Modeling and simulation of magnet-guided active endoscopic capsules manipulated by robots

The rising use of wireless endoscopy capsules for the medical examination of the digestive tube has brought about an innovative step of medical experience. However, proceeding only by means of gravity and visceral peristalsis greatly restricts its clinical application, since their location, posture, and velocity cannot be controlled. The technology described in this paper uses an external magnetic field which is generated by two cuboidal extern permanent magnets (EPM) to drive the endoscopy capsule with one cuboidal permanent magnet (IPM) inside. EPM1 and EPM2 are fixed on the end-effector of two robots respectively. By changing the relative postures of robots, the interaction force and torque between IPM and EPMs change so that the endoscopy capsule can be controlled for full degree of freedom. In this paper, the interaction magnetic force components and torque components are analytically calculated based on Ampere molecular current hypothesis, Dipole theory and BiotSavart´s law. The exact 3D analytical expressions are obtained and used for calculating the magnetic forces and torques, shape optimization and velocity control directly rather than ordinary numerical methods.