JPS6238879Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an earth sensor that is mounted on, for example, a three-axis attitude control satellite and detects roll and pitch attitude errors of the satellite.

As is well known, earth sensors are classified into scanning type and static type. Figure 1a
indicates the scanning type, in which the earth sensor is operated dynamically and its field of view 11,
The attitude error information of the satellite is obtained based on the time taken by the satellite 12 to cross the earth 13. That is, the sensor outputs signals shown by solid lines or dotted lines for the fields of view 11 and 12 as shown in FIG.
The mechanism for dynamically scanning the earth in this way is complex, and it has been difficult to extend its operational life.

On the other hand, FIG. 2 shows a static type. In this earth sensor, apertures 21, 22, 23, 2 are formed by lenses (not shown).
An image of the earth (indicated by a dotted line) is formed at 4, and this earth image is detected by thermal infrared detectors 25 to 28 provided in the apertures 21 to 24, respectively.
The attitude error information of the satellite is obtained from the difference between the detection output signals of the detectors 25 to 28 (corresponding to the shaded area in the figure). That is, the detectors 25, 27
Roll information is obtained from the difference between the output signals of the detectors 26 and 28, and pitch information is obtained from the output signals of the detectors 26 and 28. However, in this earth sensor, the detectors 25 to 28 and the aperture 2
When the width W of 1 and 24 is increased, the error of the detection signal becomes larger. Therefore, this width W is made as narrow as possible, but if the width W is narrow, if the satellite altitude changes, the earth image may become larger than the diameter of the circle formed by the apertures 21 to 24 and the detectors 25 to 28. , may become smaller, making it impossible to obtain an attitude error signal. Therefore, this earth sensor cannot be applied to a satellite whose orbital altitude changes significantly.

This idea was made based on the above circumstances, and its purpose is to arrange first and second linear detection element arrays consisting of a plurality of elements on a base on which an image of the earth is formed, and to By obtaining satellite attitude error information from the width of the signal corresponding to the earth image obtained by the array or the positional relationship, it is possible to accurately detect the attitude error even when the satellite altitude changes. Yes, with a long operating life and an earth presence signal (earth detection signal that indicates the presence of the earth within the field of view of the earth sensor)
The aim is to provide an earth sensor that can obtain the following.

An embodiment of this invention will be described below with reference to the drawings.

In FIGS. 3 and 4, 31 is a base body.
A lens 32 is provided in front of this base body 31,
An image of the earth is formed on the base body 31 by this lens 32 . On the front surface of the base body 31, detecting element rows 33 and 34 are provided as first and second linear detecting element rows for thermal infrared rays, spaced apart by a predetermined distance in the direction of the pitch axis of the satellite and parallel to the roll axis. , the earth image is detected by the detection element arrays 33 and 34. This detection output signal is sent to the signal processing circuit 35.
A signal corresponding to the attitude error of the satellite is generated. That is, the attitude error in the pitch axis direction is determined by the signal width obtained from each detection element array 33, 34, that is, the difference in the number of elements outputting signals, and the attitude error in the roll axis direction is determined by the difference in the signal width obtained from each detection element array 33, 34, or the number of elements outputting signals. 34
It is determined from the positional relationship of the signals obtained from at least one of the following.

FIGS. 5 and 6 explain the operation of the earth sensor. When the attitude error of the satellite is zero, the earth image 41 is formed at the center of the base body 31 as shown in FIG. Therefore, each detection element row 3
A signal consisting of 0 and 1 output from 3 and 34
The widths of the signals (indicated by solid lines and broken lines, respectively) are equal, and their positional relationship is symmetrical with respect to the center of the detection element arrays 33 and 34. On the other hand, if the satellite has an attitude error, the earth image 41 moves within the base 1 and is formed as shown in FIG. Therefore, each detection element row 3
A signal consisting of 0 and 1 output from 3 and 34
The widths of the signals made up of the detection element arrays 33 and 34 are different, and their positional relationship is asymmetrical with respect to the center of the detection element arrays 33 and 34. This signal causes the signal processing circuit 35 to generate an attitude error signal, and this signal controls the attitude of the satellite so that the output signals of the detection element arrays 33 and 34 are equal as shown in FIG.

It is also possible to obtain the signal width and position as a function of time as shown in FIGS. 4 and 5 by scanning each element in the detection element rows 33 and 34 in turn. 33, 34
It is also possible to process the output signal as a high/low bit pattern.

According to the above configuration, the detection element rows 33, 34 are provided in parallel to the base 31, and the detection element rows 33, 34 are provided in parallel to the base body 31.
4, the attitude error of the satellite is determined by detecting the earth image. Therefore, since the earth image detection range is wider than that of conventional static type earth sensors, it is possible to perform sufficient attitude error detection even when the altitude of the satellite changes.

Additionally, since the sensor is not mechanically driven, it can have a longer operating life than conventional scanning-type earth sensors.

Furthermore, FIG. 7 shows a circuit for generating an earth presence signal (earth detection signal). That is, the output signals of each detection element array 33 and 34 are sent to a comparator 62 via an OR circuit 61 provided in the signal processing circuit 35.
is supplied to A reference threshold signal is set in this comparator 62, and this threshold signal and the output signal of the OR circuit 61 are compared. Therefore, a part of the earth image 41 is detected by, for example, the detection element array 33,
34, it is possible to obtain an earth presence signal. Therefore, it is possible to widen the detection range of the sensor.

Note that this invention is not limited to the above-mentioned embodiment, and it is also possible to apply this invention to other flying objects other than satellites, for example. It goes without saying that various other modifications can be made without departing from the gist of the invention.

As detailed above, this invention enables an earth sensor that can accurately detect attitude errors even when the satellite's altitude changes, has a long operating life, and can also obtain earth presence signals. can be provided.

[Brief explanation of the drawing]

Figures 1a, b and 2 are diagrams shown to explain different conventional earth sensors, Figure 3 is a diagram showing the configuration of a detection element array applied to this invention, and Figure 4 is a diagram showing this invention. Configuration diagrams showing an example of an earth sensor related to
are diagrams shown to explain the operation of the earth sensor according to this invention, and FIG. 7 is a diagram showing a configuration for obtaining an earth presence signal. 31...Substrate, 33, 34...Detection element row, 3
5...Signal processing circuit.

Claims (1)

[Scope of utility model registration request] A base body on which an earth image is formed, and first and second elements each comprising a plurality of elements arranged parallel to each other and spaced apart from each other by a predetermined distance on this base body, each of which outputs a signal when the earth image is formed. a linear detection element array;
Of this first linear detection element array, the number of elements in the first linear detection element array that outputs a signal by imaging the earth image, and the number of elements in the second linear detection element array, the earth image The second output signal is output by imaging the
detecting an attitude error in the first direction from the difference in the number of elements in the linear detection element arrays, and outputting a signal by imaging an earth image in at least one of the first and second linear detection element arrays; and a signal processing circuit that detects an attitude error in a second direction orthogonal to the first direction from a deviation of the center position of the linear detection element array from the center of the linear detection element row. .