Design of adaptive variable structure controllers with application to robot manipulators

Based on the Lyapunov stability theorem, the adaptive variable structure control (AVSC) schemes with perturbation estimation are proposed in this paper for nonlinear system with model uncertainties and external disturbance, so that the robust tracking problems can be solved. All systems considered contain perturbation in the input matrix gain. By introducing a perturbation estimation process embedded in both proposed control schemes, not only the perturbation can be estimated, but also the control energy can be reduced. In addition, the proposed control schemes also contain an adaptive mechanism in order to automatically adapt the unknown upper bound of perturbation estimation error, so that the property of uniformly ultimate boundedness for the closed-loop system is guaranteed.