JPS60215499A - 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 [Technical Field of the Invention] The present invention relates to an earth sensor that is mounted on a flying object such as an artificial satellite and detects the attitude of the flying object with respect to the earth.

[Prior art]

A conventional sensor of this type is shown in FIG. In Figure 1, (l) is the earth, (2a) and (
2b) is the field of view of a pair of optical systems that detect the infrared radiant energy of the earth's edge, and (3) is the earth sensor.

(4) is an artificial satellite. If the satellite (4) has no attitude error, if the fields of view (2a) and (2b) are arranged so that the incident energy from fields (2a) and (2b) is equal, one satellite (4) will have an attitude error θ. When this occurs, the attitude error θ can be measured by calculating the difference in incident energy from the fields of view (2a) and (2b). However, this type of sensor has a drawback that if the sun, moon, etc. enter the field of view (2a) or (2b), the earth sensor (3) cannot detect an attitude error.

Conventional earth sensors that have improved this drawback include the following. FIG. 2 is a configuration diagram of a conventional earth sensor, and FIG. 3 is a principle diagram showing the relationship between the earth 11) and the field of view. In Figure 2, (5a) (5b), (5c
), (5d) are infrared detectors consisting of an infrared detection element and a processing circuit, (6a) and (6b) are photodetectors that detect original energy from the sun or the moon.

(7a) and (7b) are 1 light detection i (Sa) and (6
(8a) and (8b) are infrared detectors (5a) using the signals of the interference detection circuits (7a) and (7b).

A switching circuit (5b), (5c), and (5d) selects a signal that is not interfered with, and (9) is a processing circuit that processes the signal from the infrared detector and generates an attitude detection signal.

In FIG. 3, (2C) and (2d) are the field of view of the infrared detector, and (10a) and (10b) are the field of view of the photodetector. In the figure, in the absence of interference from the sun or the moon, infrared energy in fields of view (2a) and (2b) is converted into electrical signals by infrared detectors (5a) and (5b), respectively, and by switching circuit (8a) and (8b), the signal is input to the processing circuit (9), converted into an attitude angle signal, and output. Here, if the sun or moon is incident near or within the field of view (2a), the infrared detector (5a)
The attitude angle can be detected because not only the earth's infrared energy but also the radiant energy from the sun or January is added. Therefore, the visual field (I Da ) is outside the visual field (2a).
The interference of the sun or the moon is detected by the photodetector (6a) with a The attitude angle is detected using the output of an infrared detector (5c) having a field of view (2c) at a position where it is not subject to interference.

However, conventional sensors of this type require a one-element detector to detect solar or lunar interference, which has the disadvantage that the entire device becomes large and complicated. Also, rather than the sun or moon gradually approaching from outside the field of view (2a) and the field of view of the photodetector (10a).

When it appears in the field of view (2a) from the other side of the earth il+.

Since the switching from the infrared detector (5a) to the infrared detector (5c) is performed after interference occurs, there is a drawback that the attitude angle is not detected during the switching period.

[Summary of the invention]

The present invention has been made in order to improve these drawbacks, and provides an earth sensor with a simple configuration that is not affected by solar or lunar interference.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 4 is a block diagram of an embodiment of the present invention. In the figure, 111 is a timer circuit that generates an interference pattern such as an orbital period or an annual period, and 0 or 0 is a logic circuit that generates an infrared detector selection signal from the interference pattern of the timer circuit a0.

FIG. 5 is a field of view (2a) showing an embodiment of the present invention.

It is a principle diagram showing the relationship between (2b), (2c), (2d) and the earth +11. In the figure, N indicates the north pole and S indicates the south pole.

