Research On Feedback Scheduling Methods Of Networked Control System

Network control system is a fully distributed, networked, real-time feedback control system. It is the comprehensive application of the computer, control subjects and network technology. On the one hand, NCS brings to the system of open, digital interconnect, etc. On the other hand it also brings some unexpected performance to the system because of the distinct characteristics of the network, such as network delay, packet loss and network resources competition. How to solve these problems becomes a hot international academic research. Based on the resource competition, the thesis mainly researches network system scheduling.Firstly, RM and EDF, common open-loop scheduling algorithms, are studied and analyzed in scheduling performance. In order to better simulate the network control system, Truetime toolbox, is introduced. By simulation, RM and EDF scheduling performance are compared, and their characteristics are respectively verified.Secondly, two kinds of classical feedback scheduling algorithm in network scheduling are introduced in detail. One is integrated feedback scheduling, and the other is feedback control real-time scheduling. On the integrated feedback scheduler, sampling period distribution and priority scheduling strategy are presented in detail. It realizes simultaneously scheduling of the sampling period and packet in control loop. By simulation, compared the integrated feedback method and EDF scheduling algorithm, the results show that the integrated feedback scheduling is better, and achieves better performance expectations than EDF. For feedback control real-time scheduling, the basic FC_EDF scheduling method is studied, and each part is described in particular.Thirdly, based on the classical integrated feedback scheduling, fuzzy feedback control theory is introduced to the scheduling, and the integration fuzzy feedback scheduler is designed. At the same time, the steps of design are described particularly. Last, simulation results show that the scheduling performance of integration fuzzy feedback scheduler is better than classical integrated feedback scheduler. It can effectively deal with the nonlinear uncertainty, and has good robustness and adaptability. Finally, framework structure is improved, based on feedback control real-time scheduling FC-EDF by increasing the admission controller and service level controller. Feedback scheduling model is also given and the stability of the model is analyzed in the paper. In order to solve the scheduling problem of task of fuzzy uncertainty in the unpredictable environment, the fuzzy feedback control real-time scheduling is presented to resolve scheduling problem in the unpredictable environment and to improve the dispatcher success rate of important data.