Reduction of Calibration Comparison Uncertainty due to Mounting for 3-Axis Accelerometers using the Intrinsic Properties Model
Michael Gaitan, Iris M. Lopez Bautista, Jon Geist
We provide experimental results showing that the calibration of tri-axis accelerometers based on the device's intrinsic properties alleviates the uncertainty due to misalignment of the device under test in comparison to the use of the sensitivity matrix for laboratory comparisons and measurement repeats. The intrinsic properties of a tri-axis accelerometer are based on a (u, v, w) coordinate system model that represent the direction of maximum sensitivities of each of the three accelerometers (U, V, W) and are assumed not to be perfectly orthogonal to each other. The model defines scalar values for the responsivity of each of the accelerometers and the angles between each of the (u, v, w) axes. The calibration procedure requires rotation of the device in the gravitational field around each of the cartesian coordinate (x, y, z) axes of a 2-axis rotation table, where the z axis of the instrument is aligned in parallel with the direction of the gravity. The intrinsic properties can be mapped onto the (x, y, z) coordinate system of the instrument to produce the sensitivity matrix. Although the sensitivity matrix could be solely determined, one component in driving down the uncertainty of laboratory comparisons and calibration repeats relates to misalignment in mounting the device onto the instrument, which can dominate the uncertainty in a measurement comparison. We show that the uncertainty of the cross-axis terms is the dominate factor down to a 0.01° misalignment at a 100 μV noise associated with the measurement. The misalignment component can be exacerbated when calibrating modern Microelectromechanical Systems (MEMS)-based accelerometers, which are typically a few millimeters in dimension.
, Lopez, I.
and Geist, J.
Reduction of Calibration Comparison Uncertainty due to Mounting for 3-Axis Accelerometers using the Intrinsic Properties Model, Metrologia, [online], https://doi.org/10.1088/1681-7575/abeccf, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=931382
(Accessed October 22, 2021)