Artificial satellite, power transmission system, and power transmission method

Abstract

To enable acquisition of electric energy to become a power source for a probe or the like, in a long period shade or a permanent shade on a surface of a celestial body that is a planet other than the earth in the solar system or a satellite.SOLUTION: An artificial satellite 10 revolves around a celestial body 1 that is a planet other than the earth in the solar system or a satellite, and transmits power to a power receiving device 20 positioned in a long period shade or a permanent shade where sunlight does not hit a celestial body 1 surface for a prescribed long period or permanently. The artificial satellite 10 includes: a power generator 11 for generating electric energy from sunlight; and a power transmission device 13 for converting the electric energy to electromagnetic waves, and transmitting the electromagnetic waves to the power receiving device 20 on the celestial body 1 surface. The artificial satellite 10 repeatedly revolves around the celestial body 1 in an orbit which passes through an upper area of the power receiving device 20. The power transmission device 13 transmits the electromagnetic waves to the power receiving device 20 from the upper area.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technique for transmitting power from an artificial satellite orbiting a celestial body such as a planet other than the Earth or a satellite (for example, the Moon) to a power receiving device disposed on the surface of the celestial body. [Background technology]

[0002] Machines such as probes that operate on the surface of celestial bodies such as the moon require electrical energy as their power source. For example, solar panels could be installed on the moon's surface to generate electrical energy from sunlight and store it in the probe's storage battery. The probe and other machines could operate using the electrical energy from the storage battery as their power source.

[0003] Patent Document 1 discloses a technique related to some of the embodiments of the present application. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-309581 Summary of the Invention [Problem to be solved by the invention]

[0005] However, on the surfaces of planets and moons other than Earth in the solar system, there are areas that are not exposed to sunlight for long periods of time (for example, for more than half a month in Earth time) (hereinafter referred to as long-term shadow) and areas that are permanently not exposed to sunlight (hereinafter referred to as permanent shadow).

[0006] For example, because the Moon's rotation period is about 27 days, many areas of the Moon's surface are in long-term shadow, with no sunlight for about two weeks. Permanent shadows also exist within large (e.g., hundreds of kilometers across) craters in the Moon's polar regions.

[0007] Therefore, in long-term or permanent shade, electrical energy cannot be generated from sunlight, and it is difficult for machines such as probes to obtain electrical energy as a power source.

[0008] Therefore, an object of the present invention is to make it possible to obtain electrical energy to power a probe or other machine in the long-term or permanent shadow of the surface of a celestial body that is a planet or moon other than Earth in the solar system. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, an artificial satellite according to the present invention is an artificial satellite that orbits a celestial body that is a planet or a satellite other than the Earth in the solar system, and transmits power to a power receiving device that is located in a long-term shadow or permanent shadow on the surface of the celestial body where sunlight does not shine for a predetermined long period of time or permanently, a power generation device that generates electrical energy from sunlight; a power transmitting device that converts the electrical energy into electromagnetic waves and transmits the electromagnetic waves to a power receiving device on the surface of the celestial body; The artificial satellite repeatedly orbits the celestial body in an orbit that passes through an area above the power receiving device, and the power transmitting device transmits the electromagnetic waves from the area above the power receiving device to the power receiving device.

[0010] A power transmission system according to the present invention includes the above-described satellite and the above-described power receiving device.

[0011] The power transmission method according to the present invention is a power transmission method for transmitting power from an artificial satellite orbiting a celestial body that is a planet or satellite other than the Earth in the solar system to a power receiving device that is located in long-term shade or permanent shade on the surface of the celestial body where sunlight does not shine for a predetermined long period of time or permanently, comprising: flying the artificial satellite so as to repeatedly orbit the celestial body in an orbit that passes through an area above the power receiving device; generating electrical energy from sunlight using a power generation device provided on the satellite; The satellite's power transmitting device converts the electrical energy into electromagnetic waves and transmits the electromagnetic waves from the upper region to the power receiving device, and the power receiving device converts the electromagnetic waves from the power transmitting device into electrical energy. [Effects of the Invention]

[0012] According to the present invention, a satellite repeatedly orbits a celestial body in an orbit that passes over an area above a power receiving device in the long-term or permanent shadow of the celestial body's surface, and generates electrical energy from sunlight using its power generating device. The satellite's power transmitting device converts the generated electrical energy into electromagnetic waves and transmits the electromagnetic waves from the area above the power receiving device to the power receiving device. The power receiving device receives the electromagnetic waves and converts them into electrical energy. Thus, electrical energy can be obtained to power a probe or other machinery in the long-term or permanent shadow of the celestial body's surface. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a block diagram illustrating a power transmission system according to an embodiment of the present invention. [Figure 2] This shows an artificial satellite orbiting a celestial body. [Figure 3] FIG. 10 is an explanatory diagram showing an artificial satellite passing over an area above a power receiving device. [Figure 4] FIG. 4 is a diagram corresponding to the partially enlarged view of FIG. [Figure 5] FIG. 10 is a block diagram showing a power transmission system when using an arrangement pattern of a plurality of light-emitting units. [Figure 6] 1 is a flowchart illustrating a power transmission method according to an embodiment of the present invention. [Figure 7] FIG. 10 is an explanatory diagram of a first modification, showing an artificial satellite passing over an area above a power receiving device. [Figure 8] 10 is a flowchart showing a power transmission method according to a first modified example. [Figure 9] FIG. 11 is a block diagram showing a power transmission system according to a third modified example. [Figure 10]11 is a flowchart showing a power transmission method according to a third modified example. DETAILED DESCRIPTION OF THE INVENTION

[0014] An embodiment of the present invention will be described with reference to the drawings. In addition, common parts in the drawings are given the same reference numerals, and duplicated explanations will be omitted.

[0015] (Power transmission system) Fig. 1 is a block diagram showing a power transmission system 100 according to an embodiment of the present invention. The power transmission system 100 includes a satellite 10 orbiting a celestial body 1 (Fig. 2) and a power receiving device 20 disposed on the surface of the celestial body 1, and is a system for transmitting power from the satellite 10 to the power receiving device 20. Fig. 2 shows the satellite 10 orbiting the celestial body 1. Fig. 3 shows the satellite 10 as it passes over the area above the power receiving device 20.

