U.S. patent application number 16/614624 was filed with the patent office on 2020-05-21 for navigation system, spacecraft and optical marker.
The applicant listed for this patent is ASTROSCALE JAPAN INC.. Invention is credited to Ken MAEDA.
Application Number | 20200160551 16/614624 |
Document ID | / |
Family ID | 59790902 |
Filed Date | 2020-05-21 |
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United States Patent
Application |
20200160551 |
Kind Code |
A1 |
MAEDA; Ken |
May 21, 2020 |
NAVIGATION SYSTEM, SPACECRAFT AND OPTICAL MARKER
Abstract
Simplify, downsize and reduce power of devices which comprise
the satellite navigation system used in approach and docking in
space. The navigation system 1 which estimates an attitude of a
target object T in space comprises: an optical marker 10 that is
attached to the target T and reflects light; a lighting device 20
that irradiates the target object T with light of a predetermined
wavelength band; an image acquisition device 30 that acquires an
image of the optical marker 10 which has reflected the light of the
predetermined wavelength band; and an image processing device 40
that processes the image acquired by the image acquisition device
30 and thereby estimates the attitude of the target object T. The
lighting device 20 and the image processing device 30 are loaded on
a spacecraft 2.
Inventors: |
MAEDA; Ken; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ASTROSCALE JAPAN INC. |
Tokyo |
|
JP |
|
|
Family ID: |
59790902 |
Appl. No.: |
16/614624 |
Filed: |
May 16, 2018 |
PCT Filed: |
May 16, 2018 |
PCT NO: |
PCT/JP2018/018963 |
371 Date: |
November 18, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01B 11/272 20130101;
G01S 5/163 20130101; G01C 23/00 20130101; G06T 7/70 20170101; G06T
2207/10032 20130101; B64G 1/58 20130101; B64G 1/646 20130101; G06T
2207/30204 20130101; G01B 11/26 20130101; B64G 3/00 20130101 |
International
Class: |
G06T 7/70 20060101
G06T007/70; B64G 1/58 20060101 B64G001/58; B64G 3/00 20060101
B64G003/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 19, 2017 |
JP |
2017-100022 |
Claims
1. A navigation system which estimates an attitude of a target
object in space comprising: an optical marker that is attached to
the target object and reflects light; a lighting device that
irradiates the target object with light of a predetermined
wavelength band; an image acquisition device that acquires an image
of the optical marker which has reflected the light of the
predetermined wavelength band; and an image processing device that
processes the image acquired by the image acquisition device and
thereby estimates the attitude of the target object, wherein the
lighting device and the image acquisition device are loaded on a
spacecraft.
2. The navigation system according to claim 1, wherein the light of
the predetermined wavelength band is absorbed by a heat insulation
film which forms a surface of the target object.
3. The navigation system according to claim 1, wherein the image
processing device is loaded on the spacecraft.
4. The navigation system according to claim 1, wherein the image
processing device is allocated on a ground station.
5. The navigation system according to claim 1, wherein the lighting
device includes a light emitting diode.
6. The navigation system according to claim 1, wherein the optical
marker includes a retro-reflective material.
7. The navigation system according to claim 1, wherein multiple
optical markers are attached to a predetermined surface of the
target object and are positioned rotationally asymmetrically with
respect to a virtual axis which is vertical to the surface.
8. The navigation system according to claim 1, wherein the image
acquisition device includes an optical lens and an imaging sensor,
and wherein the optical lens is provided with an optical filter
which transmits the light of the predetermined wavelength band.
9. A spacecraft comprising: a lighting device that irradiates an
optical marker which is attached to a target object in space and
reflects light with light of a predetermined wavelength band; and
an image acquisition device that acquires an image of the optical
marker which has reflected the light of the predetermined
wavelength band, wherein the image which has been acquired by the
image acquisition device is processed and whereby an attitude of
the target object can be estimated.
10. An optical marker which is attached to a target object in space
before the target object is launched into space, wherein: the
optical marker reflects light of a predetermined wavelength band
which has been radiated from a lighting device of a spacecraft; an
image of the optical marker which has reflected the light of the
predetermined wavelength band is acquired by an image acquisition
device of the spacecraft; and the image is processed by an image
processing device and whereby an attitude of the target object can
be estimated.
