Flying object, pointing control system and observation method

Abstract

To make it possible to fix a fluctuation direction of an electric field vector of horizontal polarization to be irradiated on an observation object at a right angle relative to a specific plane.SOLUTION: A observation satellite 200 is configured to adjust a directional direction of an antenna 201 so that an azimuth direction Az matches a normal line direction of a specific plane to be defined based on a normal line direction of an object plane in a position to be designated of the observation object 102, and a bore site direction of the antennal 201 is directed at the observation object 102; irradiate a beam toward the bore site direction of the antenna 201; and receive the beam reflected upon the observation object 102 by using the antenna 201, in which the observation object 102 exists in a front view direction when viewing from the observation satellite 200, or a rear view direction when viewing from the observation satellite 200.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to beam pointing control for observing an observation target. [Background technology]

[0002] Conventionally, observations have been carried out using spacecraft. Non-Patent Document 1 discloses that the beam is controlled to rotate so that the beam is directed toward an observation target. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-95226 [Patent Document 2] U.S. Patent Application Publication No. 2021 / 0018613 [Non-patent literature]

[0004] [Non-Patent Document 1] A tomographic formulation of spotlight-mode synthetic apertureradar,Proc IEEE,vol.71,pp.917-925 Summary of the Invention [Problem to be solved by the invention]

[0005] In Non-Patent Document 1, the beam direction (vector) is aligned with the direction of the object to be observed, but rotation around the beam direction is not defined. Therefore, the direction of variation of the electric field vector of the electromagnetic waves irradiated onto the object of observation cannot be controlled to the intended direction, and the object of observation cannot be observed under the desired electric field vector incidence conditions.

[0006] The present disclosure aims to make it possible to fix the direction of variation of the electric field vector of horizontally polarized waves irradiated onto an object to be observed perpendicular to the normal direction of the plane on which the object is located. [Means for solving the problem]

[0007] The flying object of the present disclosure is an antenna for emitting a beam and receiving the beam reflected by an observation target located on the Earth's surface; an antenna control device that adjusts the direction of the antenna so that the azimuth direction of the antenna coincides with the normal direction of a specific plane defined based on the normal direction of a target plane at the position of a specified observation target, and so that the boresight direction of the antenna is directed toward the observation target; a beam control device that irradiates a beam in the boresight direction of the antenna; a receiving device that receives a beam reflected by the target using the antenna; Equipped with. The observation target exists in a forward direction as seen from the flying object or in a backward direction as seen from the flying object. The specific plane is a plane formed by the relative direction of the antenna with respect to the observation target and the normal direction of the target plane. The target plane is the ground surface at the location of the target. The antenna control device adjusts the direction of the antenna in accordance with the movement of the flying object. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to fix the direction of variation of the electric field vector of the horizontally polarized wave irradiated onto the observation target at a right angle to the normal direction of the plane on which the observation target is located. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a configuration diagram of a satellite observation system 100 according to a first embodiment. [Figure 2] FIG. 2 is a configuration diagram of an observation satellite 200 according to the first embodiment. [Figure 3] FIG. 2 is a schematic diagram of an observation method according to the first embodiment. [Figure 4] 3 is a flowchart of an observation method according to the first embodiment. [Figure 5] Schematic diagram of the conventional observation method. [Figure 6] FIG. 1 is a schematic diagram of a first example according to the first embodiment. [Figure 7] FIG. 10 is a schematic diagram of a second example according to the first embodiment. [Figure 8] FIG. 10 is a schematic diagram of a third example according to the first embodiment. [Figure 9] FIG. 10 is a schematic diagram of a fourth example according to the first embodiment. [Figure 10] FIG. 10 is a schematic diagram of an observation method according to the second embodiment. [Figure 11] FIG. 11 is a schematic diagram of an observation method according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] In the embodiments and drawings, the same or corresponding elements are denoted by the same reference numerals. The description of elements denoted by the same reference numerals as those already described will be omitted or simplified as appropriate. Arrows in the drawings primarily indicate the flow of signals, data, or processes.

[0011] Embodiment 1 The satellite observation system 100 will be described with reference to FIGS.

