TECHNISCHE UNIVERSITÄT MÜNCHEN Lehrstuhl für Angewandte Mechanik Design and Realization of a Humanoid Robot for Fast and Autonomous Bipedal Locomotion Entwurf und Realisierung eines Humanoiden Roboters für Schnelles und Autonomes Laufen Dipl.-Ing. Univ. Sebastian Lohmeier 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.-Ing. Udo Lindemann Prüfer der Dissertation: 1. Univ.-Prof. Dr.-Ing. habil. Heinz Ulbrich 2. Univ.-Prof. Dr.-Ing. Horst Baier Die Dissertation wurde am 2. Juni 2010 bei der Technischen Universität München eingereicht und durch die Fakultät für Maschinenwesen am 21. Oktober 2010 angenommen. Colophon The original source for this thesis was edited in GNU Emacs and aucTEX, typeset using pdfLATEX in an automated process using GNU make, and output as PDF. The document was compiled with the LATEX 2" class AMdiss (based on the KOMA-Script class scrreprt). AMdiss is part of the AMclasses bundle that was developed by the author for writing term papers, Diploma theses and dissertations at the Institute of Applied Mechanics, Technische Universität München. Photographs and CAD screenshots were processed and enhanced with THE GIMP. Most vector graphics were drawn with CorelDraw X3, exported as Encapsulated PostScript, and edited with psfrag to obtain high-quality labeling. Some smaller and text-heavy graphics (flowcharts, etc.), as well as diagrams were created using PSTricks. The plot raw data were preprocessed with Matlab. In order to use the PostScript- based LATEX packages with pdfLATEX, a toolchain based on pst-pdf and Ghostscript was used. The bibliography was prepared with biblatex. The fonts in this thesis are the light versions of the Kp-Fonts by the Johannes Kepler project. © 2010 by Sebastian Lohmeier. All rights reserved Author contact: [email protected] This thesis is also available as a printed book published by Verlag Dr. Hut München, Germany (ISBN 978-3-86853-734-5). To my parents The danger of the past was that men became slaves. The danger of the future is that men may become robots. True enough, robots do not rebel. But given man’s nature, robots cannot live and remain sane, they become ‘Golems,’ they will destroy their world and themselves because they cannot stand any longer the boredom of a meaningless life. —Erich Fromm, The Sane Society Abstract This thesis covers the mechatronic conception, design and realization of a hu- manoid walking robot. Weighing approximately 60 kg, the robot stands 180 cm tall and has 25 actuated degrees of freedom in a redundant configuration. The mechanical structure is characterized by the consistent lightweight design with high effective stiffness. The lightweight servo actuators combine high-dynamic brushless servo motors with precision gearings and sensors into a compact pack- age. Moreover, the resultant inertia of the legs is minimized by a sophisticated design of the structure and drive mechanisms, resulting in a superior acceleration behavior. The sensor layout comprises angular sensors for direct measurement of the joint angles, a high-precision inertial measurement system and force/torque sensors in the feet. Using the trajectory generation and control system which is not in the scope of this work, the current speed of locomotion is 3.34 km/h. Keywords: humanoid robots, anthropomorphic robots, legged locomotion, mecha- tronics, robot design, sensors Zusammenfassung Diese Arbeit beschreibt die mechatronische Konzeption, Konstruktion und Re- alisierung eines humanoiden Laufroboters. Der Roboter ist 180 cm groß, wiegt zirka 60 kg und verfügt über 25 angetriebene Freiheitsgrade in einer redundanten Konfiguration. Die mechanische Struktur ist durch den extremen Leichtbau mit hoher effektiver Steifigkeit charakterisiert. Die hochdynamischen Gelenkantriebe kombinieren bürstenlose Servomotoren, Untersetzungsgetriebe und Sensorik zu kompakten Einheiten. Daneben werden die Massenträgheitsmomente der Beine durch konstruktive Maßnahmen minimiert. Daraus resultiert ein überragendes Beschleunigungsverhalten. Neben Winkelsensoren zur direkten Messung der Ge- lenkwinkel verfügt der Roboter über ein hochgenaues inertiales Messsystem und Kraftsensoren in den Füßen. Mit dem Bahnplanungs- und Regelungssystem, das nicht Bestandteil dieser Arbeit ist, konnte bisher eine Maximalgeschwindigkeit von 3,34 km/h erreicht werden. Stichworte: humanoide Roboter, anthropomorphe Roboter, zweibeiniges Laufen, Mechatronik, Konstruktion, Sensorik vii Acknowledgments This thesis summarizes my research carried out at the Institute of Applied Me- chanics, Technische Universität München. Developing the humanoid robot Lola almost from scratch has been a unique opportunity and certainly one of the biggest challenges