Description
TECHNICAL FIELD
[0001] The present application is based on Japanese Application No.
(Patent Application) 2017-100022 filed on May 19, 2017 and contents
described therein are adopted here.
[0002] The present invention relates to a navigation system, a
spacecraft and an optical marker.
BACKGROUND ART
[0003] There are satellites on the earth orbit which approach and
dock to other satellites for supply, equipment repair, retrieval
associated with mission completion and so forth. In recent years,
various techniques of estimating a position and an attitude
(perspective and rotating state) of a target satellite for approach
and docking have been proposed for safe and efficient approach and
docking.
[0004] For example, in Non-Patent Document 1 proposes a technique
to estimate the attitude of the target object by an arithmetic
operation device based on the light from a Flash Lidar. More
specifically, irradiating a target object with laser light from a
Flash Lidar, detecting light reflected out of the target object by
a two-dimensional array type photodetector, and then outputting an
image of the target object and estimating the attitude of the
target object. Also to increase the accuracy of attitude
estimation, advanced image processing technique without utilizing
the Flash Lidar are proposed in Non-Patent Document 2.
CITATION LIST
Patent Literature
[0005] [Non-Patent Document 1]: R. W. Dissly and five others, FLASH
LIDARS FOR PLANETARY MISSIONS, International Workshop on
Instrumental for Planetary Missions (2012), 2012, Internet <URL:
http://www.lpi.usra.edu/meetings/ipm2012/pdf/1145.pdf>. [0006]
[Non-Patent Document 2]: M. Aviles, and three others, A Complete
IP-based Navigation Solution for the Approach and Capture of Active
Debris, 67th International Astronautical Congress (IAC), September
2016, Internet<URL:
http://iafastro.directory/iac/archive/tree/IAC-16/A6/6/IAC-16,A6,6,5,x337-
49.brief.pdf>.
SUMMARY OF INVENTION
Technical Problem
[0007] However, the technique described in the Non-Patent Document
1 has several issues. To irradiate the target object with the laser
light, it consumes large electric power. Also the outputted image
data is two-dimensional therefore the data volume is large and a
special processing system such as an FPGA is required. The
technique described in the Non-Patent Document 2 also has an issue
of highly complicated and precise image processing. For approach
processing, it required a human resource to extract characteristic
points of the target object and make a model. This requires a large
effort for designing a navigation system. Also, devices for such
existing navigation techniques are more complicated and larger, and
consume more power. For a small-size, around 100 kg, satellite,
adopting such existing navigation techniques is difficult not only
due to the costs for development and manufacturing, also size, mass
and power budget.
[0008] The present invention contributes to simplify, downsize and
reduce power consumption of devices in the satellite navigation
system for approach and docking in space.
Solution to Problem
[0009] The present invention is a navigation system viable for
small-size satellites to estimate the attitude of the target object
in space. This system comprises: an optical marker that is attached
to the target object and reflects light; a lighting device that
irradiates the target object with light of a predetermined
wavelength band; an image acquisition device that acquires an image
of the optical marker which has reflected the light of the
predetermined wavelength band; and an image processing device that
processes the image acquired by the image acquisition device and
thereby estimates the attitude of the target object, wherein the
lighting device and the image acquisition device are loaded on a
spacecraft.
[0010] In addition, a spacecraft according to the present invention
can estimate the attitude of the target object. It comprises: a
lighting device that irradiates an optical marker which is attached
to a target object in space and reflects light of a predetermined
wavelength band; and an image acquisition device that acquires an
image of the optical marker which has reflected the light of the
predetermined wavelength band, wherein the image acquired by the
image acquisition device is processed by an image processing
device.
[0011] Further, a target object is equipped an optical marker
before being launched into space. The optical marker reflects light
of a predetermined wavelength band radiated from a lighting device
of a spacecraft; an image of the optical marker which has reflected
the light of the predetermined wavelength band is acquired by an
image acquisition device of a spacecraft; and the image is
processed by an image processing device. As a result, a spacecraft
can estimate the attitude of the target object.
