Static Error
Angular rate sensors output a residual voltage even when subjected to absolutely no rotational motion. This phenomenon, known as zero rate offset, represents the bias error of a gyroscope at rest. This unwanted signal is caused by mechanical stress and manufacturing imperfections in the internal micro-electromechanical elements.
It must be measured and subtracted from the output to prevent angle drift over time.
Calibration Baseline
Laboratory testing of gyroscopes relies on highly stable, non-rotating reference platforms. To determine the zero rate offset, the sensor is secured inside a shielded chamber to isolate it from external vibration. The system records the average output over several minutes to calculate the baseline bias.
Thermal Sensitivity
Micro-machined silicon structures are sensitive to thermal gradients that distort their electrical output. The zero rate offset varies with temperature, which can lead to significant navigation errors if not properly compensated. This drift is mapped across a wide temperature range and stored in the sensor’s non-volatile memory.
Field Adjustment
Practical systems must regularly recalibrate their sensor baselines to account for aging and mounting stress. When implementing zero rate offset compensation in the field, the software detects periods of absolute rest and updates the bias reference. This calculation must be executed when the system is stationary to avoid confusing actual rotation with sensor drift.
Continuous updates of this baseline are essential for maintaining the precision of inertial measurement units over extended runs.
