Best Student Paper Award — ISMR 2026.

Abstract

Minimally invasive surgery requires steerable tools that can navigate tortuous anatomy without trauma, yet actuating continuum robots at the millimeter scale remains challenging. This work presents a hydraulically actuated, polymer-based continuum robot with an outer diameter of just 2.14 mm, fabricated from MRI-compatible, non-conductive materials. A custom coiled hydraulic actuator paired with internal routing blocks constrains force transmission to the centerline, reducing undesirable “screw-motion” twisting by 58.8% and producing dominant planar bending. To enable precise control despite the nonlinear behavior of the soft actuator, we formulate a physical model and refine it with a data-driven Preisach hysteresis model, predicting tip deflection with a root-mean-square error of 2.26°. The robot is demonstrated in a 2D aortic-arch phantom, navigating tortuous vascular pathways and achieving tip deflections greater than 180°, highlighting its potential for minimally invasive, MRI-safe interventions.

Recommended citation: C. Gu, T. A. Brumfiel, N. Malhotra, and J. P. Desai, “Design and Modeling of a Polymer-based Hydraulic Continuum Robot for Minimal Invasive Surgery,” International Symposium on Medical Robotics (ISMR), 2026. (Best Student Paper Award)