[0016] The artificial satellite 10 may orbit the celestial body 1 (for example, the moon) within about 100 km of the surface of the celestial body 1 or at an altitude of about 100 km, but the artificial satellite 10 may also orbit the celestial body 1 at other altitudes.

[0017] The celestial body 1 may be, for example, the moon (satellite of the Earth). However, according to the present invention, the celestial body 1 may also be a planet in the solar system other than the Earth, or a satellite of that planet. The surface of the celestial body 1 is formed of a solid material, not gas. Note that the celestial body 1 may have no atmosphere, or may have an atmosphere (for example, a thin atmosphere).

[0018] (power receiving device) The power receiving device 20 is located in long-term shadow or permanent shadow on the surface of the celestial body 1. For example, the power receiving device 20 may be launched from Earth and landed on the surface of the celestial body 1, or may be manufactured or assembled on the celestial body 1 and then located on the surface of the celestial body 1. As a result, the power receiving device 20 may be located in long-term shadow or permanent shadow on the surface of the celestial body 1. Long-term shadow is an area that is not continuously exposed to sunlight for a long period of time (for example, for three days, one week, two weeks (half a month) or more in Earth time). Permanent shadow is an area that is permanently not exposed to sunlight. Permanent shadow may be, for example, an area that exists on the inner surface of a crater in the polar region of the celestial body 1 (for example, the moon).

[0019] The power receiving device 20 receives electrical energy from the satellite 10 as a power source for operating (being active) a predetermined machine 2 in, for example, long-term or permanent shade. The machine 2 can operate by consuming this electrical energy.

[0020] Machine 2 may be, for example, a probe that performs exploration in long-term or permanent shade. Probe 2 may be configured to be able to move (e.g., run) on the surface of celestial body 1. Probe 2 may be equipped with, for example, both or either of equipment (e.g., a laser range finder or camera) for observing the topography of the surface of celestial body 1 and a working device (e.g., a robotic arm) for performing tasks such as excavating the surface of celestial body 1, cutting rocks, and collecting rocks. Probe 2 may also be equipped with other exploration equipment or devices.

[0021] The power receiving device 20 may include a power receiving unit 21 and a storage battery 22. The power receiving unit 21 receives electromagnetic waves transmitted from the satellite 10 and converts the electromagnetic waves into electrical energy. In this embodiment, the electromagnetic waves are radio waves (microwaves or millimeter waves) (the same applies hereinafter), but are not limited thereto. The power receiving unit 21 may be, for example, a power receiving rectenna (rectifying antenna). The power receiving rectenna 21 has an antenna and a rectifier circuit, receives the electromagnetic waves transmitted from the satellite 10 with the antenna, and converts the received electromagnetic waves into DC power (electrical energy) with the rectifier circuit. The power receiving device 20 may be provided with a control device for operating the power receiving rectenna 21 with high efficiency.

[0022] The power receiving unit 21 has a power receiving surface that receives the electromagnetic waves (microwaves or millimeter waves). The power receiving surface may face in the opposite direction to the direction of gravity of the celestial body 1 or in a direction oblique to the opposite direction. When viewed from a direction directly facing the power receiving surface, the shape of the power receiving surface may be rectangular, circular, or elliptical. The power receiving surface may also be formed as a flat surface. However, the shape of the power receiving surface is not limited to these shapes, as it may depend on the topography of the location where the power receiving unit 21 is installed.

[0023] When viewed from a direction directly facing the receiving surface of the receiving unit 21 (for example, the antenna of the receiving rectenna 21), the dimensions of the receiving surface in each direction perpendicular to that direction may be 10 m or more and 100 m or less (in one example, the dimensions are approximately 30 m), but are not limited to this range.

[0024] The storage battery 22 stores the electric energy converted by the power receiving unit 21 .

[0025] The power receiving device 20 may be provided separately from the specified machine 2. In this case, the power receiving device 20 is equipped with a charger 23. The charger 23 supplies the electrical energy stored in the storage battery 22 to the storage battery of the specified machine 2 (e.g., the probe 2). Therefore, the storage battery of the specified machine 2 stores electrical energy from the charger 23 of the power receiving device 20. For example, the specified machine 2 moves to the position of the charger 23 of the power receiving device 20 and receives electrical energy from the charger 23 at that position. In this case, the power receiving device 20 (charger 23) may be placed as a charging station at a fixed position in long-term shade or permanent shade.

[0026] According to the present invention, the power receiving device 20 may be provided in the above-mentioned predetermined machine 2 (for example, the probe 2). In this case, the predetermined machine 2 can be operated by the electric energy stored in the above-mentioned storage battery 22, and the power receiving device 20 does not need to have the above-mentioned charger 23. In this case, the machine 2 may operate in a region below the orbit of the satellite 10 (in long-term shadow or permanent shadow).

[0027] (artificial satellite) The artificial satellite 10 is launched from the Earth and placed in an orbit around the celestial body 1. As a result, the artificial satellite 10 repeatedly orbits the celestial body 1 in the orbit that passes through the region above the power receiving device 20 (hereinafter also simply referred to as the upper region).

[0028] The artificial satellite 10 includes a power generation device 11, a storage battery 12, a power transmission device 13, a camera 14, an image processing unit 15, and an attitude adjustment unit 13b.

[0029] The power generation device 11 generates electrical energy from sunlight while the satellite 10 flies in the orbit. The power generation device 11 may generate electrical energy from sunlight whenever sunlight is received. The power generation device 11 may be, for example, a solar power generation panel.

[0030] The storage battery 12 stores the electrical energy generated by the power generation device 11 .

[0031] The power transmitting device 13 converts the electric energy generated by the power generating device 11 into electromagnetic waves and transmits the electromagnetic waves to the power receiving device 20. The power transmitting device 13 may be configured to transmit the electromagnetic waves intensively (for example, only in) a target direction described below. In this embodiment, the power transmitting device 13 converts the electric energy stored in the storage battery 12 into electromagnetic waves and transmits the electromagnetic waves to the power receiving device 20.

