Attitude angle sensor correcting apparatus for an artificial satellite

• US 6,336,062 B1
• Filed: 12/07/2000
• Issued: 01/01/2002
• Est. Priority Date: 12/10/1999
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Yamashita, Toshiaki
• Primary Examiner(s): Camby, Richard M.
• Application Number:
  US09/731,028
• Time in Patent Office: 390 Days
• Field of Search: 701/13, 701/14, 701/4, 701/266, 244/158, 244/164, 244/171, 702/5, 348/144, 348/117
• US Class Current: 701/13
• CPC Class Codes: B64G 1/1021 Earth observation satellites
• CPC Class Codes: B64G 1/245 Attitude control algorithms for spacecraft attitude control
• CPC Class Codes: B64G 1/365 using horizon or Earth sensors
• CPC Class Codes: B64G 1/66 Arrangements or adaptations of apparatus or instruments, not otherwise provided for

Abstract

An attitude angle sensor correcting apparatus for an artificial satellite of the present invention includes a satellite attitude estimator. The satellite attitude estimator reads geographical image data out of an image data memory, produces a GCP (Ground Control Point) position included in the image data by stereo image measurement, and then estimates the instantaneous satellite attitude angle on the basis of a relation between the measured GCP position and a true GCP position. An attitude angle sensor data corrector corrects measured attitude angle data with estimated satellite attitude data output from the satellite attitude estimator and corresponding in time to the measured attitude angle data. The attitude angle sensor data corrector outputs an estimated satellite attitude signal.

Claims

1. An attitude angle correcting apparatus for an artificial satellite, comprising:

an attitude angle sensor data memory for storing a signal output from sensing means responsive to an attitude angle of the artificial satellite;

an image data memory for storing geographical image data representative a same geographical area, where a (Ground Control Point) GCP is located, shot at a plurality of positions;

a satellite attitude estimator for generating estimated attitude data of the artificial satellite on the basis of a difference between a true GCP value representative of a true position of the GCP and a measured GCP value produced by image measurement using said geographical image data stored in said image data memory; and

an attitude angle sensor data corrector for estimating an attitude angle of the artificial satellite by using said estimated attitude data, and then correcting measured attitude angle data, which is read out of said attitude angle sensor data memory, with said attitude angle estimated to thereby generate an estimated attitude angle signal.

2. An apparatus as claimed in claim 1, wherein a plurality of GCPs (Ground Control Points) are located on geometry represented by said geometrical image data.

3. An apparatus as claimed in claim 2, wherein said satellite attitude estimator estimates an attitude angle of the artificial satellite by describing, for each of the GCPs whose positions can be measured on the basis of said geographical image data and whose true values are known, a relation between the measured GCP value and the true GCP value by use of a Moor-Penrose quasi-inverse matrix.

4. An apparatus as claimed in claim 2, wherein when said satellite attitude estimator relates the measured value and the true value of each of the GCPs, positions of which can be measured on the basis of the geographical image data and true values of which are known, by using a constant coefficient matrix:

$E=\left[\begin{array}{ccc}{e}_1& e_2& e_3\\ e_4& e_5& e_6\\ e_7& e_8& 1\end{array}\right]$

said satellite attitude estimator estimates an attitude angle error of the artificial satellite by using a result of singular value resolution of said constant coefficient matrix.

5. An apparatus as claimed in claim 1, wherein said satellite attitude estimator estimates an attitude angle of the artificial satellite by describing, for each of the GCPs whose positions can be measured on the basis of said geographical image data and whose true values are known, a relation between the measured GCP value and the true GCP value by use of a Moor-Penrose quasi-inverse matrix.

6. An apparatus as claimed in claim 1, An apparatus as claimed in claim 2, wherein when said satellite attitude estimator relates the measured value and the true value of each of the GCPs, positions of which can be measured on the basis of the geographical image data and true values of which are known, by using a constant coefficient matrix:

$E=\left[\begin{array}{ccc}{e}_1& e_2& e_3\\ e_4& e_5& e_6\\ e_7& e_8& 1\end{array}\right]$

said satellite attitude estimator estimates an attitude angle error of the artificial satellite by using a result of singular value resolution of said constant coefficient matrix.