The Role of the Robot Mass and Velocity in Physical Human-Robot Interaction - Part II: Constrained Blunt Impacts

The desired coexistence of robotic systems and humans in the same physical domain, by sharing their workspace and actually cooperating in a physical manner, poses the very fundamental problem of ensuring safety to the user. In this paper we will show the influence of the robot mass and velocity during blunt unconstrained impacts with humans. Several robots with weights ranging from 15–2500 kg at different velocities are impacted with a mechanical human head mockup. This is used to measure the so-called Head Injury Criterion, mainly a measure for brain injury. Apart from injuries indicated by this criterion and a detailed analysis of chest impacts we point out that e.g. fractures of facial bones can occur during collisions at typical robot velocities. Therefore, this much more probable injury mechanism in robotics has to be evaluated more in detail.