A CMG FINE ATTITUDE CONTROL SYSTEM

• US 3,741,500 A
• Filed: 04/21/1971
• Issued: 06/26/1973
• Est. Priority Date: 04/21/1971
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Sam P. Liden
• Inventors: Liden, Sam P.
• Primary Examiner(s): Reger, Duane A.
• Assistant Examiner(s): Kunin, Stephen G.
• Application Number:
  US05/136,088
• Time in Patent Office: 797 Days
• Field of Search: 33/226Z 74/5.34,5.6 244/1SS,1SA,3.2,3.21,3.23,79 318/489
• US Class Current: 244/165
• CPC Class Codes: B64G 1/286 using control momentum gyroscopes (CMGs)
• CPC Class Codes: Y10T 74/1221 Multiple gyroscopes

Abstract

The invention teaches an attitude control system for providing control torques on a vehicle, such as a space satellite, using four single gimbal control moment gyroscopes. The relatively simple constant-gain steering law permits three axis control after failure of any one of the four control moment gyroscopes.

Claims

1. An attitude control system for controlling the attitude of a vehicle comprising a first pair of control moment gyroscopes, a second pair of control moment gyroscopes, wherein the gimbal axes of said first pair of control moment gyroscopes are essentially parallel, the gimbal axes of said second pair of control moment gyroscopes are essentially parallel, the net angular momentum vector of said first pair has a predetermined value at an initial condition that is equal and opposite to a corresponding predetermined value of the net angular momentum of said second pair, means for controlling the amplitude and direction of the net angular momentum of each of said pair of control moment gyroscopes from said initial condition, whereby the net angular momentum vector of the control system may be modified, and means for controlling the angular rate of each of the gimbals in said pairs of control moment gyroscope in accordance with a steering law of the form:

Alpha 1c 1 1 -1 Kx Hxc Alpha 2c 1/h 1 -1 -1 Ky Hyc Alpha 3c 1 -1 1 Kz Hzc Alpha 4c 1 1 1 wherein Alpha c is the commanded gimbal rate of the identified gyro, h is the angular momentum of each gyro, all equal, H is the commanded angular rate of the vehicle about the identified axis, Kx, Ky, Kz are gain constants having values depending upon the angular orientations of the gyro gimbal axes relative to the identified vehicle axes.

2. An attitude control system for controlling the attitude of a vehicle comprising a first pair of control moment gyroscopes, a second pair of control moment gyroscopes, wherein the net angular momentum vector of said first pair has a predetermined value at an initial condition that is equal and opposite to a corresponding predetermined value of the net angular momentum vector of said second pair, means for controlling the amplitude and direction of the net angular momentum of each of said pair of control moment gyrocopes from said initial condition, whereby the net angular momentum vector of the control system may be modified, and means responsive to failure of any one of the gyroscopes for modifying said initial condition of the remaining gyro of the failed pair and that of the remaining pair of gyros.

3. The control system as claimed in claim 2 including means for controlling the angular rate of each of the operative gyros in said pairs of control moment gyroscopes in accordance with a steering law of the form Alpha 1c 1 1 -1 Kx'"'"''"'"'Hxc Alpha 2c 1 -1 -1 Ky'"'"''"'"'Hyc 1/h Alpha 3c 1 -1 1 Kz'"'"''"'"'Hxc Alpha 4c 1 1 1 wherein Alpha c is the commanded gimbal rate of the identified gyro, h is the angular momentum of each gyro, all equal, H is the commanded angular rate of the vehicle about the identified axis, and Kx'"'"''"'"', Ky'"'"''"'"', Kz'"'"''"'"' are gain constants having values depending upon the angular orientations of the gyro gimbal axes relative to the identified vehicle axes and modified for a failed gyro, and wherein the row of the 4 X 3 matrix corresponding to the failed gyro is zero.