NEUROBIOLOGICALLY-BASED CONTROL SYSTEM FOR AN ADAPTIVELY WALKING HEXAPOD by WILLIAM ANTHONY LEWINGER Submitted in partial fulfillment of the requirements For the degree of Doctor of Philosophy Research Advisor: Dr. Roger D. Quinn Department of Electrical Engineering and Computer Science Systems and Control Engineering CASE WESTERN RESERVE UNIVERSITY May 2011 CASE WESTERN RESERVE UNIVERSITY SCHOOL OF GRADUATE STUDIES We hereby approve the thesis/dissertation of ________________________________________________________William Lewinger candidate for the __________________________________________Doctor of Philosophy degree *. (signed)_________________________________________________Roger Quinn (EMAE/EECS) (Chair of the Committee) Michael Branicky (EECS) _________________________________________________ Roy Ritzmann (BIOL) _________________________________________________ _________________________________________________Wyatt Newman (EECS) _________________________________________________ _________________________________________________ 04 January 2011 (Date) ____________________ * We also certify that written approval has been obtained for any proprietary permission contained therein. ii Copyright © 2011 by William Anthony Lewinger All rights reserved iii This dissertation is dedicated to Roger, who has been a constant supporter, advocate, mentor, advisor, and friend throughout the whole graduate studies process. Thanks Roger! © 2008 Tatsuya Ishida iv TABLE OF CONTENTS TABLE OF CONTENTS ............................................................................................................1 LIST OF FIGURES ...................................................................................................................8 LIST OF ABBREVIATIONS.....................................................................................................15 GLOSSARY ..........................................................................................................................17 CHAPTER I ..........................................................................................................................23 INTRODUCTION ...................................................................................................................23 1.0 General...................................................................................................................23 1.1 Background............................................................................................................24 1.2 Goals ......................................................................................................................29 1.3 Thesis Contributions..............................................................................................30 1.4 Chapter Topics.......................................................................................................33 CHAPTER II .........................................................................................................................35 REVIEW OF PREVIOUS LEGGED ROBOT RESEARCH .............................................................35 2.0 General...................................................................................................................35 2.1 18-DoF Hexapod Robot Designs...........................................................................35 2.1.1 TUM Walking Machine...................................................................................37 2.1.2 Tarry I and Tarry II..........................................................................................38 2.1.3 Robot II............................................................................................................40 2.1.4 BILL-Ant-p......................................................................................................42 2.1.5 Lynxmotion Hexapod Kits...............................................................................46 1 2.1.6 AMOS-WD06..................................................................................................49 2.1.7 Micromagic Systems Hexapod Robot Series...................................................51 2.1.8 A-pod ...............................................................................................................54 2.1.9 Additional 18-DoF Hexapod Robots ...............................................................57 2.2 Hexapod Robot Control Schemes..........................................................................59 2.2.1 Leg Control Methods.......................................................................................59 2.2.1.1 Pure Mechanical Systems ..........................................................................59 2.2.1.2 Software-Implemented Fixed Step Path ....................................................61 2.2.1.3 Inverse Kinematics (IK).............................................................................63 2.2.1.4 Central Pattern Generators (CPGs) and Artificial Neural Networks (ANNs).......................................................................................................66 2.2.2 Leg Coordination Methods ..............................................................................68 2.2.2.1 Coupled Mechanical Systems....................................................................70 2.2.2.2 Fixed Programmed Gaits ...........................................................................72 2.2.2.3 Dynamically Selectable Gaits....................................................................73 2.2.2.4 Oscillators / Central Pattern Generators (CPGs) .......................................74 2.2.2.5 Cruse’s Rules for Leg Coordination ..........................................................77 2.2.2.6 Walknet......................................................................................................79 CHAPTER III........................................................................................................................82 BIOLOGICALLY-INSPIRED LEGGED LOCOMOTION – ANT – AUTONOMOUS (BILL-ANT-A) DESIGN ...............................................................................................................................82 3.0 General...................................................................................................................82 2 3.1 Physical Design......................................................................................................83 3.1.1 Body.................................................................................................................84 3.1.2 Legs..................................................................................................................87 3.1.3 Neck and Light Sensors ...................................................................................93 3.2 Electrical System ...................................................................................................94 3.2.1 Leg Control System.........................................................................................94 3.2.2 Power System.................................................................................................100 CHAPTER IV......................................................................................................................103 LEG CONTROL...................................................................................................................103 SENSORY-COUPLED ACTION SWITCHING MODULES (SCASM)........................................103 4.0 General.................................................................................................................103 4.1 Biological Basis for Leg Control .........................................................................104 4.2 Introduction to Sensory-Coupled Action Switching Modules (SCASM) ...........106 4.3 Implementation of SCASM for Intra-Leg Joint Control......................................112 4.3.1 Single-Leg Test Platform...............................................................................112 4.3.2 Two-Leg Test Platform..................................................................................116 4.3.3 BILL-Ant-a ....................................................................................................121 4.4 Reflexes................................................................................................................132 4.4.1 Searching Reflex............................................................................................133 4.4.2 Elevator Reflex..............................................................................................138 4.5 Modulation of SCASM........................................................................................141 3 CHAPTER V.......................................................................................................................158 LEG COORDINATION .........................................................................................................158 BIOLOGICALLY-INSPIRED LEGGED LOCOMOTION – LOW COMPUTATION POWER EMERGENT GAIT SYSTEM (BILL-LEGS)............................................................................................158 5.0 General.................................................................................................................158 5.1 Biological Inspiration...........................................................................................159 5.2 BILL-LEGS Implementation...............................................................................164