in my life so far. Many people have contributed to this thesis and I would like to use the opportunity to express my gratitude to some of them. First and foremost I want to express my deep and sincere gratitude to my advisor Professor Heinz Ulbrich for the excellent research environment and giving enough freedom for own creativity. His patience and irrefutable confidence in my skills were beneficial for the success of this research. I also wish to express my warm and sincere thanks to Professor Friedrich Pfeiffer, the former head of the institute, for a lot of good advice and ideas and many helpful discussions. I warmly thank our academic director, Dr. Thomas Thümmel, for his support and continuing commitment to the robotics group. Thomas managed our project resources and largely kept us free from most administrative and formal burdens. Starting off with only two doctoral candidates, the Lola project was divided simply into “Software” and “Hardware.” I am particularly indebted to Thomas Buschmann, my co-worker and good friend, who took over the “Software” part. His theoretically accurate and thorough works on the robot simulation and con- troller were one of the foundations for the success of the project. To me, working together with Thomas was a stroke of luck as our ways of thinking and working were quite similar and, where not, complemented each other. I really need to thank Markus Schwienbacher and Valerio Favot who joined the team in a later project phase. In his Diploma thesis Markus developed, assembled and calibrated the force/torque sensors with enthusiasm and great attention to detail. I appreciate his efforts in resolving Lola’s teething problems. Markus, thank you so much for the fruitful discussions and competent suggestions! Valerio tested the PCBs for the local controllers and wrote all the code for them. Also, special thanks are due to Mathias Bachmayer, who developed the DSP boards for Lola’s decentralized controllers. The official presentation of Lola at the HANNOVER MESSE 2010 was the grand finale before turning in this dissertation. Regarding our trade fair presence, I thank Alexander Ewald for taking over all the organizational stuff. And my thanks go to the developers of Lola’s visual perception system, Dr. Felix von Hundelshausen and Gerhard Rohe from the Institute of Autonomous Systems Technology, University of the Bundeswehr, München, for the pleasant cooperation. During my first year at the institute I have had the pleasure to work with Dr. Klaus Löffler, the developer of Johnnie’s balance controller. Klaus shared the office with me and has always been a competent and excellent advisor as I took my first tentative steps into the field of humanoid robotics. Thank you for the collaboration ix x Acknowledgments during the countless public performances of Johnnie in 2003/04. The designer of Johnnie’s mechatronic system, Dr. Michael Gienger, had already left the institute before I started. Nevertheless, he was a competent advisor and always there to discuss about biped robots. Klaus and Michael, your results and experience were more than helpful and contributed substantially to this research! I warmly need to thank Dr. Andreas Zagler for getting me excited about robotics and for encouraging me to take up this position. The countless customized mechanical and electronic components would not have been possible without the enthusiasm and willingness of the institute’s me- chanical and electronic workshops. My sincere thanks are due to Wilhelm Miller, Walter Wöß, Simon Gerer, Philipp Schneider and Tobias Schmid. I very much appreciated their amazing skills to machine even the most complex parts with unparalleled precision. Until his retirement, Walter was a great help during the as- sembly of Lola. Wilhelm Miller, the former manager of the mechanical workshop, deserves a special mention. He fostered the manufacturing with optimism and never ending perseverance. He was always there to talk about my ideas and solve any unsolvable problems concerning precision mechanics. I have fond memories of numerous discussions—be it technical or non-technical. Sadly, he was not given the time to see Lola walking: he passed away during the first weeks of assembly. I am also greatly indebted to our electronics engineer, Georg Mayr, for numerous helpful discussions and for developing most of the electronics hardware. His experience and openness for my ideas were beneficial. For this dissertation I would like to thank my proof-readers: Michael, Markus, Thomas Buschmann, Dr. Martin Schwaiger and Valerio for their time, interest and many helpful comments. I would also like to thank the other two members of my dissertation commit- tee, the second