| Since the geomagnetic field is globally distributed and stable for a long time, it has been applied to attitude determination technology of simplified guided ammunition and become a hotspot both in the foreign and domestic research. However, the magnetic information detected by magnetic sensor consists of three kinds:geomagnetic field, projectile magnetized field and the error information caused by the sensor itself. The detecting error made by projectile magnetized field is difficult to calculate and compensate. Therefore, it’s very essential to analyze the ferromagnetic materials which lead to the magnetized field, establish an error model and finally find out a calibration method that is suitable for projectile attitude determination system.Firstly, the magnetization characteristics of hard ferromagnetic material and soft ferromagnetic material in the projectile have been analyzed. ANSYS EMG has been used to build a model of projectile and obtain the magnetized field vectors of ferromagnetic materials in a weak magnetic field similar to geomagnetic field. Secondly, according to the simulation results, the mathematic model of hard ferromagnetic error and soft ferromagnetic error has been established. Calculation methods of10coefficients in the ellipse fitting model have been achieved, which turn out to be right after being verified by MATLAB. Thirdly, the hardware module has been designed and software module been programmed to realize the system function. Finally the experimental system for the calibration system has been built up. The environmental disturbance errors calibration experiment is conducted. The results show that the error of pitch angle and roll angle attitude are less than3degree after calibration, which proves the validity of the calibration system.The research of this topic is significant for the development of projectile attitude determination technology and valuable for the engineering applications. |
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