Research On Delay Analysis And Compensation Control Of Networked Control System

Since computer was introduced to control system, computer and network technology have been developed fast up to now. Control systems are becoming networked and more intelligent, as a form of control system in future. Researches on networked control systems (NCS) have significant value. Due to the introduction of network, NCS is different from the conventional point-to-point control systems. Phenomenon such as networked induced delay, data packet loss and packet disorder exist in the feedback channel objectively. Time delay and packet loss are both important aspects in the current studies of NCS. Delay and packet loss in industry Ethernet is random and uncertain. When the load of network is heavy, delay, packet loss and other undesirable phenomena are usually more serious. The characteristic of uncertainty increases complexity of modeling of the control system. NCS is a kind of uncertain time delay system, linear matrix inequality (LMI) is one of main tools to analyze the stability of retarded systems. Short delay and long time delay of NCS are analyzed respectively and controllers are designed under stabilities of the two situations.For the NCS with short delay, system is modeling as a dynamic system limited by structural event rate and designs a state feedback controller. Then a solution algorithm of the admissible upper bound of delay in this model is given. As for the problem that solving feasibility of linear matrix inequality system (LMIs) with multiple unknown parameters is difficult, a rapid combination algorithm is presented. In this algorithm, parts of LMIs are properly combined to solve to narrow the scope of unknown parameters. Then the calculation time complexity is reduced, which is conducive to the further research on design of the optimal controller. At last, when the open-loop system is stable or not, truetime platform is used to verify the feasibility and validity of the design model.For the long delay NCS containing delay that is non integer times of the sampling period, the delay were considered as the integer times of sampling period and the short time delay part. Using the output feedback mechanism and combining with the theory of singular system, the system is modeled as a Markovian jump linear system. Then the Lyapunov second law is used to analysis the stochastic stability of the system. In the three cases that delay jump probabilities matrix is known, partially known and unknown, the stability results of the system and the solving strategy of controller are given respectively.A PID tracking control system in the Truetime platform is build. When delay or packet loss rate change, the influence on the dynamic and steady performance of the system are studied respectively. Simulation result show that if system is stable, then the upper bound of the time delays and packet loss exist indeed. Finally, in the STM32 platform, using uIP protocol, a basic design method and the hardware selection of main part of NCS are given.