Research On Capsule Type Micro Robot Inside Flexible And Elastic Wall

Minor injury and interposition therapy features safety, reliability, painlessness and short recovery. With the development of the MEMS and micro manufacturing technology, interposition therapy becomes possible. The developing trend of bi-medical engineering is that more and more requirements are proposed on micromation, portability and economy.Driven by our developed non-contact drive and control system for producing rotating magnetic field, a new capsule type medical micro robot prototype with function of self-compensation for radial clearance is proposed in virtue of hyperelasticity of rubber material, which is suitable to move inside flexible and elastic wall. And robot prototype is developed.Clearance compensating principle depends up to rubber material with hyperelasticity and radial extending mechanisms in synchronization on which copper blocks with spiral structure are installed.When the robot is driven, centrifugal force along radial direction from copper blocks with spiral structure installed on radial extending mechanisms in synchronization inside capsule exerts pressure on internal surface of capsule and pushes it expanding in radial direction, and clearance between outer surface of capsule and elastic wall is minimized greatly. As a result, thickness of dynamic oil membrane is reduced and propulsion is increased. Motion inside flexible and elastic wall is realized.In this dissertation, kinetic characteristics of the spire-type micro robot are analyzed based on Reynolds equation. Mathematic models such as the axial propulsive force, liquid load torque, swimming velocity and weight bearing capacity are established. Furthermore, the influences on kinetic characteristics by spiral parameters are discussed, the influence on swimming speed by considering viscosity of liquid is analyzed and Kinetic response characteristics of robot is studied by simulation with software MATLAB. Meanwhile, dynamic process of radial expansion is studied; dynamic balance equation of clearance self-compensation in flexible and elastic wall is established, and clearance self-compensation and swimming characteristics are studied theoretically and experimentally based on characteristics of radial clearance, and start-up rotating speed is proposed. The experimental results show the correctness of theoretical analysis. Finally real experiments inside pig intestine are conducted both horizontally and vertically. The results demonstrated that the proposed clearance compensating method can improve driving performance of robot greatly and this robot has laid a foundation for medical application.