Design, Modelling and Characterisation of a Miniature Fibre-Reinforced Soft Bending Actuator for Endoluminal Interventions

TL;DR

This paper presents the design, modelling, and validation of a miniature fibre-reinforced soft bending actuator for endoluminal interventions, demonstrating high curvature, structural robustness, and suitability for integration into minimally invasive robotic platforms.

Contribution

It introduces a novel fibre-reinforced soft actuator at the centimetre scale, with validated FEM models and optimized configurations for medical robotic applications.

Findings

Achieved a bending angle of over 200 degrees experimentally.

Validated FEM models accurately predict actuator performance.

Maintained structural robustness up to 100 kPa pressure.

Abstract

Miniaturised soft pneumatic actuators are crucial for robotic intervention within highly constrained anatomical pathways. This work presents the design and validation of a fibre-reinforced soft actuator at the centimetre scale for inte- gration into an endoluminal robotic platform for natural-orifice interventional and diagnostic applications. A single-chamber geometry reinforced with embedded Kevlar fibre was de- signed to maximise curvature while preserving sealing integrity, fabricated using a multi-stage multi-stiffness silicone casting process, and validated against a high-fidelity Abaqus FEM using experimentally parametrised hyperelastic material models and embedded beam reinforcement. The semi-cylindrical actuator has an outer diameter of 18,mm and a length of 37.5,mm. Single and double helix winding configurations, fibre pitch, and fibre density were investigated. The optimal 100 SH configuration achieved a bending angle of 202.9{\deg} experimentally and 297.6{\deg} in simulation, with structural robustness maintained up to 100,kPa and radial expansion effectively constrained by the fibre reinforcement. Workspace evaluation confirmed suitability for integration into the target device envelope, demonstrating that fibre-reinforcement strategies can be effectively translated to the centimetre regime while retaining actuator performance.