Open-Loop Position Control of a Miniature Magnetic Robot Using Two-Dimensional Divergence Control of a Magnetic Force

Abstract

Miniature magnetic robots have attracted considerable attention as promising tools in biomedical applications due to their wireless actuation and precise controllability in a minimally invasive manner. Traditionally, magnetic microrobots have been controlled by globally applied magnetic torques and forces generated by external magnetic actuation systems (MASs), which typically require closed-loop control with real-time vision tracking - a challenging requirement in in-vivo environments. To address this issue, this paper suggests a novel open-loop control scheme for magnetic robots, using two-dimensional (2D) divergence control of a magnetic force generated by stationary electromagnets. Constraint equations for the currents applied to the electromagnets were established to achieve 2D divergence control of a magnetic force. Numerical simulation and experimental validations demonstrate that this approach can generate sufficient magnetic forces that either converge at or diverge from a target point, enabling effective open-loop position control of a miniature magnetic robot. Due to the absence of vision feedback and mechanical motions of magnets, the proposed control strategy could be more clinically applicable for medical applications of magnetic robots.