[0012] With aforementioned configuration, it becomes possible to
estimate the attitude of the target object. The light of the
predetermined wavelength band radiated from the lighting device of
the spacecraft is made to reflect out of the optical marker which
is attached to the target object in space. The image acquisition
device acquires the image of the optical marker which has reflected
the light of the predetermined wavelength band. The image
processing device processes acquired image and estimates the
attitude. If, for example, the target object is a satellite, its
surface is most likely coated with a heat insulation film which
absorb the light of the predetermined wavelength band (for example,
near-ultraviolet range light having a wavelength band of 300 nm to
400 nm). When the optical marker is attached to the target object
surface which would absorb the light of the predetermined
wavelength band, the image acquisition device can easily acquire
the image of the optical marker which reflects the light of the
predetermined wavelength band and image processing is also not
difficult. Accordingly, it is possible to simplify and downsize the
configuration of the image acquisition device and to reduce the
electric power consumption of the image processing device.
Consequently, it is possible to reduce the development and
manufacturing costs of the navigation system and to downsize the
spacecraft which loads the image acquisition device thereon. The
image processing device may be either loaded on the spacecraft or
allocated on a ground station.
[0013] In the navigation system, the lighting device that includes
a light emitting diode may be adopted.
[0014] By adopting such a configuration, it is possible to
configure the lighting device which requires lower power and to
irradiate the optical marker longer distance.
[0015] In the navigation system, the optical marker that includes a
retro-reflective material may be adopted.
[0016] By adopting such a configuration, it becomes possible to
match the direction of the incoming and outgoing light of the
optical marker. This enables the acquisition of the optical marker
image regardless of the attitude of the target object.
[0017] In the navigation system in accordance with the present
invention, multiple optical markers may be attached to a
predetermined surface of the target object and the optical markers
may be positioned rotationally asymmetrically with respect to a
virtual axis which is vertical to the predetermined surface.
[0018] By adopting such a configuration, it becomes possible to
easily estimate rotating states of the optical markers (eventually,
a rotating state of the target object).
[0019] In the navigation system in accordance with the present
invention, the image acquisition device that includes an optical
lens and an imaging sensor may be adopted. In such a case, the
optical lens may have an optical filter which transmits the light
with the predetermined wavelength band.
[0020] By adopting such a configuration, it is possible to prevent
the imaging sensor to acquire an image other than the light with
the predetermined wavelength band (for example, the
near-ultraviolet range light having the wavelength band of 300 nm
to 400 nm). Accordingly, it is possible to easily identify the
images of the optical markers.
Advantageous Effects of Invention
[0021] The present invention simplifies, downsizes and reduces
power consumption of the devices which configure the satellite
navigation system for approach and docking in space.
BRIEF DESCRIPTION OF DRAWINGS
[0022] FIG. 1 is a configuration diagram illustrating one example
of a configuration of a navigation system according to one
embodiment of the present invention.
[0023] FIG. 2 is an explanatory diagram illustrating one example of
arrangement of optical markers which configure the navigation
system according to one embodiment of the present invention.
DESCRIPTION OF EMBODIMENTS
[0024] Hereinafter, an embodiment of the present disclosure is
described with reference to the drawings.
[0025] At first, the configuration of a navigation system 1
according to one embodiment of the present invention will be
described. This is adapted to estimate the attitude of a target
object (such as a satellite) T in space and includes an optical
marker 10, a lighting device 20, an image acquisition device 30 and
an image processing device 40 as illustrated in FIG. 1. The
lighting device 20, the image acquisition device 30 and the image
processing device 40 are loaded on a spacecraft (a chaser satellite
which approaches the target object T) 2. The spacecraft 2 is
attached to the rocket and separate from a rocket after the launch.
After the separation, it autonomously maneuver in space.
[0026] The optical marker 10 is attached to a predetermined surface
S of the target object T as illustrated in FIG. 1 and FIG. 2. It is
configured to reflect light. The optical marker 10 is configured to
reflect at least the light of the predetermined wavelength band
(for example, the near-ultraviolet range light having the
wavelength band of 300 nm to 400 nm) which would be absorbed by a
heat insulation film placed on the surface of the target object T.
The optical marker 10 which reflects light of all wavelength bands
also may be adopted.