[0032] In this embodiment, every time the satellite 10 passes over the area above the power receiving device 20, the power transmitting device 13 transmits electromagnetic waves from the area above the power receiving device 20 to the power receiving device 20. For example, every time the satellite 10 passes over the area above the power receiving device 20, the power transmitting device 13 may transmit to the power receiving device 20 electromagnetic waves with the maximum energy that can be transmitted per unit time, but the present invention is not limited to this.

[0033] The camera 14 acquires an image of the surface of the celestial body 1 from the satellite 10 while the satellite 10 is flying in the above-mentioned orbit. The camera 14 may be a visible light camera (e.g., a CCD camera) that generates a visible light image of the surface of the celestial body 1. The camera 14 is attached to the main body 10a of the satellite 10 (FIG. 2).

[0034] The artificial satellite 10 may be equipped with an attitude control device 17. The attitude control device 17 maintains the attitude of the main body 10a of the artificial satellite 10 relative to the direction of gravity of the celestial body 1 (hereinafter simply referred to as the direction of gravity) at a constant target attitude. The attitude of the camera 14 relative to the main body 10a of the artificial satellite 10 may be constant. In this case, the camera 14 may be attached to the main body 10a of the artificial satellite 10 so that the orientation of the camera 14 attached to the main body 10a of the artificial satellite 10 in the target attitude is aligned with the direction of gravity. This allows the orientation of the camera 14 to be maintained in the direction of gravity while the artificial satellite 10 is orbiting the celestial body 1.

[0035] The attitude control device 17 may include a gravity direction detection unit 17a (for example, an acceleration sensor) that detects the direction of gravity acting on the main body 10a of the satellite 10, and an attitude adjustment device 17b (for example, an actuator such as a flywheel, or a thruster that ejects gas) that operates to keep the attitude of the satellite 10 constant with respect to the detected direction of gravity. Note that multiple cameras 14 may be provided, and the orientations of the multiple cameras 14 may be different from each other so that at least one of the cameras 14 can acquire an image of the surface of the celestial body 1 regardless of the attitude of the main body 10a of the satellite 10 with respect to the celestial body 1.

[0036] The camera 14 is provided to generate an image showing an index indicating the position of the power receiving device 20. The index may be provided at the position of the power receiving device 20 on the surface side of the celestial body 1. The index may be, for example, a light-emitting unit 24 that emits light upward from the surface side of the celestial body 1. As an example, the light-emitting unit 24 may be a light source that emits light that spreads radially upward (the same applies to each of a plurality of light-emitting units 24 and a group of light-emitting units 24, which will be described later). As a result, for example, if the light-emitting unit 24 is located within the field of view (angle of view) of the camera 14, the light-emitting unit 24 will be recognizable in the image captured and generated by the camera 14 in this state. In another example, the light-emitting unit 24 may emit light (e.g., laser light) that travels in only one direction (the same applies to each of a plurality of light-emitting units 24 and a group of light-emitting units 24 described below). In this case, the power receiving device 20 includes a tracking device that controls the orientation of the light-emitting unit 24 (each light-emitting unit 24) so that the light emission direction of the light-emitting unit 24 is directed toward the satellite 10. This tracking device calculates the current position of the satellite 10 relative to each light-emitting unit 24 from time to time based on the orbital information of the satellite 10, and controls the orientation of the light-emitting unit 24 (each light-emitting unit 24) as described above based on the calculated position. The orbital information may be received from the satellite 10.

[0037] In addition, the image processing unit 15 determines whether or not the above-mentioned indicator is present in the image captured by the camera 14, and inputs the result of the determination (hereinafter simply referred to as the presence or absence of the indicator) to the power transmission device 13 (the power supply control unit 13c described below).

[0038] The image processing unit 15 detects the direction of the power receiving device 20 as seen from the artificial satellite 10 as the target direction based on the above-mentioned indicator shown in the image captured by the camera 14. Reference data representing the above-mentioned indicator (for example, the above-mentioned predetermined polygonal shape) may be stored in advance in the image processing unit 15, for example, and the image processing unit 15 may detect the target direction as described above based on the reference data and the above-mentioned image.

[0039] The power transmitting device 13 transmits electromagnetic waves from the area above the power receiving device 20 toward the target direction every time the satellite 100 passes over the area above the power receiving device 20, based on the presence or absence of an index in the image captured by the camera 14 (the above-mentioned judgment result of the image processing unit 15) and the target direction detected by the image processing unit 15.

[0040] The indicator may be a plurality of light-emitting elements 24 that emit light. The plurality of light-emitting elements 24 are arranged in a predetermined pattern. That is, the plurality of light-emitting elements 24 form an arrangement pattern of the light-emitting elements 24. The plurality of light-emitting elements 24 may be arranged at a plurality of locations on the power receiving surface of the power receiving device 20 or at a plurality of locations surrounding the power receiving surface. For example, the plurality of light-emitting elements 24 may be arranged at positions that become vertices of a virtual polygon of a predetermined shape as the arrangement pattern. Each light-emitting element 24 may be provided in the power receiving device 20 and emit light using electrical energy from the storage battery 22. The plurality of light-emitting elements 24 may be, for example, three or more light-emitting elements 24.

[0041] When the indices are a plurality of light-emitting elements 24 that are emitting light, the reference data described above is pattern information that represents the arrangement pattern of the plurality of light-emitting elements 24. The pattern information may be stored in or input to the image processing unit 15. The image processing unit 15 detects the direction of the power receiving device 20 as seen from the satellite 10 as the target direction based on this pattern information and the image captured by the camera 14 (i.e., the plurality of light-emitting elements 24 that are emitting light and appear in the image). For example, the target direction is detected based on the position of the arrangement pattern of the plurality of light-emitting elements 24 that are emitting light in the image.

