Study On Delay In Networked Control Systems With Medium Access Constraints

NCS which integrates computer,networks,communication and automatic control, provides several advantages,has became more and more common used.But certain delays and medium access constraints are inserted into NCS loop by the introduction of communication network..As the demand on the control system increases it will be more and more important to take these factors into account in the analysis and the design of the control systems.Based on a discrete linear time-invariant system,with the medium access constraints and time-varying delays or Markov delays,this paper has investigated the stability of the NCS.And at the same time,consider the case when the system has uncertainty.The main research works are as follows:First,Give an introduction about NCS' background,concept.A survey of the NCS delay research work is given.Then proposes the main work the thesis done.Second,aimed at the NCS with medium access constraints and time-varying delay, we present the theorem that makes the system stable.Further more,we get the corollary when the system has system uncertainty or when the delay is constant,and give arithmetic of the maximal upper bound of the time delay,for which system is stable.At last,we give the simulation results when delay is constant,validate the validity of the theorem.Third,Using state-argument method,model the system with medium access constraints and Markov delay as a jump system.Give an introduction about the knowledge of jump system,the theory to make a jump system mean square stability is presented,then using the V-K iteration to calculate the controller gain.At the same time, the system uncertainty is taken into account.Next using an arbitrary two dimension discrete linear time-invariant system as a simulation example,simulation results indicates the control scheme can insure mean square stability of the NCS.At last,use the control scheme in chapter 3 to control the lateral displacement track model for vehicle.And the simulation results prove that the control scheme can use in the real system,and can obtain favourable results.