Multivariable Adaptive Sliding-Mode Observer-Based Control for Mechanical Systems

In this paper, we present the design of an observer-based controller for perturbed mechanical systems using two-independent adaptive sliding-mode structures (ASMSs). The purpose of the proposed method is to compensate for external disturbances and modeling uncertainties of general mechanical plants. Assuming that only position measurements are available, the proposed control approach is based on a reduced-order velocity observer. We investigate the stability of estimation and tracking sliding-mode dynamics simultaneously, as well as the overall closed-loop dynamics. An extension of the proposed approach to the case of generalized mechanical dynamics is then developed. Experiments using a rotary electromechanical system and simulations of a two-rotative-joint robot are developed to demonstrate the effectiveness of the proposed design and to compare it with a discontinuous ASMS-based and continuous nonlinear full-state feedback controls.