Sliding Mode-Based Asynchronous And Reliability Control Of Multi-Mode Switched Systems

Complex industrial systems are often accompanied by complex characteristics such as parameter evolution,working condition migrations and operation mode changes,which can be manifested as a process of switching between multiple operation modes.The multi-mode switched system can adjust the control strategy according to the system operation state,break through the limitations of a single control mode,and realize the complementary advantages of multiple control strategies.The relevant research has significant theoretical value,and has been deeply explored and applied in many fields such as automobile industry,aerospace,intelligent transportation,etc.At present,modern industrial systems that integrate complex network communication and large-scale sensors are often accompanied by problems such as limited communication,lack of observation data and network topology switching,resulting in asynchrony or wrong sequence between system modes and control signals,which is universal,seriously undermining the robustness,real-time and reliability of the system.At the same time,the influence is further exacerbated by factors such as multiple fault concurrency of actuators,parameter uncertainties,and external disturbances.The sliding mode control strategy has the advantages of simple structure design,easy implementation and strong robustness to internal and external disturbances of the system.To this end,this thesis aims to make in-depth research on the sliding mode-based asynchronous and reliability control theory of the multi-mode switched system,and its application in the aircraft anti-skid braking system.The main innovations are as follows:(1)An integral-type asynchronous sliding mode control method based on robust passivity and finite-time boundedness is proposed.For a class of delayed uncertain singular multi-mode switched systems,considering the problem of switching asynchrony between the system mode and the controller,an asynchronous coupling mechanism of switching is constructed based on the prior statistical probability information of the matching between the system and controller modes.An integral-type asynchronous sliding mode control method based on robust passivity is proposed,and a criterion for ensuring the stochastic stability and robust passivity of the closed-loop system is obtained.The integral function in the design of the sliding surface can not only avoid the problem of high-frequency oscillation caused by the derivation of the fast-changing subsystem,but also make the sliding mode dynamics smoother,thereby reducing the chattering effect.Furthermore,considering the multi-mode switched system with unstable subsystems or the mode dwell time of the subsystem is too short,a class of dual-switched multi-mode systems dominated by the upper-layer deterministic switching signals and Markov chains is constructed by introducing a priority regulator,and a finite-time integral-type asynchronous sliding mode control method based on the average dwell time technique is proposed.The problem of joint design of deterministic switching signal and asynchronous sliding mode control law is solved by means of modedependent average dwell time technique.The fast convergence and boundedness of sliding mode dynamics in the approaching and sliding phases are analyzed by using finite-time boundedness theory,which reduces the conservatism of control system and the blindness of switching signal design.(2)An output feedback asynchronous sliding mode control method based on fuzzy rules and artificial time delay is proposed.Considering some problems such as partially unmeasurable state,time cost constraint and control asynchrony,a mode-dependent output feedback asynchronous sliding surface based on fuzzy rules and artificial delay term is constructed for a class of fuzzy model-based and discrete-time multi-mode switched systems.By introducing a random variable representing the working mode of the controller,and combining the statistical probability information of the matching between the subsystem and sub-controller,the switching asynchronous issue is characterized.The mode-dependent output-feedback asynchronous sliding mode control method based on fuzzy rules effectively reduces the conservatism of control design and improves the robustness of the system.The artificial-delay output term embedded in the sliding surface effectively improves the convergence speed of the closed-loop system.At the same time,the criterion for ensuring the stochastic stability of the closedloop system and the optimization algorithm for solving the optimal delay value are provided.(3)An adaptive and anti-saturated fault-tolerant reliability control methods based on sliding mode strategy are proposed.For a class of multi-mode switched systems with multiple concurrent faults,an adaptive sliding-mode fault-tolerant reliability control law is designed to ensure the robust fault-tolerant compensation of the closed-loop system in the event of multiple concurrent faults such as actuator stuck,outage,and failure.The stochastic stability criterion of sliding mode dynamics under multiple fault concurrency is further obtained.Moreover,an observer-based antisaturation sliding mode fault-tolerant reliability control method is proposed for a system with actuator alignment,failure,additive faults,and control input saturation limitation.The robust stability of the closed-loop augmented system under multiple faults and control input saturation is achieved by using an ellipsoid approximation algorithm and H∞ control technique.(4)An optimal slip ratio super-twisting sliding mode tracking control approach for aircraft anti-skid braking system based on multimode switching strategy is proposed.Firstly,an aircraft anti-skid braking system(ABS)model is established that integrates the longitudinal,vertical and pitch dynamics of the aircraft,and a higher-order sliding-mode differentiator is designed based on the aircraft braking distance,which realizes the simultaneous estimation of aircraft velocity and acceleration,and reduces the measurement cost.Based on the runway characteristics and wheel stability analysis,a polyphase cutting algorithm based on the Fibonacci sequence is proposed to divide the entire braking process into multiple subphases,that is,multiple modes.According to the braking mode of the aircraft,the optimal slip ratio and its regulation parameters are switched and tracked accurately and fastly by the super-twisting sliding mode control law,which realizes efficient anti-skidding and braking control.This algorithm effectively reduces the sensitivity and dependence of the braking process on the runway characteristics and braking environment,and provides a theoretical basis for the realization of all-weather anti-skid braking control.