[0027] In the present embodiment, five optical markers 10 are
attached to the predetermined surface S of the target object T as
illustrated in FIG. 2. The optical markers 10 are positioned
rotationally asymmetrically with respect to a virtual axis A
positioned at the center which is vertical to the predetermined
surface S. It becomes possible to estimate the rotating state of
the target object T around a predetermined rotation axis (not
illustrated) by locating the optical markers 10 in this way.
Meanwhile, the rotation axis of the target object T may not
necessarily match the virtual axis A. When the target object T
rotates around the rotation axis, the respective positions of
multiple optical markers 10 are changed. Rotating state of the
target object T could be estimated from the analyzing the optical
markers 10 position before and after rotation.
[0028] The optical marker 10 which includes the retro-reflective
material is adopted. Accordingly, it becomes possible to match the
direction of the incoming and outgoing light of the optical markers
10.
[0029] The lighting device 20 irradiates the target object T with
the light of the predetermined wavelength band. The lighting device
20 includes the light emitting diode and is attached to a
predetermined position of the spacecraft 2 as illustrated in FIG.
1. The attachment position of each lighting device 20 and the
number of the lighting devices 20 to be attached may be
appropriately decided in accordance with the position of each
optical marker 10 and the number of the optical markers 10 to be
allocated.
[0030] The wavelength band of the light that the lighting device 20
radiates may be appropriately decided in accordance with the type,
the material and so forth of the heat insulation film which is
formed on the surface of the target object T. For example, it is
known that a surface on which a heat insulation film made of
silver-coated Teflon is formed absorbs about 95% of energy of light
of a wavelength band of 305 nm to 315 nm. It is also known that a
surface on which a heat insulation film made of aluminized Kapton
is formed absorbs at least 85% of energy of the light of the
wavelength band of 300 nm to 400 nm. Therefore, it is possible to
irradiate the optical markers 10 with the light having the
above-mentioned wavelength bands by the lighting device 20 and to
make the light having the above-mentioned wavelength bands reflect
out of the optical markers 10. The inventors of the present
invention have observed the point that the heat insulation films
made of the silver-coated Teflon, the aluminized Kapton, white
paint and so forth absorb the near-ultraviolet range light and
achieved the present invention by adopting a configuration that
optical markers 10 reflect the light of such wavelength bands.
[0031] The image acquisition device 30 acquires an image of the
optical marker 10 which has reflected the light of the
predetermined wavelength band. In the present embodiment, the image
acquisition device 30 which includes an optical lens and an imaging
sensor is adopted and the optical lens is provided with an optical
filter which transmits the light of the predetermined wavelength
band. A wavelength band (for example, from 300 nm to 400 nm) which
would be absorbed by the heat insulation film formed on the surface
of the target object T may be adopted as the predetermined
wavelength band. The image acquisition device 30 is attached to a
predetermined position of the spacecraft 2 as illustrated in FIG.
1. The attachment position of the image acquisition device 30 may
be appropriately decided in accordance with the position of each
optical marker 10 and the number of the optical markers 10 to be
allocated.
[0032] The image processing device 40 processes the image acquired
by the image acquisition device 30 and thereby estimates the
attitude of the target object T. A processor which reads various
programs and various pieces of data used for image processing and
attitude estimation out of a memory and executes arithmetic
operations relating to image processing and attitude estimation may
be adopted as the image processing device 40. In the present
embodiment, the image processing device 40 is loaded on the
spacecraft 2.
[0033] Hereinafter, a method of estimating the attitude of the
target object T by the navigation system 1 according to the
embodiment of the present invention will be described.
[0034] First, the spacecraft 2 moves toward the target object T and
faces the predetermined surface S of the target object T. The
spacecraft radiates the light of the predetermined wavelength band
from the lighting device 20 toward the target object T so as to
make the light of the predetermined wavelength band reflect out of
each optical marker 10 attached to the target object T. Then, the
image acquisition device 30 loaded on the spacecraft 2 acquires the
image of the optical marker 10 which has reflected the light of the
predetermined wavelength band. On this occasion, only the light of
the predetermined wavelength band is detected due to the optical
filter provided on the optical lens of the image acquisition device
30. The image processing device 40 on the spacecraft processes the
image acquired by the image acquisition device 30 and estimates the
attitude of the target object T.
