Probabilistic analysis of a repairable robot-safety system composed of (n - 1) standby robots, a safety unit, and a switch

Purpose - The purpose of this paper is to study reliability, availability, and mean time to failure of a repairable robot-safety system composed of (n-1) standby robots, a safety unit, and a switch. Design/methodology/approach - Generalized expressions for system state probabilities, system availability, reliability, and mean time to failure are developed when the failure rates of robot and safety unit are constant and the failed system repair times are arbitrarily distributed. Supplementary variable and Markov methods were used to develop these expressions. Findings - This study clearly demonstrates that standby robots and the repair process help to improve system availability. Practical implications - This study will help maintenance engineers and reliability practitioners to become aware of the combined effect of standby robots and the repair process on the performance of the robot-safety system. Consequently, they will make better maintenance related decisions in organizations such as automobile manufacturers that use robots quite frequently. Originality/value - This paper has studied the effects of having redundant robots and the repair facilities on the performance of a robot-safety system with perfect mechanism to turn on a standby robot. This is one of the first attempts to study the combined effects of all these factors on a robot-safety system.