Research On The Key Technology Of The Maglev Accelerometer Based On Gap Magnetic Force Measurement

The accelerometers, which are mainly used in small-sized and high accuracy INS, are not suitable for long time and long distance navigation. This is mainly because the accuracy of the accelerometers is not high enough and has not been raised for a long time. The weakness of the quartz-flex accelerometer’s measure method includes the flexible beam instability deformation, the change of electromagnetic characteristics of permanent magnetic actuator, and the differential of current expression value and the actual electromagnetic power. The electrostatic suspended accelerometer has the problem including limitation of use environment, weak power, small range, and only suitable for weak acceleration measurement of the slow variable. Accordingly, this subject proposes a new, high-precision acceleration measure method based on magnetic suspension and the magnetic force expression with air-gap magnetic field array detection.The biggest advantage of this accelerometer is the air-gap magnetic field measurement and the direct expression of inertia force, so the influence of inaccuracy in inertia measurement will be reduced to the lowest degree to improve the accuracy and stability of acceleration measurement. With the theoretical analysis and simulation modeling to this new magnetic suspended accelerometer, the performance mainly depends on the magnetic field sensor and magnetic force inversion calculation based on Synthesis of multi points of magnetic field information. Moreover, considering the level of the magnetic suspension theory nowdays, the system is mainly limited in their dynamic stability characteristics of magnetic material performance. From the view of these problems, we have carried out the more in-depth works:1) The technical principle of high precision magnetic field sensor which fits for the air gap magnetic field detection is researched and application analysis is conducted through experiment and simulation. On the basis of simulation, the design structure of a device with abnormal large magnetoresistance effect is improved to make it better for the measurement of air-gap magnetic field of magnetic suspended accelerometer. The manufacturing technique of this kind of magnetic field sensor using graphene as the basis material is put forward in the research and technological test is conducted, which confirms the feasibility of manufacturing technique of this device.2) The technology of magnetic force of limited synthetic discrete point magnetic field sensitive suspension in the air gap is researched. The relative precision of computation between the simplified model maxwell stress tensor method and the traditional virtual displacement method is compared by simulated analysis, which indicates that a high precision magnetic force calculated value can still be obtained even selecting a few discrete points on the condition of adopting reasonable magnetic structure.A testing system of the air gap magnetic field measurement for the characterization of magnetic is designed in the research. The magnetic induction intensity of array point in the air gap is measured through scanning way and the discrete maxwell stress tension calculation method is used to compound the magnetic field force of coasting body imposed by driving system. A good consistency is obtained through comparison with the observed magnetic force.3) The analysis points out that magnetic hysteresis characteristics is the key factor which influences the dynamic stability characteristics of magnetic levitation system.Thus, the synthetic mechanism and method of massive solid super paramagnetic materials is researched. The technical route of synthesizing superparamagnetic iron oxide nanoparticles with polymer materials is designed and a reasonable preparation technology is formed. The relevant technical test of the synthetic material and the process test shows that this kind of material has already had a certain super paramagnetic properties. However, it has some defects in aspects such as mechanical characteristics, permeability and so on. A right path of development is found to further improve the property of this material through analysis.4) According to the comprehensive analysis and study to the new magnetic suspended accelerometer, an experiment platform of 2D magnetic suspension acceleration measurement system with Z axis constraints was been designed and fabricated. In the current research stage, high permeability ferrite was used in the magnetic structure, and the micro linear Hall magnetic sensors were used to measure the air-gap magnetic field. The gravity field experiments with magnetic suspension control were carried out, and the result suggests that the air gap magnetic field measurement and expression method can effectively eliminate the effects of system hysteresis, compared with the current expression method, in the measurement of the acceleration and tilt angle. So this method can improve the performance of inertial measurement. The actual accuracy of acceleration measurement system is not very high, limited by the current structure and circuit performance, but shis new measuring method has shown the potential to achieve high precision and high performance.Through the research of this subject, it is promising to realize the high precision magnetic suspended accelerometer, and the work would contribute to the navigation application with long endurance and high precision.