[0042] In this case, the power receiving device 20 may have a group of light-emitting units 24 including a plurality of light-emitting units 24. That is, the power receiving device 20 may have a group of light-emitting units 24 including the above-described plurality of light-emitting units 24 and one or more additional light-emitting units 24. The number of light-emitting units 24 in one group may be, for example, four or more, five or more, or more. FIG. 4 is a diagram corresponding to the partially enlarged view of FIG. 3, and shows the group of light-emitting units 24 and related configuration. In the example of FIG. 4, the group of light-emitting units 24 is light-emitting units 24a to 24i.

[0043] In such a case, the power receiving device 20 may have a light-emission control unit 25 that changes which of the plurality of light-emitting units 24 are to emit light. The light-emission control unit 25 may change which of the plurality of light-emitting units 24 are to emit light, under the condition that the plurality of light-emitting units 24 that are to be caused to emit light by the light-emission control unit 25 are selected from a group of light-emitting units 24. In this case, the following configuration A or configuration B may be adopted.

[0044] <Configuration A> Among the group of light-emitting units 24, a plurality of predetermined arrangement patterns may be used as a plurality of indicators. A plurality of pieces of pattern information representing these arrangement patterns may be stored in advance in the image processing unit 15. The light-emitting control unit 25 changes the plurality of light-emitting units 24 to be caused to emit light under the condition that the plurality of light-emitting units 24 caused to emit light by the light-emitting control unit 25 form an arrangement pattern represented by one of the plurality of pattern information. This change may be made repeatedly. For example, the light-emitting control unit 25 may change the plurality of light-emitting units 24 to be caused to emit light each time the artificial satellite 10 makes one orbit around the celestial body, at other regular intervals, or at any arbitrary intervals.

[0045] On the other hand, the image processing unit 15 determines, based on the stored plurality of pattern information and the image captured by the camera 14, whether an index (plurality of emitting light-emitting units 24) corresponding to the arrangement pattern represented by any of the plurality of pattern information is present in the image, and if present, detects the direction of the power receiving device 20 (power receiving unit 21) as seen from the artificial satellite 10 as the target direction based on the index and the image.

[0046] <Configuration B> 5 is a block diagram showing a power transmission system 100 according to the configuration B. In this power transmission system 100, the satellite 10 further includes a communication unit 18, and the power receiving device 20 further includes a communication unit .

[0047] The light-emission control unit 25 changes the number of light-emitting units 24 to be illuminated and controls the transmission of pattern information representing the arrangement pattern of the number of light-emitting units 24 to be illuminated after the change. That is, the light-emission control unit 25 causes the communication unit 26 of the power receiving device 20 to transmit the pattern information to the satellite 10. As a result, the pattern information is wirelessly transmitted to the satellite 10. Note that this transmission control may be repeated, for example, until the communication unit 26 of the power receiving device 20 receives a notification signal indicating that the pattern information has been received. The light-emission control unit 25 may repeatedly change the number of light-emitting units 24 to be illuminated. In this case, each time the number of light-emitting units 24 is changed, the light-emission control unit 25 controls the transmission of pattern information representing the arrangement pattern of the number of light-emitting units 25 to be illuminated after the change, as described above. In the case of configuration B, in the initial state before the number of light-emitting units 24 is changed, the light-emission control unit 25 may control the transmission of pattern information representing the arrangement pattern of the number of light-emitting units 24 to be illuminated initially, as described above.

[0048] Meanwhile, when the communication unit 18 of the satellite 10 receives pattern information from the communication unit 26 of the power receiving device 20, it inputs the pattern information as an index to the image processing unit 15. Based on the latest pattern information input from the communication unit 18 and the image captured by the camera 14, the image processing unit 15 determines whether multiple light-emitting units 24 forming the arrangement pattern of the pattern information are present in the image, and if present, detects the direction of the power receiving device 20 (power receiving unit 21) as seen from the satellite 10 as the target direction based on the multiple light-emitting units 24. Note that, when the communication unit 18 of the satellite 10 receives pattern information from the power receiving device 20, it may wirelessly transmit the notification signal to that effect to the power receiving device 20.

[0049] <Components of the power transmission device> The power transmitting device 13 may include a power transmitting unit 13a, an attitude adjusting unit 13b, and a power supply control unit 13c.

[0050] The power transmitting unit 13a converts the electric energy generated by the power generating device 11 into electromagnetic waves and transmits the electromagnetic waves to the power receiving device 20. In this embodiment, the power transmitting unit 13a is supplied with power from the storage battery 12, thereby transmitting the electromagnetic waves.

[0051] In this embodiment, the power transmitting unit 13a may be a power transmitting antenna. The power transmitting unit 13a transmits electromagnetic waves intensively in a specific direction (for example, only in a specific direction). In this case, the power transmitting unit 13a may be a directional antenna. The specific direction will be simply referred to as the power transmitting direction (antenna orientation) below. The power transmitting unit 13a may be attached to the main body 10a of the satellite 10 so that its attitude with respect to the main body 10a of the satellite 10 can change. As the attitude of the power transmitting unit 13a changes, the power transmitting direction as seen from the main body 10a of the satellite 10 changes.

[0052] The attitude adjustment unit 13b changes the attitude (orientation) of the power transmission unit 13a so that the power transmission direction coincides with the target direction. Such attitude adjustment unit 13b may be, for example, a drive device (e.g., a motor) that changes the attitude of the power transmission unit 13a relative to the main body 10a of the satellite 10 by swinging the power transmission unit 13a about predetermined axes relative to the main body 10a of the satellite 10. Note that instead of or in addition to the attitude adjustment unit 13b changing the attitude of the power transmission unit 13a, an attitude adjustment device 17 provided on the satellite 10 may adjust the attitude of the main body 10a of the satellite 10 relative to the celestial body 1. This may adjust the power transmission direction to the target direction (in this case, such adjustment is performed in step S34, which will be described later).

[0053] Power supply control unit 13c controls the transmission of electromagnetic waves by power transmission unit 13a by controlling the supply of power from storage battery 12 to power transmission unit 13a. Based on the presence or absence of the index in the image captured by camera 14 and the target direction, power supply control unit 13c causes power transmission unit 13a to transmit electromagnetic waves from the upper region toward the target direction every time satellite 10 passes through the upper region.

