Decentralized control of robot manipulators via state and proportional-integral feedback

Asymptotic regulation to a constant set-point by state feedback, and PI (proportional integral) control is considered for n-link multibody systems. Global asymptotic stability of these regulators is shown using Lyapunov´s direct methods. The main contribution is the exclusion of explicit gravity cancellation. The implication of the above is the ensuing robustness of the controllers to parameter and payload variations. Furthermore, it is shown that the controllers can be implemented in a decentralized manner at each joint despite the nonlinear interconnections among the joints.