Research On Recursive Network Delayed Predictive Control In Networked Control System

Networked control system is a spatially distributed and real-time feedback control system where the links from sensor to controller (’backward channel’) and from controller to actuator (’forward channel’) are not connected directly but closed through some form of network. At the beginning of the 21st century,19 foremost experts and 23 famous scholars all over the world pointed out that networked control system is the future-oriented trend in’Directions in Control in an Information-Rich World——A summary of the report of the panel on Future Direction in Control, Dynamics, and Systems’. Therefore, networked control system is becoming a rising academic research direction which attracts extensive attention in the computer, automation and communication domains. Moreover, the influence of networked delay on the control system is the key consideration and research.This paper focuses on the analysis and synthesis in wireless networked control system from the design and algorithm of the control systems. A novel asynchronous differential measurement approach to compute the time-varying network induced delay which exists in each period of networked control systems is proposed, and a networked-predictive-control scheme is designed in which the predictive steps can be computed dynamically. The new scheme does not need any time delay measurement, can resolve the sampling period mismatch between the networked control systems and the physical objects themselves and then can improve the performance in systems.Firstly, this paper analyze the existence of networked transmission delay from the physical layer, MAC sublayer and multihop, route in IEEE 802.15.4 wireless network and the existence of networked wait delay from the nodes sleeping, large-scale network and new nodes entering network. Base on the computer control system theory, I think about the constraint condition and value boundary of system sampling period. Hence, in networked control system, the mismatch between the networked control systems and the physical objects themselves can cause systems instability.Secondly, system structure is designed as a distributed networked control system Network model adopts mesh communication ZigBee. Base on the analysis of the communication transaction’s time sequence with/without beacons, a novel asynchronous differential measurement approach is proposed which is independent of the whole networked clock synchronization. In this approach, networked delay is computed using the message communication and bidirectional networked transmission delay inconformity is resolved using request/response message byte size.Then, an approach is proposed to compute the predictive steps and control period. Hence, the control period can meet the requirements of the minimum delay and system sampling period. Base on the idea of separation between the sampling and control period, I use the various sampling period which meet the requirements of communication to replace the control period of generalize predictive controller. This scheme can guarantee system stability and overcome the disadvantages of predictive steps in traditional generalize predictive control. At last, I prove the scheme can guarantee the stability of wireless networked control system from theory. Hence a numerical experiment is given to demonstrate that, this scheme has strong potential to improve the performance of system with various networked delay and proves its validity and effectiveness.