Control And Scheduling Co-design In Networked Control System

With the development of NCS (Networked Control System), more and more researchers focus on the scheduling of network which can improve the QoS (Quality of Service) of network and reduce the chance of collision and Congestion in network, then it can reduce the network induce time delay and the rate of data packet loss, so scheduling has great signification on improving the performance of NCS. For network and control system having effect and restriction on each other, the method of control and scheduling co-design is the best way to solve this problem, which can guarantee the QoS of network and the QoC (Quality of Control) of control system.The process of control and scheduling co-design needs to study the performance of control system affected by scheduling in theory, which can support to choose the method of scheduling. To analyze the performance of control system, the model of NCS scheduling is established with communication constrain both in its input and output channel, which can be transform into discrete-time switched system by expressing the status of scheduling as communication sequence.On studying the controllability and observability of the model, utilizing the theory of recursive invariant subspace and its character, a necessary and sufficient condition is deduced for the controllability and observability of the model under static scheduling, what's more the relation of NCS's controllability and observability is presented between before and after the static scheduling.The stability and robustness of the model are analyzed under state feedback by utilizing the method of multiple Lyapunov function, then the necessary and sufficient condition of the robustness is presented via LMI (Linear Matrix Inequality) and the method of designing H∞controller also is presented. The results are extended to the scheduling of multi-system which is modeled as above.Under state feedback, the guaranteed cost control of the model is studied, and its necessary and sufficient condition is obtained. The method of solving guaranteed cost controller is deduced too, based on which the same of optimal guaranteed cost control is investigated and extended to the multi-system.Based on RM(Rate Monotonic) and EDF(Earliest Deadline First),the two-dimension scheduling strategy is proposed to deal with the scheduling in NCS, which can realize to distribute priority and bandwidth in two level, and the condition of bandwidth schedulability is obtained based on the task schedulability of RM and EDF. This strategy can utilize RM and EDF to schedule different task in the same network.The sampling period is linker between QoC and QoS, which plays a important role in control and scheduling co-design. So it is necessary to study variable-sampling from the standpoint of theory and application in NCS. In theory, the variable-sampling is modeled as discrete-time switched system, then the results of robustness obtained above is applied to it to get the method of H∞controller designing in variable-sampling NCS. From the application, an online network predictive control method based on LS-SVM (Least Squares Support Vector Machine) is proposed. Utilizing training data window and training data throuhold, an online training method which adapts to NCS is developed based on LS-SVM. The solution of control variable can be solved by integrating the method of GPC (Generalized Predictive Control). The results of simulation show that the method is robust to deal with the problem of time-delay, packet loss and variable-sampling in NCS.