Gastrointestinal Disease Detection Sysytem Based On Wireless Power Transmission

Committed to noninvasive,painless and multi-parameters gastrointestinal diseases detection,robotic capsule has been paid much attention by domestic and abroad engineers and medical researchers,and become one of the hotspots in the medical device field.Subsidized by the national natural science foundation of China(31170968)and the Shanghai science and technology commission(14441902800),this paper focused on researches about robotic capsule.Combined with the characteristics of gastrointestinal tract,analyzes the movement form of robotic capsule was analyzed and specific structure was designed imitating inchworm movement.To meet the robot miniaturization and biosafety standards,radial expanding mechanism with closed linkage structure was designed to achieve adjustable radial expansion and axial stretching mechanism with screw nut structures to achieve the axial movement.An innovative point is that the radial expanding mechanism can realize large expansion ratio so that robotic capsule can be expanded to ?42mm at an initial size of ?13mm,also validity of radial expanding mechanism was verified through experiments.Wireless power transmission system was considered as a resolution of power supply of robotic capsule,which can solve problems of power lack caused by for button battery and biosafety led by cable-power supply.In this paper,regular wireless power supply principle including electromagnetic resonance,electromagnetic induction and microwave were analyzed and compared.Combined with the specific application circumstances of the robotic capsule,wireless power transmission based on electromagnetic induction coupling was established as the power supply of robotic capsule.Principles of the skin effect and proximity effect existing in AC coil were analyzed and comparison experiments between litz wire and copper wire were conducted.Then,considering the specific structure of the robot,a hollow cylindrical magnetic core with four circumferentially uniformly distributed rectangular grooves was presented and its corresponding winding pattern was designed to obtain a new three-dimensional orthogonal receiving coil.The power transmission efficiency of receiving coil in serial and parallel connection of were theoretically analyzed and calculated.At last,a test platform was built and wireless power transfer efficiency is not less than 5% when the receiving coil at any orientation.In order to control the robotic capsule,control system based on PIC16F690 microcontroller was set up.And combining the characteristics of robot motion,wireless communications,motor drive,current detection and power regulator modules were optimized.Also,package size and power consumption were fully considered in the chip selection process so as to achieve miniaturization and low power requirements of the control circuit.