Design and Implementation of Two Undergraduate Laboratories Teaching PID Controller Design and Robotics Using Simulink and LEGO NXT A thesis presented to the faculty of the Russ College of Engineering and Technology of Ohio University In partial fulfillment of the requirements for the degree Master of Science John Bales August 2014 © 2014 John Bales. All Rights Reserved. 2 This thesis titled Design and Implementation of Two Undergraduate Laboratories Teaching PID Controller Design and Robotics Using Simulink and LEGO NXT by JOHN BALES has been approved for the Department of Mechanical Engineering and the Russ College of Engineering and Technology by Robert L. Williams II Professor of Mechanical Engineering Dennis Irwin Dean, Russ College of Engineering and Technology 3 Abstract BALES, JOHN, M.E., August 2014, Mechanical Engineering Design and Implementation of Two Undergraduate Laboratories Teaching PID Controller Design and Robotics Using Simulink and LEGO NXT Director of Thesis: Robert L. Williams II This paper outlines the design and implementation of a novel system to design undergraduate laboratories with. An initial laboratory form was written for the Robotics and Control of Robotic Manipulators class utilizing a LEGO NXT system and the Simulink programming environment. This laboratory form is given to students and then revised after each student group based on answers to a questionnaire, direct observation, and direct questioning during the laboratory period. This process is repeated after each group. This subjective data was gathered and grouped into three groups for analysis. Grouping was used to showcase trends caused by changes made to the lab during the iteration process. The same process is utilized in the Linear Systems Control class. Recommendations are made for future laboratories that will feature the student designed controller from Linear Systems Control in the mandatory tasks assigned during the Robotics class. This allows the student to take previous work and build upon it, exposing them to the design process, and allows the University to receive a larger return on any investments it might make in LEGO NXT systems. 4 Acknowledgements The author would like to acknowledge the following people for their support on the project: Dr. Robert Williams, for his inspiration of the initial project and his helpful guidance throughout this project, committee members Dr. Greg Kremer, Dr. Seann Dikkers, and Dr. Junghun Choi for their invaluable and much needed feedback, and Jan- Marie Ruminski for her excellent editing and sounding board skills. 5 Table of Contents Page Abstract................................................................................................................................3 Acknowledgements..............................................................................................................4 List of Tables .......................................................................................................................7 List of Figures......................................................................................................................8 1. Introduction......................................................................................................................9 1.1 Background................................................................................................................9 1.2 LEGO Mindstorms NXT .........................................................................................10 1.3 MATLAB and Simulink ..........................................................................................11 1.4 Literature Review.....................................................................................................11 1.4.1 Robotic Projects and Teaching Methods ......................................................12 1.4.2 Controls Projects and Teaching Methods .....................................................13 2. Thesis Objectives...........................................................................................................16 3. Project Information ........................................................................................................17 3.1 Questionnaire ...........................................................................................................18 3.2 Mechanics and Control of Robotic Manipulators Lab.............................................18 3.2.1 The Planned Robotics Laboratory .....................................................................19 3.2.2 The Implemented Robotics Laboratory .............................................................21 3.2.3 The Planned Robot.............................................................................................23 3.2.4 The Implemented Robot ....................................................................................23 3.3 Linear Systems Control Laboratory.........................................................................24 3.3.1 The Planned Linear Systems Laboratory...........................................................25 3.3.2 The Implemented Linear Systems Laboratory...................................................28 4. Project Results and Discussion ......................................................................................33 4.1 Data and Discussion from Robotics and Control of Robotic Manipulators .............33 4.2 Data and Discussion from Linear Systems Control..................................................47 5. Conclusions and Recommendations ..............................................................................57 5.1 Conclusions...............................................................................................................57 5.2 Recommendations.....................................................................................................58 References..........................................................................................................................60 Appendix A: Data from Robotics and Control of Robotic Manipulators..........................62 Appendix B: Data from Linear Systems Control...............................................................64 Appendix C: Commonly Encountered Errors....................................................................66 Appendix D: Robotics Laboratory-1st Iteration .................................................................67 Appendix E: Robotics Laboratory-Final Iteration .............................................................69 Appendix F: Sensor Library...............................................................................................74 Appendix G: Robotics Laboratory-Solutions to Tasks 1-3................................................75 Appendix H: Controls Laboratory-1st Iteration..................................................................77 Appendix I: Controls Laboratory-Final Iteration...............................................................83 Appendix J: Future Robotics Laboratory...........................................................................92 Appendix K: Future Controls Laboratory..........................................................................98 Appendix L: Questionnaire..............................................................................................107 Appendix M: Guide to Installing Matlab Toolboxes.......................................................109 6 Appendix N: Explanation and Code for the PID Controller............................................110 7 List of Tables Page Table 1: Z-N Table for Controller Tuning.........................................................................25 Table 2: Summation of the Changes Made to the Robotics Laboratory............................33 Table 3: Summation of the Changes Made to the Controls Laboratory ............................47 Table 4: Z-N Table for Controller Tuning ........................................................................82 Table 5: Lap Times for Each Controller ...........................................................................89 Table 6: Z-N Table for Controller Tuning ........................................................................90 Table 7: Lap Times for Each Controller .........................................................................104 Table 8: Z-N Table for Controller Tuning ......................................................................105 8 List of Figures Page Figure 1: LEGO NXT brick with included sensors ...........................................................10 Figure 2: PID Line-Following Simulink Program with sound pausing added .................20 Figure 3: Line-Following Robot ........................................................................................24 Figure 4: Simulink Program for Line-Following Robot....................................................27 Figure 5: Final Controller Design......................................................................................31 Figure 6: Practical and Theoretical Difficulty of the First Task........................................37 Figure 7: Practical and Theoretical Difficulty of the Second Task ...................................38 Figure 8: Student Robot Example One ..............................................................................40 Figure 9: Student Robot Example Two .............................................................................41 Figure 10: Student Robot Example Three .........................................................................42