Increasing the Stiffness of Tendon-Driven Continuum Robots Via Multi-Constraints
Bassel Zebian, Thomas Booth, Radhouene Neji, and Christos Bergeles
AI summary
Problem
Tendon-driven continuum robots suffer from low stiffness that limits load-bearing capacity, while conventional stiffening methods either demand permanent design changes, bulky external infrastructure, or unsafe increases in tendon tension.
Approach
By routing extra tendons to intermediate points along the backbone and synchronizing them with a multi-diameter capstan, the robot's deformation is segmented to programmably boost stiffness while maintaining standard actuation degrees of freedom.
Key results
- Up to 662% increase in structural stiffness
- 34.5% reduction in open-loop kinematic control error
- Validated kinematic and static models matching experimental deflection data
- Prototype maintains conventional tendon tension levels under load
Why it matters
This design enables safer, more load-bearing continuum robots for minimally invasive surgery and narrow-space manipulation without complex external hardware or excessive actuation forces.
Abstract
Increasing the stiffness of tendon-driven contin- uum robots for sufficient load-bearing ability without compro- mise in increasing tendon tension or limiting motion ability is a valuable yet challenging endeavor for safe and dexterous manipulation. To address this challenge, this paper proposes the concept of multiple constraints for tendon-driven continuum robots and investigates its capability in programmable stiffness strengthening. The concept introduces multiple tendon based constraints along the continuum structure, where all tendons can be actuated synchronized without exceeding the controllable degrees of freedom of conventional system. The schematic robot mechanism is given for the proposed concept, and the corresponding kinematic and static models are derived and verified. The ability of maintaining the tendon tension to the same level as the conventional system is illustrated using sim- ulation. Implementing the proposed concept in a prototypical experimental robotic platform shows a stiffness improvement of up to 662% and a reduction in open loop kinematic control error of 34.5%.