3D Collision-Force-Map for Safe Human-Robot Collaboration

Collaborative robots, i.e. robots designed for direct interaction with a human, present a promising step in robotic manufacturing. However, their performance is limited by the safety demands of standards. In this article, we measure the forces exerted by two robot arms (UR10e and Kuka LBR iiwa) on an impact measuring device in different positions in the robot workspace and with various velocities. Based on these measurements, we investigate the Power and Force Limiting regime presented in ISO/TS 15066. Impact forces are in practice hard to calculate analytically as many properties of the robots are not available (e.g., proprietary control algorithms). This motivates the use of simple, yet reasonably accurate, approximations. Our results show that height of the impact location is also an important factor and that an accurate model of the robot can be created from a limited number of impact samples. Previous work predicted impact forces based on other factors (distance, velocity, weight), yet these predictions are less accurate. This would allow a fast estimation of the impact forces in the robot's workspace and thus make it easier to design a safe human-robot collaboration setup.