[0012] ***Configuration Description*** The configuration of a satellite observation system 100 as an observation system will be described with reference to FIG. The satellite observation system 100 includes an observation satellite 200 as an airborne object and a ground station 110. The satellite observation system 100 is an example of an observation system that performs observations using an airborne object, such as an artificial satellite or an aircraft. The observation satellite 200 is an artificial satellite that observes the observation target 102. The observation is performed by emitting a beam and receiving the beam reflected by the observation target 102 located on the Earth's surface. The artificial satellite is also called a spacecraft. The antenna 201 is also called an antenna. The pointing target 101 is a point directed by the antenna 201. Specifically, the observation target 102 is the pointing target 101. The observation target 102 is an object that is observed. A specific observation target 102 is an object fixed to the earth's surface. The ground station 110 communicates with the observation satellite 200 .

[0013] The dashed arrow passing through the observation satellite 200 represents the orbit of the observation satellite 200. The orbit is also called a path.

[0014] The dashed arrow from the observation satellite 200 to the target 101 indicates the beam direction. The beam direction Beam is the direction of the beam emitted from the antenna 201. The beam is an electromagnetic wave.

[0015] The satellite position Psat is the position of the observation satellite 200. The satellite position Psat corresponds to the position of the antenna 201. The three arrows attached to the observation satellite 200 indicate the boresight direction Boa, the azimuth direction Az, and the elevation direction El. The boresight direction Boa is the boresight direction of the antenna 201 . The azimuth direction Az corresponds to the horizontally polarized wave excitation direction of the antenna 201. The elevation direction El is the elevation direction of the antenna 201, and is perpendicular to the boresight direction Boa and the azimuth direction Az.

[0016] The target position Pg is the position of the observation target 102 . The upward arrow attached to the observation target 102 represents the normal direction N. The normal direction N is the normal direction of the object plane at the position of the observation object 102 . The target plane is a plane based on the position of the observation target 102. Specifically, the target plane is the earth's surface. When the observation target 102 is a building, the normal direction N corresponds to the direction of the floors of the building.

[0017] The configuration of the observation satellite 200 will be described with reference to FIG. The observation satellite 200 includes an antenna 201S, an antenna 201R, a position sensor 202, and an attitude sensor 203. The antenna 201S is the antenna 201 for transmission. The antenna 201R is the antenna 201 for reception. The position sensor 202 is a sensor for determining the position of the observation satellite 200. A specific example of the position sensor 202 is a GPS. GPS is an abbreviation for Global Positioning System. The attitude sensor 203 is a sensor for measuring the attitude of the observation satellite 200. A specific example of the attitude sensor 203 is a star tracker.

[0018] The observation satellite 200 includes devices (computers) such as a communication device 211 and a target recording device 212. The observation satellite 200 includes a pointing control system 220. The pointing control system 220 includes devices such as a pointing control device 221, an antenna control device 222, and a beam control device 223. The observation satellite 200 includes devices such as a receiving device 231 and an observation result recording device 232 . The apparatus includes a processing circuit. The processing circuitry may be dedicated hardware or may be a processor that executes a program stored in a memory. When the processing circuitry is dedicated hardware, the processing circuitry may be, for example, a single circuit, a multiple circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof. ASIC is an abbreviation for Application Specific Integrated Circuit. FPGA is an abbreviation for Field Programmable Gate Array.

[0019] The ground station 110 comprises a communication device 111 .

[0020] ***Explanation of Operation*** The operation procedure of the observation satellite 200 corresponds to the observation method.

[0021] The characteristics of the observation method will be explained based on Figure 3. The solid arrow from the observation target 102 to the antenna 201 indicates the relative direction of the antenna 201 with respect to the observation target 102 . The shaded plane is the plane in which the electric field vector of the horizontal polarization of the beam lies. The dashed arrow attached to the observation target 102 in the shaded plane indicates the direction in which the electric field vector of the horizontally polarized beam incident on the observation target 102 varies. The dotted arrow attached to the observation target 102 on the ground surface represents the elevation direction El projected onto the ground surface.

[0022] The equipment on the observation satellite 200 operates as follows. The antenna control device 222 adjusts the pointing direction of the antenna 201 so that the azimuth direction Az of the antenna 201 coincides with the normal direction of the specific plane and so that the boresight direction Boa of the antenna 201 points toward the pointing target 101. The antenna control device 222 adjusts the pointing direction of the antenna 201 in accordance with the movement of the observation satellite 200. The specific plane is a plane formed by the relative direction of the antenna 201 with respect to the observation target 102 and the normal direction N of the ground surface at the position of the observation target 102. The beam control device 223 irradiates a beam in the direction of the antenna 201S. However, since the antenna 201S is directed toward the observation target 102, the beam control device 223 does not need to adjust the beam direction from the direction of the antenna 201S by electronic scanning. The receiver 231 receives the beam reflected by the object 102 using the antenna 201R.

