On Event-Triggered Strategy For Output Saturated Systems

Output saturation,also known as sensor saturation,is widely encountered in the actual physical control systems.The reason is that the sensor devices can only provide a limited range of measurement.When the sensor saturates,the controller cannot ob-tain the accurate information about plant state and output,which will deteriorate the system performance and even cause instability.On the other hand,in networked con-trol systems,limited network transmission bandwidth and computation resources often lead to network congestion,packet loss,transmission delay and other problems.As an aperiodic sampling control method,the event-triggered strategy can effectively config-ure limited communication resources while ensuring the expected system performance.Based on the above background,the event-triggered rules and controllers are designed for the output saturated systems under different situations in this thesis.The specific contents are as follows:Firstly,an observer-based output feedback event-triggered controller is proposed for neutrally stable systems with output saturation in the network environment.Suf-ficient conditions for guaranteeing the global asymptotic stability of the closed-loop system are given,and their feasibility is also discussed.Meanwhile,the expression of the minimum event interval is obtained by comparison lemma,which indicates that the proposed static event-triggered rule can eliminate Zeno phenomenon,and thus ensures that the proposed event-triggered strategy can be implemented in practice.Then,nu-merical simulation examples are given to verify the proposed method,and the parameter selection rules of triggering conditions are discussed.Secondly,by considering the general output saturated systems with external un-certain disturbance,a dynamic event-triggered output feedback H_?controller is formu-lated.The triggering events of the sensor-controller channel and the controller-actuator channel are performed asynchronously,and Zeno phenomenon can be effectively elimi-nated by forced dwell time.The emulation-based design method and co-design method for the controller parameters and the event-triggered condition parameters are proposed one by one.And both of them can guarantee the local L₂performance and asymptot-ic stability of the closed-loop system with/without disturbance.The superiority of the proposed method is then verified by an example of F-8 aircraft.Finally,an event-triggered controller based on static anti-windup compensation is designed for systems with input saturation,output saturation and uncertain disturbance.The signals between the sensor-controller channel and the controller-actuator channel are transmitted asynchronously,while the controller output signal and the difference sig-nal at both ends of the actuator are transmitted synchronously in the controller-actuator channel.In addition,the static anti-windup compensator can expand the system domain of attraction.And this improved dynamic event-triggered strategy can further enlarge the event-triggered interval without affecting the allowable range of the initial state and the external disturbance.