Evaluating Thermal Hysteresis Limits in MEMS Accelerometer Static Leveling
MEMS thermal hysteresis creates non-repeatable zero-g offset shifts up to 3 mg, driving uncompensable arcsecond tilt errors in static leveling systems.
Static Tilt Error
Angular Deviation
Constant angular deviation in the output of an inclinometer or accelerometer that occurs when the device is held in a fixed orientation. Static tilt error represents the difference between the actual angle of the sensor and the angle reported by the measurement system. It arises from internal offsets and mechanical misalignment of the sensing element.
Source Bias
Electronic noise and thermal instability in the signal conditioning circuit often appear as a shift in the zero-point. The physical mounting of the sensor onto the circuit board also introduces a fixed angle that the software must account for. These factors combine to create a persistent offset that does not change over time if the temperature remains constant.
Correction Technique
Calibrating the sensor involves measuring its output at known positions to calculate the offset. This value is then subtracted from all future measurements to improve the accuracy of the tilt reading. High-end sensors include internal compensation algorithms that use dedicated temperature probes to adjust for thermal effects on the bias.
Optical references provide the baseline for these adjustments during final qualification.
Precision Requirement
Applications like structural monitoring or precision leveling require the error to be within a few millidegrees. Regular verification against a known reference ensures that the device maintains its performance over its service life. Monitoring the drift in this error provides a way to predict the eventual failure of the instrument.