Dynamic characteristics of an intestine capsule robot with variable diameter

This paper proposes an intestine capsule robot with variable diameter. It is driven by external rotating magnetic field and has the function of automatic radial clearance compensation. An external magnetic field generating device and a capsule robot with variable diameter are developed. Radial dynamic balance equation and kinematics equation of the capsule robot traveling inside flexible elasto-wall environment are established, and dynamic characteristics of the capsule robot inside flexible elasto-wall pipe and rigid wall pipe environments are analyzed and compared. Simulations and experiment results show that its dynamic characteristics in both pipes are almost the same. Under the action of radial clearance compensation, fluid dynamic pressure around outer surface of the capsule robot and its propulsion, as well as its adaptability to diameter change range, are significantly improved. Its propulsion and moving speed are controlled by adjusting rotating angular speed of the rotating magnetic field. This innovative capsule robot with radial clearance compensation has a promising prospect for inside intricate gastrointestinal (GI) tract in non-invasive therapy applications.