On May 20, 2019, Robin Chhabra, Assistant Professor at Carleton University and the Canada Research Chair in Autonomous Space Robotics and Mechatronics, held a seminar on “Geometric Space Robotics: Towards Resilient Autonomy of Space Missions” at the department of Aerospace Engineering of Sharif University of Technology. Dr. Chhabra is the founder and director of the Autonomous Space Robotics and Mechatronics Laboratory (ASRoM-Lab), where he conducts research in advanced Guidance, Navigation and Control (GN&C) of space robotic systems. Specifically, he deploys differential geometric structures to study the highly nonlinear dynamics of space systems and design novel practical GN&C technologies to facilitate long-term and reliable autonomy of such multidisciplinary systems while operating in hostile and uncertain outer space environments.
An inseparable component of international space exploration and exploitation programs is space robotics, ranging from space manipulators to planetary rovers, and typically being constrained, mobile and flexible. Such multidisciplinary systems ought to reliably perform operations in hostile outer space environments to accomplish space missions. Autonomy is particularly essential for future space robotics, since they must collaboratively operate millions of miles away from the Earth, in partially understood environments, while dealing with disturbances, communication delays, and fast, complex and frequent missions, all of which render teleoperation impractical. In addition to advanced technologies, novel intelligent Guidance, Navigation and Control (GN&C) methodologies, capable of capturing unique characteristics of space robotic systems, should thus be in place to enable their long-term and reliable autonomous performance.
As an alternative approach, in Dr. Chhabra’s talk, the role of geometric mechanics in the analysis and autonomous control of space robotic systems with the application in the future space missions was reviewed. These applications range from asteroid sampling to planetary exploration missions, where autonomy is one of the key features. Due to their mobility, space robotic systems normally have unactuated and constrained degrees of freedom with highly nonlinear coupling effects. Nevertheless, they are inherently symmetric from a geometric perspective. To study this symmetry, first an introduction was given on a group theoretic categorization of joints that leads to a generalized product of exponentials formula for the kinematics of multibody systems with multi-degree-of-freedom and nonholonomic joints. Then tools in geometric mechanics were employed to propose a unifying approach to the dynamical reduction of free-base and nonholonomic multibody systems with symmetry. As the result, a nonlinear output-tracking control law is derived in the reduced phase space that exponentially stabilizes any feasible trajectory.
In the second part of the talk, the mission and vision of the Autonomous Space Robotics and Mechatronics Laboratory (ASRoM-Lab) at Carleton University was introduced. At this research lab concepts, algorithms, theories and methodologies are developed for the long-term, reliable autonomy of the robotic and mechatronic systems that will be deployed in the next-generation space missions. More specifically a focus is on the contributions of ASRoM-Lab on on-orbit servicing, extraplanetary exploration and deep-space exploration programs.