Novel Design of a Passive Variable Stiffness Joint Mechanism: Inspiration From Biomechanics of Hand Joints Available to Purchase

Passive variable stiffness at the human hand joints is shown to be critical for achieving stable and dexterous grasping and manipulation. Our long-term goal is to implement it in robotic hand joints. We introduce a novel design, using linear springs and non-circular cam, for a variable stiffness joint mechanism that mimics the passive stiffness characteristics of human hand joints. We present a methodology based on the principle of virtual work for synthesizing the cam shape in the joint. Key innovations of our design are a) human-like joint stiffness profile, b) large joint range of motion, and c) modular arrangement for varying torque range. We have built a prototype for validating our approach and the experimental results demonstrate that the proposed joint mechanism fulfills the design goals of our study.