The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 22, 1998
Filed:
Aug. 25, 1995
Carl Henry Hubert, Cranbury, NJ (US);
Martin Marietta Corp., East Windsor, NJ (US);
Abstract
A spacecraft includes a body defining a center of mass, and an attitude control system, for generating attitude error signals representing deviation of the body from a desired attitude. A plurality of thrusters mounted on the body have nominally parallel thrust components, in a particular direction. The thrusters are arranged in pairs, which produce opposed torques. A velocity change controller is coupled to the thrusters, for generating pulsatory firing command signals for the thrusters for a particular total time duration, for achieving a desired velocity change in the desired direction. A thruster control system is coupled to the attitude control system and to the thrusters, for causing the thrusters of the pair to be fired in a differential manner, and with the relative pulse width of the first and second portions of the pulse cycle being controlled in response to the attitude error signals to vary the torque about the center of mass for attitude control, while maintaining constant the total firing time of the thrusters. Since the total firing time of the thrusters of the pair is constant, the .DELTA.V is unaffected by attitude control.