An azimuth rate inertial navigation system

An inertial navigation system which combines features of the platform type and the strap-down type is described. The azimuth rate is obtained from integrating azimuth rate signals measured with an azimuth gyroscope mounted on a horizontal gimbal. Details of the rate platform, the mechanization equations, the initial alignment techniques, calibration, and drift compensation are discussed. A computer simulation was performed to study error propagation characteristics arising from navigational positioning errors, the velocity errors, and attitude errors. The system offers fast alignment, calibration, and compensation of the horizontal gyroscope through use of an optical system and reference to predefined azimuth angles of land marks and geographical latitudes. The system is intended for transport aircraft and missile guidance.