Research On The Localization Of Alternating Magnetic Dipole Source In Geomagnetic Environment

Magnetic positioning technology with all-weather,the required equipment,and signal processing,has drawn the attention of the people gradually,especially with the lower noise and the higher accuracy of the magnetic sensor.Which make it possible to detect weak magnetic anomaly signals.The magnetic field information detected by the magnetic sensor is used to obtain the position information and the movement status of the target,which can be widely applied in the related fields,such as resource exploration and military applications.As the noise from the geomagnetic environment and other magnetic sources,this paper is devoted to study the localization methods of alternating magnetic dipole source.Using the magnetic field of the alternating magnetic dipole source collected by a single three-component magnetic sensor,the localization of moving target with known velocity is analyzed.Using the magnetic field of the alternating magnetic dipole source collected by at least two three-component magnetic sensors,the localization of moving target with unknown velocity is analyzed.Using the magnetic field of the alternating magnetic dipole source collected by at least three three-component magnetic sensors,a new method for localization of moving target to determine both the position and rotation angle with three magnetic sensors is proposed.In order to reduce the error of the measurement,a self-calibration algorithm of a single three-component magnetic sensor and the azimuth error of a plurality of three-component magnetic sensors are studied.The theoretical analysis of simulation and experimental results show that the position information and angle information agree well with the actual moving state of the target,which verifies the feasibility of the localization algorithm.It is of great significance in the application of engineering.The main contributions of this thesis are as follows:(1)Research on the localization of alternating magnetic dipole sourceA large number of traditional methods have been developed to locate targets with static magnetic fields,however,the relation between the problem of localization of moving objectives with alternating magnetic fields and the localization with a static magnetic field is rarely studied.A novel method of target localization based on coherent demodulation was proposed in this paper,which could avoid the interference of the environmental magnetic field.(2)Research on the localization of alternating magnetic dipole source with knownand unknown speedUsing the magnetic field of the alternating magnetic dipole source collected by a single three-component magnetic sensor,the localization of moving target with known velocity is analyzed.Using the magnetic field of the alternating magnetic dipole source collected by at least two three-component magnetic sensors,the localization of moving target with unknown velocity is analyzed.The theoretical analysis of simulation and experimental results show that the position information agree well with the actual moving state of the target,which verifies the feasibility of the localization algorithm.(3)Research on the localization of alternating magnetic dipole source with angle offsetA new method for localization of moving object to determine both the position and rotation angle with at least three magnetic sensors is proposed.Which demonstrated that the position and rotation angle of ferromagnetic target having roll,pitch or yaw in its movement could be calculated accurately and effectively with three vector sensors.The theoretical analysis of simulation and experimental results show that the position information and angle information agree well with the actual moving state of the target,which verifies the feasibility of the localization algorithm.(4)Research on hybrid algorithm for the localization of magnetic targetLocalization of mobile magnetic target can be attributed to the solution for a class of nonlinear programming problem.Regarding to the complication of the calculation of the objective function and the shortage of the real-time localization of magnetic target,a hybrid algorithm was proposed.Firstly,using the Particle Swarm Optimization algorithm to get a beginning of the solution;then utilizing Gauss-Newton algorithm to acquire the accurate solution.The position of the target could be obtained accurately and rapidly without knowing of the initial position.(5)Research on error calibration model of fluxgate sensor in stably geomagnetic environmentTri-axis fluxgate magnetometers are widely used to measure magnetic field in engineering,but the measurement precision is influenced by the zero-offset error,sensitivity error and non-orthogonal error.Error self-calibration model of the performance for the fluxgate sensor is established,and the linear neural network is proposed to readuce the self-correct the performance error.Regarding to inconsistent orientation of different fluxgate sensors,error mutual-calibration model of the performance is established and the least square method is given.The theoreticalanalysis and experimental results proved the rationality and feasibility of the error calibration algorithm.It can effectively improve the measurement accuracy of fluxgate gradiometer using a set of field data collected in a stable geomagnetic environment.