JP2001180600A - Satellite position observation device - Google Patents

Abstract

(57) [Summary] [Problem] Implementation of approach control to a satellite, orbit control around a satellite without mounting a special reflector on the target satellite and without limiting the approach direction to the target satellite It is an object of the present invention to obtain a satellite observation device capable of obtaining a measured value of a relative position and a relative velocity between a target satellite and an approaching spacecraft necessary for the satellite. SOLUTION: A single image sensor with a constant lens magnification mounted on an approaching spacecraft side observes a satellite as an approaching target, periodically acquires a target satellite image, and acquires an observation image by the image sensor. Thereafter, a binarization process is performed to extract a target satellite portion having a higher luminance than the surroundings, and thereafter, the area of the binarized image corresponding to the target satellite portion is calculated, and the actual satellite size and lens The distance of the target satellite to the image sensor and the distance change rate are calculated from the area of the satellite binary image on the observation image based on the magnification.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a general satellite orbiting an orbit for, for example, transporting cargo such as onboard equipment and fuel, or inspecting and repairing a fault location, which is mounted on a spacecraft, and Satellite position observing device for measuring the distance between target satellites, the distance change rate, the relative position, the relative speed, and the absolute position and absolute speed of the target satellite required when performing a rendezvous to the vicinity of the selected satellite Things.

[0002]

2. Description of the Related Art First, a conventional satellite position observation apparatus of this type will be described. FIG. 4 is a diagram showing a conventional satellite position observing device. In the figure, reference numeral 1 denotes a satellite position observing device, and the satellite position observing device 1 includes a target reflector 2 mounted on a target satellite 9 and a spacecraft 14 approaching. It comprises an observation device head unit 3 and an observation device electronic circuit unit 4 to be equipped. Here, the target reflector 2 is a corner cube reflector having a retroreflection characteristic of reflecting light in the same direction as the incident direction of light, and is a target satellite 9 to be observed.
Must be installed in advance. Further, the observation device head unit 3 includes a laser beam irradiation device 5 for irradiating the target reflector 2, an image sensor 6 for obtaining a prospective angle and a distance from the laser reflected light from the target reflector 2, and a phase measurement device 7. It is composed of

A laser beam 8 emitted from a laser beam irradiation device 5 is reflected by a target reflector 2, and the reflected light is observed by an image sensor 6 and a phase measurement device 7. The distance is measured by measuring the difference between the phase at the time of transmitting the modulated signal irradiated from the laser beam irradiation device 5 and the phase at the time of receiving the reflected light by the target reflector 2 by the phase measuring device 7. Measurement of the expected angle is performed by the laser beam irradiation device 5
The reflected light of the irradiated laser is observed on the image sensor imaging surface 10 of the image sensor 6, and the position in the observation field, that is, the image position corresponding to the expected angle is calculated by the observation device electronic circuit unit 4 and output. . The operation of the observation device head unit 3 is controlled by the observation device electronic circuit unit 4, and the distance and the estimated angle of the target reflector 2 with respect to the observation device head unit 3 are output. The information on the distance and the estimated angle output from the observation device electronic circuit unit 4 is sent to the attitude control device 16 of the spacecraft 14, and the distance change rate is calculated from the temporal change of the distance information.
Further, by combining the attitude information of the spacecraft 14 itself and the information of the distance and the expected angle output from the observation device electronic circuit section 4, the relative position between the target satellite 9 and the spacecraft 14 and
Calculate the relative speed. These pieces of information are used for controlling the approach of the spacecraft 14 to the target satellite 9.

[0004]

In the case of transporting cargo such as experimental equipment and fuel, or inspecting or repairing a malfunctioning part, etc., a general target satellite is not necessarily approached by a rendezvous. Attachment of special equipment to the target satellite for reasons such as that it is not necessarily developed for the purpose, attitude control becomes impossible when the target satellite fails, and the target satellite may be rotating naturally. It is desirable that the satellite position observation device can be used regardless of the attitude of the target satellite. However, the conventional satellite position observation device has the following problems.

