Development of a Variable Stiffness High Resolution Tension Sensor for Tendon-Driven Robot Hands

Abstract

Tendon-driven robotic hands face a fundamental “Triple Trade-Off” among high force control bandwidth, low mechanical impedance, and precise force estimation. This extended abstract presents a novel variable-stiffness tension sensor designed to overcome these conflicting requirements. By integrating a nonlinear spring mechanism into the tendon routing path, the sensor dynamically modulates its physical stiffness according to the applied tension while simultaneously providing high-resolution force feedback. Experimental results confirm that the system’s force control bandwidth dynamically increases from 12.70 Hz to 19.53 Hz as the tendon tension scales up. Furthermore, the feasibility of the system was validated on a 3DoF tendon-driven robotic finger, successfully demonstrating the sensor’s high sensitivity by delicately actuating a 50 gf mechanical keyboard switch at low tensions.