Digital Accelerometer Heterodyne Interferometry Calibration Method

Accelerometer is a kind of inertial sensor and is increasingly widely used in the fields of aerospace,inertial navigation,automobile industry,etc.The MEMS digital accelerometer has gradually replaced the traditional mechanical accelerometer due to its advantages of small size,low power consumption and low noise.However,the current digital accelerometer calibration method is static,lack of a dynamic calibration method with high-accuracy and broad frequency range to calibrate its scale factor and sensitivity phase.Therefore,an accelerometer heterodyne interferometer calibration setup is designed in this paper,and relies on the powerful parallel processing capability of FPGA and optimizes the calibration process,this setup can high-accuracy dynamic and real-time calibrate the analog and digital accelerometers in high,medium and low frequency ranges.The main contents of this dissertation are as follows:(1)The problems of the heterodyne laser interference signal acquisition and demodulation methods in current heterodyne interference calibration methods are studied.A heterodyne interference calibration method based on S/PDIF digital signal decoding is proposed based on the shortcomings of current digital accelerometer calibration.(2)An accelerometer calibration system based on PC decoding S/PDIF digital signal was built.The alignment method between S/PDIF decoded signal and accelerometer output signal was studied to ensure its sensitivity amplitude and phase calibration accuracy.The experimental results show that the relative standard deviation and standard deviation of the calibrated sensitivity amplitude and phase are less than0.560% and 0.356°,respectively.The comparison experiment of this calibration method and the current calibration method was designed,and the maximum relative deviation and phase difference are less than-0.965% and 0.334°,respectively,which confirms the calibration results of the calibration method are accurate and reliable.(3)An accelerometer calibration system based on FPGA decoding S/PDIF digital signal was built.The alignment method between S/PDIF decoded signal digital signal and other digital signals was studied,which can improve the maximum acquisition time.and This method is suitable for low-frequency vibration calibration and carries out high-accuracy and dynamic real-time calibration for analog quantity and digital accelerometers.The experimental results showed that the maximum relative standard deviation and standard deviation of the calibrated factor correction and sensitivity phase of this method are 0.061% and 0.047°,respectively.The comparison experiment of this calibration method and the NS-calibration method based on FPGA are accomplished.The maximum relative deviation and sensitivity phase of the calibrated factor correction and sensitivity phase are-0.543% and 0.101°,respectively,which validates that the calibration results of this calibration method are accurate and reliable.