Research On Control Method For Input-saturated Systems Based On Low-gain Feedback

In the actual control system,because the physical limitations of the device or instruments,input saturation is widespread.Ignoring input saturation in the controller design will degrade system performance and even lead to system instability.Therefore,the research of input-saturated systems has been widely concerned by scholars at home and abroad.For inputsaturated systems,designing the controller to improve the dynamic performance of the closedloop system,to improve the dynamic performance of the system while saving the cost of system computing resources,and to ensure the stability of the closed-loop control system within a finite-time,these are all hot topics of research.Therefore,the design of time-varying controller and event-triggered finite time control have important theoretical meaning and practical application value in the research of input-saturated system.This paper mainly studies the control method of input-saturated systems based on low-gain feedback.The main content includes the following parts:The first part is the introduction,which mainly introduces the background and significance of the input-saturated systems,event-triggered control,finite-time control,spacecraft rendezvous system and the current research status at home and abroad.The second part studies the design of time-varying controllers for input-saturated systems.Firstly,based on the low-gain feedback,and the introduced time-varying parameters,and the time-varying state feedback controller is designed according to the parametric Riccati equation and the parametric Lyapunov equation,which makes the closed-loop systems exponential stability and improves the dynamic performance of the systems.Secondly,when the state in the actual system is not completely measurable,a time-varying output feedback controller based on observer is designed.Finally,the effectiveness of the proposed method is demonstrated through numerical simulation.The third part studies the finite-time control of input-saturated systems based on eventtriggered strategy.Firstly,based on the low-gain feedback,and the introduced time-varying parameters,a finite-time state feedback controller is designed to make the closed-loop system stable within a finite-time.In order to avoid Zeno phenomenon,the minimum time lower bound of the adjacent trigger interval of event trigger is proved.Secondly,when the state in the actual system is not completely measurable,a finite-time output feedback controller based on an observer is designed.Finally,the effectiveness of the proposed method is verified by numerical simulation.In the fourth part,we study the spacecraft rendezvous system with actuator saturation based on the previous two chapters.Firstly,the relative motion equation of the spacecraft rendezvous system with actuator saturation is established.Secondly,according to the relative motion equation and combining the controller design methods of the previous two chapters,the two methods are applied to the controller design of the spacecraft rendezvous system.Finally,simulations verify that both methods can successfully achieve the spacecraft rendezvous mission.The fifth part is summary and outlook,summarizing the main results of this article,and prospecting the research work in the further.