The force model of wireless active actuation for capsule endoscope in the GI tract

We presents a new closed loop approach for the active actuation of wireless capsule endoscope inside the human GI tract. A magnet is enclosed in the capsule, and its position, orientation, and movement are detected by a magnetic localization system. To actuate the capsule, an external rotative magnetic field is applied around human body such that a driving force is created in the capsule by the magnet. Through the spiral structure on the capsule surface, the capsule is rotated to move forward or backward with the aid of mucus of the GI tract. According to the hydromechanical lubrication theory and Newton viscous law, we build the traction force model, the friction force model and the locomotion speed model. In this paper, the simulation results of all these three mathematical models are given, which will provide theoretical guide to design the spiral impeller structure of the capsule and estimate the motion force induced by external magnetic field.