Continuum Robot Segments with High Output Stiffness Via Diagonal Backbones
Ethan Eisenhauer, Joshua Gaston, Eli Milam, Caleb Rucker
AI summary
Problem
Conventional continuum robots suffer from low output stiffness and passive S-shaped deformation under tip loads, causing unwanted deflection and vibrations that limit precision and payload capacity.
Approach
The authors introduce a segment design with a diagonally routed flexible backbone and parallel push-pull rods, which geometrically constrains bending to eliminate the passive S-shape mode while preserving standard kinematic control.
Key results
- Elimination of passive S-shaped deformation under external loads
- Development and validation of 1-DOF constant-curvature and 2-DOF variable-curvature kinematic models
- Experimental confirmation of dramatically increased output stiffness and tip load handling
- Multi-segment prototype demonstration showing minimal disturbance during 3D trajectory tracking
Why it matters
This approach allows continuum robots to safely carry heavier payloads and maintain precise control in surgical and confined-space applications without complex actuation routing.
Abstract
Continuum robots offer unique advantages for ap- plications such as minimally invasive surgery, navigation through confined environments, and safe human-robot interaction. How- ever, while most continuum robot segments are designed to ex- hibit constant curvature over their length, they passively deform into a non-constant curvature s-shape when holding payloads at the tip, and their dynamic movement is often subject to unwanted vibration of the passive non-constant curvature modes. In this paper, we propose a simple solution to dramatically improve these issues: a continuum robot segment design that utilizes a diagonal backbone and flexible push-pull actuation rods. This simple modification to common continuum-robot construction enables us to eliminate the passive s-shaped mode, creating a bending segment that can handle large loads without significant deformation or vibration while requiring no more actuation force than conventional designs. We show that a modified version of 1-DOF constant-curvature kinematics accurately describes the structure when actuator translations are equal and opposite. We also develop and validate a 2-DOF model that predicts tip position and orientation resulting from more general actuation inputs. The models and increased output stiffness were verified experi- mentally and the concept was demonstrated on a multi-segment robot following a 3D trajectory with minimal disturbance from added loads.