[0035] In the navigation system 1, estimation of the attitude of
the target object T becomes possible by radiating the light of the
predetermined wavelength band from the lighting device 20 to
reflect out of each optical marker 10 attached to the target object
T in space, acquiring the image of the optical marker 10 which has
reflected the light of the predetermined wavelength by the image
acquisition device 30, and processing the acquired image by the
image processing device 40. If the target object T is a satellite,
its surface is coated with the heat insulation film having the
feature of absorbing the light of the predetermined wavelength band
(for example, the near-ultraviolet range light having the
wavelength band of 300 nm to 400 nm). When each optical marker 10
is attached to the target object T which has the surface which
would absorb the light of the predetermined wavelength band in this
way, it becomes possible to easily acquire the image of the optical
marker 10 which reflects the light of the predetermined wavelength
band by the image acquisition device 30 and to process the image.
Accordingly, it enables to simplify and downsize the configuration
of the image acquisition device 30 and to reduce the electric power
consumption of the image processing device 30. As a result, it is
possible to reduce the development and manufacturing costs of the
navigation system 1 and to downsize the spacecraft 2 which loads
the image acquisition device 30 thereon.
[0036] In addition, in the navigation system 1, the lighting device
20 which includes the light emitting diode is adopted. Therefore,
it is possible to save power for lighting device 20 and irradiate
the optical marker 10 with from longer distance.
[0037] In addition, in the navigation system 1, the
retro-reflective material is selected for optical marker 10 to
match the direction of incoming and outgoing light of the optical
marker 10. It enables the acquisition of the optical marker 10
image regardless the attitude of the target object T.
[0038] In addition, in the navigation system 1, multiple optical
markers 10 are attached to the predetermined surface S of the
target object T and are positioned rotationally asymmetrically with
respect to the virtual axis A which is vertical to the surface S.
This enables one to easily estimate the rotating states of the
optical markers 10 (eventually, the rotating state of the target
object T).
[0039] In addition, the image acquisition device 30 which includes
the optical lens and the imaging sensor is adopted and the optical
lens is provided with the optical filter which transmits the light
of the predetermined wavelength band (for example, the
near-ultraviolet range light having the wavelength band of 300 nm
to 400 nm) in the navigation system 1. This filter prevents the
imaging sensor to acquire an image of light other than the light of
the predetermined wavelength band. Accordingly, it becomes easy to
identify the images of the optical markers 10.
[0040] In the present embodiment, the image processing device 40 is
loaded on the spacecraft 2 as an example, however it may be
allocated on the ground station. In such a case, transmission means
is provided to transmit image data acquired by the image
acquisition device 30 of the spacecraft 2 to image processing
device 40 on the ground.
[0041] In addition, in the present embodiment, the optical markers
10 are attached to the predetermined surface S of the target object
T as an example. However the surface to which the optical markers
10 are attached may not necessarily be flat and may have some
unevenness. In addition, the number of the optical markers 10 is
not limited to five.
[0042] In addition, although in the present embodiment, a satellite
(target satellite) is exemplified as the target object T, the
target object is not limited to a satellite.
[0043] The present invention is not limited to the above-mentioned
embodiment and a configuration that the inventors and others have
made by appropriately adding design changes to the above-mentioned
embodiment is also included into the scope of the present invention
as long as it has the characteristics of the present invention.
That is, the respective elements that the above-mentioned
embodiment includes, such as the arrangement, materials,
conditions, shapes, sizes and so forth, are not limited to those
which are exemplified and may be appropriately changed. In
addition, the respective elements that the above-mentioned
embodiment includes may be combined with one another as long as it
is technically possible and combinations of the respective elements
are also included into the scope of the present invention as long
as they have the characteristics of the present invention.
REFERENCE SIGNS LIST
[0044] 1 navigation system [0045] 2 spacecraft [0046] 10 optical
marker [0047] 20 lighting device [0048] 30 image acquisition device
[0049] 40 image processing device [0050] A virtual axis [0051] S
predetermined surface [0052] T target object
* * * * *
References