We propose a safety-optimizing method for safety strategies of human-care robots using our danger evaluation method. First, various safety evaluation methods are discussed, and an optimizing method of safety design is proposed. Second, we make a comparative study of two general safety control methods, and then a method of optimizing robot control is proposed. These proposed methods enable us to optimally distribute cost among several safety strategies, and to derive suitable approaching motion of a multi-link manipulator to a human. The validity and effectiveness of these methods are demonstrated by numerical analysis. As a result, the design and control to increase safety are successfully obtained.

Proposes a safety evaluation method for use in various kinds of control strategies for human-care robots. In the case of a careless collision between a robot and a human, impact force and impact stress are chosen as evaluation measures, and a danger-index is defined to quantitatively evaluate the effectiveness of each safety strategy used for control. As in a previous paper on safety design, this proposed method allows us to assess the contribution of each safety control strategy to the overall safety performance of a human-care robot. In addition, a new type of 3D robot simulation system for danger-evaluation is constructed on PC. The system simplifies to evaluate danger about both design and control of various kind of human-care robots to quantify the effectiveness of various safety strategies.