Research On Scheduling Methods Of Networked Control System

Networked Control System (NCS) are integration of controlling science, computing science and networking technology, and it has been noticed hotly in recent years. The competition of network resource and network delay bring traditional control theories and methods new meanings and research directions, one important proportion of which is network scheduling. Being incorporated with the public data network, NCS becomes an open, digital-connected system. It also improves its reliability and fault-tolerant ability. On the contrary, the public data network also brings the network-induced time delay which we don't desire.Firstly, the detail summary of some basic contents, scheduling issues and recent scheduling methods research on NCS is made.Secondly, Ethernet, ControlNet, DeviceNet are three kinds of networks used in industry. These three kinds of networks are compared, and their Medium Access Control (MAC) protocols are analyzed in detail.Thirdly, scheduling methods of NCS are researched. Technologies for integration of controlling and scheduling are explored. Bring in TrueTime simulation tools. RM scheduling algorithm and EDF scheduling algorithm are simulated and compared in different network transmission speeds on given MATLAB simulation platform of NCS. And the results prove their characteristics separately.Finally, in order to meet the performance requirement of NCS, optimize network scheduling, and improve network efficiency, the paper bring in optimization issue on scheduling of NCS. The influence of sampling period to NCS is discussed. Based on control performance optimization and network scheduling condition, considering system control and network scheduling, an optimized model and sampling period selection algorithm are proposed. An example which shows that the algorithm satisfies performance requirement for NCS, optimizes network scheduling, and improves network efficiency is given.