A new VSJ mechanism for multi-directional passivity and quick response

摘要

We propose a novel variable stiffness joint (VSJ) mechanism that achieves the desired stiffness by using elastic deformation of silicone rubber cushions (SRCs). This mechanism can absorb the forces from multiple direction by the flexibility of SRCs and guarantee high safety. To react adequately against unpredictable collision or to manipulate an unstable object skillfully, a joint should be designed to have a stiffness adjustment capability in a short time. The proposed mechanism adjusts stiffness by controlling the position of an elliptical cam that pushes or pulls the support wall of the SRCs to surround them. The elastic deformation of the SRCs can be restricted according to the degree of the surrounded region of the SRCs. As a result, we can control the joint stiffness easily. Furthermore, the rotation of the cam from 0 deg. to 90 deg. accomodates the entire range of stiffness;, as a result, we can expect a fast adjustment of the stiffness. In this paper, we describe in detail the mechanism and the theoretical model for the stiffness adjustment. Moreover fundamental performances on the stiffness range, adjustment speed, and movability of the joint are shown through several experiments, and the problems in actual use are discussed.