The safety assessment of human-robot systems. (4th report Evaluation of hazard control measures for an industrial robothandling work pieces)

Abstract

An actual unmanned manufacturing station consisting of an NC machine and an industrial robot is assumed. The main hazards of the robot to a human, which occur during troubleshooting in an automatic operation mode, are enumerated using "Action-Chain-Models". Fault Trees of accidents caused by the hazards are given as subsets of "Logic Models for the Analysis of Accident-Causation-Mechanisms", and minimal cut structures are represented by Priority-AND gates to consider sequential properties of basic events. Furthermore, a manual safety mechanism, an automatic one, and a combination of the two, which cut off the power sources of the robot when a human enters a hazardous zone, are evaluated by comparing expected numbers of occurrences of the top events.