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Shijiazhuang, China

Zhang Y.,Mechanics Engineering College | Zhang G.,Mechanics Engineering College | Shi Z.,Mechanics Engineering College | Yin G.,Mechanics Engineering College
Chinese Journal of Sensors and Actuators | Year: 2013

According to the problem that calibration of triaxial magnetic field sensor needs known equal magnetic field, put forward a calibration method of triaxial magnetic field sensor under unequal magnetic field environment. By changing the the relative position of triaxial magnetic field tensor and permanent magnet, built the the error calibration model involving nonorthogonality angles of three-axis, different sensitivity values of every axis and magnetic moment of permanent magnet. Getting the nonorthogonality angles of three-axis, different sensitivity values by generic algorithm optimizing. By changing the direction of magnetic axis, getting the zero-shit error using the average value of two magnetic values of opposite direction. It proved the correctness of the calibration method of triaxial magnetic field sensor under unequal magnetic field environment by simulation experiment, and it provides a valid method for practice calibration of triaxial magnetic field sensor. Source


Zhang G.,Mechanics Engineering College | Zhang Y.,Mechanics Engineering College | Li Z.,Mechanics Engineering College | Fan H.,Mechanics Engineering College
Huazhong Keji Daxue Xuebao (Ziran Kexue Ban)/Journal of Huazhong University of Science and Technology (Natural Science Edition) | Year: 2013

The main goal of this study is to give the localization of magnetic field gradient tensor when carriers parallelly moving. The problems existing in the localization methods were analyzed. The magnetic field value of an object was replaced with the magnetic moment of the object, and the nonlinear system of localization equations for position parameters was built by measuring the tensors of two points. The unknown parameters of the equations were optimized by GA (genetic algorithm), and the position parameters were calculated. Simulation results show that the tensor localization method for carriers parallelly moving is better than the existing tensor localization methods, because of its high localization precision. Thus, this method can locate the underground hidden objects under the environment of geomagnetic field. Source


Gang Y.,Mechanics Engineering College | Yingtang Z.,Mechanics Engineering College | Hongbo F.,Mechanics Engineering College | Zhining L.,Mechanics Engineering College
Journal of Applied Remote Sensing | Year: 2014

Magnetic dipole localization methods that rely on measurement of the magnetic field vector are compromised by the relatively strong background geomagnetic field. A localization method that uses only magnetic gradient tensor data is proposed. The localization equations are established by transforming Euler's equation of degree -3 into degree -4 and using the orthogonality of the intermediate eigenvector of the magnetic gradient tensor that is produced by a magnetic dipole and the source-sensor displacement vector. To measure the quantities required in the localization equations, we designed a magnetic gradient tensor system in which finite differences are used to approximate the first- and second-order spatial gradients of magnetic field components. Numerical simulations show that the proposed method can accurately and uniquely solve for the location of a magnetic dipole in the presence of the geomagnetic field, and the experimental results show the superiority and the practicability of the proposed method. © 2014 SPIE. Source


Zhang G.,Mechanics Engineering College | Zhang Y.,Mechanics Engineering College | Fan H.,Mechanics Engineering College | Sun Y.,Mechanics Engineering College | Li Z.,Mechanics Engineering College
Proceedings of the 2012 2nd International Conference on Instrumentation and Measurement, Computer, Communication and Control, IMCCC 2012 | Year: 2012

Due to the noises in signals of magnetic gradient tensor system influence the tracking precision heavily, put forward a denosing method based on SVD. Described the principle of magnetic gradient tensor tracking and gave a plane structure of tensor system. Analysed the noises in magnetic gradient tensor signals. Described the process of SVD, and analysed the characteristic of singular values represent signal and noises. To confirm a good reconstruction order κ, adopt the method of fuzzy mean C to do cluster analysing on singular values. At last designed an experiment of magnetic gradient tensor tracking and collected the real signals. Using the denosing method based on SVD to reduce the noises in signals and the signals reached to a good SNR. © 2012 IEEE. Source


Zhang G.,Mechanics Engineering College | Zhang Y.-T.,Mechanics Engineering College | Yin G.,Mechanics Engineering College | Ren G.-Q.,Mechanics Engineering College | And 2 more authors.
Chinese Journal of Geophysics (Acta Geophysica Sinica) | Year: 2016

To solve the problem that the measurement accuracy of the magnetic tensor detection system is influenced by the magnetic tensor generated by the carrier, and existence of nonlinearity, separated patterns and too many coefficients in the existing compensation model, this work proposes an integrated linear compensation method for the magnetic tensor carrier. First, the magnetic tensor system is built, and the whole magnetic tensor is replaced by the expression of 5 elements. The magnetization characteristic of the hard magnetic material that comprises the carrier is analyzed, and the connatural magnetic field from carrier hard magnetic material does not vary with the change of carrier attitude and position. The mathematic model of the connatural magnetic field is constrcuted. The mechanism of the induced magnetic field from carrier soft magnetic material is analyzed, and the induced magnetic field is equivalent to the magnetic field superposition of several magnetic dipoles. The mathematic expression of the induced magnetic field is derived. The carrier magnetic tensor compensation model is established combined with the influence of the connatural magnetic field and the induced magnetic field, and the magnetic tensor compensation model with 20 coefficients is established by variable substitution and combined reduction. If we rotate the magnetic tensor system and carrier more than 4 attitudes under the equal magnetic field environment, and put the measured value of the magnetic tensor and magnetic field components into the carrier magnetic tensor compensation model, we can get the 20 magnetic tensor compensation coefficients. When the magnetic tensor system is applied to search the target, we can calculate the magnetic tensor value of the carrier with the 20 magnetic tensor compensation coefficients and the three components of the magnetic field. The magnetic tensor value of the target can be determined with the total magnetic tensor value subtracting the magnetic tensor value of carrier, and the carrier magnetic tensor compensation is realized. On the wide lawn, the magnetic tensor system is fixed on the three-axis non-magnetic turntable, a piece of iron of 0.003 m3 as the simulation carrier is put on the this turntable also with a certain distance from the magnetic tensor system. The three-axis non-magnetic turntable is rotated at different attitudes (to get more calculation accuracy, 10 attitudes are carried out), the measurement data of the magnetic tensor system are recorded. Using the magnetic tensor compensation method of this paper, the 20 magnetic tensor compensation coefficients of the simulation carrier are obtained with the measurement data. To test the validity of this compensation method, the three-axis non-magnetic turntable is rotated at another 4 attitudes, and the magnetic tensor value from the simulation carrier can be got with the 20 magnetic tensor compensation coefficients and the three components of magnetic field measured by the magnetic tensor system. The influence of the magnetic tensor of the simulation carrier is up to 653 nT/m before compensation, and the general targets can be submerged by it. After compensation, the influence is reduced to 32 nT/m, and to a certain extent, the magnetic tensor of the simulation carrier is compensated. In this paper, the carrier magnetic tensor compensation model considering the connatural magnetic field and induced magnetic field is established. The model includes 20 magnetic tensor compensation coefficients, which can be solved by the model and the measurement data. The magnetic tensor generated by the carrier can be calculated using the 20 compensation coefficients and the three components of the magnetic field, and the carrier magnetic tensor compensation is realized. It is proved that the calculated magnetic tensor is very close to the real ones of the carrier by real measuring experiment, and the compensation method in this paper can effectively accomplish carrier magnetic tensor compensation. © 2016, Science Press. All right reserved. Source

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