Safety evaluation method of robot arm considering energy of contact

In this paper, we propose a method for evaluating the safety of a robot arm mechanism. We summarize the trend of international standards with respect to the evaluation index of robot arms and their safety, and propose a method of evaluating mass characteristics based on human pain tolerance. This method is based on the mass characteristics of the arm: we calculate the virtual mass at the contact point, convert it to the reduced mass taking contact with a human body part into consideration, obtain the contact transfer energy and evaluate whether the permissible energy for each part is exceeded or not. We also evaluate the safety characteristics of two kinds of arm mechanism, and verify the distribution of transmitted energy and safe velocity during contact in the movable range. The proposed evaluation of mass characteristics related to safety is applicable to various arm mechanisms if only the mass distribution of the arm is known. It is a highly versatile method.