Robust tracking for MIMO nonlinear time-dependent mismatched uncertain systems: non-adaptive versus adaptive control

摘要

This paper considers the problem of robust output-tracking control for multi-input multi-output (MIMO) nonlinear systems in the presence of mismatched time-dependent uncertainties. It first generalizes the stable combined-variable perturbation method (SCVPM) which was proposed by Li et al. (1996) to derive a new robust controller and its adaptive version for MIMO systems to track a desired trajectory. It is shown that both controllers not only stabilize the closed-loop systems but also guarantee that the tracking errors remain in an O(ε) neighbourhood of the origin, where ε is a small design parameter of the controller. Moreover, the adaptive robust controller is only based on the nominal system, and no a priori data on the uncertainties are needed. Therefore, it is more feasibly implemented than the non-adaptive controller.