Fault-Tolerant Multi-Robot Operational Strategy for Material Transport Systems Considering Maintenance Activity

In automated robotic systems, a robot undergoing corrective maintenance (i.e., repair) or preventive maintenance (i.e., inspection) may become a disturbance of operations for other working robots. Therefore, maintenance of a robot has to be performed adequately. Multi-robot systems have the capability for the substitution and complement of such a robot. To introduce the multi-robot technology in industrial applications, we propose fault-tolerant multi-robot operational strategies for a material transport system focusing on the robot behavior. Working robots, while switching between normal and fault-tolerant operational strategies reactively according to the presence or absence of a robot undergoing maintenance, accomplish tasks. Through simulation experiments, the effectiveness of the proposed strategies is discussed. In addition, an integrated strategy for some failure rates of the robot is investigated. Finally, a maintenance activity for the robots is modeled on the basis of reliability engineering and the reasonability of preventive and corrective maintenance is discussed.