Reasearch On Magnetic Localization Method Of Capsule Robot Actuated By Permanent Magnet

Today,the incidence of gastrointestinal diseases is relatively high,and gastrointestinal cancer is one of the high mortality cancers.However,if early screening and diagnosis are obtained,the cure rate of these diseases can be greatly improved.The intubation method used in traditional gastrointestinal endoscopy can bring a strong sense of discomfort to the patient,and at the same time has the risk of damaging human tissues.With the development of medical devices,capsule robots have gradually become a hot spot in scientific research.The robot can be swallowed into the body by the patient due to its size like a capsule,and the built-in miniature camera completes the image acquisition work.Meanwhile,it can use the magnetic localization method to track the embedded permanent magnet to obtain the position and orientation information of the capsule robot to help the doctor diagnose and treat.However,the capsule robot mostly relies on the peristalsis of the intestine itself to observe the area to be detected in the body,which means that the diagnosis process is uncontrollable.In order to further improve the reliability of the capsule robot and the convenience of doctors’ diagnosis and treatment,it is necessary to accurately realize the simultaneous actuating and positioning of the capsule robot.This paper proposes a localizing method for a magnetically-actuated capsule robot based on permanent magnet tracking technology.On the basis of using the magnetic localization method to track the capsule robot,an external magnetic source is introduced to achieve active control of the robot’s movement,that is,simultaneously actuating the capsule robot and capturing its pose.At the same time,the realization of actuation and localization functions can solve the problem of passive movement of the capsule robot in the digestive tract,enabling doctors to observe suspicious lesions in all directions,reducing the rate of misdiagnosis.In addition,this technology has also laid a reliable foundation for the capsule robot to combine functions such as biopsy sampling and fixedpoint application.First,the simultaneous actuation and localization of the capsule was theoretically verified.The comparison and analysis of the magnetic field model ensured the accuracy of the magnetic field description and provided reliable magnetic field modeling for the permanent magnet tracking in the later stage.In addition,in order to realize the active control of the capsule robot while avoiding the disadvantages of using electromagnetic coils such as energy consumption,an external permanent magnet was introduced.Through the analysis of the interaction between the permanent magnets and the movement environment of the capsule,the sensor selection and other parameters were determined,and finally a corresponding experimental platform was built.Since multiple magnetic sources would cause great interference for the tracking of the capsule robot and lead to localization failure,this paper also introduced an optical tracking system.The camera captures the markers fixed with the external magnet,and the pose information of the external magnet can be obtained in real time,then we can effectively separate the magnetic field of target from the spatial composite magnetic field measured by sensors,which is called the single object magnetic tracking method.Experimental results show that the proposed method has good localization accuracy.In static experiments,the average position error is 2.6mm,and the orientation error is1.54°.Compared with the traditional multi-target magnetic localization method,it has a great improvement.In dynamic experiments,the method proposed in this paper has a better localization effect than the multi-target method.The experiment in this paper verifies the effectiveness of the proposed method and will play a positive role in promoting the development of capsule robots.