Bounded torque control for robot manipulators subject to joint velocity constraints

Abstract

This paper presents a bounded torque control design to solve the set-point regulation problem for robot manipulators subject to joint velocity constraints. The control objectives are achieved by exploiting the passivity properties of the system and utilizing barrier function ideas to reshape the control Lyapunov function. The structure of the modified control Lyapunov function is reminiscent of those used in the artificial potential field method. The resulting controllers are modified proportional-derivative controllers which are simple, intuitive, and can easily be implemented in practice. In addition, asymptotic stability of the closed-loop system is guaranteed, all joint velocity constraints are strictly satisfied for all time, and the demanded torque input is bounded in norm, irrespective of the initial condition. The effectiveness of the proposed control design is demonstrated through simulations on a 2-link planar manipulator