On Control And Scheduling For Networked Control Systems

Feedback control systems wherein the control loops are closed through a real-time network are called networked control systems (NCS), which have completely distributed structure and are the integrated application of control, computing and network technology. The primary advantages of an NCS are extensive control areas, less system wiring, low-cost operation and ease of system maintenance. Whereas, the insertion of the network in control systems also bring a lot of new problems such as time delay, data transmission, information scheduling and so on. How to solve these problems and fully play the advantage of NCS has become a research focus. This dissertation carries out the research on NCS in the view of control and scheduling.At the beginning, considering the uncertain time-varying delay, the combined compensation control methods are designed, which include fuzzy-PID controller and Smith prediction based on fuzzy-PID controller. The control methods are validated through simulation.Secondly, the information scheduling of NCS is discussed in the following part. Based on fuzzy control theory, a fuzzy dynamic scheduling algorithm is presented. And then taking the effect of sampling period on the performance of NCS into consideration, the fuzzy dynamic scheduling algorithm is further studied with time variable sampling periods. Simulation is carried out using Truetime toolbox and validates the algorithms.Next, the methods of control and scheduling co-design for NCS are discussed. The optimal sampling period satisfying the stability and scheduling of NCS is obtained through solving the nonlinear programming problem, which is used both in RM scheduling and EDF scheduling. Considering the fuzzy dynamic scheduling algorithm with variable sampling periods, the NCS is modeled as a discrete time system with parametrical uncertainties by mathematical transformation and matrix theory. Then based on Lyapunov and LMI theories a state feedback controller is designed and the control and scheduling co-design of NCS is achieved. Also the property of the method is validated by simulation using feasp toolbox.Finally, the thesis is summarized and the open problems for further research are also discussed.