Research On Coordinating Load By More Real-time Parameter For Redundant Network Base On CAN Protocol

Feedback control systems wherein the control system components (sensors, controllers, actuators, etc.) are closed through a real-time network are called networked control systems (NCSs). In order to ensure the safety and reliability of the whole system, redundant design idea is commonly used to build the NCSs, and network communication redundancy is one of its main content. However, redundant network plays the role only when the main network is out of order in the actual application process. The utilization of the redundant network is low, and it is difficult to overcome the "bottleneck" of network traffic and restrain the control performance and real-time of the system. Therefore, the research taking into account the network communication, control performance and reliability has become the common concern subject in NCSs, and has important theoretical significance and practical value.In order to make better use of the redundant network bandwidth resources, the research work is carried out to coordinate load by Multi-parameters under considering the control performance and system reliability. For NCSs with redundant network, a scheduling strategy of coordinating the traffic load and supporting network redundancy is proposed. It improves the control performance and real-time of the system through the rational allocation of bandwidth resource in the primary and secondary network, and can be completed quickly switch in redundant network under fault conditions to ensure the reliability. The main contents are as follows:Firstly, the goal of coordinating network load has been proposed. According to Quality of Control (QoC) and Quality of Service (QoS), the system performance parameters are obtained by analyzing the control performance and real-time performance of the system in detail to lay the foundation for future studies.Secondly, the scheduling strategy of coordinating network load base on load balancing has been proposed to use free resource of backup network and to reduce the communication load in the primary network. The scheduling strategy of coordinating the traffic load ensures the equal of the network utilization between the primary network and secondary network through changing the communication channel of nodes. Experiments show that the scheduling strategy improves the control performance and real-time performance of the NCSs effectively.Then, the improved scheduling strategy of coordinating network load base on feedback control and load balancing has been proposed. In order to further optimize the allocation of network bandwidth resource with redundant network, the scheduler obtains the status information of the NCSs and decides the communication channel and priority online of each network node dynamically through fuzzy control and load balancing algorithms. The control performance and load balancing are both considered to coordinate network load in this strategy. Experiments show that the improved scheduling strategy can allocate network resources better and further optimize the control performance and real-time performance of the control system.Finally, the redundant strategy has been designed to ensure that the system can work properly under fault conditions. When the primary network fault, the nodes can switch the transmission channel quickly through making full use of CAN bus error handling mechanism and reduce the data latency. It improves the reliability and stability of the system.