DEVICE FOR CONTROLLING THE ATTITUDE OF A SPACE SATELLITE UTILIZING GEOMAGNETIC FIELD

• US 3,681,583 A
• Filed: 09/22/1969
• Issued: 08/01/1972
• Est. Priority Date: 09/27/1968
• Status: Expired due to Term

• Current Assignee: Masamichi Shigehara, Moritada Kubo, Shozo Yasui
• Original Assignee: Masamichi Shigehara, Moritada Kubo, Shozo Yasui
• Inventors: Kubo, Moritada, Shigehara, Masamichi, Yasui, Shozo
• Primary Examiner(s): Morrison, Malcolm A.
• Assistant Examiner(s): Wise, Edward J.
• Application Number:
  US04/859,823
• Time in Patent Office: 1,044 Days
• Field of Search: 235/150.2 244/1SS
• US Class Current: 701/13
• CPC Class Codes: B64G 1/244 Spacecraft control systems
• CPC Class Codes: B64G 1/32 using earth's magnetic field
• CPC Class Codes: B64G 1/36 using sensors, e.g. sun-sensors, horizon sensors
• CPC Class Codes: B64G 1/361 using star sensors
• CPC Class Codes: B64G 1/363 using sun sensors
• CPC Class Codes: B64G 1/365 using horizon or Earth sensors
• CPC Class Codes: B64G 1/366 using magnetometers
• CPC Class Codes: B64G 1/369 using gyroscopes as attitude sensors

Abstract

The present invention enables the attitude of a spinning satellite to be effectively controlled by introducing current through an attitude control coil wound around the spin axis so as to allow the spin axis to be oriented to the desired direction on the basis of the interaction between coil current and the geomagnetic field. The direction and magnitude of current to be introduced into said attitude control coil is determined by composing a switching function S E . (kB X B) using a vector operator from the vector B of an earth'"'"''"'"'s magnetic field measured by a magnetometer, the vector KB of the direction of the spin axis of the satellite supplied by an attitude sensor and an error vector E corresponding to the difference between the spin axis and desired direction as supplied by an error detector and then defining the notation and magnitude of the resultant function S.

Claims

1. A device for controlling the attitude of a space satellite comprising:

means for computing a switching function S E . (kB X B) from the vector B of the geomagnetic field at the point of the satellite in the orbit, the vector kB of the satellite'"'"''"'"'s attitude, and an error vector E corresponding to the difference between the vectors of the satellite'"'"''"'"'s angular moment in the direction of said attitude vector and in a desired direction, a coil fixed to the satellite for controlling its attitude, a source for supplying current to said attitude control coil, and switching means responsive to said operation device for controlling current from said source according to the value of the switching function S is which is computed by said operation device.

2. A device for controlling the attitude of a space satellite provided on the satellite utilizing the geomagnetic field which comprises:

a coil fixed to the satellite for controlling its attitude, means for detecting the vector B of the geomagnetic field at the point of the satellite in the orbit, means for Detecting the vector kB of the satellite'"'"''"'"'s attitude, means for determining an error vector E corresponding to the difference between the vectors of the satellite'"'"''"'"'s angular moment in the direction of the attitude vector and a desired direction, means for generating a switching function S E . (kB X B) from the values of these vectors, and switching means responsive to said generating means for controlling current to be introduced into the attitude control coil in accordance with said switching function.

3. A process for controlling the attitude of a spinning satellite having an attitude control coil wound around the spin axis thereof comprising the steps of:

obtaining the vector B of the geomagnetic field at the position of the satellite in the orbit, obtaining the vector KB of the satellite'"'"''"'"'s attitude, obtaining an error vector E corresponding to the difference between the vectors of the satellite'"'"''"'"'s angular moment in the direction of the attitude vector and a desired direction, obtaining a switching function S by combining said vectors B, KB and E in accordance with a predetermined relationship S E . (kB X B), and controlling the magnitude and direction current to be introduced into said control coil in accordance with said switching function S, to orient the spin axis of the satellite to the desired direction on the basis of the interaction between coil current and the geomagnetic field.

4. A process for controlling the attitude of a spinning satellite according to claim 3 further comprising the steps of:

obtaining first information on the location and attitude of the satellite when it communicates with a ground station for the nth time, obtaining second information predicting the location and attitude of the satellite when it communicates with the ground station for the (n+1)th time by using said first information, obtaining third information predicting simulating vectors B, KB and E in accordance with said second information, and controlling the attitude of said satellite during the (n+1)th time period in accordance with said third information.