Control Synthesis For Systems Subject To Saturation Via Event-triggered Strategy

As a typical nonlinearity,the saturation exists in most practical systems.The actual control quantity of system may not reach the expectation because of the limitation of saturation.Furthermore,the closed-loop performance of the system could be easily affected and even lead to the destruction of the stability of the system.The existence of saturation should be considered when designing the control law of saturating constrained system.Besides of the common single-layer symmetrical saturation,there are also asymmetrical saturation,multi-layer nested saturation and other forms of saturated nonlinearity in practical engineering.Event-triggered strategy adopts aperiodic sampling mechanism.Only when the trigger condition is satisfied,the state of the system will be updated.Otherwise,the latest control signal will be used all the time.On the basis of ensuring the system's performance,the system channel does not need to be occupied for a long time.Therefore,event-triggered control strategy could save communication and computing resources.The research on the control problem of saturating constrained systems under event-triggered mechanism is helpful to design a more efficient control strategy.In this paper,the control problem of systems with different saturation constraints under event-triggered mechanism is studied.Firstly,the event-triggered controller is designed for systems with general saturation constrained actuator.The optimization algorithm for enlarging the estimation of the domain of attraction is given.The minimum of trigger time interval is calculated to prove the avoidance of Zeno Behavior.The simulation examples illustrate the proposed results.Secondly,the stabilization of systems with asymmetric saturation is studied.An improved event-triggered condition is designed by the involving of the saturation threshold,which has higher degrees of freedom.The estimation of stable region of the asymmetric saturated system is given.It is proved that the minimum trigger time interval of the system is bigger than 0.The differences between the modified condition and the general relative event-triggered condition in the system performance index are compared by the numerical simulation.Finally,for the system subject to multi-layer nested saturation,the controller design is studied under the event-triggered mechanism,which could be suitable for different layer of the nested saturation.The calculation of the minimum trigger time interval is given,and the estimation of the domain of attraction of the system is expanded.The influence of different saturation layers numbers on the system's performance is also illustrated.