Stiffness Ellipse Control of Tendon Mechanisms with Nonlinear Springs

Abstract

Versatile and safe manipulators are required for use in human environments. A tendon mechanism with nonlinear springs that can mechanically adjust joint stiffness is one candidate that can satisfy the requirements of versatility and safety. In this paper, a hybrid stiffness ellipse control for controlling both mechanical and control stiffness at the end of the manipulator is proposed for the tendon mechanisms. This study shows the transformation of the stiffness ellipse at the ends of arms to joint stiffness. The transformation is applied to both mechanical joint stiffness and controller gain of joint angle controller. Simulation results verify the validity of the proposed method.