[0054] Furthermore, instead of having the attitude adjustment unit 13b, the power transmitting device 13 may have a plurality of power transmitting units 13a that form a phased array. In this case, the power supply control unit 13c controls the phase of the power supplied to each power transmitting unit 13a, thereby causing mutual interference between electromagnetic waves generated by the plurality of power transmitting units 13a, resulting in an electromagnetic wave that is transmitted in a target direction. In this way, the power transmitting device 13 may transmit an electromagnetic wave in a target direction.

[0055] <Configuration and processing of power transmission timing control> As described above, camera 14 captures the surface of celestial body 1, continuously generates images of the surface, and continuously inputs the images to image processing unit 15. As described above, if an index representing the position of power receiving device 20 is present in the images continuously input from camera 14, image processing unit 15 outputs a signal to that effect to power feeding control unit 13c. If power is being supplied from storage battery 12 to power transmitting unit 13a when the signal is received, power feeding control unit 13c continues this power supply. If power is not being supplied from storage battery 12 to power transmitting unit 13a when the signal is received, power feeding control unit 13c starts this power supply.

[0056] On the other hand, as described above, when an indicator representing the power receiving device 20 is not present in the images continuously input from the camera 14, the image processing unit 15 outputs a signal to that effect to the power feeding control unit 13c. If the power feeding control unit 13c is supplying power from the storage battery 12 to the power transmitting unit 13a when the signal is received, the power feeding control unit 13c stops this power supply. If the power feeding from the storage battery 12 to the power transmitting unit 13a is stopped when the signal is received, the power feeding control unit 13c continues to stop this power supply.

[0057] By this process, every time the satellite 10 passes over the area above the power receiving device 20, the power transmitting device 13 transmits electromagnetic waves from the area above the power receiving device 20.

[0058] (Power transmission method) 6 is a flowchart showing a power transmission method according to an embodiment of the present invention. This power transmission method is a method for transmitting power to a power receiving device 20 located on the surface of the above-mentioned celestial body 1, and is performed by the above-mentioned artificial satellite 10. This power transmission method includes steps S1 to S3.

[0059] In step S1, the artificial satellite 10 is caused to fly so as to repeatedly orbit the celestial body 1 in an orbit that passes over the area above the power receiving device 20. For example, a rocket carrying the artificial satellite 10 is launched from the Earth, and the artificial satellite 10, which is separated from the rocket in outer space, flies toward the celestial body 1 and is injected into the above-mentioned orbit of the celestial body 1. As a result, the artificial satellite 10 begins to orbit the celestial body 1 in the above-mentioned orbit.

[0060] Thereafter, even while steps S2 and S3 are being performed, the artificial satellite 10 continues to fly around the celestial body 1 in the above orbit.

[0061] In step S2, electrical energy is generated from sunlight by the power generation device 11 provided on the satellite 10. Also in step S2, the power generation device 11 stores the generated electrical energy in the storage battery 12 of the satellite 10. Step S2 is subsequently performed during a time period when the power generation device 11 is exposed to sunlight, even when step S3 is being performed.

[0062] In step S3, every time the satellite 10 passes over an area above the power receiving device 20, the power transmitting device 13 of the satellite 10 transmits electromagnetic waves from the area above the power receiving device 20, and the power receiving device 20 converts the electromagnetic waves from the power transmitting device 13 into electric energy. Step S3 may include steps S31 to S40.

[0063] In step S31, the camera 14 of the artificial satellite 10 generates an image of the surface of the celestial body 1. In step S32, the image processing unit 15 determines whether or not an index representing the position of the power receiving device 20 exists in the image generated in step S31. For example, the image processing unit 15 determines whether or not an index representing the power receiving device 20 exists in the image generated in step S31 based on reference data of the index (for example, a plurality of pieces of pattern information stored in advance or the latest pattern information received from the power receiving device 20).

[0064] If the determination result in step S32 is positive (i.e., if it is determined that an index exists in the image), the process proceeds to step S33, and steps S31 and S32 are performed again. That is, step S33 and steps S31 and S32 are performed again in parallel. On the other hand, if the determination result in step S32 is negative, the process does not proceed to step S33, and steps S31 and S32 are performed again.

[0065] In step S33, the image processing unit 15 detects the direction of the power receiving device 20 (index) relative to the main body 10a of the satellite 10 as the target direction, based on the position of the index in the image generated in the immediately preceding step S31. This target direction may be the direction at the time step S31 is performed, or may be the direction at a future time when step S36 or S37, described later, will be performed based on this target direction. In the latter case, the image processing unit 15 detects the target direction at a future time when step S36 or S37 will be performed, based on known information about the orbit and flight speed of the satellite 10, a known delay time from when the target direction was detected in the immediately preceding step S31 until when step S36 or S37, described later, will be performed based on the target direction, and the position of the index in the image generated in step S31. The image processing unit 15 inputs the detected target direction to the power transmitting device 13 (attitude adjustment unit 13b). After step S33 is completed, the next step S34 is performed.

[0066] In step S34, attitude adjustment unit 13b adjusts the attitude of power transmission unit 13a so that the power transmission direction of power transmission unit 13a coincides with the target direction input in the immediately preceding step S33. By repeatedly performing steps S31 to S34, power transmission unit 13a is adjusted to face the power receiving device 20 (target direction) even if the relative position and orientation relationship between satellite 10 and power receiving device 20 changes due to the flight of satellite 10. Therefore, even when power transmission is continued in step S37 described below, power transmission unit 13a is adjusted to face the power receiving device 20 (target direction).

[0067] Steps S33 and S34 are performed each time the determination result in step S32 is affirmative.

[0068] On the other hand, if the determination result in step S32 is positive, steps S33 and S34 are performed as described above, and step S35 is also performed. That is, steps S33, S34 and step S35 are performed in parallel.

[0069] In step S35, it is determined whether the power transmission unit 13a is transmitting electromagnetic waves to the power receiving device 20. This determination may be made by the power supply control unit 13c. If the determination result in step S35 is negative (if the power transmission unit 13a is not transmitting electromagnetic waves to the power receiving device 20 at this point), the process proceeds to step S36.

