Collision Detection and Reaction: A Contribution to Safe Physical Human-Robot Interaction

TLDR

Users feel safe when they can stop a robot in autonomous motion, yet no quantitative analysis of collision reaction strategies has been performed. The study presents methodologies and experimental tests for detecting and reacting to collisions in physical human‑robot interaction, and builds a mechanical verification platform to objectively compare these strategies. Using a lightweight robot designed for interactive tasks, the authors implement reactive control strategies, conduct collision tests, and employ a mechanical verification platform to demonstrate feasibility and safety. The collision detection and reaction methods reliably reduce contact forces to safe levels, with evaluations showing effectiveness up to robot velocities of 2.7 m/s.

Abstract

In the framework of physical Human-Robot Interaction (pHRI), methodologies and experimental tests are presented for the problem of detecting and reacting to collisions between a robot manipulator and a human being. Using a lightweight robot that was especially designed for interactive and cooperative tasks, we show how reactive control strategies can significantly contribute to ensuring safety to the human during physical interaction. Several collision tests were carried out, illustrating the feasibility and effectiveness of the proposed approach. While a subjective "safety" feeling is experienced by users when being able to naturally stop the robot in autonomous motion, a quantitative analysis of different reaction strategies was lacking. In order to compare these strategies on an objective basis, a mechanical verification platform has been built. The proposed collision detection and reactions methods prove to work very reliably and are effective in reducing contact forces far below any level which is dangerous to humans. Evaluations of impacts between robot and human arm or chest up to a maximum robot velocity of 2.7 m/s are presented.