The satellite (4) is on a geostationary orbit and has a field of view (2a), (2
c) is assumed to be located near the equator, and the same reference numerals in Figure 1 are used as already explained. FIG. 6 is a timing chart showing the output turn of the timer circuit υ. In the figure, 03 is the interference pattern for the visual field (2a) and (2b) in the annual cycle, O
a is the daily solar interference pattern in the field of view (2a),
0!9 is the daily solar interference pattern on the field of view (2b). Considering the field of view arrangement shown in Figure 5,
Fields of view (2a) and (2b) are subject to solar interference near the vernal and autumnal equinoxes. Therefore, taking into account the size of the fields of view (2a) and (2b), etc., the interference pattern θ moat is set so that the switching signal is generated several days before and after the vernal and autumnal equinoxes. Also, if the artificial satellite (4) is a geostationary satellite, the field of view (2a) will receive interference from the sun near sunset. The interference pattern 04 is set so as to generate a switching signal for several minutes before and after 1, taking into consideration the frequency. Similarly, for the field of view (2b), the interference pattern a! generates a switching signal for several hours before and after sunrise around the vernal and autumnal equinoxes. Set 9. Therefore, the logic circuit Q2 creates an interference pattern 0 and (
If the switching circuit (8a) is operated according to the product of 14) and the signal from the infrared detector (5a) to (5c,) is input to the processing circuit (9), when the field of view (2a) receives 7>E interference, The attitude angle is detected by the field of view (2c) that is not subject to interference.

Similarly, the interference pattern 0 country and a are determined by the logic circuit az.
By operating the switching circuit (8b) based on the field product and inputting the signal from the infrared detector (5b) to the processing circuit (9), the field of view (2b) will not be interfered with. The attitude angle is detected using the field of view (2d). Also, the detector (5C) and (5dy') field of view (
2C) and (2d) are located at some distance from the detection axis, so the detection accuracy and sensitivity are somewhat lowered, but the earth sensor according to the present invention detects them near the time when interference occurs. Because switching only occurs.

This time is very short.

In addition, for 4+, t, and brightness of 1 or more, the case where the field of view is placed near the equator in the Shizuka orbit has been described.

The present invention is not limited to this, and can be applied to any visual field arrangement and trajectory by setting an interference pattern according to the visual field arrangement and trajectory.

〔Effect of the invention〕

As described above, the earth sensor according to the present invention has a simple configuration and can detect the attitude angle without being affected by interference from the sun or the moon.

[Brief explanation of drawings]

Figure 1 is a conceptual diagram of the earth sensor, Figure 2 is the conventional earth sensor. Principle diagram shown, 4th
FIG. 5 is a configuration diagram showing an embodiment of the present invention, FIG. 5 is a principle diagram showing the relationship between the earth and the field of view in an embodiment of the invention, and FIG. 6 is a timing chart showing an interference pattern. In the figure, (1) is the earth, (2a), (2b), (
2c). (2d) is the field of view of the infrared detector, (3) is the earth sensor,
(4) is artificial surgery m, (5a), (5b), (5C)
, (5d) is an infrared detector, (Sa), (6b) is a photodetector-(7a)s (7b) is an interference detection circuit,
(8a) and (8b) are switching circuits, and 19) is a processing circuit. (10a), (10b) are the field of view of the photodetector, 01) is the timer circuit, (l is the logic circuit, (11, (14),
(Ii is the interference pattern. The same symbols in each figure indicate the corresponding parts. Agent Masuo Oiwa Figure 1! Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] An earth sensor mounted on a flying object such as an artificial satellite and detecting the attitude of the flying object with respect to the earth includes an optical system that collects infrared radiation energy from the edge of the earth, and an optical system that collects the infrared rays emitted by this optical system. A detector consisting of a plurality of detection elements that detects energy, a switching circuit that selects the detection element to be used from among the detection elements, and an element selection signal that predicts solar and lunar interference and inputs an element selection signal to this switching circuit. An earth sensor comprising: a timing circuit; and a processing circuit that operates a switching circuit based on the output of the timing circuit, processes the output signal of a detection element selected by the switching circuit, and generates an attitude detection signal.