A Rotation Measurement Localization System For Capsule Endoscopy Based On Permanent Magnet Marking Technology

Capsule endoscopes that have gradually abundant function need assistance of positioning technology. The capsule endoscopes can help doctor judge location of lesions accurately, and assist capsule fixed-point dosing, positioning to collect liquid samples, etc. The size of equipments based on radio frequency, ultrasonic or magnetoelectricity have limited the freedom of the subjects. A more reasonable capsule positioning system has been designed in this paper, and it is of great significance for diagnosis and treatment of gastrointestinal diseases.This paper studies a rotation measurement localization system based on permanent magnet marking capsule reconnaissance equipment. Firstly, the mathematical model of the rotation measurement positioning is established. Magnetic field intensity information is converted into voltage signal by the GMR sensor GF708.The sensor is used in the system researching the sensor signal features under different directions and the sizes of the magnetic field. The signal is carried on with amplify processing and filter processing, and then the signal is sent to the PC. LAB VIEW software is used on the PC for reading, preprocessing and storaging data sent by MCU. The design of this system includes the following content:1. The validation of the mathematical model and the determination of scientificity of the rotation measurement.2. Selection of permanent magnet, and the measuring range of the parameters.3. Parameters modification, and the optimization of model. Finally, the system can realize positioning, and the errors of the system are also analyzed.Experimental results show that average positioning error is less than 0.19cm, the average deflection angle error is less than 0.019radian, and the average angle error is less than 0.049 radian in the case that the permanent magnet parallels to the plane of rotation and in the plane of rotation. The accuracy of the system can meet the positioning of the capsule endoscopy. The scheme of the positioning system is feasible. In fact, the system needs to improve positioning accuracy in space.