Composite Hierarchical Anti-disturbance Control For Stochastic Systems With Multiple Disturbances

Since the stochastic system is an important branch of the actual engineering system,the problem anti-disturbance control for stochastic systems has received much attention.Based on this,the main contents are stated as follows:Firstly,a class of stochastic systems with multiple disturbances,which include disturbance whose time derivative is bounded and the white noises,are considered in this paper.To estimate the unknown bounded disturbance,a stochastic disturbance observer is proposed.Based on the observer,a disturbance observer-based disturbance control scheme is constructed such that the composite closed-loop system is asymptotically bounded.Finally,a simulation example is given to demonstrate the feasibility and effectiveness of the proposed scheme.Secondly,a composite fault tolerant control(CFTC)with disturbance observer scheme is considered for a class of stochastic systems with faults and multiple disturbances in this paper.The disturbances are divided into two parts.One represents the stochastic disturbance with partial known information which is formulated by an exogenous system.The other is independent Wiener process.A stochastic disturbance observer is designed to estimate exogenous disturbance using pole placement.And a composite fault diagnosis observer with disturbance observer is constructed so that the first type of disturbance can be rejected and the fault can be diagnosed.Furthermore,a composite fault-tolerant controller is proposed to compensate disturbances and faults.Finally,simulation examples are given to demonstrate the feasibility and effectiveness of the proposed scheme.Thirdly,a class of stochastic systems with multiple disturbances,time-varying fault and unknown nonlinearity are considered.Firstly,the unknown nonlinearity is approximate by a fuzzy logic system.Secondly,fuzzy stochastic disturbance observer and fault diagnosis observer are designed.Based on which,a composite fuzzy and fault controller is proposed to make the composite system satisfy robust asymptotical stability and its H_? performance satisfies a prescribed level.