That is, in the conventional satellite position observing apparatus 1, the laser beam 8 radiated by the laser beam irradiating device 5 is applied to the target reflector 2 mounted on the target satellite 9.
In order to measure the distance and the estimated angle by reflecting the light, it is assumed that the target reflector 2 is mounted on the target satellite 9. That is, it is necessary to mount a special device on the target satellite, and it is impossible to apply the approach to a general satellite. Further, the beam width of the laser light 8 irradiated from the laser light irradiation device 5 and the laser light 8
Relative to the target reflector 2 mounted on the target satellite 9 because of the range of the angle of reflection of the target reflector 2 that reflects light and the range of the lens field of view of the image sensor 6 that observes the laser light 8. , And can be measured only within the expected angle range. That is, it is necessary to grasp the attitude of the target satellite 9 and approach the target reflector 2 from within a specified angle range, and it is impossible to use the conventional satellite position observation device 1 regardless of the approach direction. It is.

The present invention has been made to solve the problems in such a conventional satellite position observation device, and will be described in detail below.

[0007]

According to a first aspect of the present invention, a single image sensor with a constant lens magnification mounted on the approaching spacecraft observes a satellite as an approaching target and periodically outputs a target satellite image. After obtaining the observation image by the image sensor, a binarization process is performed to extract a target satellite portion having a higher luminance than the surroundings, and thereafter, the target satellite portion 2 corresponding to the target satellite portion is extracted.
The area of the binarized image is calculated, the distance of the target satellite to the image sensor and the rate of change in distance are calculated and output from the area of the satellite binarized image on the observed image based on the actual satellite size and lens magnification. Is achieved by

According to a second aspect of the present invention, the satellite position observing device according to the first aspect of the present invention is mounted on a spacecraft approaching a target satellite orbiting in a circular orbit, and the approaching spacecraft measured by the satellite position observing device is provided. The distance between the target satellites and the distance change rate information
Estimate the relative position and relative speed between the target satellite and the approaching spacecraft by filtering using an orbit estimator using the Hill equation that describes the relative motion between the approaching spacecraft and the target satellite during inertial flight It is achieved by doing.

According to a third aspect of the present invention, a satellite position observing device according to the second aspect of the present invention is mounted on a spacecraft having a GPS approaching a target satellite, and absolute navigation information (space with respect to a fixed earth coordinate system) acquired by the GPS is installed. By using the relative position and relative speed information between the target satellite and the approaching spacecraft acquired by the satellite position observation device, the absolute position of the target satellite in the earth's fixed coordinate system can be determined. It is achieved by calculating.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing a satellite position observation device of the present invention. In FIG. 1, 1, 3, 4,
6, 9, and 10 are the same as those in FIG. 11 is an image preprocessing unit, 12 is an image memory, and 13 is an image measurement processing unit.

The image preprocessing section 11 transfers an image obtained by the image sensor 6 to an image memory 12. FIG. 3 shows a state of the image memory 12 in the image preprocessing unit 11. The image data on the image memory 12 is recorded as a numerical value corresponding to the luminance. As shown in FIG. 3, by selecting the approach to the target satellite 9 during sunshine, the image of the target satellite 9 illuminated by the sun is captured. The image data corresponding to the portion has high brightness with respect to the surrounding outer space. Therefore, as shown in FIG. 3, the image pre-processing unit 11 performs a binarization process in which pixel data on the image memory 12 having a luminance equal to or higher than a certain threshold value is set to 1 and the others are set to 0, thereby achieving a target. The captured image portion of the satellite 9 can be extracted. That is, the portion of the target satellite 9 extracted by the binarization process is 1 and the other portions are 0. Here, the area of the target satellite 9 on the imaging surface can be obtained by summing the number of 1s in the image memory 12. This area is defined as S1.

Here, assuming that the average projection area on the image memory 12 of the image sensor 6 when the target satellite 9 is observed from the point separated by the specified distance X0 m by the image sensor 6 is S0, Is equal to the distance R between the target satellites 9 when the area of the target satellite is S1.

