Human Safety Mechanisms of Human-Friendly Robots: Passive Viscoelastic Trunk and Passively Movable Base

Abstract

We would like to give robots the ability to secure human safety in human-robot collisions capable of arising in our living and working environments. However, unfortunately, not much attention has been paid to the technologies of human robot symbiosis to date because almost all robots have been designed and constructed on the assumption that the robots are physically separated from humans. A robot with a new concept will be required to deal with human-robot contact. In this article, we propose a passively movable human-friendly robot that consists of an elastic material-covered manipulator, passive compliant trunk, and passively movable base. The compliant trunk is equipped with springs and dampers, and the passively movable base is constrained by friction developed between the contact surface of the base and the ground. During unexpected collisions, the trunk and base passively move in response to the produced collision force. We describe the validity of the movable base and compliant trunk for collision force suppression, and it is demonstrated in several collision situations.

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

“…the Head Injury Criterion (HIC) [6], [7]) were mainly evaluated in simulation so far. Further approaches are outlined in [8], [9], [10], but the importance of human biomechanics was barely investigated. To fill this gap we decided to measure the potential danger emanating from the DLR lightweight robot III (LWRIII) by impact tests at a certified crash-test facility.…”

Injury evaluation of human-robot impacts

“…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. This means that even such an enormous robot as the KR500 cannot pose a significant threat by means of impact to the human head measured by typical severity indices from automobile crash-testing 6 , see Fig.…”

“…In this video the effect of robot mass, robot speed, and constraints in the environment on injury severity during human-robot impacts are explained and supported by various crash-tests. 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.…”

Develop Human Safety Mechanism for Human-Symbiotic Mobile Manipulators: Compliant Hybrid Joints

“…In a collision, his or her joints and body should make a passive compliant motion. Lim and Tanie (2000) fully examined the human reaction to a collision with his or her environment, they thought, first, the produced impact/collision force is absorbed by the skin with a viscoelastic characteristic; second, if the collision force exceeds the tolerable limit of the elastic tissue, his or her shoulder and waist joints passively move to cope with the collision; finally, if the magnitude of the collision force exceeds the friction force developed between his or her feet and the ground, he or she unconsciously steps/slips on the ground to the direction of the collision force and reduces the collision force. They were interested in the viscoelastic compliant motion of a human's waist and the slipping and stepping motion of his or her feet, and introduced a human friendly robot.…”