Static Gravity Reference Vector Determination for Sensor Calibration
Static gravity reference determination requires site gravimetric surveying and arcsecond stage indexing to isolate true sensor bias from facility tilt errors.
Cross Axis Coupling Coefficient
Sensitivity Parameter
Scalar value expressing the sensitivity of a transducer to inputs directed perpendicular to its primary sensing axis defines the degree of signal contamination in multi axis systems. The cross axis coupling coefficient provides a measure of the error as a percentage of the full scale output. High quality sensors aim for a value below one percent to ensure that motion on one axis is not wrongly attributed to another.
This parameter is a fundamental part of the instrument specification.
Transverse Error
Physical misalignment of the sensing element inside the package often creates this unwanted response. A cross axis coupling coefficient arises when the proof mass or diaphragm is not perfectly centered. Etching tolerances in micro electromechanical systems contribute to these small geometric variations.
During assembly, the orientation of the die relative to the pins can also influence the result. These mechanical offsets are difficult to eliminate entirely during the manufacturing process.
Signal Distortion
Inaccuracies in one measurement channel can distort the results of a calculated vector sum. The cross axis coupling coefficient causes an apparent increase in magnitude when motion occurs on a secondary axis. This effect is particularly problematic in vibration monitoring where high frequency signals might overlap.
Using a decoupling matrix in the data acquisition software can help mitigate the impact. The matrix uses the known coefficients to mathematically remove the crosstalk between channels.
Orthogonality Verification
Verification of the coefficient occurs on a specialized centrifuge or a vibration table. The cross axis coupling coefficient is measured by applying a known force along one axis while monitoring the output of the other two. Any detected signal on the dormant axes is recorded as the coupling error.
This test confirms that the sensor meets the requirements for precision navigation or structural analysis. Results from this test determine the final grade of the sensor.