Research On A Micro Robot System And Wireless Power Transfer Technology For Gastrointestinal Tract Inspection

Since the death rate of gastrointestinal diseases in the modern society is very high, inspection of gastrointestinal(GI) tract at early stage is critical. In order to avoid disadvantages of traditional endoscopies like inspecting processes which are complicated, discomforts for patients, limited inspecting range, and to transcend limits of capsule endoscopies like inability to inspect actively, limited duration, blind spots in the inspecting process, this paper presents a micro robot inspecting system for GI tract and corresponding wireless power transfer technology.Beginning with related works on GI tract inspection around the world, this paper analyzes advantages as well as disadvantages of several works and thus demonstrates that the micro robot inspecting system presented in this paper is advanced. Inchworm-like locomotion pattern is chosen for the robot. Aiming to limit the size of the robot to miniature scale, clapping mechanisms using spiral legs and axial stretching mechanism using screw and nut are designed. These mechanisms allow the micro robot to be able to move inside GI tract and to be safe to biological tissue. In order to control the micro robot in real time, a control circuit based on a microcontroller is designed, which includes wireless communication transceiver module, motor driving module, movement detecting module and current detecting module. Then programs for mechanism control, wireless communication, movement detection and current detection are written. The inchworm-like locomotion is realized to ensure the stability and effectiveness of the robot’s movement.Wireless power transfer is in dispensable in order to provide the robot unlimited function time and to allow it to move without any cable. This paper reviews some recent major wireless power transfer techniques and choose inductive coupling method. The efficiency of inductive coupling power transfer is analyzed. To improve the efficiency of the wireless power transfer, the AC resistance of the transmitting coil is discussed thoroughly. Based on the theories of skin effect and proximity effect, a model to calculate the AC resistance of the transmitting coil made with litz-wire is developed. Experiments show that theoretical predictions are in agreement with the measured results. This theoretical model can be very useful in optimizing the wireless power transfer efficiency and accelerate the design process of the wireless power transfer system.This paper designed mechanisms which are suitable to gastrointestinal tract environment, as well as control module which contains both hardware and software. After completing the fabrication and debugging of all parts of the micro robot inspecting system, functional tests for each module of the system and movement tests in pipelines as well as in vitro intestinal are carried out. It is shown in these tests that the micro robot can move effectively and steadily, which proves the reasonability of the inchwormlike locomotion pattern, the reliability and safeness of the mechanisms, and the effectiveness of the wireless power transfer.