Safe physical human-robot interaction: Measurements, analysis and new insights

Physical human-robot interaction and cooperation has become a topic of increasing importance and of major focus in robotics research. Industrial and domestic applications unifying the workspace of humans and robots are foreseeable in the close future and will require safe and dependable robot design and control. In this paper we will give an overview of our systematic evaluation of safety in human-robot interaction, covering various aspects of major significance. Based on initial impact tests we carried out with the DLR-LWRIII, several industrial robots of increasing weight were evaluated and the influence of robot mass and velocity was investigated. Such non-constrained impacts are only partially capturing the nature of human-robot safety. A possibly constrained environment and its effect on resulting injuries have to be discussed and evaluated. Apart from these impact tests and simulations we will analyze the major problem of quasi-static clamping, which poses under certain circumstances a serious threat to the human even for low-inertia robots. After treating blunt impacts and contacts with and without the human being clamped, various soft-tissue injuries likely to occur in robotics and related physical injury tolerances are introduced. Finally, possible injuries relevant in robotics are summarized and systematically classified.