Elegant anti-disturbance control for stochastic systems with multiple heterogeneous disturbances based on fuzzy logic systems

There are a large number of non-harmonic disturbances generated by nonlinear exogenous systems in realistic engineering. The current disturbance observer is not applicable for estimating the non-harmonic disturbance with unknown nonlinear dynamics, thus greatly reducing the accuracy of the controller. This paper addresses a class of stochastic systems with multiple heterogeneous disturbances including white noise and non-harmonic disturbance with unknown smooth nonlinear function, which can be approximated by fuzzy logic systems. Based on the approximation of the unknown nonlinear function, an adaptive disturbance observer (ADO) is constructed to estimate non-harmonic disturbance. Combining disturbance observer-based control with fuzzy control, an elegant anti-disturbance control (EADC) scheme is proposed such that the composite system achieves asymptotically bounded in mean square. Simulation examples show that the state responses of the system gradually approache ± 0 . 05 from divergence, indicating that the effectiveness of the controller is satisfactory. In addition, the anti-disturbance control accuracy of EADC approximately improves 70 ~ 200 times compared with H ∞ control. The simulation results demonstrate the feasibility and effectiveness of the proposed scheme.