Implementation of Reliable Robot Control System for Nuclear Power Plant Manipulation

We implement a reliable robot control system for performing maintenance/repairing in nuclear power plant. Systems entered in extreme environments should have high reliability, since their failures cause much longer maintenance time. Our system is designed to have a threelevel hierarchical structure – slave/master/supervisory controllers – by considering the degree of radiation hazard. The slave controller, which is placed in the most hazardous region, has duplex processors designed with cold-standby method and dual-CAN (Control Area Network) communication structure to ensure high reliability. It performs sensing and actuation. The master controller with real-time OS of QNX, which is placed in semi-hazardous zone, performs control function. The master and slave controllers construct a feedback control loop with dual-CAN communication channel between them. A 10 Mbps Ethernet transfers robot state information from the master controller to the supervisory controller, which is placed in safety zone. Also it commands from the supervisory controller to the master controller. The overall control system operates the given control job with 1ms control period and 4ms monitoring period, and 3 msec fault recovery time.