BACKSTEPPING-BASED ADAPTIVE CRITIC DESIGN FOR UNCERTAIN NONLINEAR SYSTEMS

Abstract

A novel control system design approach is proposed, based on backstepping theory and adaptive critic design (ACD) for a class of uncertain nonlinear systems. It ensures the systems' stability and accurately track the reference commands under large parametric perturbation. This approach is based on backstepping theory so that the whole system is not divided into slow and fast subsystems compared with dynamic inversion (DI). However, backstepping can ensure the little robustness of the closed-loop systems. To solve this problem, ACD is employed, which is designed without any information of the parametric perturbation. In the ACD, variable structure control is employed to make the systems asymptotically stable. To evaluate the performance of uncertain nonlinear systems using the proposed approach, an empirical study is conducted on a two-link manipulator to validate the new controller. Results show that the nonlinear system using the proposed controller can achieve asymptotical stability and good dynamic response characteristics when large model uncertainties exist.