Christopher Damaren

Professor and Director of Institute for Aerospace Studies, 
University of Toronto

Research Interest: the development of control systems for formation flying spacecraft, the development of robust controllers for (possibly) nonlinear systems, the passivity theorem and small gain theorem, the development of control systems for solar sails.

Speech Title:Time-Varying Convex Output Combinations for Adaptive Flexible Manipulator Endpoint Control

Abstract:The problem of controlling the end-effector motion of a structurally flexible robot manipulator is addressed using passivity ideas.  Previous work in this area has involved the use of an output called the mu-tip rate which represents a convex combination of the true end-effector rates and the rigid end-effector  rates determined using only joint motions and rigid kinematics. For large payloads it can be shown that the dynamical mapping from a suitable input involving the joint torques to the mu-tip rates is passive for values of mu (the convex combination parameter) in the range [0,1).  For a payload with finite mass properties, the range for passivity is [0,mu*)  where the critical value mu* depends on a suitable ratio of the payload mass properties to those of the manipulator plus payload system.  The present paper examines the problem of using a time-varying value of mu which is determined from estimated payload mass properties identified using a passivity-based adaptive control scheme.  The adaptation of the value mu(t) is also based on passivity ideas.

Bio: Chris Damaren received the BASc in Engineering Science (Aerospace Option) from the University of Toronto in 1985. He went on to receive the MASc and PhD degrees in 1987 and 1990, respectively, both in aerospace engineering from the University of Toronto Institute for Aerospace Studies (UTIAS). From 1990 to 1995 he was an Assistant Professor in the Department of Engineering at Royal Roads Military College in Victoria, British Columbia, Canada. From 1995 to 1999 he was a Senior Lecturer in the Department of Mechanical Engineering at the University of Canterbury in Christchurch, New Zealand. Since 1999 he has been at UTIAS and is currently a Professor and the Director. From 2008 to 2013, he served as the Vice-Dean Graduate Studies for the Faculty of Applied Science and Engineering. His research interests are in the areas of dynamics and control of space systems.  He is a Fellow of the Canadian Aeronautics and Space Institute and an Associate Fellow of the American Institute of Aeronautics and Astronautics.