Characteristics of magnetic torque of a capsule micro robot applied in intestine

A wireless drive and control method using rotational magnetic field on a capsule micro robot is proposed, and both outer and inner actuators are Nd-Fe-B magnet cylinders with multiple magnetic poles in tegular shape alternating with dissimilar radial magnetization, through magnetic coupling with rotational magnetic field generated by the rotating outer actuator, the capsule robot is rotated by an embedded inner actuator, and axial thrust is generated by fluid dynamic pressure distributing on outer surface of the robot with spiral blade, thus the screw motion of the micro robot in intestine is realized. Mathematical model on magnetic torque is established based on equivalent magnetic charge method, and the characteristics of magnetic torque with respect to structural parameters of actuators and swimming effect of the robot are studied theoretically and experimentally. Index Terms--Capsule micro robot, equivalent magnetic charge method, magnetic torque, spiral drive.