[0023] The procedure for the observation method will be described with reference to FIG. In step S110, the observation satellite 200 receives one or more pieces of target information. The target information indicates the target position Pg, the normal direction N, and the observation conditions. The observation conditions specify the observation orbit and satellite observation point, etc. The observation orbit is the orbit along which the observation is carried out. The satellite observation point is the location where the observation is carried out. The observation satellite 200 observes the observation target 102 from the satellite observation point of the observation orbit.

[0024] The information will be accepted as follows: The operator inputs the target information into the control device of the ground station 110 . The communication device 111 transmits the input target information to the control device. The communication device 211 receives the target information. The object recording device 212 includes a storage device such as a memory, and records the received object information. An object list is stored in the object recording device 212. The object list indicates one or more pieces of object information.

[0025] In step S120, the direction control device 221 calculates the direction of direction (Boa, Az, El) and beam direction Beam of the antenna 201 based on the target information.

[0026] The direction of pointing of the antenna 201 and the beam direction Beam are calculated in the following procedure. The position sensor 202 measures the position of the observation satellite 200 at each time. The attitude sensor 203 measures the attitude of the observation satellite 200 at each time. The pointing control device 221 selects from the target list target information that indicates observation conditions that match the satellite position Psat. The pointing control device 221 calculates the pointing direction and beam pointing direction Beam of the antenna 201 based on the satellite position Psat, the target position Pg, and the normal direction N. The target position Pg and the normal direction N are indicated in the selected target information.

[0027] The calculation of the direction of direction (Boa, Az, El) of the antenna 201 and the beam direction Beam will be described in detail later.

[0028] In step S130, the antenna controller 222 directs the antenna 201 in a direction of pointing.

[0029] The antenna 201 is oriented as follows: The direction control device 221 outputs an antenna direction command. The antenna direction command indicates the direction of the antenna 201. The output antenna direction command is input to the antenna control device 222. The antenna control device 222 points the antenna 201 in the pointing direction specified by the antenna pointing command. At this time, the antenna control device 222 points the antenna 201 in the pointing direction specified by the antenna pointing command by adjusting the attitude of the observation satellite 200 or the attitude of the antenna 201. However, the antenna control device 222 may point the antenna 201 in the pointing direction by adjusting the attitude of the observation satellite 200 and the attitude of the antenna 201. Alternatively, the antenna control device 222 may point the antenna 201 in the pointing direction specified by the antenna pointing command by adjusting only the attitude of the observation satellite 200. Alternatively, the antenna control device 222 may point the antenna 201 in the pointing direction specified by the antenna pointing command by adjusting only the attitude of the antenna 201. The attitude of the observation satellite 200 is adjusted by controlling an attitude control device provided on the observation satellite 200. Examples of the attitude control device include a reaction wheel, a control moment gyro, and a thruster. The antenna 201 may also be equipped with a drive mechanism. The attitude of the antenna 201 is adjusted by controlling the drive mechanism equipped in the antenna 201. An example of the drive mechanism is a gimbal. The antenna controller 222 performs feedback control or feedforward control to adjust the attitude of the observation satellite 200 and the attitude of the antenna 201, respectively.

[0030] In step S140, the beam control device 223 irradiates a beam from the antenna 201 in the beam pointing direction Beam.

[0031] The beam is applied as follows: The beam pointing control device 221 outputs a beam pointing command. The beam pointing command indicates the beam pointing direction (Beam). The output beam pointing command is input to the beam control device 223. The beam control device 223 uses the antenna 201S to irradiate a beam in the beam direction Beam specified by the beam direction command.

[0032] In step S150, the observation satellite 200 obtains the observation results for the observation target 102. The observation result is data obtained by observing the observation target 102.

[0033] The observation results are obtained as follows. The beam (transmitted wave) emitted from the antenna 201S is reflected by the object 102 to be observed. The beam (reflected wave) reflected by the observation target 102 is incident on the antenna 201R. The receiver 231 receives the beam from the antenna 201R and processes the received beam, thereby obtaining an observation result. The observation result recording device 232 includes a storage device such as a memory, and records the observation results.

