An inchworm-like locomotion mechanism based on magnetic actuator for active capsule endoscope

Locomotion mechanism is a necessity for development of an active capsule endoscope. In this paper, we propose an inchworm-like locomotion mechanism, which is composed of a permanent magnet, a plunger, a solenoid and a cone-shaped polymer. When an alternating current is applied to the solenoid, the magnet Will make a reciprocating movement under the electromagnetic force. With the friction difference produced by the polymer, the actuator could propel itself forward on a 2D surface. The working principle and kinetic model of the mechanism are analyzed. A prototype with a size of Phi 12*37mm were fabricated to study the feasibility of the mechanism. Experiments were carried out on the surfaces of various frictional coefficients. The results show that the actuator works more efficiently on the surface of the glass than on the paper, because the polymer has better clamping effect on the former. The velocity changes with the frequency and amplitude of the current. The mechanism consumes a low power and it can work under a relatively low voltage (less than 20V). It has the potential for actuation of an active capsule endoscope.