Adaptive quasi-sliding mode control for discrete-time multivariable systems

In this paper, the discrete-time adaptive quasi-sliding mode control for mu ltivariable systems with perturbations and partial model uncertainties is s tudied. Even though no a priori knowledge of the perturbations is required, the dead-zone function is constructed based on the on-line estimates of th e upper bound of the perturbations. By applying the adaptation algorithm wi th dead-zone, the unknown model parameters are estimated. Then, a discrete quasi-sliding mode adaptive controller with no chattering is synthesized to guarantee the global stability of the closed-loop systems in the sense tha t all signals remain bounded. If some information of the perturbations is k nown, the controller can be modified to improve the performance of the cont rolled systems. Examples and simulation results are presented to illustrate the proposed algorithms.