Research On Active Colon Microrobot System

With the improvement of people’s material conditions,digestive tract disease has become one of the important diseases threatening people’s quality of life,especially colon cancer.At present,the most important examination method of colon is through the traditional endoscope,but in this process,it brought great pain to the patients,and there were blind areas,there were misdiagnosis,missed diagnosis phenomenon,which leads to many people miss the opportunity of early detection;capsule endoscope was easy to be missed because of its movement mode,which limited the promotion of clinical application.In this paper,with the support of the key research and development program of Shandong Province,a colon microrobot system which can realize active motion is studied.Based on the physiological characteristics of human colon,the basic morphology and biomechanical characteristics of colon are analyzed in detail.Combined with the internal environment of colon,the structure and functional requirements of colon microrobot are clarified.The active expansion contraction motion mode and micro DC motor driving mode of the robot are determined through calculation and analysis.When the micro DC drive motor rotates,the lead screw drives the nut to move in opposite or opposite direction,so as to realize the movement of 65 mm expansion diameter of the expansion mechanism;there are three groups of expansion feet,each group is assembled by two members,the expansion feet are connected with the nut hinge through the pin,the hinge holes of the pin and the expansion feet adopt clearance fit,and the hinge holes of the nut adopt interference fit,the expansion of the robot As the nut moves along the lead screw,the expansion and contraction of the tension group are realized;the walking mechanism is also designed with the linkage mechanism,and the same driving mode is adopted with the expansion mechanism,so as to realize the maximum expansion diameter of 60 mm to adapt to the diameter change of the colon driven by the expansion mechanism,and realize the trapezoid contact and mutual cooperation between the mechanisms,so as to realize the movement of the colon microrobot.Based on the biomechanics of colonic tissue,the mathematical model of colonic stress-strain is established.The material characteristics of colon and the influencing factors of colonic stress-strain are obtained.The contact mechanism and motionmechanism suitable for colonic robot are designed.The contact safety of colon can be improved safely and effectively without damaging the colorectal tissue.Through the comprehensive analysis of dynamics and critical step distance,the motion characteristics of the colon microrobot are clarified.Through the analysis of the critical step distance of the colorectal robot,the critical step distance of the colorectal micro robot is calculated to be 13.074 mm,which further proves the feasibility of the active expansion walking motion of the colorectal robot.Through ABAQUS simulation analysis,the colon microrobot can move forward 3.3mm in a complete movement gait,with a movement speed of 2.2mm/s,the maximum contact force between the expansion mechanism and the colon is 2.3N,the maximum contact force between the walking mechanism and the colon is 1.7N,which is less than the maximum bearing force of the colon of 2.4N.The colon microrobot has the movement safety and trafficability in the colon.The analysis of the running environment of the robot and the simulation analysis further clarify the movement performance of the colon microrobot,which provides an important reference for the development of the movement technology of the colon robot.The research significance of this paper is to promote the development of active minimally invasive diagnosis and treatment technology of colon diseases,so as to improve the prevalence of diagnosis and treatment of colon diseases and ensure people’s life and health.