Spiral Micro In-Pipe Robots In Liquid Environment

With the expanding of applied range of endoscopic technology and minimal invasive surgery technology, studies on the autonomic micro in-pipe robots have been more and more important. In this paper, according to the liquid pipelines in the special industrial environments and the small inner pipelines of the human body filled with body fluid, no invasive inner and outer spiral micro in-pipe robots and inner spiral micro in-pipe robots based on liquid environments are proposed. The theoretical analysis and experimental study on the micro in-pipe robots are conducted. The micro-robot is probably used in the blood vessel, and it can realize of inspection, sampling, drug spot deliverance and other functions.The paper firstly puts forward the defects of traditional pipeline detection methods in the industry and the medical field, and depicts important research significance of the micro in-pipe robots in industry and minimally invasive surgery, and further analyzes the developments and existing problems of passive capsule endoscopes, peristaltic robots, active capsule robots, swimming robots, spiral robots and nanorobots. Finally, the research starting point and the main content of research are presented.The paper presents two structural design schemes of the spiral micro in-pipe robots, and the dynamic equations of the liquid in pipelines are established while spiral robots running, and then the flow field is solved by the computational fluid dynamics method. The influence of various parameters(liquid density, liquid viscosity, pipeline diameter, eccentricity, curved pipeline, outer spiral speed, inner spiral speed, inner and outer spiral speed sum and robotic running speed, etc.) on robotic motion performance(include axial thrust force, pressure of pipeline wall and load capacity of blood, etc.) is obtained. The relationship between the axial thrust force, pressure of pipeline wall, load capacity of blood and circumferential drag torque of inner and outer spiral micro robots, single sectional outer spiral robots and double sectional outer spiral robots and their outer shell rotating speed is compared. In order to verify the feasibility of inner and outer spiral micro robots in pipelines filled with liquid, from the analysis of the robotic working principle, a set of epicyclic gear train that simulates inner and outer spiral working status of the running robot is designed, and the structure of the robot system is designed, and the inner and outer spiral micro robotic system is made. The unloaded and in-pipe operation experiment of the inner and outer spiral robot are conducted, and the experimental result is analyzed.Through the introduction of pulsating blood flow function as the inlet condition, the robotic axial thrust force, maximal and minimal pressure of pipeline wall of the inner and outer spiral robot and the inner spiral robot are numerically calculated in a flow pulsation cycle under the pulsating flow effect, and the influence of the robotic various running speeding on the robotic axial thrust force and the maximal pressure of pipeline wall is analyzed.The spiral robotic axial thrust forces and pressures of pipeline wall in the free state are calculated. The influence of the inner spiral structure parameters(notch width, groove bottom width, dip angle, groove depth, spiral angle and thread number) of the inner spiral robot in the free state on the energy consumption index and the inner spiral axial thrust force is numerically analyzed. By the orthogonal optimization design method, the optimal combination of the six inner spiral structural parameters is obtained. Similarly, the influence of the outer spiral structure parameters of the inner and outer spiral robot on the robotic axial thrust force is numerically analyzed. By the orthogonal optimization design method, the optimal combination of the six outer spiral structural parameters is obtained.Finally, the paper summarizes all the studies and points out the innovations and discusses which studies should be made in future.