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.
Capacitive MEMS Accelerometer
Microelectromechanical Sensor
Sensing instrumentation defines the class of silicon-based microdevices that translate physical acceleration into readable electrical signals through changes in electrostatic capacitance. Inside a capacitive MEMS accelerometer, microscopic finger-like structures move relative to fixed electrodes when subjected to acceleration. This architecture is widely used in automotive safety systems and mobile electronics.
Transduction Process
When an acceleration forces the proof mass to shift, the distance between the moving fingers and the fixed plates changes. This displacement alters the capacitance, which is measured by an integrated application-specific circuit. The circuit converts the differential capacitance into a voltage proportional to the acceleration.
This design provides high sensitivity and low power consumption, making it ideal for continuous monitoring of machinery. The microscale geometry prevents large mechanical forces from damaging the delicate components, ensuring long-term durability.
Environmental Sensitivity
Thermal fluctuations represent the primary source of instability in these sensors, causing the silicon structure to expand and contract. This expansion shifts the sensor output, introducing errors that can be mistaken for actual motion. Package stress and humidity also affect the capacitance, requiring protective sealing for industrial applications.
Calibration Routine
Manufacturers perform multi-axis tumble tests to determine the zero-g offset and scale factor of each unit. These tests rotate the sensor through the gravitational field, allowing precise scaling against the constant force of gravity. Correcting for thermal drift requires heating the sensor during calibration to build a compensation matrix.