[0070] In step S36, power supply control unit 13c starts supplying power from storage battery 12 to power transmission unit 13a. As a result, power transmission unit 13a starts transmitting electromagnetic waves. Note that power transmission device 13 may be configured to perform step S36 after completing the above-described step S34, which is performed in parallel with this step S35. Therefore, in this step S36, transmission unit 13a transmits electromagnetic waves in the target direction, which is the direction of power receiving device 20.

[0071] On the other hand, if the determination result of step S35 is positive, the process proceeds to step S37. In step S37, power supply control unit 13c continues supplying power from storage battery 12 to power transmission unit 13a. This causes power transmission unit 13a to continue transmitting electromagnetic waves. At this time, since the power transmission direction of power transmission unit 13a has been adjusted to the target direction in the repeated step S34, transmission unit 13a transmits electromagnetic waves in the target direction, which is the direction of power receiving device 20.

[0072] If the result of the determination in step S32 is negative, steps S31 and S32 are performed again, as described above, and step S38 is also performed.

[0073] In step S38, it is determined whether the power transmission unit 13a is transmitting electromagnetic waves in the target direction to the power receiving device 20. This determination may be made by the power supply control unit 13c. If the determination result in step S38 is positive (if the power transmission unit 13a is transmitting electromagnetic waves at this point), the process proceeds to step S39.

[0074] In step S39, the power supply control unit 13c stops the power supply from the storage battery 12 to the power transmission unit 13a, causing the power transmission unit 13a to stop transmitting the electromagnetic wave in the target direction.

[0075] On the other hand, if the determination result in step S38 is negative, the process proceeds to step S40. In step S40, the power supply control unit 13c continues to stop the power supply from the storage battery 12 to the power transmission unit 13a. As a result, the power transmission unit 13a continues to stop transmitting electromagnetic waves.

[0076] In steps S36 and S37, the power supply control unit 13c may supply power corresponding to the maximum energy to the power transmitting unit 13a so that the power transmitting unit 13a transmits electromagnetic waves with the maximum energy. Here, the maximum energy is the maximum energy of electromagnetic waves that the power transmitting unit 13a can transmit per unit time.

[0077] Through the above-described steps S36 and S37, the power receiving device 20 converts the electromagnetic waves from the power transmitting device 13 into electric energy, and uses the electric energy to operate the predetermined machine 2 in long-term or permanent shade. For example, the electric energy is supplied to the machine 2 via the storage battery 22 and the charger 23.

[0078] (Effects of the embodiment) According to this embodiment, the satellite 10 repeatedly orbits the celestial body 1 in an orbit that passes through an area above the power receiving device 20 on the surface of the celestial body 1. In this case, every time the satellite 10 passes through the area above, the power transmitting device 13 of the satellite 10 transmits electromagnetic waves from the area above to the power receiving device 20. As a result, the power receiving device 20 repeatedly receives the electromagnetic waves from the satellite 10 and converts the electromagnetic waves into electrical energy. Therefore, the power receiving device 20 can repeatedly obtain electrical energy from the electromagnetic waves. Therefore, in the long-term or permanent shadow of the surface of the celestial body 1, electrical energy can be obtained by the power receiving device 20, and the electrical energy can be used to operate the probe 2 or another machine 2.

[0079] The image processing unit 15 detects the target direction, which is the direction of the power receiving device 20 as seen from the main body 10a of the artificial satellite 10, based on an index in the image. If the index is a light emitting unit 24 that emits light upward from the surface side of the celestial body 1, the target direction can be detected even if the power receiving device 20 is located in darkness such as long-term or permanent shade.

[0080] In this regard, the arrangement pattern of the multiple light-emitting units 24 can be used as an indicator precisely because the power receiving device 20 (power receiving unit 21) is placed against a wall or in permanent shade for a long period of time. In this way, the multiple light-emitting units 24 emit light in the darkness of a wall or permanent shade for a long period of time, so their arrangement pattern is clearly reflected in the image. Therefore, the multiple light-emitting units 24 can be used as a highly reliable indicator. Furthermore, in a celestial body 1 without an atmosphere, the arrangement pattern in the image based on the light from the multiple light-emitting elements 24 is not affected by the atmosphere (absorption, refraction, and scattering of the light), so the arrangement pattern of the multiple light-emitting elements 24 can be used as an indicator. The arrangement pattern can be used as an index even in a celestial body 1 having a sparse atmosphere to the extent that the arrangement pattern in the image can be recognized by the image processing unit 15. In other words, even if the light of the plurality of light-emitting units 24 is affected by the atmosphere, the arrangement pattern of the plurality of light-emitting units 24 can be used as an index even in a celestial body 1 having a sparse atmosphere to the extent that fluctuations in the arrangement pattern in the image due to this effect are within the range that can be recognized.

[0081] Furthermore, when the arrangement pattern of the plurality of light-emitting units 24 is used as an index, the image processing unit 15 detects the target direction, which is the direction of the power receiving device 20, based on the index. This makes it possible to avoid erroneous recognition of the target direction and to prevent the power generated by the artificial satellite 100 from being transmitted to an unintended location (for example, power theft).

[0082] Furthermore, when the electromagnetic waves transmitted to the power receiving device 20 are microwaves (or millimeter waves) as in this embodiment, even if non-metallic regolith accumulates on the power receiving surface of the power receiving unit 21, power can be transmitted to the power receiving device 20 by the power transmitting device 13.

[0083] By having satellite 10 orbit celestial body 1 at an altitude of approximately 100 km or less above the surface of celestial body 1, the distance between power transmitting unit 13a and power receiving unit 21 during power transmission can be approximately 100 km or less. Such a short power transmission distance can improve power transmission efficiency and increase the amount of power transmitted without increasing the scale of satellite 10 as a power transmitting satellite.

[0084] The present invention is not limited to the above-described embodiments, and various modifications may be made within the scope of the technical concept of the present invention. For example, the power transmission system 100, the satellite 10, or the power receiving device 20 according to the embodiments of the present invention may not have all of the above-described features, or may have only some of the above-described features.

