JPS63241414A - Star scanner - Google Patents

Abstract

PURPOSE:To improve the accuracy of attitude control by arranging plural linear light receiving parts across the scanning direction of a star image formed by an optical system, and making the linear light receiving parts wide in width on the side where scanning speed is fast and narrow on the side where the scanning speed is slow and making the width of detection pulses constant. CONSTITUTION:The slit A1 of a light shielding plate 12 arranged crossing the scanning direction of the star image formed by the optical system 11 is formed in such a trapezoid shape which the width is wide on the side of the moving speed of the star image is fast and narrow on the side where the speed is slow. Then the width of a pulse sent out of a photoelectron amplifier tube 13 as to a star having an optional elevation angle is made constant and the pulse is sent to a signal processing circuit 14, which measures the generation time of the pulse. Thus, the accuracy of the detection time of the start is made constant and the start is securely identified; and the attitude of a space flying object in spin motion is controlled with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a star ski system used for detecting the attitude of a spacecraft performing a spin motion, for example.

(Conventional technology) The star scanner mounted on a conventional spacecraft is
As shown in the figure, an optical system 11 that forms an image of a star, and a light shielding plate 12 in which V-shaped (or N-shaped) slits AI and A2 are formed are arranged on the focal plane of this optical system 11. , a photomultiplier tube 13 placed behind it, and a signal processing circuit 14 for extracting star detection data from the output signal of the photomultiplier tube 13.

That is, as shown in FIG. 4(a), the star image formed by the optical system 11 moves due to the spin of the flying object and crosses the slits Al and A2 of the light shielding plate 12, respectively.

At this time, the light passing through the slits At and A2 is detected by the photomultiplier tube 13, and is extracted as a pulse signal having an amplitude Is corresponding to the intensity of the light, as shown in FIG. 3(b).

On the other hand, since the slits At and A2 are formed in a V-shape (or N-shape), two (or three) pulses detected by the photomultiplier tube 13 are generated by one star image. Furthermore, the time interval T at which these pulses occur is such that the star image is a slit Al.

It is determined by the position across A2, that is, the angle of incidence (elevation angle) of the incident light. Therefore, stars can be identified by determining the pulse amplitude Is and the pulse interval T DI.

However, in the conventional star scanner as described above, the slits Al and A2 are rectangular as shown in FIG.
It varies depending on the position across. For this reason, the same figure (b),
As shown in (c), the width of the obtained pulses also differs. On the other hand, the signal processing circuit 14 measures the generation time of the above-mentioned pulse as detection data of the star image, but since the output signal of the photomultiplier tube 13 includes various noises in addition to the above-mentioned pulse, the time It is difficult to reduce the measurement accuracy to less than the pulse width.

(Problems to be Solved by the Invention) As described above, in conventional star scanners, the detection accuracy of star images and the measurement accuracy of detection time vary depending on the position where the star image crosses the slit. There were some problems, such as making it difficult to do so.

This invention was made to solve the above problem.
It is an object of the present invention to provide a star scanner in which the measurement accuracy of the detection time of a star image is constant regardless of the position where the star image passes through a slit, and thereby the star can be reliably identified.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, a star scanner according to the present invention includes an optical system for forming a star image, and a star image formed by this optical system. a plurality of linear light receiving sections disposed to intersect with the scanning direction of the linear light receiving sections; and a signal processing section that arbitrarily extracts each output of the linear light receiving sections to generate star image detection data; The width of the fast-scanning side of the star image on the shaped photodetector is widened, and the width of the slow-scanning side is narrowed.

(Function) In the star scanner with the above configuration, the width of the slit is wide at the position where the star image moves fast, and the slit width is small at the position where the speed is slow, so the width of the detection pulse is almost constant, and the star image is detected. The accuracy is also almost constant.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1(a) shows the shape of the slit At of the star scanner according to the present invention, and since the other parts are the same as those shown in FIG. 3, their description will be omitted here. In other words, this slit A1 has a trapezoidal shape, with a wider width on the faster side of the star image movement and a narrower width on the slower side.

Here, with reference to FIG. 2, the relationship between the line of sight direction of the star scanner and the elevation angle of the star with respect to the spin axis 2 of the satellite will be explained. That is, the moving speed v5 of the star image imaged on the light shielding plate 12 by the optical system 11 makes the spin rate of the satellite ω[rad/see]...(1) However, f is the focal point of the optical system 11. Distance [a+III], θ
0 is the elevation angle [deg] of the star, and θ is the angle [deg] between the spin axis 2 and the line of sight direction of the star scanner.

Therefore, if the desired pulse width is ΔT[5ecl, then Δ
The width of the slit is W so that T is constant... (2) If the slit A1 is formed on the light shielding plate 12 to have such a width W as shown in FIG. , the same figure (
As shown in b) and (c), a pulse with a constant width is obtained from the photomultiplier tube 13 for a star at an arbitrary elevation angle.

Therefore, the star scanner with the above configuration can maintain the accuracy of star detection time constant regardless of the elevation angle of the star or the moving speed of the star image, so it is possible to reliably identify stars. Can be done.

Therefore, it can be used for highly accurate attitude control of a spacecraft performing a spin motion.

In the above embodiment, the width of the slit is expressed by a curve according to equation (2), but if the pulse width does not need to be completely constant, this curve may be approximated to a straight line. In this case, the shape of the slit becomes tapered. Furthermore, although the purpose of the above embodiment was to make the pulse width constant,
By changing the width of the slit, it may be possible to obtain an arbitrary pulse width for the position. Furthermore, it goes without saying that the light shielding plate 12 and the photomultiplier tube 13 may be constituted by a photodiode, a CCD, or the like having a slit-shaped light receiving section.

[Effects of the Invention] As described above, according to the present invention, the measurement accuracy of the detection time of a star image is constant regardless of the position at which the star image passes through the slit, and thereby stars can be reliably identified. We can provide a star scanner that can

[Brief explanation of drawings]

1 and 2 are for explaining an embodiment of the star scanner according to the present invention, respectively, and FIG. 1(a)
is a diagram showing the shape of the slit in the same example, FIG. 1(b),
(c) is a diagram showing the pulses obtained when using the slits shown in (a), FIG. 2 is a diagram for explaining the operating principle of the same embodiment, and FIG. 3 is the configuration of a conventional star scanner. FIG. 4 is a diagram for explaining the operation of a conventional star scanner, and FIG. 5 is a diagram for explaining the pulse width obtained by the slit of a conventional star scanner. 11. ...Optical system, 12... Light shielding plate, 13... Photomultiplier tube, 14... Signal processing circuit, At, A2...
slit. Applicant's agent Patent attorney Takehiko Suzue Figure 2 Figure 3

Claims (1)

[Claims] An optical system that forms a star image, a plurality of linear light receiving sections arranged to intersect the scanning direction of the star image formed by this optical system, and each output of the linear light receiving sections can be arbitrarily set. and a signal processing unit that generates star image detection data by extracting data from the linear light receiving unit, and widening the width of the linear light receiving unit on the side where the star image scanning speed is high;
A star scanner characterized by a narrow width on the slow side.