[0034] The calculation of the orientation direction in step S120 will now be described in detail. The pointing control device 221 calculates the following equations: As a result, the pointing direction (Boa, Az, El) and the beam pointing direction Beam of the antenna 201 are calculated.

[0035]

number

[0036] The arrows above each symbol represent vectors.

[0037] The boresight direction Boa corresponds to the relative direction of the satellite position Psat with respect to the target position Pg. The boresight direction Boa is calculated by calculating equation (1-1). The azimuth direction Az corresponds to the normal direction of a plane (specific plane) formed by the boresight direction Boa and the normal direction N. When the observation target 102 is located on the right side of the nadir point trajectory as seen from the observation satellite 200, the azimuth direction Az is calculated by calculating formula (1-2R). When the observation target 102 is located on the left side of the nadir point trajectory as seen from the observation satellite 200, the azimuth direction Az is calculated by calculating formula (1-2L). The nadir point trajectory is the trajectory of points directly below the observation satellite 200. In other words, the nadir point trajectory corresponds to the orbit of the observation satellite 200 projected onto the Earth's surface. The elevation direction El corresponds to the cross product of the boresight direction Boa and the azimuth direction Az. The elevation direction El is calculated using equation (1-3). The beam pointing direction Beam is equal to the boresight direction Boa as shown in equation (1-4).

[0038] Each direction may be expressed in vector form, or in angle form indicating an angle from a reference direction.

[0039] ***Supplement to the first embodiment*** The first embodiment relates to beam pointing control for keeping constant the direction of variation of the electric field vector of a beam irradiating an observation target 102 in observation using a SAR (synthetic aperture radar). The antenna controller 222 controls the two degrees of rotational freedom of the antenna 201 to make the azimuth direction of the antenna 201 coincide with the normal vector of a specific plane. The two degrees of rotational freedom are rotations around any two axes. The specific plane is a plane formed by the relative position vector from the observation target 102 to the antenna 201 and the normal vector of the observation target 102 to the Earth's surface. The antenna control device 222 controls the remaining one rotational degree of freedom of the antenna 201, thereby directing the boresight direction of the antenna 201 toward the observation target 102. The one rotational degree of freedom is rotation of the antenna 201 around an axis in the azimuth direction. Through this series of controls, the beam is directed toward the observation target 102. Furthermore, the angle between the direction of variation of the electric field vector of the horizontally polarized wave irradiated onto the observation target 102 and the normal vector of the Earth's surface of the observation target 102 is fixed at a right angle.

[0040] ***Effects of the First Embodiment*** Figure 5 explains the beam pointing control used in conventional spacecraft observations. The spacecraft is equipped with an antenna. "Intersection" means the intersection of the boresight direction of the antenna and the Earth's surface. The two solid arrows at the intersection represent the direction of the elevation of the antenna projected onto the Earth's surface, and the direction of the azimuth of the antenna projected onto the Earth's surface. Conventionally, the beam is directed to the target by controlling its rotation, which is achieved by electronic scanning or mechanical driving. However, although the beam direction (vector) is aligned with the direction of the observation target, the rotation around the beam direction is not defined. Furthermore, the direction of the fluctuation of the electric field vector of the electromagnetic waves irradiated onto the observation target has not been controlled to the intended direction. Therefore, there was an issue that it was not possible to observe the observation target under the desired electric field vector incidence conditions.

[0041] According to the first embodiment, it is possible to fix the direction of variation of the electric field vector of the horizontally polarized wave irradiated onto the observation target at a right angle to the normal direction of the ground surface of the observation target.

[0042] ***Description of Example*** The target position Pg may be set in the observation satellite 200 from the ground station 110, or may be set in the observation satellite 200 based on the conditions of the target 101. The satellite position Psat may be measured by the observation satellite 200, or may be calculated by the ground station 110 and set in the observation satellite 200. For example, the ground station 110 measures the distance from each of a plurality of radars to the observation satellite 200, and calculates the satellite position Psat by triangulation. The normal direction N may be set from the ground station 110 to the observation satellite 200, or may be calculated in the observation satellite 200 based on the target position Pg.

[0043] An example of the observation target 102 will be described below.