[0013]

(Equation 1)

From the distance information R (t) and R (t + ΔT) between the target satellites 9 obtained by obtaining the ΔT time interval, the distance change rate is as shown in Expression 2.

[0015]

(Equation 2)

That is, by performing the calculations in accordance with Equations 1 and 2 by the image measurement processing unit 12, the distance and the rate of change of distance to the target satellite 9 can be measured and output.

In this embodiment, the case where image information is used has been described. However, in a laser radar and a radio wave sensor using a surface reflected wave from a target satellite instead of image information, the spread of reflected light and the reflected wave Based on strength
It goes without saying that the distance and the rate of change of distance can be measured and output by the same processing.

Embodiment 2 FIG. FIG. 1 is a configuration diagram of a satellite observation device according to a second embodiment of the present invention. Embodiment 2
As shown in FIG. 1, the satellite position observation device 1 according to the first embodiment described above
Is mounted on the spacecraft 14 approaching. Here, it is assumed that the target satellite 9 orbits a circular orbit around the earth, and the spacecraft 14 also orbits a circular orbit having substantially the same eccentricity.
It is assumed that the target satellite 9 is approached by inertial flight.

Here, the target satellite 9 is observed from the spacecraft 14 by the satellite position observation device 1 according to the first embodiment. Here, it is assumed that the distance between the target satellite 9 and the approaching spacecraft 14 and the distance change rate information are output from the satellite position observation device 1 every ΔT seconds. Here, the relative motion between the target satellite 9 and the spacecraft 14 approaching by inertial flight can be described by the Hill equation shown in Equation 3.

[0020]

(Equation 3)

Here, the estimated state quantity x = (Xp, Yp, Z
Assuming that p, Xv, Yv, Zv) (Xp, Yp, Zp: relative position in Hill coordinate system, Xv, Yv, Zv: relative velocity in Hill coordinate system), the dynamics of relative motion expressed by Equation 3 is by using the dynamics between the target satellite 9 and proximity to spacecraft 14, d x / dt
= F (x (t), t) is as shown in Expression 4.

[0022]

(Equation 4)

Further, the distance from the satellite observation device 1 and the distance change rate information are converted into the observation value vector z by z = (ρ, dρ / dt).
Assuming that (ρ: distance between the target satellite and the approaching spacecraft, dρ / dt: rate of change in distance between the target satellite and the approaching spacecraft), the observation value vector z is as shown in Equation 5 using the estimated state quantity. .

[0024]

(Equation 5)

By using the dynamics of the relative motion expressed by the equations (4) and (5) and the observation equation, the equation (6) is obtained.
As shown in (1), by using a Kalman filter which is an optimal state estimation method from sequential input data, it is possible to obtain an optimal estimated value of a state quantity x which is a relative position and a relative speed. (Equation 6 is “Applied Optima
l Estimation, Gelb, 1974.)

[0026]

(Equation 6)

The processing by the Kalman filter shown in Equation 6 is performed by software in the image measurement processing unit 13 in the satellite position observation apparatus 1 mounted on the approaching spacecraft 14, so that the space approaching the target satellite 1 is obtained. The relative position and speed between the machines 14 can be estimated.

In this embodiment, the case where image information is used has been described. However, instead of image information, a laser radar using a surface reflected wave from a target satellite and a distance and a rate of change in distance measured by a radio wave sensor are used. It is needless to say that the relative position and relative speed between the target satellite 1 and the approaching spacecraft 14 can be estimated by the same processing based on the measurement information.

Embodiment 3 FIG. 2 is a configuration diagram of a satellite position observation device according to a third embodiment of the present invention.

A satellite position observation device 1 according to the third embodiment
As shown in FIG. 2, the spacecraft 14 approaching the target satellite 9 uses the satellite position observation device 1 according to the second embodiment.
Mount on top. As shown in FIG. 2, a GPS receiver 15 is mounted on the approaching spacecraft 14, and can measure an absolute position (referred to as (XA, YA, ZA)) in the earth fixed coordinate system. .

