Safety Evaluation of Physical Human-Robot Interaction via Crash-Testing

Abstract

Abstract-The light-weight robots developed at the German Aerospace Center (DLR) are characterized by their low inertial properties, torque sensing in each joint and a load to weight ratio similar to humans. These properties qualify them for applications requiring high mobility and direct interaction with human users or uncertain environments. An essential requirement for such a robot is that it must under no circumstances pose a threat to the human operator. To actually quantify the potential injury risk emanating from the manipulator, impact test were carried out using standard automobile crash-test facilities at the ADAC 1 . In our evaluation we focused on unexpected rigid frontal impacts, i.e. injuries e.g. caused by sharp edges are excluded. Several injury mechanisms and so called Severity Indices are evaluated and discussed with respect to their adaptability to physical human-robotic interaction.

Injury evaluation of human-robot impacts

“…In [6] results and implications from impact tests at certified crash-test facilities with the DLR Lightweight Robot III (LWRIII) were obtained, see Fig. 1a.…”

“…A numerical value of ≤ 650 corresponds to very low injury by means of the EuroNCAP 4 . For further information on HIC, AIS and other Severity Indices (not only for the head), please refer to [6]. In order to cover a wide range of robots and be able to verify the saturation effect explained in [6], we compare the LWRIII with typical industrial robots 5 of different weight, see Fig.…”

“…This is a manufacturer independent crash-test program, based on the Abbreviated Injury Scale (AIS). For further information on these issues please refer to [6]. 5 , corresponding to a Cartesian velocity of 2.9 m/s and 3.7 m/s, the measured HIC for the 2350 kg robot was 135 and 246.…”

“…Although there is some literature present treating safety issues in human-robot interaction [1], [2], [3], [4], [5], there was so far no effort taken to analyze real world threats via impact tests at standardized crash-test facilities. This was to our knowledge only carried out in [6] up to now.…”

Anthrob - A printed anthropomimetic robot

“…In the past decade there was an increased interest in human-friendly robots, especially in the areas of service or rehabilitation robotics, where a possible impact can cause severe injuries or even death [2] Currently, three approaches are used to reduce these risks. These are (i) to employ additional sensors to anticipate impacts, (ii) to use more complex control strategies, such as joint torque control, to reduce the severity of inevitable collisions [3] or (iii) to exploit the concept of compliant tendon-driven actuation by imitating the human muscular system.…”