Study On Networked Control System's Scheduling

Network control system (NCS) is a traditional feedback control system closed via network, which is a sort of completely distributed, networked and real-time feedback control system. The competition of network resources and propagation delay raise a new scientific field where traditional control theories and methodology can not be applied. Network scheduling is an essential part of this novel domain. Based on existent results on network control scheduling, the main research work is as follows:In order to discuss system sample time and the network delay' influence on system performance and get good performance, on the condition of scheduling-availability and system stability, combining with RM principle, the scheduling model is given to count the sample frequency. At last, the example is presented.Because the static scheduling algorithm is not qualified for the NCS's real time feature, so the dynamic algorithm, which is proved that it can get good performance in the non-busy network condition, is discussed. The general dynamic algorithm cannot perform well in the busy network condition and schedule the information aimlessly. So the feedback dynamic algorithm is given to make the NCS more reliable and get good system performance.Because the previous researches can't get the real-time delay and packet loss rate, the NCS's schedule strategies based on the Hidden Markov Model is proposed. The HMM is proposed to model the networked control system, to predict the delay and packet loss rate in the next time as an important parameter of the Quality of service. The HMM is combined with the feedback theory in order to adjust sampling period. An example is given to prove that the method is certain efficient when the delay and packet loss is obvious and traditional scheduling algorithm is unavailable.In the end, based on the true-time simulation software, the NCS scheduling experiments terrace is introduced. In the end, the simulation examples are displayed.