Global asymptotic tracking of robot manipulators with a simple decentralised non-linear PD-like controller

In this study, the authors address the problem of global asymptotically tracking control of uncertain robot manipulators with a simple decentralised non-linear proportional plus derivative like controller. The proposed controller is formulated with a decentralised structure without reference to modelling information and the control gains are easily determined based on some well-known bounds extracted from the robot dynamics, and thus it is easy to implement. The global asymptotic stability of the closed-loop system is shown with Lyapunov´s direct method. Even when the proposed scheme is modified to avoid the possible chattering in practical implementation, the overall performance remains appealing. Simulations performed on a two degree-of-freedom robot manipulator demonstrate the effectiveness of the proposed approach.