Marine Geographic Three-Component Magnetometer Based On Fluxgate Technology

Geomagnetic field is a vector field,which has two characteristics of magnetic field intensity and direction.Magnetometer is a general term of instrument and equipment that can measure magnetic field intensity and direction at the same time.In marine geological exploration and geophysical research,the three-component measurement of geomagnetic field can retrieve more characteristics of magnetic source and obtain more detailed geological structure information than the total field measurement.The output data of the traditional three-component magnetometer is based on the instrument coordinate system.Therefore,in the later stage of data processing,magnetic data need to be converted into geographic coordinate system combined with carrier attitude data.If the magnetic data is not synchronized with the attitude data acquisition,the conversion results will be deviated.In this paper,a magnetometer is developed based on fluxgate technology,which can directly output three-component data of geomagnetic field in geographic coordinate system.At the same time,the key technology of the magnetometer body error correction has been deeply studied,and the correction of the body error has been realized.In order to realize the design of magnetometer system,the research background and significance of the subject are clarified firstly,and the related research and development status of equipment for three-component measurement of geomagnetism at home and abroad are investigated.Then,the principle and mechanism of fluxgate technology are studied,the structure and characteristics of fluxgate probe are analyzed,and the differences between single component probe and three component probe are compared.The advantages of three component probe are highlighted.The phenomenon of magnetic anomaly and the principle of magnetic anomaly detection mechanism are discussed.Secondly,the hardware design,embedded software design and upper computer software design of the magnetometer data acquisition board are realized.The geomagnetic three-component data in the instrument coordinate system are converted to the geographic coordinate system by matrix transformation.Then,the definition of ontology error of magnetometer is summarized,the composition of ontology error is analyzed,the ontology error model is established,and the ontology error correction based on particle swarm optimization algorithm is studied and implemented.In the testing part of the magnetometer system,a series of testing processes,such as laboratory basic test,static contrast test of Hangzhou geomagnetic station,comprehensive test of Qiandaohu Lake and comprehensive test of South China Sea,are introduced in detail.The error correction algorithm is used to correct the test data and draw the plane distribution map of the geomagnetic field.The test results verify the reliability of the magnetometer.Finally,in view of the problems existing in the magnetometer system,the suggestions for further improvement and optimization are put forward,and the future research directions and trends of magnetic measurement technology and related instruments are prospected.