부산대학교 도서관

Wireless capsule endoscopes (WCEs) enable non-invasive and comfortable gastrointestinal (GI) explorations, thus preventing the danger of conventional endoscopy. Consequently, patients are encouraged to undergo GI tract examinations. However, passive locomotion of commercially available WCEs is a major technical problem which seriously limits their clinical efficiency. Magnetic actuation of the capsule, where an external magnetic field is usually used to interact with an internal magnetic component, is the most promising solution for active locomotion. Considering a rotating permanent magnet as a magnetic field generator, magnetic force and torque can be used for propulsion at the same time. The optimal actuator magnet placement is discussed in this paper to manage the attractive magnetic force contribution along the desired movement direction, which shortens the capsule’s travel time. The problem is formulated as an optimization problem and a fitness function based on magnetic force and torque is presented. A binary genetic algorithm is used to solve the optimization problem and the optimal relative position of the capsule with respect to the external permanent magnet is found. Then, the capsule is actuated in a PVC lumen experimentally. The results show that the capsule’s travel speed in the optimal configuration is approximately 50% higher than that obtained with the common radial configuration. The capsule is also actuated in four simulated scenarios that consider friction, a collapsed lumen, and gravity. The superiority of the optimal actuation configuration is demonstrated.