Sensor Alignment
Mechanical sensor frames maintain precise right angles between sensing directions to prevent cross axis interference. In multi axis sensors, axis orthogonality drift occurs when temperature shifts or structural aging causes the angles between sensing directions to change. This spatial deformation introduces measurement errors by projecting acceleration or rotation from one channel into another.
Calibration Metric
Metrologists measure misalignment in milliradians relative to a reference cube or optical surface. The calibration procedure applies a known rotation or gravity vector while monitoring the off axis channels to isolate the drift component from static misalignment. Accurate characterization of this drift allows the compensation software to apply corrected rotation matrices during active operation.
This process depends on repeatable thermal step cycles in the calibration laboratory.
Thermal Sensitivity
Differential expansion remains the primary cause of spatial sensor deformation. Housing materials with mismatched thermal expansion coefficients generate uneven stress when temperature cycles occur. This stress bends the silicon or ceramic sensing substrate, leading to a permanent change in the measurement axis direction.
Tolerance Threshold
Acceptable deviation limits are dictated by the target application, with high precision inertial navigation demanding less than fifty microradians of drift across the entire operational temperature range. Verification happens through multi axis rate table testing in thermal chambers, where the sensor undergoes rotation across multiple thermal plateaus. Long term stability relies on selecting zero expansion glass ceramics or isotropic alloys for the sensor mount.
