Development of a Variable Stiffness High Resolution Tension Sensor for Tendon-Driven Robot Hands
Ginwoo Pyo, Chunghyeon Lee, Seokhwan Jeong
AI summary
Problem
Tendon-driven robotic hands struggle to balance high force control bandwidth, low mechanical impedance, and precise high-resolution force estimation, a fundamental triple trade-off that limits dexterous manipulation.
Approach
The authors integrated a nonlinear spring mechanism into the tendon routing path to dynamically modulate physical stiffness based on applied tension, paired with optical displacement sensing for precise force feedback.
Key results
- Force control bandwidth dynamically increased from 12.70 Hz to 19.53 Hz as tension scaled up
- Successfully actuated a 50 gf mechanical keyboard switch demonstrating high low-tension sensitivity
- Validated on a 3-DoF tendon-driven robotic finger confirming mechanical transparency
- Developed a mathematical model linking tendon tension to nonlinear spring displacement
Why it matters
Provides a practical hardware solution for balancing compliance and rigidity in tendon-driven robots, advancing dexterous manipulation and human-level dynamic control.
Abstract
Tendon-driven robotic hands face a fundamental “Triple Trade-Off” among high force control bandwidth, low mechanical impedance, and precise force estimation. This ex- tended abstract presents a novel variable-stiffness tension sensor designed to overcome these conflicting requirements. By inte- grating 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 3- DoF tendon-driven robotic finger, successfully demonstrating the sensor’s high sensitivity by delicately actuating a 50 gf mechanical keyboard switch at low tensions.