[0044] The first embodiment will be described with reference to FIG. The observed target 102 is a locus of points located on the Earth's surface in a direction that matches the direction of travel of the observation satellite 200. The direction of travel of the observed target 102 corresponds to the direction of travel of the observation satellite 200 projected onto the Earth's surface. The observed target 102 moves in accordance with the movement of the observation satellite 200. The antenna control device 222 adjusts the direction of the antenna 201 in accordance with the progress of the observation target 102 and the progress of the observation satellite 200 .

[0045] A second embodiment will be described with reference to FIG. The observed target 102 is a locus of points located on the Earth's surface in a direction that does not match the direction of travel of the observation satellite 200. The observed target 102 moves through the observation area regardless of the travel of the observation satellite 200. The antenna control device 222 adjusts the direction of the antenna 201 in accordance with the progress of the observation target 102 and the progress of the observation satellite 200 .

[0046] A third embodiment will be described with reference to FIG. The observed target 102 may be a representative point on the path of a locus of points located on the Earth's surface in a direction that coincides with the direction of travel of the observation satellite 200. The representative point is the position of the observed target 102 at any time during the observation period. The antenna control device 222 calculates the pointing direction when a representative point at the satellite observation point is set as the observation target 102. The pointing direction is maintained during the observation period. The relationship between the pointing direction of the antenna 201 and the spatial coordinate system is fixed. By maintaining the relationship between the pointing direction of the antenna 201 and the spatial coordinate system during the observation period, the following effects are obtained: At all times during the observation period, the angle between the direction of variation of the electric field vector of the horizontally polarized waves irradiated onto the Earth's surface and the Earth's surface normal vector at the radio wave irradiation point is fixed at approximately a right angle. The radio wave irradiation point is the intersection of the beam pointing and the Earth's surface. The spatial coordinate system may be an orbital coordinate system or an inertial coordinate system.

[0047] A fourth embodiment will be described with reference to FIG. The observation target 102 is a point underground. The radio wave irradiation point is the intersection of the beam direction and the ground surface. The target position Pg is the position of the observation target 102 . The normal direction N is the normal direction of the earth's surface at the latitude and longitude of the target position Pg. The normal direction of the target plane is the same as the normal direction N.

[0048] Embodiment 2 The mode in which a beam is emitted deviated from the direction of the antenna 201 will be described with reference to FIG. 10, focusing mainly on the differences from the first embodiment.

[0049] ***Configuration Description*** The configuration of the satellite observation system 100 is the same as that in the first embodiment. However, the target 101 does not have to be the target 102 .

[0050] ***Explanation of Operation*** The characteristics of the observation method will be explained based on FIG. The antenna control device 222 adjusts the pointing direction of the antenna 201 so that the azimuth direction Az of the antenna 201 coincides with the normal direction of a specific plane, and so that the boresight direction Boa of the antenna 201 points in a direction deviated from the direction pointing at the observation target 102 according to the deviation angle θ. The specific plane is a plane formed by the relative direction of the antenna 201 with respect to the observation target 102 and the normal direction of the ground surface at the position of the observation target 102. The beam control device 223 irradiates the beam in a direction deviated from the pointing direction of the antenna 201S according to the deviation angle θ by electronic scanning. The deflection angle θ is the angle in the elevation direction El of the antenna 201. The antenna 201 points to a target 101 that is farther away than an observed target 102, and the beam points to the observed target 102 that is closer than the pointed target 101. Alternatively, the antenna 201 points to the target 101 which is closer than the target 102 , and the beam points to the target 102 which is farther away than the target 101 .

[0051] The observation method is performed in the same manner as in the first embodiment (see FIG. 4). However, the target information received in step S110 further indicates the deflection angle θ. The calculation formula for the direction of orientation in step S120 is as follows:

[0052]

number

[0053] rotation{X,Y,Z} means the operation of rotating unit vector X right by Z degrees around unit vector Y.

[0054] The azimuth direction Az corresponds to the cross product of the relative direction of the satellite position Psat with respect to the target position Pg and the normal direction N. When the observed target 102 is located on the right side of the nadir point locus as seen from the observation satellite 200, the azimuth direction Az is calculated by calculating formula (2-1R). When the observed target 102 is located on the left side of the nadir point locus as seen from the observation satellite 200, the azimuth direction Az is calculated by calculating formula (2-1L). The elevation direction El corresponds to the direction in which the relative direction of the satellite position Psat with respect to the target position Pg is rotated around the axis of the azimuth direction Az according to the deflection angle θ. The elevation direction El is calculated by calculating equation (2-2). The boresight direction Boa is equivalent to the cross product of the azimuth direction Az and the elevation direction El. The boresight direction Boa is calculated using equation (2-3). The beam direction (Beam) corresponds to the relative direction of the target position (Pg) with respect to the satellite position (Psat). The beam direction (Beam) is calculated by calculating equation (2-4).

