Reference velocity demodulation method for accelerometer shock testing based on enhanced CEEMD and threshold correction

Abstract

High-G accelerometers are critical for measuring high shock signals and must be calibrated to improve measurement accuracy. A laser Doppler velocimeter (LDV) is required to calibrate a high-G accelerometer to provide a high-precision reference velocity. The LDV signal must be demodulated to obtain the velocity. However, the phase method is susceptible to noise interference, while the conventional periodic distribution method is challenging to demodulate and severely affected by signal oscillations. We propose a novel periodic distribution method based on enhanced complementary ensemble empirical mode decomposition (CEEMD) and threshold correction (PDECTC) to demodulate the LDV signal. First, the LDV signal is processed with CEEMD to obtain multiple intrinsic mode functions (IMFs) and the residual. Next, each IMF is partially zeroed to obtain the noise-reduced LDV signal. Then, the over-threshold peak of the noise-reduced LDV signal is calculated. Finally, the demodulated velocity of the LDV signal is obtained by correcting the noise-reduced LDV signal according to the over-threshold peak point and calculating all the zero points. Simulation and experimental results show that the proposed method outperforms the phase method based on enhanced CEEMD (PEC) and the periodic distribution method based on enhanced CEEMD (PDEC) and can significantly reduce noise interference. The results show that the proposed method can accurately demodulate the LDV signal to obtain a highly accurate reference velocity, improving the reliability of accelerometer shock testing.