DexterousMag: A Reconfigurable Electromagnetic Actuation System for Miniature Helical Robot

Abstract

Despite the promise of magnetically actuated miniature helical robots for minimally invasive interventions, state-of-the-art electromagnetic actuation systems are often space-inefficient and geometrically fixed. These constraints hinder clinical translation and, moreover, prevent task-adaptive trade-offs among workspace coverage, energy distribution, and field/gradient capability. We present DexterousMag, a robot-arm-assisted three-coil electromagnetic actuation system that enables continuous geometric reconfiguration of a compact coil group, thereby redistributing magnetic-field and gradient capability for task-adaptive operation. The reconfiguration is realized by a parallel mechanism that exposes a single geometric DOF of the coil group, conveniently parameterized by the polar angle. Using an FEM-based modeling pipeline, we precompute actuation and gradient libraries and quantify the resulting trade-offs under current limits: configurations that favor depth reach expand the feasible region but reduce peak field/gradient, whereas configurations that favor near-surface capability concentrate stronger fields/gradients and support lifting. We validate these trade-offs on representative tasks (deep translation, planar tracking, and 3D lifting) and further demonstrate a proof-of-concept online geometry scheduling scheme for combined tasks, benchmarked against fixed-geometry settings. Overall, DexterousMag establishes continuous geometric reconfiguration as an operational mechanism for enlarging the practical envelope of miniature helical robot actuation while improving energy efficiency and safety.