[0055] ***Supplement to Embodiment 2*** The antenna controller 222 controls the two degrees of freedom of rotation of the antenna 201 to make the azimuth direction of the antenna 201 coincide with the normal vector of a specific plane. The specific plane is a plane formed by the relative position vector from the observation target 102 to the antenna 201 and the normal vector of the observation target 102 to the Earth's surface. The antenna control device 222 controls the remaining one degree of freedom of rotation of the antenna 201, thereby directing the boresight direction of the antenna 201 toward the target 101 deviated from the observation target 102 (a position deviated in the elevation direction El projected onto the Earth's surface) according to the deflection angle θ. The beam control device 223 directs the beam to the observation target 102 by electronic scanning. Through this series of controls, the beam is directed toward the observation target 102. Furthermore, the angle between the direction of variation of the electric field vector of the horizontally polarized wave irradiated onto the observation target 102 and the normal vector of the Earth's surface of the observation target 102 is fixed at a right angle. Furthermore, by setting the deflection angle θ, it is possible to reduce the rotation rate of the antenna 201 around the boresight axis.

[0056] When the deflection angle θ is zero, the second embodiment is equivalent to the first embodiment.

[0057] ***Effects of the Second Embodiment*** According to the second embodiment, it is possible to fix the direction of fluctuation of the electric field vector of the horizontally polarized wave irradiated onto the observation target at a right angle to the normal direction of the ground surface of the observation target, without significantly improving the rotation rate around the boresight axis of the platform antenna.

[0058] ***Description of Example*** The deflection angle θ may be set from the ground station 110 to the observation satellite 200 or may be set at the observation satellite 200 itself.

[0059] The deflection angle θ is set as an angle around the axis of the azimuth direction Az. The deflection angle θ causes the pointing point to deviate from the target in the elevation direction El. This is an embodiment that takes into consideration that the adjustment range by electronic scanning is usually large in the elevation direction El.

[0060] The examples of the first embodiment may be applied to the second embodiment.

[0061] Embodiment 3 The mode in which a beam is emitted deviated from the direction of the antenna 201 will be described with reference to FIG. 11, focusing mainly on the differences from the first embodiment.

[0062] ***Configuration Description*** The configuration of the satellite observation system 100 is the same as that in the first embodiment. However, the target 101 does not have to be the target 102 .

[0063] ***Explanation of Operation*** The characteristics of the observation method will be explained based on FIG. The two-dot chain line attached to the observation satellite 200 represents the direction of the cross product of the normal direction N of the observation target 102 and the relative direction of the antenna 201 with respect to the observation target 102 . The dotted arrows attached to the target 101 on the ground surface represent the elevation direction El and azimuth direction Az projected onto the ground surface.

[0064] The antenna control device 222 adjusts the pointing direction of the antenna 201 so that the azimuth direction Az of the antenna 201 coincides with the normal direction of a specific plane, and so that the boresight direction Boa of the antenna 201 points in a direction deviated from the direction pointing at the observation target 102 according to the deviation angle θ. The specific plane is a plane formed by the relative direction of the antenna 201 with respect to the observation target 102 and the normal direction of the ground surface at the position of the observation target 102, rotated around the normal direction of the ground surface at the position of the observation target 102 according to a plane rotation angle φ. The beam control device 223 irradiates the beam in the direction of the observation target 102 by electronic scanning.

[0065] The observation method is performed in the same manner as in the first embodiment (see FIG. 4). However, the target information received in step S110 further indicates a surface rotation angle φ and a deflection angle θ. The calculation formula for the direction of orientation in step S120 is as follows:

[0066]

number

[0067] rotation{X,Y,Z} means the operation of rotating unit vector X right by Z degrees around unit vector Y.

