Performance characterization of the dry tuned-gimbal gyro for application to precision spacecraft attitude reference systems

An analytical characterization of the dry-tuned gyro used in strapdown gimballed inertial navigation systems is presented. The dynamic behavior of a gyro is expressed in terms of equations for the case rates, pickoff rates, misalignments, the angular momentum vector, the time rate of change of the motor torquer angle, and the torques. Static equations are presented for fixed bias errors, the apparent scale factor for relating torque measurements to true rate, the acceleration sensitivities, and misalignments of the gyro case frame from a system-level reference frame. Bandwidth selection for digital sampling of the rate output and aliasing are discussed in terms of tradeoffs. Optimized filtering techniques are required for spacecraft applications in order to achieve high accuracy and low noise. The filtering is carried out through computations of the power spectral density at the rate or angle level, together with autocorrelation functions to detect the random drift of the dry tuned gyro.