Research On GPC-Based Networked Control Systems

Control systems in new century are characterized by the Networked Structure. The networked control system structure has become a new trend, whose sensors, controllers and actuators are all connected using networked intelligent node. Compared with the traditional structure, it has the advantages of less wires, good flexibility, higher reliability and share of information resources, etc. But meanwhile, some problems such as time delay, data package loss, ect may accur along with the intrduction of network. These problems will not only deteriorate the performance of control system, but also cause system instability. Based on detailed analysis of the disadvantages brought by network, the design of single-loop control system and cascade control system under network environment are studied in this paper.First of all, the basic issues of networked control systems are intrduced, especially the causes and effects of network-induced delay and data packet dropout are analyzed in detail. On this basis, a network predictive control scheme based on Generalised Predictive Control(GPC for short) algorithm is proposed for a class of single-loop networked control system with both random networked-induced delay and limited data packet dropout. Suppose that the controller is event-driven, the sensor and actuator are time-driven, the controller computes according to generalised predictive control algorithm, a network conpensator is set in front of the plant to realize the network compensation in both forward channel and feedback channel.Secondly, four typical configurations of Networked Cascade Control Systems (NCCSs for short) are presented. For one type of NCCS with random network-induced delay, a networked cascade compensation method is proposed based on an improved cascade generalised predictive control algorithm:the primary controller is configured with Implicit Generalized Predictive Control algorithm, while the secondary controller is bulit with traditonal GPC algorithm. Taking advantage of characteristics of GPC algorithm, the compensation of the delay in NCCS is well realized by setting two network compensators before the secondary controller and the actuator respectively.