The event-time triggered network control structure for CAN-based motion systems

Design of precision and safety-critical applications usually adopts time-triggered protocols as the communication infrastructure to achieve real-time performance. Due to the event-triggered nature of the controller area network (CAN), some modified time-based protocols are proposed for the CAN bus like TT-CAN and FTT-CAN. This paper proposes a CAN-based motion control system by introducing the event-time structure. To overcome the drawback of losing messages caused by the network transmission rate for network control systems (NCS), a motion command estimator is adopted to estimate the lost commands or messages. Thus, the CAN-based motion control system achieves desired control performance even under lower transmission rate or heavier message loading on the bus. The proposed event-time structure has been successfully applied to a DYNA MTYE 1007 CNC machine. Experimental results indicate that precise tracking accuracy in different CAN transmission rate has been well maintained in the proposed motion control system