Tracking of a 3.D.O.F robot using adaptive robust control under uncertainties

In this paper, a control approach for tracking control of robot manipulators is developed which not only parametric uncertainties but also unstructured uncertainties such as friction, disturbances and un-modeled dynamics are considered. Disregarding the unstructured uncertainties may cause an unstable closed loop control system. A robust controller is designed based on Lyapunov method, using robot physical properties and known bounds of uncertainties. It is then proven that the closed loop system has global exponential stability. The bounds of unstructured uncertainties are estimated by adding an adaptive controller to the robust controller. It is verified that the proposed control system has global asymptotic stability. A case of study is a three links elbow robot where the analytical works and simulation results show a good performance of the control system.