Trajectory Tracking via Independent Solutions to the Geometric and Temporal Tracking Subproblems

Abstract

Trajectory tracking is accomplished by obtaining separate solutions to the geometric path-tracking problem and the temporal tracking problem. A methodology enabling the geometric tracking of a desired planar or spatial path to any order with a nonredundant manipulator is developed. In contrast to previous work, the equations are developed using one of the manipulator’s joint variables as the independent parameter in a fixed global frame rather than a configuration-dependent canonical frame. Both these features provide significant practical advantages. Furthermore, a strategy for determining joint velocities and accelerations at singular configurations is provided, which allows the manipulator to approach and/or move out of a singular configuration with finite joint velocities without sacrificing the geometric fidelity of tracking. An example shows a spatial six-revolute robot tracking a trajectory using the developed method in conjunction with resolved-acceleration feedback control.