Observer-based command filtered adaptive fuzzy control for fractional-order MIMO nonlinear systems with unknown dead zones

Abstract

In order to cope with the explosion of complexity problem in backstepping control, a commonly used method is to use a filter, which will bring filter error and impair control performance. This article investigates the adaptive fuzzy backstepping control of uncertain fractional-order MIMO strict feedback nonlinear systems with unknown dead zones and partial unmeasurable system states. A fuzzy state observer is proposed to reconstruct the state of the system. Fuzzy logic systems are employed to estimate unknown functions. Considering that the explosion of complexity caused by the repeatedly differentiating of the intermediate control signal, a command filter is constructed, and a compensation signal is proposed to decrease filter errors. The proposed method can ensure that all signals are semi-globally uniformly ultimately bounded and the tracking and observation errors finally converge to a small region of the origin. Simulation examples are given to show the viability and practicability of the proposed method.