Prof. Zheng Hong Zhu
York University, Canada
Speech Tittle: Deep Reinforcement Learning for Autonomous Space Debris Capture by Free-Floating Space Robotic Manipulator
Abstract: This talk presents the integration of deep reinforcement learning (DRL) for path planning and visual servoing in the autonomous capture of space debris using a free-floating 6 DOF space robotic manipulator. The inherent dynamics of the manipulator create a distinct dynamic coupling with its base spacecraft, where the end effector's pose is directly influenced by the combined movements of both entities. Such interactions challenge the spacecraft's positional and attitudinal consistency, further complicating manipulator control and path planning. In response, we have developed model-free path planning and grasp control strategies employing DRL, leveraging the deep deterministic policy gradient optimization and enhanced by the actor-critic architecture. This system adeptly combines policy gradient approaches with temporal-difference learning, undergoing continuous adjustments within a simulated domain. The presentation delves into the intricacies of reward function shaping for the manipulator's path planning, accounting for convergence speed, kinematic reliability, sensor disturbances, and the manipulator-to-spacecraft mass distribution. Moreover, we introduce a DRL-oriented algorithm designed for debris acquisition via a 3-finger robotic hand with an emphasis on fine-tuning the reward function to optimize grasp outcomes. To interact with the debris, we have incorporated an eye-in-hand camera integral to the manipulator's visual servoing. This tool accurately discerns the 3D pose of the target debris by merging photogrammetry, adaptive extended Kalman filtering, and neural network methodologies. Validation of these algorithms is executed through computational simulations, highlighting the end effector's capacity to accurately and reliably maintain the desired pose for debris interactions. Finally, we present the development of an advanced hardware-in-the-loop testbed, fortified with active gravity offsetting, to validate DRL algorithms in space conditions.
Biodata: Dr. Zheng H. (George) Zhu received B.Eng. (1983), M.Eng. (1986), and Ph.D. (1989) degrees in Engineering Mechanics from Shanghai Jiao Tong University in China. He also received his M.A.Sc. degree (1998) in Robot Control from the University of Waterloo and Ph.D. degree (2004) in Mechanical Engineering from the University of Toronto in Canada. He is currently a Professor and Tier I York Research Chair in Space Technology with the Department of Mechanical Engineering at York University in Toronto, Canada. Before joining York University in 2006, he worked as a senior stress/structural engineer in Curtiss-Wright Indal Technologies in Mississauga, Canada. From 2019-2022, he served as the inaugural Academic Director of Research Commons at the Vice-President Research and Innovation Office. His research interests include dynamics and control of tethered space systems, spacecraft attitude dynamics, computational control, space robotics control, machine learning, and space debris removal. He has authored and co-authored more than 340 articles. Dr. Zhu is the Principal Investigator of two CubeSat missions for deorbiting space debris for sustainable use of space and measuring the environmental impact of permafrost thawing in Northern Canada. Dr. Zhu is an elected Member of the International Academy of Astronautics, College Member of the Royal Society of Canada, Fellow of the Canadian Academy of Engineering, Fellow of the Engineering Institute of Canada, Fellow of the Canadian Society for Mechanical Engineering, Fellow of the American Society of Mechanical Engineers, Academician of International Academy of Astronautics, Associate Fellow of American Institute of Aeronautics and Astronautics. He is the recipient of the 2021 York President’s Research Excellence award, the 2021 Robert W. Angus Medal by the Canadian Society for Mechanical Engineering, the 2019 PEO Engineering Medal in R&D by Professional Engineer Ontario, the 2013 & 2018 NSERC Discovery Accelerator Supplement awards, and ranked in the Top 2% Most cited Scientists of All Knowledge Fields Combined since 2020 by a Stanford University list.
Prof. Chih-Yung Wen
The Hong Kong Polytechnic University, Hong Kong, China
Biodata: Professor Wen received his Bachelor of Science degree from the Department of Mechanical Engineering at the National Taiwan University in 1986 and Master of Science and PhD from the Department of Aeronautics at the California Institute of Technology (Caltech), U.S.A. in 1989 and 1994 respectively. He worked at Caltech as a Research Fellow from February 1994 to July 1994 and then continued his teaching and research works at the Department of Mechanical Engineering at the Da-Yeh University, Taiwan. He was promoted to full professorship in February 2002. He had been the Chairman of the Department of Mechanical and Vehicle Engineering from August 1997 to July 2000, and the Provost from August 2004 to July 2006 in the Da-Yeh University, Taiwan. In August 2006, Professor Wen joined the Department of Aeronautics and Astronautics of the National Cheng Kung University (NCKU), Taiwan, before joining the Department of Mechanical Engineering, The Hong Kong Polytechnic University in 2012 as professor. While serving in HKPolyU, he has been the associate head (research) of ME department and the interim head of AAE from 2015 to 2019 and from 2019 to 2021, respectively. He is currently serving as the head of AAE. Professor Wen has authored and co-authored more than 300 scientific papers, conference papers and book chapters. He was also awarded 15 patents. His current research interests are in the areas of (1) Technology development of UAVs and MAVs; (2)Hypersonic/Supersonic aerothermodynamics; (3) Shock/Droplet and Shock/Bubble Interactions; (4) Detonation; (5) Flow Control by plasma actuators; and (6) Urban Environment Simulation. Professor Wen, served as associate editor of the prestigious international journal—AIAA Journal and the vice chair of the technical committee of fluid mechanics, ASME. He is currently an HKIE Fellow and AIAA Associate Fellow and editor of Shock Waves Journal, and Advanced in Aerodynamics. He is also a member of, various key professional boards and bodies related to the Aerospace Engineering.