Pre- and post-grasping robot motion planning to capture and stabilize a tumbling/drifting free-floater with uncertain dynamics

Abstract

This paper focuses on optimal and seamless guidance of robotic manipulators, in both pre- and post-grasp phases, to capture and stabilize a tumbling and drifting free-floating object. All dynamics parameters of the object are assumed to be unknown with the exception its mass and the trace of the inertia matrix. In the pre-grasping phase, an optimal trajectory is planned to intercept a grasping point on the target with zero relative velocity subject to acceleration limit and adequate target alignment while minimizing the fly time and/or distance. In the post-grasping phase, the manipulator damps out the targets's angular and linear momentums as quickly as possible subject to the constraint that the magnitude of the exerted force and torque remain below their pre-specified values. The unknown parameters in addition to the relative linear and angular velocities of the target needed for the motion planning are estimated by a Kalman filter estimator. Finally, an end-to-end validation of the robotic operation for grasping and stabilizing a tumbling/drifting free-floating object using the proposed robot motion planning scheme is presented by combination of experimental and simulation results.