Design Of Magnetic Positioning System Based On Gradient Tensor

With the improvement of magnetic sensor measurement accuracy and signal processing technology,magnetic positioning technology has been developed rapidly.Gradient tensor method is one of the most widely used methods in magnetic location technology and has its unique advantages.The magnetic gradient tensor positioning method has a simple measurement method,a large amount of magnetic field information,and a strong stability of the gradient tensor positioning system,which can show good anti-interference in the measurement process,and can be widely used in military and medical fields.Aiming at the problems that the localization results in the traditional static magnetic target-based localization system are easily affected by interference factors such as environmental noise and geomagnetic field,as well as the lack of accuracy of the traditional single-point localization algorithm,this paper investigates the localization method based on alternating magnetic sources.The demodulation principle of the alternating magnetic signal is analyzed,and on this basis,the anti-interference effect of the positioning system when the circular planar spiral coil is used as the source of the alternating magnetic signal is studied.In order to improve the accuracy of the localization algorithm,the gradient tensor localization algorithm based on the extended Kalman filter is studied,and the feasibility of the algorithm in this paper is verified by comparing the localization effect of this algorithm with the traditional single-point localization algorithm through simulation.Finally,the localization experiment was conducted based on the alternating magnetic signal source,and the localization results matched the real trajectory,which verified the effectiveness of the work in this paper.The main research contents of this paper are as follows:(1)In order to reduce the influence of geomagnetic field and other interfering magnetic fields in the measurement environment on the location results of magnetic target source,this paper studies the location method of alternating magnetic signal source.The electric planar coil is used as magnetic signal source and the signal generating circuit is used as driving device to generate strong and stable alternating magnetic field.After the alternating magnetic field signal is measured by the sensor array at the receiving end,the DC signal is obtained after phase-locked amplification processing,and then the location algorithm is used to solve the position information of the magnetic signal source.(2)Aiming at the structural design of transmitting coil,the magnetic field distribution of square planar spiral coil and circular planar spiral coil in space is compared.Under the same simulation conditions,according to the magnetic field distribution diagram of the two,it can be seen that both the size of induced magnetic field and the uniformity of magnetic field distribution,the circular planar spiral coil has obvious advantages over the square planar spiral coil.(3)To improve the accuracy of the localization algorithm,the magnetic gradient tensor localization algorithm based on extended Kalman filter is studied.Based on the extended Kalman filtering algorithm and single-point localization algorithm,we combine the magnetic gradient tensor localization model to solve the position information of the magnetic target,and verify the effectiveness of the algorithm by multi-group path localization simulation.Based on the valid simulation results,practical tests were conducted,and the results showed that the magnetic gradient tensor localization algorithm based on the extended Kalman filter has high localization accuracy and can obtain localization results closer to the real value compared with the traditional single-point localization algorithm.