A class of nonlinear PID global regulators for robot manipulators

In this paper we propose a class of nonlinear PID global regulators for manipulators which do not include their dynamics in the central law. The structure of this class of global regulators is based on a linear PD feedback, plus an integral action driven by a nonlinear function of the joint position error, and the addition of the gradient of a C/sup 1/ artificial potential function satisfying some typical features required by the energy shaping methodology. By using Lyapunov's direct method and LaSalle's invariance principle we provide simple explicit conditions on the regulators gains to ensure global asymptotic stability.