Sensor Design
Inertial measurement hardware converts mechanical acceleration into a measurable electrical signal through the elastic deformation of a proof mass suspended on a quartz hinge. A quartz flexure accelerometer employs a single-crystal quartz suspension system to provide exceptional structural stability across wide thermal gradients. High-purity quartz minimizes internal damping and thermal expansion effects, which protects the signal from bias instability during rapid changes in environment.
Sensitivity in these devices arises from the piezoelectric properties of the material, where applied forces induce strain that alters the resonant frequency of the sensing element.
Calibration Procedure
Manufacturers establish precision by testing the output against a known gravity vector provided by a high-stability centrifuge or a tilt table. Linear acceleration creates a force on the proof mass, which the quartz suspension resists through a restorative spring constant. Control circuits monitor the resulting displacement to maintain the proof mass in a null position, producing a current proportional to the acceleration.
Bias offsets appear when the physical center of the mass shifts, requiring specific voltage injection to maintain the reference point. Operators identify scale factor errors by comparing the output slope against a reference standard over the full input range.
Environmental Constraint
Installation effects degrade performance when stress transfers from the mounting surface to the instrument chassis. Mechanical vibration at high frequencies creates rectified error signals if the mounting interface lacks sufficient rigidity. Thermal gradients across the housing cause internal stress, shifting the zero-g bias and creating non-repeatable errors that manual trim pots cannot easily correct.
Vacuum sealing prevents air damping from changing the performance characteristics as barometric pressure shifts. Humidity levels rarely affect the internal sensing core but damage the electrical connectors if the seals fail.
Signal Resolution
Electronic integration requires a current-to-voltage conversion stage that introduces noise if the design lacks proper shielding. Digitization occurs after amplification to ensure that the noise floor remains well below the smallest acceleration threshold the device needs to detect. Stability of the power supply influences the short-term noise density and limits the ability to resolve minute variations in vehicle motion.
High-impedance inputs prevent loading effects from distorting the sensitive charge signals generated by the quartz elements. Long-term accuracy depends upon the stability of the reference voltage used in the feedback loop.
