Research On H? Output Tracking Control For Networked Control Systems With Network-induced Time Delays

In recent years,networked control systems(NCSs)have been widely used in the industrial fields and have received extensive attentions from scholars.Compared with traditional point-to-point control systems,NCSs have the advantages of high flexibility,easy reconfiguration,and less integrated wiring.Network-induced time delay is one of the inevitable factors in the NCSs,it will reduce NCSs stability and even make NCSs unstable.In addition,tracking control is an important issue in the field of control theory and applied research.Therefore,the study of output tracking control problems for NCSs with network-induced time delays has important theoretical and practical significance.At present,the existing researches on network-induced time delays are still not perfect.In this paper,based on the H? control method,the tracking control problems for NCSs subject to network-induced time delays are studied.The main research contents are as follows:(1)For the NCSs with network-induced short time delays,the H? output tracking control problem for NCSs is studied.Firstly,for the exponential uncertainties in the sampling system of physical plant caused by the network-induced short time delays,the robust control method and the time delay nominal point technology are used to transform them into the sum of the nominal terms and the norm-bounded uncertainties,this method facilitates systematic analysis and design for the augmented closed-loop systems.The uncertain augmented closed-loop system is established by combining the physical plant and the reference model.Then,by using Lyapunov-Krasovskii theory and LMIs(Linear Matrix Inequalities)techniques,the sufficient conditions of the augmented closed-loop system satisfying the H? output tracking performance and the solving methods of the H? state feedback tracking controller gains are given.Finally,the effectiveness of the designed H? state feedback tracking controller is verified by a numerical simulation example based on Matlab.(2)For the NCSs subject to network-induced long time delays,the H? output tracking control problem for NCSs is studied.Firstly,for the exponential uncertainties in the sampling system of physical plant caused by the network-induced long time delays,the robust control method and the time delay nominal point technique are used to convert them into the sum of the nominal terms and the norm-bounded uncertainties.The uncertain augmented closed-loop system is established by combining the physical plant and the reference model.Then,by using Lyapunov-Krasovskii theory,discrete Jensen inequality and LMIs techniques,the sufficient conditions of the closed-loop system satisfying the H? output tracking performance and the solving methods of the H? state feedback tracking controller gain are given.Finally,the effectiveness of the designed H? state feedback tracking controller is verified by a numerical simulation example based on Matlab.(3)Taking DC motor as the physical plant,based on Matlab platform,the problems of networked speed regulation with network-induced time delays are studied.Considering the situation that the network-induced time delays are short time delays and long time delays,the DC motor networked closed-loop sampling system model are established,respectively.Based on the research content(1)and(2),the H? state feedback tracking controllers are designed,respectively.The effectiveness of the designed H? tracking control algorithms is verified by Matlab simulation.