Research On The Intelligent Scheduling Methods For Networked Control Systems

Not only with the continuous development and improvement of the control science and the computer technology, but along with the rapid increasing of the ability of the network communication, meanwhile because of the reduction cost of the system equipment and the rich of the shared resource of the network, the traditional point-to-point control system is gradually being taken place by the Networked Control Systems (NCS) with the intelligent nodes, networked structure and management of distributed. The problems such as complex structure, high cost, not easy to expand and the less transmission of information in the traditional control system could be solved. At the same time. the communication network is brought into the NCS, which caused some problems. for instance, network-induced delay, packet dropout, node driven mode, limited bandwidth, single-packet and multiple packet transmission, scheduling and so on. the problem has become a hot issue in domestic and foreign scholars in the field of the NCS.The control performance and stability of the Networked Control Systems are dependent not only on the control algorithm, but also on the scheduling of shared network resources. The study on the Networked Control Systems is primarily for scheduling in this paper, and the details are as below:Limited bandwidth is a kind of crucial factors to affect the Networked Control Systems. The fuzzy control is brought into the frame system of feedback control scheduling in real-time, then a fuzzy dynamic feedback scheduling algorithm based on allocation of the limited bandwidth is given. The deviation and deviation rate of corresponding control loop is considered in the algorithm, with its results to adjust to the priority of the control loops in dynamic, the real-time requirement of the systems can be met. so the network could have a better quality of service. The simulation results show that the fuzzy dynamic feedback scheduling algorithm is superior to the EDF (Earliest Deadline First), and this method could improve the robust performance of the Networked Control Systems.According to the network-induced delay affect on the performance of the networked control systems (NCS), the design of an adaptive fuzzy P1D controller for NCS based on random delay is proposed. The deviation and deviation rate are taken as the reference input for the controller, using fuzzy reasoning algorithm, with its results to adjust to optimize the parameters of kp, kd and kt in dynamic, and considering the performance index of1AE (Integral of the Absolute Error) to evaluate the output quality of the system. The simulation results illustrate that the designed controller achieved the purpose of improving affected by random delay, the controller could improve the quality of control of the NCS in effectively, and the real-time requirement of the system can be met.