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Professor C.J. Damaren
University of Toronto
Institute for Aerospace Studies
4925 Dufferin St., Ontario, Canada M3H 5T6
Phone: +1-416-667-7704
Fax: +1-416-667-7799
Email: damaren (at_sign) utias.utoronto.ca
Web: Click Here
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This research group is headed by Professor Chris Damaren. He obtained his doctorate at UTIAS in 1990 in the area of control systems for flexible spacecraft. In the 1990’s most of his research concentrated on control system design for large structurally flexible robot manipulator systems such as the Space Station robotic systems developed by Canada. Most of this work was performed at Royal Roads Military College in Victoria, BC and the University of Canterbury in Christchurch, New Zealand. Since joining the faculty of UTIAS in 1999, his research group has been involved in the dynamics and control of spacecraft including the orbital, attitude, and structural motions of these systems.
Some recently completed research theses have include topics such as nonlinear filtering for spacecraft attitude determination, direct methods for low thrust optimization of interplanetary transfers, control of a flexible beam using a tip-mounted control moment gyro, control strategies for stable orbits around Phobos, position accommodation and compliance control for robotic excavation, and optimization of strictly positive real controllers for large flexible space structures.
A major current research thrust is the development of control systems for formation flying spacecraft. The goal here is to control the relative motion between multiple spacecraft. Some of this work is in collaboration with the UTIAS Space Flight Laboratory (SFL) who will eventually launch a pair of nanosatellites called CanX-4 & 5. This will provide an opportunity to implement the control strategies on orbit. Our research group has examined many aspects of the control problem including the development of suitable reference trajectories, optimal maneuvers for transitioning between different formation types, and the design of feedback controllers and state estimation methods.
Another major research area centres on the use of the Earth’s magnetic field and the torques it produces on current loops to provide control torques for spacecraft attitude control. This is fundamentally a time-varying problem because the field changes as the spacecraft moves around in its orbit. Our group has developed special methods for developing stabilizing feedback controllers which control the currents in the loops on board the spacecraft and hence the torques that are experienced.
More fundamental research is currently being undertaken by two doctoral students. James Forbes is studying controller design for (possibly) nonlinear systems using two celebrated results in feedback control theory: the passivity theorem and small gain theorem. The idea is to use the stability properties predicted by the latter theorem to deal with systems which have passive characteristics at low frequency but exhibit passivity violations at high frequency. Applications included flexible space structures with collocated sensors and actuators. Stefan LeBel is studying the application of nonlinear robust control theory for the control of aerospace problems such as formation flying and attitude control. The bottleneck here is the Hamilton-Jacobi equation. Special algorithms have been developed for constructing approximate solutions to it.
Future research by the group will look at controlling the motions of flexible spacecraft using a distribution of control moment gyros (including the problem of optimally locating these devices on the structure), magnetic control methods for flexible spacecraft, and the control of spacecraft formation flying using purely impulsive control inputs.