Research On Scheduling And Control Of Networked Control System

Networked control systems (NCS) are widely applied in the modern industry control, which have advantages of less wires, good flexibility and share of information resources. However, some new issues such as network-induced time delay, network scheduling, multiple-packet transmission and dropping packets also appear. Therefore, analysis and design of NCS have been a hot research problem in the control theory and engineering area. The key issues of time delay and scheduling in the NCS are studied in this dissertation. Main achievements are as follows:(1) The detail summary of some basic contents, issues, and recent research in networked control system is made.(2) Due to the existence of networked delays, the asynchronous sampling mechanism of distributed sensors and a single time delay for sensor-controller and controller-actuator of multiple input and multiple output (MIMO) system are analyzed. Then, combined the theory of token bus protocol (IEEE 802.4), a modeling methodology based on token bus protocol is proposed, the stability of the networked control system model is analyzed as well.(3) ControlNet is adopted in networked control system based on token protocol. Aimed at the time-varying characteristics of networked delays, a method of on-line delay evaluation is proposed. The control parameters of LQR controller are adjusted along with the evaluated delays. Then, apply parallel computation arithmetic to improve resource utilization, so that sampling rates can be increased and control performance can also be improved.(4) For the improvement of communication of the whole control network and the network resources utilization, NCS scheduling is studied. The concept of token bucket is introduced, and the relations for how to dimension parameters to guarantee the performance are derived. Then, the method of traffic shaping with token bucket is designed to realize dynamic bandwidth allocation. Simulation result indicates throughput and efficiency can be improved through regulating the quantity of token.(5) Finally, a conclusion of the paper is given out, as well as the research...