Here, the target satellite 9 is observed from the approaching spacecraft 14 by the satellite position observation device 1 according to the second embodiment. In this case, the relative position and relative speed ((Xp, Yp, Zpp), (Xv, Y) of the spacecraft 14 approaching the target satellite 9
v, Zv)) are measured by the method of the second embodiment, the absolute position of the target satellite 9 in the earth fixed coordinate system is determined by the absolute position and velocity of the approaching spacecraft 14 in the earth fixed coordinate system, It can be obtained by taking the sum of the relative position and speed between the target satellite 9 and the approaching spacecraft 14.

[0032]

According to the first aspect, the approach to the satellite and the orbiting around the satellite can be performed without mounting a special reflector on the target satellite and without limiting the approach direction to the target satellite. Target satellites necessary for the implementation of
The distance between the approaching spacecraft and the distance change rate measurement value can be obtained.

According to the second aspect, the approach to the satellite can be performed without mounting a special reflector on the target satellite and without limiting the approach direction to the target satellite.
It is possible to obtain the measured values of the relative position and the relative velocity between the target satellite and the approaching spacecraft, which are necessary for the orbit control around the satellite.

According to the third aspect of the present invention, the GPS is mounted on the approaching spacecraft without mounting a special reflector on the target satellite and without limiting the approach direction to the target satellite. Relative position between the approaching spacecraft and
By acquiring the speed based on the method of the second invention,
It is possible to obtain the absolute position and velocity measurement values of the target satellite, which are necessary for controlling the approach to the satellite, controlling the orbit around the satellite, and the like.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing Embodiments 1 and 2 of a satellite position observation device according to the present invention.

FIG. 2 is a configuration diagram showing a third embodiment of the satellite position observation device according to the present invention.

FIG. 3 is a diagram showing a configuration of an image memory.

FIG. 4 is a diagram showing a conventional satellite position observation device.

[Description of Signs] 1 satellite position observation device, 2 target reflector, 3
Observation device head unit, 4 observation device electronic circuit unit, 5 laser beam irradiation device, 6 image sensor, 7 phase measurement device,
8 laser beam, 9 target satellite, 10 image sensor imaging surface, 11 image preprocessing unit, 12 image memory, 13 image measurement processing unit, 14 approaching spacecraft, 15 GPS receiver, 16 attitude control device.

Claims (3)

[Claims] 1. A single image sensor having a constant lens magnification and provided on a spacecraft approaching a target satellite and observing a satellite to be the target of the approach and periodically acquiring a target satellite image, and the image sensor Binarization processing means for extracting a target satellite portion having a higher luminance than the surroundings from the output of the target, and an observation image based on the area of the binarized image corresponding to the target satellite portion, the size of the approaching target satellite, and the lens magnification. Means for calculating a distance from the area of the binary image to the target satellite to the image sensor and a distance change rate. 2. The satellite position observation device according to claim 1, which is provided in a spacecraft approaching the target satellite by inertial flight in the vicinity of the target satellite orbiting in a circular orbit, and the approach position measured by the satellite position observation device. Based on the distance between the spacecraft and the target satellite and the rate of change of distance, the trajectory estimator using the Hill equation that describes the relative motion between the approaching spacecraft and the target satellite during inertial flight is used to approach the target satellite. A satellite position observing apparatus comprising means for measuring a relative position and a relative velocity of a spacecraft to be operated. 3. A GPS (Global Positioning System) approaching a target satellite by inertial flight near a target satellite orbiting a circular orbit.
means for measuring a relative position and a speed with respect to a target satellite by the satellite position observation device according to claim 2, and detecting an absolute position of the approaching spacecraft by absolute navigation using a GPS, provided in a spacecraft having a bal Positioning System. And means for measuring the absolute position of the target satellite in the earth fixed coordinate system based on the relative position and speed information with respect to the target satellite and the absolute position information of the approaching spacecraft by GPS. Position observation device.