191 Pages
English
Gain access to the library to view online
Learn more

Simulation and control of biped walking robots [Elektronische Ressource] / Thomas Buschmann

-

Gain access to the library to view online
Learn more
191 Pages
English

Description

Fakultät für MaschinenwesenLehrstuhl für Angewandte MechanikSimulation and Control ofBiped Walking RobotsDipl.-Ing. Univ. Thomas BuschmannVollständiger Abdruck der von der Fakultät für Maschinenwesen derTechnischen Universität München zur Erlangung des akademischen Grades einesDoktor-Ingenieurs (Dr.-Ing.)genehmigten Dissertation.Vorsitzender: Univ.-Prof. Dr. rer. nat. Ulrich WalterPrüfer der Dissertation:1. Univ.-Prof. Dr.-Ing.habil. Heinz Ulbrich2. Dr.-Ing.habil. Boris LohmannDie Dissertation wurde am 9. September 2010 bei der Technischen Universität Müncheneingereicht und durch die Fakultät für Maschinenwesen am 18. November 2010angenommen.AuthorThomas BuschmannLehrstuhl für Angewandte MechanikTechnische Universität München85747 GarchingGermanyE-Mail: ThesisThomasBuschmann@googlemail.com©2010 Thomas BuschmannAll rights reserved.A printed version is available from Verlag Dr. Hut, München (ISBN 978-3-86853-804-5)An electronic version is available at http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:91-diss-20101201-997204-1-6.AbstractThis PhD thesis covers simulation and control of biped walking robots. Simulationsand experiments were performed with the robots Johnnie and Lola developed at theInstitute of Applied Mechanics, Technische Universität München, Germany.The chapter on modeling and simulation describes the approach to simulatingthe rigid multibody dynamics.

Subjects

Informations

Published by
Published 01 January 2010
Reads 14
Language English
Document size 6 MB