[0085] Furthermore, any one of the following modified examples 1 to 3 may be adopted alone, or any combination of two or more of modified examples 1 to 3 may be adopted. In this case, the points not described below are the same as those described above.

[0086] (Change example 1) The artificial satellite 10 further includes a gravity direction detection unit that detects the direction of gravity acting on its main body 10a (hereinafter simply referred to as the gravity direction). This gravity direction detection unit inputs the detected gravity direction to the power transmission device 13 (power supply control unit 13c). Such a gravity direction detection unit may be the gravity direction detection unit 17a included in the attitude control device 17 described above as shown in FIG. 1, or may be provided separately from the attitude control device 17.

[0087] Based on the target direction detected by the image processing unit 15 and the direction of gravity detected by the gravity direction detection unit 17a, the power transmitting device 13 transmits electromagnetic waves from an area above the power receiving device 20 to the target direction for a period of time during which the magnitude of the angle θ of the target direction with respect to the direction of gravity of the celestial body 1 is within a predetermined angle range. That is, based on the target direction detected by the image processing unit 15 and the direction of gravity detected by the gravity direction detection unit 17a, the power supply control unit 13c supplies power from the storage battery 12 to the power transmitting unit 13a for a period of time during which the magnitude of the angle θ of the target direction with respect to the direction of gravity of the celestial body 1 is within a predetermined angle range.

[0088] The angle θ is the angle between the direction of gravity of the celestial body 1 at the position of the artificial satellite 10 and the target direction, as shown in Figure 7. The predetermined angle range is, for example, a range between 0 degrees and an upper limit angle. This upper limit angle may be, for example, 10 degrees, 20 degrees, 30 degrees, 40 degrees, 45 degrees, or 50 degrees.

[0089] 8 shows a flowchart of the power transmission method in the case of Modification 1. In Modification 1, step S3 is performed as follows. If the determination result in step S32 is positive (i.e., if it is determined that an index exists in the image), the process proceeds to step S33, and steps S31 and S32 are repeated again, but unlike the above, step S38 is not performed. That is, steps S38 to S40 are omitted.

[0090] In step S33, if the target direction is detected as described above, the process proceeds to step S34 and then to step S35. In modification 1, in step S35, the power supply control unit 13c determines whether the magnitude of the angle θ (FIG. 7) between the target direction detected in the immediately preceding step S33 and the direction of gravity currently detected by the gravity direction detection unit 17a is within a predetermined angle range. If the determination result in step S35 is positive, the process proceeds to step S36; if not, the process proceeds to step S37.

[0091] In step S36, the power supply control unit 13c starts supplying power from the storage battery 12 to the power transmission unit 13a. When performing step S36, if the power supply control unit 13c has already started supplying power from the storage battery 12 to the power transmission unit 13a, the power supply control unit 13c continues supplying power from the storage battery 12 to the power transmission unit 13a.

[0092] In step S37, the power supply control unit 13c stops the power supply from the storage battery 12 to the power transmission unit 13a. When performing step S37, if the power supply control unit 13c has already stopped the power supply from the storage battery 12 to the power transmission unit 13a, the power supply control unit 13c continues to stop the power supply from the storage battery 12 to the power transmission unit 13a.

[0093] According to the first modification, the power transmitting device 13 transmits electromagnetic waves from an area above the power receiving device 20 toward the target direction based on the target direction and the direction of gravity for a period of time when the angle θ of the target direction with respect to the direction of gravity is within a predetermined angle range. This allows power transmission during a period of time when the distance between the artificial satellite 10 and the power receiving device 20 is short (i.e., when the angle θ is within the predetermined angle range). This allows for increased power transmission efficiency.

[0094] The effect of Modification Example 1 can also be obtained in the above-described embodiment. That is, in the above-described embodiment, the angle of view of camera 14, whose orientation is maintained in the direction of gravity, may be set to twice the upper limit angle. This allows the above-described embodiment to achieve the same effect as Modification Example 1.

[0095] (Change example 2) The electromagnetic waves transmitted from power transmitting unit 13a to power receiving device 20 do not have to be microwaves or millimeter waves, and may be, for example, laser light. In this case, power transmitting unit 13a is a laser light source that transmits laser light to power receiving unit 21 (i.e., in the target direction), and power receiving unit 21 is a photoelectric conversion unit that converts the laser light from power transmitting unit 13a into electrical energy (electric power).

[0096] (Change example 3) 9 is a block diagram showing a power transmission system 100 according to a third modification. According to the third modification, the power receiving device 20 has a signal transmitting unit 27 that transmits a pilot signal to the satellite 10. In this case, the satellite 10 has a signal receiving unit 19 instead of the camera 14 and image processing unit 15 described above. The signal receiving unit 19 receives the pilot signal from the signal transmitting unit 27 and detects the direction of arrival of the pilot signal as the target direction. The signal receiving unit 19 inputs the detected target direction to the attitude adjustment unit 13b. The pilot signal may be a radio wave.

[0097] 10 is a flowchart showing a power transmission method according to Modification 3. In the power transmission method according to Modification 3, the above-mentioned step S31 is not performed, and step S32 is repeatedly performed while performing the above-mentioned step S2. In this step S32, the signal receiving unit 19 repeatedly determines whether or not a pilot signal from the signal transmitting unit 27 has been received.

[0098] If the determination result in step S32 is positive (i.e., if it is determined that a pilot signal has been received), the process proceeds to step S33 and step S32 is repeated again, but unlike the above embodiment, the process does not proceed to step S35.

[0099] In step S33, the signal receiving unit 19 detects the arrival direction of the pilot signal received in the immediately preceding step S32 as the direction (target direction) of the power receiving device 20 (power receiving unit 21). Then, the process proceeds to step S34 and step S35.

[0100] In step S35, the power supply control unit 13c determines whether the magnitude of the angle θ formed between the target direction detected in the immediately preceding step S33 and the direction of gravity currently detected by the gravity direction detection unit 17a is within a predetermined angle range. Here, the angle θ and the predetermined angle range are the same as the angle θ and the predetermined angle range in the above-described first modification. If the determination result in step S35 is positive, the process proceeds to step S36; otherwise, the process proceeds to step S37.

