Shape Sensing for a Soft Continuum Manipulator using Electrical Impedance Tomography (EIT)

Abstract

Soft robots offer numerous advantages for use in medical applications due to their flexibility, maneuverability and inherent softness, which increase safety in surgical procedures by reducing trauma and recovery time for patients. In recent years, soft continuum manipulators able to navigate unconstrained areas opened new opportunities in minimally invasive surgery (MIS) and endoscopic applications. A compelling requirement yet to be fulfilled is the integration of a robust proprioceptive sensing system in the manipulator. The solutions that have been explored in the literature include optical fibers and electromagnetic (EM) sensors. However, both methods have disadvantages: aside from their high cost, optical fibers have bulky hardware that is difficult to integrate in a soft continuum robot and can affect its bending, while EM trackers are sensitive to metallic tools or other EM devices [1]. Here, we investigate a sensing approach based on electrical impedance tomography (EIT) for a 1 DOF inextensible manipulator that employs hydraulic actuation. Our system consists of a Flexible Printed Circuit (FPC) with 13 electrodes embedded in the soft continuum robot. Saline is used as a conductive actuation fluid and the voltage differences detected by the electrodes are used to measure the deformations of the manipulator upon pressurization. Having low profile and biocompatible components, and leaving adequate space for additional instruments are the main advantages of EIT in medical applications. This method shows promising results and we believe that it can inspire a new generation of autonomous soft continuum robots.