Design of a Series Variable Stiffness Joint Based on Antagonistic Principle.

In order to achieve a safe human-robot interaction environment, a variable stiffness joint (VSJ) intended to apply in elbow of robot arm is introduced. The configuration of the VSJ is converted from antagonistic to series by employing a mirror pair of nonlinear elastic transmissions (NETs) which are based on compliant four-bar mechanism (CFM). In this paper, the preliminary mechanical design and the working principle details of the VSJ are presented together with systematic design process of the NET. Simulation results validate the feasibility of the design of the VSJ and the NET.