approximation interpolator algorithm [3] .8: SA algorithm simulation .9: Direct Search interpolator algorithm [3] .10: DS circle algorithm simulation .11: De-Boor algorithm [1] .57 xi do an Figure 5.12: Using DDA algorithm for NURBS [3] .14: NURBS interpolation algorithm .15: NURBS algorithm simulation.16: General interpolation algorithm .1: Real CNC machine model .3: DDA linear algorithm simulation .4: DDA circle algorithm simulation .5: SA algorithm simulation .6: DS algorithm simulation .7: The points on NURBS curve correspond to the knots .8: Simulation result of interpolation algorithm NURBS curves .9: Result of DDA on real model .10: Result of NURBS algorithm on real model .70 xii do an CHARTER 1: OVERVIEW PROJECT 1. The urgency of the project Our country's mechanical engineering has made significant development but the precision engineering industry has not really developed yet to meet the demand for high precision mechanical processes. To achieve the precision and high quality require technology of thriving CAD/CAM/CNC.
The research and manufacturing of CNC machines, the study of the control algorithms is extremely urgent to be able to grasp the technology of high precision mechanical machining. Because of these urgent requirements, we have done the topic "Study on interpolation algorithms for CNC machines". With this research, we hope to contribute to promote the country's mechanical engineering industry to develop in the future. The scientific and practical significance of the project Accuracy in mechanical machining requires many factors, such as mechanics, motors, and an indispensable part of the control algorithm.
Actually, the control and processing algorithms have developed strongly, but VietNam has not approached the newest technologies yet because of some factors. This project will bring us closer to new interpolation algorithms and achieve high precision machining requirements, that is the NURBS interpolation algorithm. Research objectives of the project Setting up the parameters for AC servo drivers. Designing a controller panel, interface boards for AC drivers.
Study on the interpolation algonthms based on pulse reference method, concentrating on NURBS algorithms. Simulating and implementing on a real model. Buiding an experimental lesson for the subject “Practice on Servo Systems”. Object and scope of the study 1.
Research scope of the project Due to limited knowledge, the topic is limited at the level of study on interpolation algorithms, simulating and testing on simple materials to serve 1 do an in the teaching and research, CNC machines have not reached the level of commercialization. Research subjects of the project CNC machines have many types, the main research object of the group is the interpolation algorithms on the CNC milling machine to control 3 AC servo motors. Methodological basis Learning about the principles, structure of each part of the mechanical and electronic system, from which operate exactly these structures. Researching simple algorithms, simulation testing, then develop NURBS algorithm on B-Spline curve of 3th order.
References from books, journals, theses and the internet are the important part of the success of the project. Specific research methods First, finding and reading all the theoretical documents related to the subject from the university library, the internet, scientific journals, theses. Simulation testing on the softwares, fixing bugs. Final, run the experiment on the model.
Thesis structure CHAPTER 1: OVERVIEW PROJECT CHAPTER 2: OVERVIEW TECHNOLOGY CNC CHAPTER 3: MECHANICAL SECTION CHAPTER 4: ELECTRIC DESIGN CHAPTER 5: INTERPOLATION ALGORITHMS CHAPTER 6: EXPERIMENTAL RESULTS 2 do an CHAPTER 2: OVERVIEW TECHNOLOGY CNC 2. CNC technology overview Computer Numerical Control (CNC) machines are automated devices controlled by computers that are used to perform various industrial tasks without direct human intervention. These are programmed to follow a sequence of steps, which contributes to their excellent accuracy and precision. CNC machining is employed in a wide range of manufacturing industries, including metal fabrication industry, mining industry, and automobile industry.
1949, US Air Force and MIT developing milling machine can be programmed. 1952, MIT launched digital control machine tool first (CINCINNATI HYDROTEL) includes multiple electronic lamp with linear interpolation function with 3 axes simultaneously and receive data through a binary punched tape code. 1965, solutions to replace instruments automatically are integrated on CNC machines. 1972, NC control system has installed on the first small computer.
1978, the flexible manufacturing systems (FMS) was created. 1985, first CNC machining center named "Milwaukee Magic", it is produced by Carney company and Treker producer (USA). 3 do an Figure 2.1: Milwaukee Magic CNC machining center Nowadays, CNC machines have been completed in design and control. Speed machine can be over 20,000 rev / min, precision machining to be able to reach 0.
CNC machine There are many type of CNC machines. The following are the common types of CNC machines.