Quantifying Gyro Noise Coefficients from Allan Variance Data
Quantify gyro noise coefficients by fitting specific logarithmic slope asymptotes to overlapped Allan deviation curves gathered in thermally stabilized static rigs.
Coriolis Vibratory Gyro
Measurement Principle
Oscillatory inertia sensors determine angular rate by monitoring the deformation of a vibrating structure under frame rotation. A coriolis vibratory gyro detects the deflection of a piezoelectric or silicon element as the device experiences motion around an input axis. Secondary vibration modes arise in direct proportion to the input rate due to the transfer of momentum between orthogonal axes.
The magnitude of this secondary mode allows extraction of the rotation signal through synchronous demodulation.
Operational Drift
Thermal gradients within the package create asymmetric stresses that shift the natural frequencies of the resonating mass. Bias stability remains the primary metric for performance degradation in these sensors, where the output indicates non-zero rotation despite a static environment. Differential expansion coefficients between the housing and the active element trigger this mechanical offset during rapid temperature cycles.
Signal Processing
Precision timing in the drive circuitry maintains the amplitude of the primary oscillation at a constant level to avoid gain errors. Digital controllers suppress quadrature signals that appear as noise during high-speed rotation. Phase-locked loops ensure the detection electronics track the fundamental resonant frequency while filtering out environmental vibration.
Calibration Standard
Certified test benches quantify the scale factor using a precision rate table that rotates the sensor at known velocities. Manufacturers establish the linearity of the device by mapping the output voltage across the entire operational range. Deviations from the expected value originate from imperfect structural alignment, which is removed through firmware compensation coefficients.