Variable compliance mechanism for human-care robot arm

This paper presents a variable compliance mechanism for a human-care robot arm. In this mechanism, we inserted an elastic plate, which we refer to as a Compliance Adjuster Plate (CAP), between the joint part and the link. Elastic deformation of the CAP enables the robot to generate compliant arm motion in reaction to external force. The compliance can be easily adjusted according to the requirements of given tasks by controlling the posture of the CAP in regard to the link. Furthermore, the strain observed on the CAP can be used to estimate the actual position of the arm-tip which is moved by an external force caused by contact with the environment. We examined the fundamental characteristics and performance of this mechanism through a comparison of theoretical analysis and the results of several experiments.