Low Frequency Calibration of Vibration Sensors

Long-stroke shakers are the backbone of low-frequency (<20 Hz) accelerometer calibrations. Such calibrations employ a laser Doppler vibrometer (LDV) to record the motion of the accelerometer device under test as it travels the linear guide of a shaker with a quasi-sinusoidal time dependence. Errors may arise if the accelerometer is subject to additional, unintended motion due to non-idealities in the shaker operation. We have developed an optical scheme to simultaneously characterize the cross-axis and rotational parasitic motions of a long-stroke shaker by leveraging the geometric properties of a corner cube retroreflector to independently measure pitch, yaw, and horizontal and vertical displacements. This allows the uncertainties due to these parasitic motions to be reduced.

We have demonstrated the calibration of accelerometers by rotation in the Earth's gravitational field at frequencies of 1 Hz and below and have applied this method to calibration of multiaxis accelerometers. We are engaged in a comparison of the performance of translational and rotational low-frequency accelerometer calibration systems.

Publications:

• J. H. Strait and R. A. Allen "Optical Characterization of Parasitic Motion in a Long-Stroke Shaker", Metrologia 62 015001(2025) DOI 10.1088/1681-7575/ad90e6
• Gaitan, M. and Geist, J. (2021), Calibration of Triaxial Accelerometers by Constant Rotation in the Gravitational Field, [online], https://doi.org/10.1016/j.measurement.2021.11052828, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=932280