All sky pointing attitude control system

摘要

In a strapped-down gyroscope space vehicle attitude control system, a method and apparatus are provided for gyro drift and input axis misalignment error compensation employing a sun and a star tracker and preselected vehicle calibration maneuvers. During the preselected maneuvers using the sun and a star as external references, the outputs of two-axis strapped-down gyroscopes nominally aligned with the optical axis of the sun and star trackers are measured. The measured outputs provide gyro drift calibration, roll, pitch and yaw axis scale factors and values corresponding to the degree of nonorthogonality between the roll axis and the pitch and yaw gyro input axes and the nonorthogonality of the roll and pitch axes relative to the yaw axis. With the calibration data so obtained stored in a special purpose digital computer, the vehicle is then rolled and yawed through precomputed angles as modified by the calibration data to acquire a target without further recourse to external references.