Exrait

Fakultät für Maschinenwesen
Lehrstuhl für Angewandte Mechanik
Simulation and Control of
Biped Walking Robots
Dipl.-Ing. Univ. Thomas Buschmann
Vollständiger Abdruck der von der Fakultät für Maschinenwesen der
Technischen Universität München zur Erlangung des akademischen Grades eines
Doktor-Ingenieurs (Dr.-Ing.)
genehmigten Dissertation.
Vorsitzender: Univ.-Prof. Dr. rer. nat. Ulrich Walter
Prüfer der Dissertation:
1. Univ.-Prof. Dr.-Ing.habil. Heinz Ulbrich
2. Dr.-Ing.habil. Boris Lohmann
Die Dissertation wurde am 9. September 2010 bei der Technischen Universität München
eingereicht und durch die Fakultät für Maschinenwesen am 18. November 2010
angenommen.Author
Thomas Buschmann
Lehrstuhl für Angewandte Mechanik
Technische Universität München
85747 Garching
Germany
E-Mail: ThesisThomasBuschmann@googlemail.com
©2010 Thomas Buschmann
All rights reserved.
A printed version is available from Verlag Dr. Hut, München (ISBN 978-3-86853-804-5)
An electronic version is available at http://nbn-resolving.de/urn/resolver.pl?
urn:nbn:de:bvb:91-diss-20101201-997204-1-6.Abstract
This PhD thesis covers simulation and control of biped walking robots. Simulations
and experiments were performed with the robots Johnnie and Lola developed at the
Institute of Applied Mechanics, Technische Universität München, Germany.
The chapter on modeling and simulation describes the approach to simulating
the rigid multibody dynamics. It includes specialized models for simulating drive
friction, nonlinear drive kinematics and the unilateral ground contact. Component
models, contact and differential equation solvers are combined to a family of robot
simulations with varying modeling depth and computational cost.
The thesis also presents a hierarchical system for real-time walking control. Novel
aspects include a trajectory generator based on spline collocation and a stabilizing
controller based on hybrid position/force control. Lola’s redundant toe and pelvis
joints are used to reduce joint speeds and avoid joint limits. All methods were
verified on both robots in walking experiments and simulations. In experiments Lola
reached a maximum walking speed of 3.34km/h. Using a computer vision system
developed at the Institute of Autonomous Systems Technology at the Universität der
Bundeswehr in Munich, Germany, Lola is also capable of safely exploring previously
unknown environments.
iiiAcknowledgments
First, I would like to thank my supervisor Professor Heinz Ulbrich for giving me the
opportunity to do this research as well as for his guidance and support throughout
the past six years. He gave me the freedom to pursue my own ideas and created an
excellent research environment at the Institute of Applied Mechanics. I feel grateful
for having had the opportunity to work on such an interesting and challenging
project. I would also like to acknowledge Professor Boris Lohmann and Professor
Ulrich Walter for serving on my thesis defense committee. This thesis would not
have been possible without the pioneering work on legged locomotion at the Institute
of Applied Mechanics led by Professor Friedrich Pfeiffer. His advice and guidance
have been invaluable.
I am deeply grateful for having had the chance to work with a number of very
talented and highly motivated people. I am especially thankful to Sebastian Lohmeier,
who was responsible for Lola’s mechatronic system architecture and who did the
detailed mechanical design (see [62]). The collaboration with him was most enjoyable,
inspiring and productive. I would like to thank Valerio Favot, who worked on Lola’s
decentral controllers and communication system, and Markus Schwienbacher, who
worked on Lola’s hardware and software. Without their terrific work, Lola would not
have taken a single step. I owe special thanks to Georg Mayr. His long experience
with legged robots, his work on Lola’s electronics and his help in maintaining the
robot Johnnie were invaluable. I would also like to thank Mathias Bachmayer for
designing Lola’s DSP boards. Experimental robotics research is impossible without
decent hardware and I am especially grateful for Wilhelm Miller, Walter Wöß, Simon
Gerer, Philip Schneider and Tobias Schmidt’s excellent work in manufacturing Lola.
Special thanks are also due to Michael Gienger and Klaus Löffler for their work in
developing the robot Johnnie that served as a research platform for many years until
Lola was fully operational. Their work was both an inspiration and the basis for the
development of Lola.
I would also like to express my gratitude to Gerhard Rohe and Felix von Hun-
delshausen from the Universität der Bundeswehr in Munich, Germany, who developed
Lola’s computer vision system. Working with both was an extremely pleasant and
rewarding experience and this thesis would have been incomplete without the research
on autonomous locomotion.
I am very grateful to Alexander Ewald for organizing the presentation of Lola at the
Hannover Messe and to Dr. Thomas Thümmel for his support and encouragement
throughout this project.
I would also like to thank my (ex-) colleagues Sebasitan Lohmeier, Markus Schwien-
bacher and Gerhard Schillhuber and my sister Kathrin for proofreading this thesis.
Finally, I would like to acknowledge the DFG‘s financial support for this research
through the research program “Natur und Technik intelligenten Laufens” (Nature
and technology of intelligent walking, DFG grant UL 105/29).
vContents
1 Introduction 1
1.1 Problem Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Background and Related Work . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2.1 A Short History of Humanoid and Animal-Like Robots . . . . . . . 4
1.2.2 Related Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3 Overview of the Thesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2 Modeling and Simulation 11
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.1.1 Related Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.1.2 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.2 Rigid Body Dynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.2.1 Topology and Degrees of Freedom . . . . . . . . . . . . . . . . . . . 13
2.2.2 Recursive Kinematics Calculation . . . . . . . . . . . . . . . . . . . . 15
2.2.3 Relative . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.2.4 Equations of Motion for the Rigid Multibody System . . . . . . . . 21
2.3 Contact and Environment Models . . . . . . . . . . . . . . . . . . . . . . . . 21
