All sky pointing attitude control system

US4012018A · kind A · utility

Assignee

• The United States of America as represented by the Administrator of the National Aeronautics and Space Administration · US

Inventors

• Kenneth R. Lorell · Palo Alto, US
• James P. Murphy · Franklin, US

Key dates

• Filing date: Oct 4, 1973
• Grant date: Mar 15, 1977
• Expiry date: Oct 4, 1993

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B64G1/361
• WIPO field: Transport
• WIPO sector: Mechanical engineering

Abstract

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.