Fixed-time fuzzy tracking control for high-order nonstrict feedback nonlinear systems with unknown virtual control gains and actuator faults

Abstract

In this paper, fuzzy fault-tolerant tracking control is investigated for high-order nonstrict feedback nonlinear systems in fixed time interval. The gain fault and bias fault in actuator are considered for high-order nonstrict feedback nonlinear systems. Contrary to the existing results, an adaptive estimation tactic is proposed to estimate the coexisting uncertainties such that no priori knowledge is needed for the adaptive parameters, in spite of unknown virtual control gains, nonlinear uncertainties, time-varying disturbances and actuator faults. Based on this tactic, the unknown virtual control gains are slackened to completely unknown, which is more practical. Unlike the general fixed time control tactics, the singularity problem has been overthrew by using the inequality transformation strategy without destroying the control performance. The growth assumptions are removed and the complex nonstrict feedback structure is overcome with the support of fuzzy logic systems (FLS). Finally, two examples demonstrate the validity of the formulated method.