Dynamic Surface Asymptotic Fault-Tolerant Control for Constrained Nonlinear Systems With Unknown Virtual Control Coefficients

This article studies the asymptotic tracking control problem for strict-feedback nonlinear systems affected by asymmetric state and input constraints, nonparametric uncertainties, actuator faults, and unknown virtual control coefficients (VCCs). Different from the previous tracking control for strict-feedback systems results, the class of systems considered is more general, while can achieve better tracking performance in term of asymptotic tracking. A nonlinear state-dependent function (NSDF) is introduced to handle full-state constraints without requiring feasibility conditions imposed on virtual controls. To deal with the “explosion of complexity,” a novel filter is developed, which can also guarantee that the boundary errors asymptotically converge to zero. To cope with unknown VCCs, a Lyapunov function is developed based on the lower bounds of unknown VCCs skillfully. By introducing the Nussbaum function and a novel smooth function, the obstacle jointly caused by input constraint and actuator faults is circumvented well. It is proved that the asymptotic convergence of tracking error is successfully ensured. Finally, simulation verification is provided to illustrate the effectiveness of theoretical results.