Stability Analysis And Controller Design For Networked Control System With Packet Dropout And Time Delay

The network connects the various nodes of the control system to form a closed-loop feedback system,called networked control systems(NCS),which will fully exert the advantages of the sensitivity,integration,remote control and node intelligence of the control system.Compared with the traditional direct point-to-point connection of the control system,the networked control system has the advantages of easy installation,low maintenance costs,information sharing and long-distance control,and it is precisely because of the existence of these advantages in the networked control system that it is applied in various industrial fields.The application of the network brings great convenience to industrial control,but also makes the analysis and design of the control system become complicated.In this paper,considering the influence of random packet droput and time delay on the control system,the stability of the system is analyzed,and the controller is designed to compensate and control the system,which is as follows:(1)For the networked control system with random packet dropout and time delay,the conditions for stabilizing the system index are analyzed.Considering a class of controlled objects whose state is not measurable,the packet dropout process in the control system is expressed as a Bernoulli random binary sequence,the state observer is designed for long delay and short delay,and the discrete system is described as an asynchronous dynamic system,and then the stability conditions are analyzed by exponential stability theory,and then the controller parameters are calculated by using the Lyapunov function and the linear inequality theorem.Finally,the simulation curve shows that the system with short adjustment time and small oscillation amplitude of the proposed method is obtained,and good control effect is obtained.(2)Further considering the controlled object with external interference,in order to reduce the impact of interference on the networked control system,a new robust model predictive control method with compensation function is proposed.For the random packet dropout and time delay in the networked control system,the method in(1)is still adopted,and the discrete system model based on the state observer with interference term is obtained,and the Lyapunov function is selected to analyze the stability conditions using the relevant theorems,and then the H? controller strategy of making the system mean square exponent stable and meeting the given performance indicators in the interference environment is obtained.Finally,the status curve and control output curve are obtained through simulation.The curve shows that the linear system converges faster and has less oscillation amplitude under the condition of uncertain parameters,and the designed H? controller has an anti-interference effect.(3)Finally,based on the research of(1)and(2),the H? controller with prediction function is redesigned for the controlled object with uncertain delay.Converts the indeterminate delay to the uncertainty coefficient in the system equation and satisfies the uncertainty matrix inequality.Similarly,random packet dropout and time delay still adopt the above processing method,obtain a state-based state observer-based linear uncertain discrete system model with interference terms,perform stability analysis based on Lyapnov’s theorem and linear matrix inequality,and give a H? controller strategy to make the system mean square exponent stable and meet the given performance indicators in the case of interference environment and uncertain parameters.Finally,the status curve and control output curve are obtained through simulation.The curve shows that the system eventually stabilizes after a certain period of oscillation in the case of external interference,and can obtain better control performance.This paper mainly analyzes the stability and designs the controller for networked control systems with random packet dropout and time delay,considering a class of controlled objects with external interference and uncertain parameters.First of all,only the controlled object with random packet dropout and time delay is considered,and then the interference is added to the model,and finally the uncertain parameter is added to the model,and the stability of the increasingly complex control system is analyzed from shallow to deep,and then the corresponding controller is designed to reduce the impact of random packet dropout,time delay,interference and uncertainty problems on the system.