Closed-Loop Magnetic Control of Medical Soft Continuum Robots for Deflection

TL;DR

This paper presents a novel closed-loop magnetic control system for soft continuum robots used in medical interventions, enabling precise, autonomous deflection control through a differential kinematic model and advanced control algorithms.

Contribution

It introduces a differential kinematic model and a quasi-static control framework with an extended state observer for magnetic soft continuum robots, enhancing autonomous control capabilities.

Findings

Effective trajectory tracking under external disturbances.

Prevents actuator joint limit reaching during operation.

Achieves fast, low-error deflection control without overshoot.

Abstract

Magnetic soft continuum robots (MSCRs) have emerged as powerful devices in endovascular interventions owing to their hyperelastic fibre matrix and enhanced magnetic manipulability. Effective closed-loop control of tethered magnetic devices contributes to the achievement of autonomous vascular robotic surgery. In this article, we employ a magnetic actuation system equipped with a single rotatable permanent magnet to achieve closed-loop deflection control of the MSCR. To this end, we establish a differential kinematic model of MSCRs exposed to non-uniform magnetic fields. The relationship between the existence and uniqueness of Jacobian and the geometric position between robots is deduced. The control direction induced by Jacobian is demonstrated to be crucial in simulations. Then, the corresponding quasi-static control (QSC) framework integrates a linear extended state observer to estimate model uncertainties. Finally, the effectiveness of the proposed QSC framework is validated through comparative trajectory tracking experiments with the PD controller under external disturbances. Further extensions are made for the Jacobian to path-following control at the distal end position. The proposed control framework prevents the actuator from reaching the joint limit and achieves fast and low error-tracking performance without overshooting.