Research On NCS Based On Node Driven Modes And Control

With the introduction of network, many new feature was arised in control system. Compare with the traditional control system, NCS has not a limiting physical space location. Network Control System which makes use of private or public data communication network instead of the traditional point to point method is a closed-loop control system that constituted by the sensors, controllers, actuators through a network connection. The advantage of NCS is low investment and maintenance cost, resourse sharing, intelligent nodes, remote control, high diagnostic capability and simple wiring. However, NCS brings many advantage but also raises some new questions.In this paper, the model and control methods of different node driven modes in NCS was researched. First of all, the defferent node driven modes of NCS with short time-delay and the different node driven modes of NCS with long time-delay were researched and analyzed, and the best choice of node driven modes was determined. Then on the basis of this choice, fuzzy PID controller was designed for the NCS with short time-delay, structure improved Smith predictor with single neuron PSD control was designed for the NCS with long time-delay. The NCS simulation experiment in every chapter was emulated and analyzed in order to verify its infectiveness. The main research work and innovations are as follows:1. Research and modeling of different node driven modes in Network Control System. Aiming at the problems of network time-delay in NCS. First of all, the network time-delay in NCS was researched and analyzed. Then,according to the two different situations of short time-delay and long time-delay, the different node driven modes of NCS was modeled and researched. Finally, the influence of different node driven modes in NCS was analyzed, and the best choices of node driven modes of short time-delay NCS and long time-delay NCS was decided:Aiming at the short time-delay NCS, the driven mode of controller node uses Event-driven; Aiming at the long time-delay NCS, the driven mode of controller node uses Time-driven. By the best choice of node driven modes, in order to ensure participate timing of the control of the controller.2. Research on NCS with short time-delay based on fuzzy PID controller. Aiming at the problems of network time-delay which is uncertainly within a sampling period in NCS with short time-delay, a fuzzy PID controller which combines fuzzy control on the basis of PID control was proposed. By conbining the fuzzy control and traditional PID control in order to compensate the influence of short random network time-delay in NCS. This controller can adapt the uncertain network time-delay, and ensure the stability of the system, and satisfy the requirements of the output peformance. The results indicated that the NCS with fixed or random short time-delay Based on fuzzy PID Controller has better control performance, and verified that it is a feasible and effective control method for NCS with short time-delay3.Research on NCS with long time-delay Based on structure improved Smith predictor with single neuron PSD Control. Aiming at the problems of network time-delay and controlled plant in Network Control System with long time-delay, a new structure improved Smith predictor with single neuron PSD control was proposed. This new controller was composed of structure improved Smith predictor and single neuron PSD controller. Improved by classic Smith predictor model structural adjustment, the structure improved Smith predictor can be used for compensating the influence of network time-delay on the performance of NCS without establishing the prediction model of network time-delay. The single neuron PSD controller can be used for solving the problems of structure improved Smith predictor model mismatch. The emulation results indicate that this new controller effectively compensates the influence of network time-delay on the performance of NCS, and has good robustness and adaptability in case of model mismatch.