[0101] In step S36, the power supply control unit 13c starts supplying power from the storage battery 12 to the power transmission unit 13a. When performing step S36, if the power supply control unit 13c has already started supplying power from the storage battery 12 to the power transmission unit 13a, the power supply control unit 13c continues supplying power from the storage battery 12 to the power transmission unit 13a.

[0102] In step S37, the power supply control unit 13c stops the power supply from the storage battery 12 to the power transmission unit 13a. When performing step S37, if the power supply control unit 13c has already stopped the power supply from the storage battery 12 to the power transmission unit 13a, the power supply control unit 13c continues to stop the power supply from the storage battery 12 to the power transmission unit 13a.

[0103] In the third modification, the above-mentioned steps S38 to S40 are omitted. [Explanation of symbols]

[0104] 1 celestial body, 2 machine (probe), 10 artificial satellite, 10a main body, 11 power generation device, 12 storage battery, 13 power transmission device, 13a power transmission unit (power transmission antenna), 13b attitude adjustment unit, 13c power supply control unit, 14 camera, 15 image processing unit, 17 attitude control device, 17a gravity direction detection unit, 17b attitude adjustment device, 18 communication unit, 19 signal receiving unit, 20 power receiving device, 21 power receiving unit (power receiving rectenna), 22 storage battery, 23 charger, 24 light emitting unit, 25 light emitting control unit, 26 communication unit, 27 signal transmitting unit, 100 power transmission system

Claims

1. An artificial satellite that orbits a celestial body other than the Earth as a planet or satellite in the solar system that has no atmosphere or a thin atmosphere, and transmits power to a power receiving device that is located in a long-term shadow or permanent shadow where sunlight does not shine on the surface of the celestial body for a predetermined long period of time or permanently, a power generation device that generates electrical energy from sunlight; a camera for imaging the surface of the celestial body; an image processing unit that detects, as a target direction, a direction of the power receiving device on the surface of the celestial body as seen from the artificial satellite, based on an indicator that indicates the position of the power receiving device and that is captured in the image captured by the camera; a power transmitting device that converts the electrical energy into electromagnetic waves and transmits the electromagnetic waves in the target direction detected by the image processing unit, the indicator is a plurality of light-emitting units that emit light in the darkness of the long-term shade or the permanent shade, and the plurality of light-emitting units are arranged in a predetermined arrangement pattern; the image processing unit detects, as the target direction, a direction of the power receiving device as seen from the satellite based on pattern information representing the arrangement pattern of the plurality of light-emitting units and the image; The artificial satellite repeatedly orbits the celestial body in an orbit that passes through an area above the power receiving device, and the power transmitting device transmits the electromagnetic waves from the area above the power receiving device.

2. the power transmission device has a storage battery that stores the electrical energy generated by the power generation device, The satellite according to claim 1 , wherein the power transmitting device converts the electrical energy stored in the storage battery into the electromagnetic waves and transmits the electromagnetic waves from the upper region to the power receiving device.

3. 3. The satellite according to claim 1, wherein the power transmitting device transmits the electromagnetic waves from the upper region of the power receiving device toward the target direction each time the satellite passes through the upper region, based on the presence or absence of the indicator in the image captured by the camera and the target direction.

4. the power receiving device has a group of light-emitting units including the plurality of light-emitting units, the plurality of light-emitting units that emit light are selected from the group of light-emitting units and are changed under the condition that they form one of a plurality of preset arrangement patterns; The image processing unit a plurality of pieces of pattern information respectively representing the plurality of arrangement patterns are stored; 4. The artificial satellite according to claim 1, wherein it is determined whether the plurality of light-emitting elements forming any of the arrangement patterns of the plurality of pattern information are present in the image based on the plurality of pattern information and the image, and if present, the target direction is detected based on the plurality of light-emitting elements.

5. the power receiving device has a group of light-emitting units including the plurality of light-emitting units, the plurality of light-emitting units that emit light are changed under the condition that they are selected from the group of light-emitting units, and pattern information that represents the arrangement pattern of the plurality of light-emitting units that emit light after the change is transmitted from the power receiving device to the artificial satellite; The artificial satellite according to any one of claims 1 to 3, wherein the image processing unit determines whether the plurality of light-emitting elements forming the arrangement pattern of the pattern information are present in the image based on the pattern information and the image received by the artificial satellite, and if present, detects the target direction based on the plurality of light-emitting elements.

6. an attitude control device that maintains the attitude of the main body of the artificial satellite in a target attitude with respect to the direction of gravity of the celestial body; a gravity direction detection unit for detecting the gravity direction of the celestial body, The satellite according to any one of claims 1 to 5, wherein the power transmitting device transmits the electromagnetic waves from the upper region of the power receiving device toward the target direction, based on the target direction detected by the image processing unit and the direction of gravity detected by the gravity direction detection unit, for a time period during which the angle of the target direction with respect to the direction of gravity is within a predetermined angle range.

7. The artificial satellite according to any one of claims 1 to 6, wherein the celestial body is the moon.

8. A power transmission system comprising the satellite according to any one of claims 1 to 7 and the power receiving device.

9. A power transmission method for transmitting power from an artificial satellite orbiting a celestial body that is a planet or satellite other than the Earth in the solar system to a power receiving device that is located in long-term shade or permanent shade on the surface of the celestial body where sunlight does not shine for a predetermined long period of time or permanently, comprising: Flying the artificial satellite according to any one of claims 1 to 7 so as to repeatedly orbit the celestial body in an orbit that passes through an area above the power receiving device, generating electrical energy from sunlight using a power generation device provided on the satellite; A power transmission method in which the satellite's power transmission device converts the electrical energy into electromagnetic waves and transmits the electromagnetic waves from the upper region to the power receiving device, and the power receiving device converts the electromagnetic waves from the power transmission device into electrical energy.

10. Each time the satellite passes through the upper region, a power transmitting device of the satellite transmits the electromagnetic waves from the upper region to the power receiving device; The power transmission method according to claim 9, wherein the electric energy converted by the power receiving device is used to operate a predetermined machine in the permanent shade or the long-term shade.

Images