JPS604500A - Solar-lunar interference removal system of earth sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for eliminating solar and lunar interference in an earth sensor used for detecting the attitude of an artificial satellite.

When the sun or the moon comes within its field of view, the Earth's center cannot generate normal output due to interference.

Hereinafter, using a scanning type earth sensor as an example, the behavior of a conventional earth sensor during solar interference and the solar interference removal method according to the present invention will be described.

Note that although a scanning type earth sensor will be described as an example here, the present invention can be similarly applied to other types of earth sensors such as a static type. Also, since lunar interference can be treated in the same way as solar interference, we will use solar interference as a representative example. Figure 1 is a diagram to explain the behavior of the earth sensor during solar interference. is a diagram looking toward the center of the earth from the center of gravity of satellite 9 when satellite 1 is in its standard attitude.

In the figure, (1) shows the earth, (2) shows the scan 1 degree of the earth sensor, and (3) shows the scan 2 of 4 sentences on the earth. This earth sensor includes 1a (51 and 1b (6)), which is the intersection of scan 1 (2) and earth edge (4), 2af'7, which is the intersection of scan 2 (3) and earth edge (4), and 2b(
From position 8).

The attitude of the satellite around the roll axis (9) and pitch axis tilt is detected. Here, the roll axis (9) is parallel to the scanning direction, and the pitch axis αQ is perpendicular to the scanning direction.

If the sun 0]) comes into the field of view of such an earth sensor and the sun aυ is on the trajectory of scan 1 (2) as shown in Figure 1, the output signal from scan 1 (2) will no longer be available. It becomes unusable. In such a case, use only the output signal of scan 2 (3).

It now detects two axes: roll and pitch.

In this case, the accuracy becomes worse than when roll and pitch are detected based on output signals from both scans.

Also, if you use both scans at the same time,
Since the zero-point error of the attitude signal differs when only one scan is used, a step-like change in the zero-point error occurs when switching from a 2-scan usage state to a 1-scan usage state due to solar interference, or vice versa. This is a factor that increases the attitude change rate error.

This invention aims to eliminate the above-mentioned drawbacks.

One embodiment of this invention will be described below with reference to FIG. 2. In the figure, 02 is.

The earth sensor, α, is the earth sensor rotating device, and a4 is the satellite body. The earth sensor rotation device Ql is mounted on the satellite main body A4)
The earth sensor H is attached to the rotating part α4. Therefore, when the earth sensor rotation device α is driven, the earth sensor a2 is rotated relative to the satellite main body α4.

rotate relative to each other. In this embodiment, the rotation axis of the earth sensor rotation device 03 is parallel to the yaw axis ae, which is the earth center orientation axis. Next, according to Figure 3.

A solar interference removal method using the apparatus shown in FIG. 2 will be explained. In FIG. 3, (1) to aU: are the same as those explained in FIG. However, this diagram shows the first
In comparison with the figure, the figure shows a case where the earth sensor α2 is rotated by a certain angle one time counterclockwise. In the figure, αη and αS indicated by broken lines are the trajectories of scan 1 to scanning scan 2 (3) when the rotation angle of the rotating part 0!9 of the earth sensor rotation device σmoat is 0.

As can be seen from the figure, when the rotation angle of the earth sensor rotation device θ is 00, the sun αυ interferes with the scan 107). However, due to the earth sensor rotation device a3.

As shown in Figure 3, if scan 1 (21) and scan 2 (3) of the earth sensor are rotated, the sun aη will no longer interfere with either scan, so both scans can be used to detect attitude errors. become.

It is assumed that the earth sensor rotation device α is driven by a command from the ground or an onboard command generated by an onboard computer.

In addition, the earth sensor rotation device (I3) is rotated.The conversion of the earth sensor output into roll and pitch attitude angle signals is performed by the sensor signal processing unit, which performs appropriate coordinate conversion calculations based on the rotation angle of the earth sensor rotation device α. This is done by running

As described above, according to the present invention, by rotating the earth sensor relative to the satellite body, it is possible to avoid solar and lunar interference, prevent deterioration of accuracy of the earth sensor due to solar-moon interference, and at the same time prevent This has the advantage of being able to prevent the occurrence of attitude change rates at the time of switching due to signal switching inside the earth sensor.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the behavior of the earth sensor during solar interference, FIG. 2 is a diagram for explaining an embodiment of the present invention, and FIG. 3 is a diagram for explaining the solar interference removal method according to the present invention. . In the figure, (1) is the Earth, and (2) is Earth sensor scan 1.
゜ (3) is Earth sensor scan 2, (4) is the edge of the earth. (5) is the intersection point 1 a of scan 1 and earth edge, (
61 is the intersection of scan 1 and earth edge 11), (7
1 is the intersection point 2a of scan 2 and earth edge, (8)
is the intersection point 2 b of scan 2 and the earth edge, (91 is the roll axis of the satellite, 雛 is the pitch axis of the satellite, aυ is the sun,
a'a is the earth sensor, 03 is the earth sensor rotation device, (I
4 is the satellite body, a is the rotating part of the earth sensor rotation device, O
e is the yaw axis of the satellite, which is the earth pointing axis, and αη is the scan 1 when the rotation angle of the earth sensor rotation device is 00, (11
6 is scan 2 when the rotation angle of the earth sensor rotation device is 00. Note that the same or corresponding parts in FIG. 9 are designated by the same reference numerals. Agent Masuo Oiwa (7) Figure 1 Figure 12

Claims (1)

[Claims] An earth sensor detects attitude errors around two axes: a pitch axis perpendicular to the orbital plane, and a roll axis perpendicular to both the pitch axis and the yaw axis, which is the earth orientation axis. It consists of an earth sensor rotation device for relative rotation, and when the relative position is such that the sun or moon enters the field of view of the earth sensor, a command from the ground or an onboard computer etc. The generated onboard command drives the earth sensor rotation device and rotates the earth sensor around the rotation axis of the earth sensor rotation device, so that the sun or moon does not enter the field of view of the earth rescue sensor. A solar-January interference removal method for an earth sensor characterized by the following.