Toward Cable-Driven Continuum Robots: Micro-Motion Augmentation Using Eccentrically Arranged Fibres with Eccentric Lumens

Micro-motion augmentation of macro-motion continuum robot can largely enhance its micro-operation capability during surgery. However, most existing micro-motion continuum robots have non-compact mechanical structure or non-smooth micro tip motion, which leads to complicated control in micro lumens. This paper proposes a micro-motion augmentation method by rotating eccentrically arranged fibres with eccentric lumens for cable-driven continuum robots. Two thermal drawn polymer fibres with an eccentric lumen on each are inserted into its eccentric lumens of the continuum robot. The micro-motion mechanism relies on small changes in the neutral axis of the continuum robot due to the rotation of the eccentrically arranged fibres. A kinematic model considering variable neural axis is built to describe the micro motion, and a simulation is conducted to investigate the deformation characteristics. The resolution and micro motion with respect to different structural parameters are also analysed. Detailed experiments are performed to validate the effectiveness of the proposed method, and results indicate that the repeatability of micro-motion is 10.1 μm (4.0 %).