Soft Tools for Robotics and Controls Implementations A Thesis Submitted to the Faculty of Drexel University by Robert M. Sherbert in partial fulfillment of the requirements for the degree of Master of Science in Electrical Engineering June 2011 c Copyright 2011 Robert M. Sherbert. All rights reserved. ii Dedications To the parents who placed me on my path, to the mentors who guided me along its many turns, and to the friends who made the long journey swift. iii Acknowledgments There are a number of people to whom I owe a great deal of thanks in completing this document. While the labor has been my own, the inspiration for it and the support to finish it have come from the community around me. In creating this work I have taken on the role of toolsmith and, as tools are worthless without their users, it is to these individuals that I am especially indebted. I would like to thank Dr. Oh for lending his vision of robotics testing and prototyping which inspired this work. You have taught me more than I realized there was to know about the modern practice of science. I would also like to thank Dr. Chmielewski for lending his experience, insight, and enthusiasm to the project. Having these ideas weighed against and improved by your practical knowledge has provided a very important validation for me. Above all I would like to thank my friends at DASL, without whom the entirety of this project would have been consigned to the dust bin long ago. You have given me not only critical feedback and suggestions but also the support and encouragement that has helped me carry this to completion. I could not have done this without you. Lastly, I thank my parents. Without you I never would have started, much less finished. I do not yet know where life will take me, but I do know that because of all of you I leave this place a better person than I came. Thank you. iv Table of Contents LIST OF FIGURES ............................................. vii ABSTRACT ................................................ ix 1. INTRODUCTION ............................................ 1 1.1 Review of Literature ....................................... 3 1.2 ProposedSolution ......................................... 5 1.2.1 Conductor ........................................... 6 1.2.2 Score ............................................. 7 2. CONDUCTOR: DESIGN ........................................ 9 2.1 ConceptofOperations ...................................... 9 2.2 FrameworkOverview ....................................... 9 2.3 ControlComponents ....................................... 12 2.3.1 State .............................................. 12 2.3.2 Controller ........................................... 14 2.4 Communication Components ................................... 15 2.4.1 Device ............................................. 15 2.4.2 Protocol ............................................ 16 2.4.3 Hardware ........................................... 18 2.5 Interfacingwith Conductor .................................... 19 2.5.1 InternalAccess ........................................ 19 2.5.2 ExternalAccess ........................................ 20 3. CONDUCTOR: TESTING/RESULTS .................................. 21 3.1 Stress Testing ........................................... 21 3.2 Example/Implementation ..................................... 22 3.2.1 HighDegreeofFreedomSystems .............................. 23 v 3.2.2 Portability ........................................... 26 3.3 Summary ............................................. 26 4. SCORE: DESIGN ........................................... 29 4.1 ConceptofOperations ...................................... 29 4.2 Systems Architecture ....................................... 29 4.2.1 Overview ........................................... 29 4.2.2 HardwareAuto-Configuration ................................ 30 4.2.3 SymbolicExpressionManager ................................ 34 4.2.4 SystemInput/Output ..................................... 37 5. SCORE: TESTING/RESULTS ..................................... 39 5.1 Hardware Auto Configuration Testing .............................. 39 5.1.1 ADCAuto-Configuration ................................... 39 5.1.2 PWMAuto-Configuration .................................. 39 5.2 Time Domain Controller Testing ................................. 43 5.2.1 ProportionalResponseTest .................................. 43 5.2.2 IntegralResponseTest .................................... 46 5.2.3 WindupIntegrator ....................................... 47 5.2.4 Derivative Response Test ................................... 49 5.2.5 Integrated System Test .................................... 54 5.3 Summary ............................................. 61 6. CONCLUSIONS ............................................ 62 6.1 Results fromConductor ...................................... 62 6.2 ResultsfromScore ........................................ 63 6.3 Contributions ........................................... 64 6.4 Future Possibilities ........................................ 64 BIBLIOGRAPHY .............................................. 65 APPENDIX A: DCMOTOR MODEL PARAMETERS .......................... 67 TABLE OF CONTENTS TABLE OF CONTENTS vi APPENDIX B: PRIMER ON RT SYSTEMS & FREERTOS ....................... 68 B.1 Function/Purpose ......................................... 68 B.2 Concepts/Terminology ...................................... 69 B.3 Types of RT Systems ....................................... 70 B.3.1 RTSystems onMicrocontrollers ............................... 70 B.3.2 RTSystemsonx86Computers ................................ 70 B.4 FreeRTOS ............................................. 71 B.4.1 Tasks ............................................. 71 B.4.2 Inter-Task Communication .................................. 72 vii List of Figures 2.1 Schematic diagram of data flow through the Conductor system .................. 9 2.2 Schematic diagram of the State’s functionality ........................... 12 2.3 Schematic diagram of the Device’s functionality .......................... 15 2.4 Schematic diagram of the Protocol’s downstream functionality .................. 16 2.5 Schematic diagram of the Protocol’s upstream functionality .................... 17 2.6 Example of Conductor log files ................................... 18 3.1 Conductor stress testing results ................................... 22 3.2 Example Conductor node arrangement ............................... 23 3.3 The code to realize the motor arrangement in Figure 3.2 ...................... 24 3.4 Example Conductor/Orocos PID controller ............................. 24 3.5 Example Conductor-Matlab interface code ............................. 25 3.6 Walking trajectory time progression with virtual mini-Hubo .................... 26 3.7 The mini-Hubo climbing stairs while driven by Conductor .................... 27 3.8 The three test systems for Conductor performing the box task ................... 28 4.1 Score system architecture ...................................... 30 4.2 Testing flowchart for score ..................................... 32 4.3 Data structure for the ADC auto-configuration code ........................ 33 4.4 A graphical depiction of an example system name table. ..................... 37 4.5 Example score script file ...................................... 38 5.1 Initializing an ADC with Score ................................... 40 5.2 PWM generator testing: config files ................................ 41 5.3 PWM generator testing: osilliscope traces ............................. 42 5.4 Score code for re-sampling ..................................... 43 5.5 Proportional test error ........................................ 44 viii 5.6 Session to configure proportional test ................................ 45 5.7 Testing the proportional response .................................. 46 5.8 Error between the Score integration of sint and the ideal − cos t ................. 47 5.9 Session to configure integral test .................................. 48 5.10 Hardware testing of the integral feature .............................. 49 5.11 Topology of a simple anti-windup technique attached to a PI controller .............. 49 5.12 Testing the anti-windup shown in Figure 5.11. ........................... 50 5.13 Code for testing the anti-windup .................................. 50 5.14 Error between the Score derivative of sint and the ideal − cos t .................. 51 5.15 Score code for integration and differentiation tests ......................... 51 5.16 Session to configure derivative test ................................. 52 5.17 Derivative response sample I/O, input is 120Hz 0.5V ramp .................... 52 5.18 Measured derivative (via PWM duty cycle) vs true ramp waveform derivative .......... 53 5.19 Simulink model of DC motor in servo configuration ........................ 54 5.20 Score code for PID system test ................................... 55 5.21 Position error of the servo motor after addition of the PID controller ............... 56 5.22 Comparison of the Simulink and Score PID controllers ...................... 57 5.23 Difference between Simulink and Score PID controllers ...................... 57 5.24 System test circuit .......................................... 58 5.25 Code configuring Score as a negative feedback controler ..................... 59 5.26 Negative feedback controller testing ................................ 60 LIST OF FIGURES LIST OF FIGURES ix Abstract Soft Tools for