Monocular Vision-Based Earth’s Graviation Method Used for Low-Frequency Vibration Calibration

At present, the sensitivity phase of low-frequency accelerometer is commonly calibrated by time synchronization (TS), which needs to strictly align its input excitation acceleration signal and output signal in the time domain. However, TS is very difficult to be implemented and has severely restricted the improvement of the measurement accuracy. A novel calibration method that combines the monocular vision method and time-spatial synchronization technique is investigated to achieve the high-accuracy sensitivity phase calibration. The sensitivity phase is accurately calibrated by determining the aligned spatial position between the excitation acceleration signal and the output signal with the monocular vision method. The sensitivity magnitude can also be simultaneously calibrated. Experimental results show that the calibrated sensitivity phase and magnitude by the investigated method agree well with those by the laser interferometry in the range from 0.3 Hz to 2 Hz. The calibration accuracy of the investigated method is especially superior to that of the laser interferometry in the range from 0.01 Hz to 0.3 Hz.