A Study of Task-Space Path-Velocity Control for Torque-Limited Redundant Manipulators under Uncertainties

This paper addresses the time-optimal path-tracking problem for redundant manipulators. By integrating path-velocity control into existing task-space robot controllers, the task-space motion can be dynamically scaled to satisfy the torque constraint under both kinematic and dynamic uncertainties. Numerical simulations and experiments demonstrate that trajectory feasibility and path-tracking accuracy of the task-space controllers can be significantly improved by integrating path-velocity control. In addition, the nullspace motion of redundant manipulators can be exploited to further improve the performance by tracking the approximate time-optimal joint trajectory associated with the tasks in nullspace.