Research Of The Scheduling Algorithm Of Networked Control System And Design Of Networked Control System Based On CAN Bus

Networked Control System is a sort of completely distributed, networked and real-time feedback control system. Differed from the common network system, messages transmitted in the NCS have the distinct characteristic of short data length, short transmission period and high real-time. Because in the NCS physical medium is shared by all the nodes, each node having message to transmit must win the privilege of access to the medium. For these reasons the network communication should be scheduled and managed. This article mainly researches the control system based on CAN bus and the scheduling theory of NCS.First, the paper introduces CAN bus in detail. And it constructs a Networked Control System with PC. This system includes many nodes. Every node includes four parts:D/A converter, A/D converter, CAN interface and ATmega128 controller. The D/A converter is mainly responsible for converting the digital signal to analog signal for the actor. The A/D converter is mainly responsible for converting the analog signal to digital signal from the senor. The CAN interface is mainly responsible for transforming digital signals in the networked control system. The paper explained the design of node, including hardware part and software part.Second, the paper analyses the scheduling algorithm of networked control system, especially the application of static RM and dynamic EDF algorithm. Via the simulation, it is discussed how RM algorithm and EDF algorithm influence the performance of networked control systems, and presented the significance of EDF scheduling algorithm in networked control systems.