Research On Key Technologies Of Ocean-earth Magnetic Field Vector Measurement System

As the inherent physical characteristics of the earth,geomagnetic field contains abundant and important information in the inner and outer space of the earth,such as the total geomagnetic field,the three components of geomagnetic field,the inclination angle,the magnetic declination angle and the gradient of geomagnetic field.These information can directly reflect and reflect the physical process of the deep earth and even the inner core of the earth,including pressure,temperature,material movement,and others.It also a natural coordinate system for aviation,aerospace and navigation.Therefore,the study of geomagnetic field is of great significance in the field of science and production.In recent years,with the development of marine resources and the exploration of marine environment,the importance of marine geomagnetic field has been paid more and more attention.At present,the marine geomagnetic field measurement is developing in the direction of continuous and vector measurement.There are not many ocean vector measuring instruments in the world,and China is under control,so there is no practical product in China.Therefore,it is of great significance to develop a marine magnetometer with continuous operation and vector measurement.Relying on the project of "development and application of marine geomagnetic field vector measuring instrument" which is a national major scientific instrument and equipment development project,this paper developed the first integrated geomagnetic field and vector measurement instrument with the accuracy of 0.1nT,which can work continuously for three months under 4500 meters and adapt to different measurement environments such as deep-sea buoy,shallow sea buoy and submarine network.The main contents and achievements of this paper are as follows:(1)A miniaturized and low power consumption geomagnetic vector magnetic sensor is developed.In order to reduce the volume and power consumption of the sensor,the physical structure and circuit design of the sensor are optimized based on the vector magnetic sensor used in terrestrial geomagnetic station and mobile geomagnetic measurement.The sensor adopts a dual core sensor structure with high temperature annealed 1j86 permalloy ribbon soft magnetic material winding gh128 alloy ring core framework,which reduces the sensor volume and increases the fluxgate signal;the magnetic core adopts winding structure,and the induction coil adopts sectional winding,which improves the sensitivity of the sensor.The signal conditioning circuit is redesigned,and the digital drive circuit and low-power devices are used to reduce the power consumption of the system.(2)The magnetic measurement support device which can adapt to the working environment below 4500 meters in deep sea is designed.The support device design of marine geomagnetic field vector measuring instrument should not only consider the strength and stiffness in deep sea environment,but also need to consider the influence of supporting device material on magnetic sensor,the pressure and sealing of electronic cabin,the stability of frame structure in the seabed,and the influence of the weight of the whole structure on the placement and recovery process.After theoretical calculation,simulation and accurate evaluation,titanium alloy material is used to reduce the influence of material on magnetic measurement and overall weight;finite element analysis is used to optimize the structural design;small volume glass floating ball is used to improve the pressure resistance and sealing performance of the electronic cabin;four ball quadrilateral structure is used to reduce the structure center of gravity and improve the structural stability;the magnetic measurement support device is verified by sea test The overall performance of the device.(3)Designed a power supply device that works continuously for three months under the constraints of limited space and weight and no magnetic interferenceUsing the idea of "increasing revenue and throttling",on the one hand,while meeting the requirements of magnetic interference,volume and weight,the battery capacity is maximized through battery equalization and other technologies;on the other hand,under the premise of completing the measurement indicators and functions,through multiple stages The low-power design of the power supply scheme and each electronic system minimizes the power consumption of the system and finally meets the design requirements of the whole machine working continuously on the seabed for three months.(4)The attitude correction technology of marine geomagnetic field vector measurement is studied.The attitude of underwater equipment cannot be adjusted,which will affect the effect of geomagnetic field measurement.The strapdown attitude measurement system is used to obtain the attitude data of magnetic sensor.The underwater attitude of the marine geomagnetic vector measuring instrument is corrected by means of the accuracy calibration of the attitude instrument itself,the compensation of the non alignment error of the attitude instrument and the sensor,and the vector reduction algorithm of the magnetic survey data.In this paper,through the design and testing of each component of the marine geomagnetic field vector measuring instrument and the integration of the whole machine,the development of the marine geomagnetic field vector measuring instrument is completed.Through the performance test of the whole station,the performance and function of the instrument are verified,and the initial design requirements and design objectives are achieved.