Research On Adaptive Variable Structure Control Of Uncertain Switching Systems With Actuator Fault

Switched systems is a hybrid system consisting of subsystems with continuous or discrete time dynamics and rules defining the switching signals between them.Switching between systems may result in variable nonlinear system characteristics,such as many limit rings or chaotic phenomena.Switching systems are widely used in engineering practice because of their switching operation status among multiple subsystems,such as multi-robot control,automotive industry,and complex dynamic network systems.Actuator failure is an important problem that puzzles automatic control system.In practical projects,the executors of control systems cannot always be upgraded and repaired in time to ensure the efficiency and safety of industrial systems.In other words,due to the aging or failure of the system equipment in the engineering equipment,the actuator may fail or degrade,resulting in system performance degradation or even instability.Variable structure control,also known as sliding mode control,has the advantages of fast response,insensitive to parameter changes and disturbances,and has been recognized as a feasible and reliable control method for imperfect or non-linear systems.So far,although some achievements have applied sliding mode control to switching systems,most of them do not take into account the uncertainties such as actuator failure,system state delay,unknown disturbance and so on.Due to the complexity of the actual system,the limitation of actuator aging failure and cost budget,the problem of switching system control becomes difficult.Based on the previous research,this paper further studies the adaptive variable structure control of uncertain switching systems with actuator failures,The specific research contents are as follows:1.An adaptive sliding mode fault tolerant control scheme is presented for a class of switched systems with actuator failures and unknown disturbances.First,a new linear sliding surface is designed.Then,the exponential stability of the closed-loop switched system under the proposed control scheme is guaranteed based on the linear matrix inequality technique,the multiple Lyapunov function method and the average dwell time method.An adaptive sliding mode controller is designed to ensure that the sliding mode approaching motion reaches in a finite time under unknown disturbances.Finally,the validity of the proposed control strategy is verified by a simulation example.2.Using variable structure control,a fault-tolerant control strategy for a class of switched systems with matched uncertainty,actuator failure and state delay is studied and presented.First,a new linear sliding manifold is presented.Then,sufficient conditions for exponential stability of switching time-delay systems in sliding mode motion are derived by using the stability theory of multiple Lyapunov functions,linear matrix inequality and average dwell time methods.Then,by using a new adaptive switching controller,the unknown boundaries matching the uncertainties are estimated online to ensure the finitetime accessibility of the target linear sliding surface.Finally,numerical and real system simulation examples are given to verify the validity of the proposed scheme.