[0068] The azimuth direction Az corresponds to the direction obtained by rotating the cross product of the relative direction of the satellite position Psat with respect to the target position Pg and the normal direction N around the axis of the normal direction N according to the plane rotation angle φ. When the observed target 102 is located on the right side of the nadir point locus as seen from the observation satellite 200, the azimuth direction Az is calculated by calculating formula (3-1R). When the observed target 102 is located on the left side of the nadir point locus as seen from the observation satellite 200, the azimuth direction Az is calculated by calculating formula (3-1L). The boresight direction Boa corresponds to the direction obtained by rotating the relative direction of the target position Pg with respect to the satellite position Psat around the axis of the normal direction N according to the plane rotation angle φ, and then rotating the direction around the axis of the azimuth direction Az according to the deflection angle θ. The boresight direction Boa is calculated by calculating equations (3-2) and (3-3). The elevation direction El corresponds to the cross product of the boresight direction Boa and the azimuth direction Az. The elevation direction El is calculated using equation (3-4). The beam direction (Beam) corresponds to the relative direction of the target position (Pg) with respect to the satellite position (Psat). The beam direction (Beam) is calculated by calculating equation (3-5).

[0069] ***Supplement to embodiment 3*** The antenna controller 222 controls the two degrees of freedom of rotation of the antenna 201 to make the azimuth direction of the antenna 201 coincide with the normal vector of a specific plane. The specific plane is a plane formed by the relative position vector from the observation target 102 to the antenna 201 and the ground surface normal vector of the observation target 102, rotated around the normal direction of the ground surface at the position of the observation target 102 according to a plane rotation angle φ. The antenna controller 222 controls the remaining one degree of freedom of rotation of the antenna 201, thereby directing the boresight direction of the antenna 201 in a direction according to the deflection angle θ. The beam control device 223 directs the beam to the observation target 102 by electronic scanning. Through this series of controls, the beam is directed toward the observation target 102. Furthermore, the angle between the direction of variation of the electric field vector of the horizontally polarized wave irradiated onto the observation target 102 and the normal vector of the Earth's surface of the observation target 102 is fixed at a right angle. Furthermore, by setting the deflection angle θ, it is possible to reduce the rotation rate of the antenna 201 around the boresight axis.

[0070] When the surface rotation angle φ is zero and the deflection angle θ is zero, the third embodiment is equivalent to the first embodiment. When the surface rotation angle φ is zero, the third embodiment is equivalent to the second embodiment.

[0071] ***Effects of the Third Embodiment*** According to the third embodiment, it is possible to fix the direction of fluctuation of the electric field vector of the horizontally polarized wave irradiated onto the observation target at a right angle to the normal direction of the ground surface of the observation target, without significantly improving the rotation rate around the boresight axis of the platform antenna.

[0072] ***Description of Example*** The plane rotation angle φ and the deflection angle θ may be set in the observation satellite 200 from the ground station 110 or may be set in the observation satellite 200 itself.

[0073] The plane rotation angle φ is set as the angle around the normal to the Earth's surface of the observation target. The plane rotation angle φ causes the pointing point to deviate in the azimuth direction Az from the observation target. The deflection angle θ is set as an angle around the azimuth axis Az. The deflection angle θ causes the pointing point to deviate from the observation target in the elevation direction El.

[0074] The example of the first embodiment may be applied to the third embodiment.

[0075] ***Supplementary explanation of implementation form*** Each embodiment is an example of a preferred embodiment and is not intended to limit the technical scope of the present disclosure. Each embodiment may be implemented in part or in combination with other embodiments. Procedures described using flowcharts, etc. may be modified as appropriate.

[0076] "Device" may be read as "unit," "process," "circuit," or "circuitry."

[0077] Various aspects of the present disclosure are described below as appendices. (Appendix 1) an antenna for emitting a beam and receiving the beam reflected by an observation target located on the Earth's surface; an antenna control device that adjusts the pointing direction of the antenna so that the azimuth direction of the antenna coincides with the normal direction of a specific plane; a beam control device that irradiates a beam in the direction of the antenna; a receiving device that receives a beam reflected by the target using the antenna; A flying object comprising: the specific plane is a plane formed by a relative direction of the antenna with respect to the observation target and a normal direction of an object plane at the position of the observation target, The target plane is the plane on which the observation target is located. Flying object.

[0078] (Appendix 2) The antenna control device adjusts the pointing direction of the antenna so that the azimuth direction of the antenna coincides with the normal direction of the specific plane and so that the boresight direction of the antenna points toward the observation target. 1. A flying object as described in Appendix 1.