2.3.1 Contact Dynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.3.2 Environment Model and Distance Computation . . . . . . . . . . . . 27
2.4 Drives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
2.4.1 Electrical Motor Dynamics . . . . . . . . . . . . . . . . . . . . . . . 31
2.4.2 Gear Friction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
2.4.3 Gear Elasticity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
2.5 Sensor Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
2.5.1 Joint Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
2.5.2 Force/Torque Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . 38
2.5.3 Inertial Measurement Unit . . . . . . . . . . . . . . . . . . . . . . . 38
2.6 Robot Models and Time Integration . . . . . . . . . . . . . . . . . . . . . . 40
2.6.1 Robot Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
2.6.2 Time Integration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
2.7 Chapter Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
3 Stability and Feasibility in Biped Walking 47
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
3.2 Basic Aspects of Biped Walking Dynamics . . . . . . . . . . . . . . . . . . . 47
3.3 Zero Moment Point and Related Concepts . . . . . . . . . . . . . . . . . . . 48
3.3.1 Zero Moment Point . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
3.3.2 Foot Rotation Indicator and Zero Rate of Change of Angular Mo-
mentum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
3.3.3 Stability Criteria Based on the Contact Wrench . . . . . . . . . . . . 51
3.3.4 Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
3.4 General Stability Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
viiviii Contents
3.5 Periodic Motions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
3.6 Chapter Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
4 Real-Time Trajectory Generation 55
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
4.2 Gait Coordination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
4.3 Step Sequence Planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
4.3.1 Standard Circular Path . . . . . . . . . . . . . . . . . . . . . . . . . 59
4.3.2 Step Parameter Calculation . . . . . . . . . . . . . . . . . . . . . . . 61
4.3.3 Reactive Step Sequence Planning . . . . . . . . . . . . . . . . . . . . 62
4.3.4 Higher Level Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . 63
4.4 Coordinate Systems and Task-Space Definition . . . . . . . . . . . . . . . . 64
4.4.1 Coordinate Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
4.4.2 Task-Space Definition . . . . . . . . . . . . . . . . . . . . . . . . . . 66
4.4.3 Relative Foot Orientation . . . . . . . . . . . . . . . . . . . . . . . . 68
4.4.4 Absolute Upper Body Orientation . . . . . . . . . . . . . . . . . . . 69
4.5 Foot Trajectory Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
4.6 Center of Gravity Trajectory Generation . . . . . . . . . . . . . . . . . . . . 74
4.6.1 Related Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
4.6.2 Problem Statement and Analysis . . . . . . . . . . . . . . . . . . . . 76
4.6.3 Center of Gravity Dynamics . . . . . . . . . . . . . . . . . . . . . . . 78
4.6.4 ZMP Reference Trajectory . . . . . . . . . . . . . . . . . . . . . . . . 79
4.6.5 Solving the Boundary Value Problem . . . . . . . . . . . . . . . . . 80
4.7 Camera Head Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
4.7.1 Inverse Kinematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
4.7.2 Reference Trajectory Generation . . . . . . . . . . . . . . . . . . . . 85
4.8 Contact Force Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
4.9 Additional Components in Trajectory Generation . . . . . . . . . . . . . . . 89
4.10 Chapter Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
5 Feedback Control 93
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
5.1.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
5.1.2 Background and Related Work . . . . . . . . . . . . . . . . . . . . . 93
5.2 Contact Force Modification . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
5.3 Hybrid Position/Force Control . . . . . . . . . . . . . . . . . . . . . . . . . 98
5.4 Inverse Kinematics and Redundancy Resolution . . . . . . . . . . . . . . . . 101
5.5 Joint Position Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
5.5.1 Joint Position Control for Johnnie . . . . . . . . . . . . . . . . . . . 104
5.5.2 Joint P Control for Lola . . . . . . . . . . . . . . . . . . . . . 106
5.6 Optimization-Based Parameter Tuning . . . . . . . . . . . . . . . . . . . . . 109
5.7 Chapter Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
6 Autonomous Walking 113
6.1 Computer Vision System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
6.2 Interfacing Walking Control and Computer Vision . . . . . . . . . . . . . . 115
7 Software System 117
7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
7.2 Software Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118Contents ix
7.3 Main Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
7.4 Real-Time System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
7.5 Chapter Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
8 Results 127
8.1 Biped Walking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
8.1.1 W Forward . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
8.1.2 Walking Sideways . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
8.1.3 Comparison of Simulation and Measurement . . . . . . . . . . . . . 130
8.2 Autonomous Locomotion . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
9 Conclusion 141
9.1 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
9.2 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
9.3 Recommendations for Future Research . . . . . . . . . . . . . . . . . . . . . 143
A Lola’s Basic Technical Data 145
B Multibody System Topology of Lola 147
C Harmonic Drive Friction Model Parameters 149
D Upper Body Kinematics 153
E Cubic Splines 155
F Local Optimization of Kinematic Redundancy 159
G Experimental Results 161
G.1 Walking Forward at 0 km/h . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
G.2 W Forward at 1 km/h . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
G.3 Walking Forward at 2 km/h . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
G.4 W Forward at 3 km/h . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
G.5 Walking Sideways at 0.7 km/h . . . . . . . . . . . . . . . . . . . . . . . . . 167
Bibliography 171