Delay Of The Network Control System Analysis And Predictive Control Strategies

Networked control systems have attracted much attention in all kinds of control science and engineering fields, this kind of systems have many advantages such as simple connection, flexible configuration, convenient maintenance and sharing information. In this paper the influence of network delay on the control performance is discussed; the structure of network delay is analyzed and the models of delay are built. Then an improved dynamic matrix control algorithm is proposed to compensate the network delay in networked control systems.In this paper, the definition and structure of NCS are illustrated, some characteristics and problems of NCS are analyzed and some methods to build the models of NCS under different network conditions are given. The hardware and software of NetCon control system are introduced. The configuration software is based on the platform of MATLAB/Simulink and Real-Time Workshop, which can integrate the Simulink seamlessly. It has the characteristics of accomplishing the code generation, compiling, link and downloading to the field network controller for running within several seconds with Real-Time Workshop.Based on the platform of MATLAB/Simulink, the influence of network delay which is longer than one sample on control performance of NCS is analyzed. NetCon controllers and liquid level experiment device in the process control laboratory are used to form an actual NCS, simulation and experiments of NCS are done. Dynamic matrix control algorithm is suitable for networked control systems, because this algorithm is modeled by limited step response of the object and it has some characteristics such as low requirement of the model, simple algorithm, easy realization, and even feedback information is used in optimizing process to implement feedback emendation which can overcome the effects of uncertainty in a way . In order to compensate the network delay, an improved dynamic matrix control algorithm is proposed. Based on the platform of MATLAB/Simulink, simulation program is written with S function to implement the simulation. And then NetCon controllers and liquid level experiment device in the process control laboratory are used to form an actual NCS, the regular dynamic matrix control algorithm and the improved dynamic matrix control algorithm are compared, and the simulation and experiment results demonstrate the correctness and effectiveness of the improved dynamic matrix control algorithm in compensating network delay.