Analysis of Human-Robot Physical Interaction at Collision

In recent years, conventional industrial manipulators are being converted to collaborative robots to increase the efficiency and flexibility of production operations. Because of those advantages, collaborative robots are also being applied even in the manufacturing sites where manipulators could not be used in the past. This trend is increasing the use of collaborative robots, and since the collaborative robot shares the workspace with the human, working environments in which the robot and the human frequent contact are created. Therefore, the importance of robot safety is also increasing because of the increasing possibility of injury from the physical collision between robots and humans. One of the methods to make a robot safe is power and force limiting. To apply the power and force limiting method to the robot for the collaborative operation, the biomechanical limits should be identified. These limits can be confirmed by a clinical test measuring the threshold of pain onset. In this paper, a protocol for measuring the mechanical pain threshold is presented. The robot can be safely used if it does not exceed the biomechanical limitations derived from this study.