Force control of a permanent magnet for minimally-invasive procedures

Magnetic actuation can be used for minimally invasive control of medical devices such as robotic catheters. However, current systems that use large permanent magnets are limited in their ability to modulate the magnetic force. In this paper we present a proof-of-concept system for closed-loop force control of a permanent magnet using shielding materials. Our system consists of a device that actuates pieces of high-permeability metal to redirect magnetic lines of flux. This is used to regulate the attractive force exerted by a large controlling magnet on a smaller moving magnet. We compare the performance of our system to FEA simulations and present experimental results for constant-force control at forces and distances that are medically relevant.