[0079] (Appendix 3) the target plane is the ground surface, the observation target is fixed to the ground surface, The antenna control device adjusts the pointing direction of the antenna in accordance with the movement of the flying object. 1. A flying object as described in Appendix 1 or Appendix 2.

[0080] (Appendix 4) the target plane is the ground surface, the observation target is traveling on the ground surface in a direction that matches the traveling direction of the flying object, The antenna control device adjusts the pointing direction of the antenna in accordance with the progress of the observation target and the progress of the flying object. 1. A flying object as described in Appendix 1 or Appendix 2.

[0081] (Appendix 5) the target plane is the ground surface, the observation target is traveling on the ground surface in a direction that does not match the traveling direction of the flying object, The antenna control device adjusts the pointing direction of the antenna in accordance with the progress of the observation target and the progress of the flying object. 1. A flying object as described in Appendix 1 or Appendix 2.

[0082] (Appendix 6) the target plane is the ground surface, the observation target is a representative point of a path of travel that travels on the ground surface in a direction that coincides with the traveling direction of the flying object, The antenna control device adjusts the pointing direction of the antenna in accordance with the movement of the flying object. 1. A flying object as described in Appendix 1 or Appendix 2.

[0083] (Appendix 7) the observation target is an underground point, The normal direction of the target plane is the same as the normal direction of the earth's surface at the latitude and longitude of the observation target. 1. A flying object as described in Appendix 1 or Appendix 2.

[0084] (Appendix 8) A pointing control system mounted on the flying object according to any one of Supplementary Note 1 to Supplementary Note 7, the antenna control device; the beam control device; A pointing control system comprising:

[0085] (Appendix 9) adjusting the direction of the antenna so that the azimuth direction of the antenna coincides with the normal direction of the specific plane; irradiating a beam in the direction of the antenna; The antenna is used to receive the beam reflected from the target. It is an observation method, the specific plane is a plane formed by a relative direction of the antenna with respect to the observation target and a normal direction of an object plane at the position of the observation target, The target plane is the plane on which the observation target is located. Observation method.

[0086] (Appendix 10) an antenna for emitting a beam and receiving the beam reflected by an observation target located on the Earth's surface; an antenna control device that adjusts the direction of the antenna so that the azimuth direction of the antenna coincides with the normal direction of a specific plane and so that the boresight direction of the antenna points in a direction deviated from the direction of pointing at the observation target according to a deviation angle; a beam control device that irradiates a beam in a direction deviated from the pointing direction of the antenna in accordance with the deviation angle by electronic scanning; a receiving device that receives a beam reflected by the target using the antenna; A flying object comprising: the specific plane is a plane formed by a relative direction of the antenna with respect to the observation target and a normal direction of the ground surface at the position of the observation target, The deflection angle is the angle in the elevation direction of the antenna. Flying object.

[0087] (Appendix 11) the antenna is directed to a target that is farther than the observation target, The beam is directed to the observation target that is closer than the target. 11. A flying object as described in Appendix 10.

[0088] (Appendix 12) the antenna is directed to a target closer than the observation target, The beam is directed to the observation target that is farther away than the directed target. 11. A flying object as described in Appendix 10.

[0089] (Appendix 13) 13. A pointing control system mounted on the flying object according to any one of claims 10 to 12, the antenna control device; the beam control device; A pointing control system comprising:

[0090] (Appendix 14) adjusting the pointing direction of the antenna so that the azimuth direction of the antenna coincides with the normal direction of the specific plane and so that the boresight direction of the antenna points in a direction deviated from the direction pointing at the observation target according to a deviation angle; irradiating a beam in a direction deviated from the pointing direction of the antenna according to the deflection angle by electronic scanning; Using the antenna, receive the beam reflected from the target. It is an observation method, The specific plane is a plane formed by the relative direction of the antenna with respect to the observation target and the normal direction of the ground surface at the position of the observation target. Observation method.

[0091] (Appendix 15) an antenna for emitting a beam and receiving the beam reflected by an observation target located on the Earth's surface; an antenna control device that adjusts the direction of the antenna so that the azimuth direction of the antenna coincides with the normal direction of a specific plane and so that the boresight direction of the antenna points in a direction deviated from the direction of pointing at the observation target according to a deviation angle; a beam control device that irradiates a beam in a direction deviated from the pointing direction of the antenna in accordance with the deviation angle by electronic scanning; a receiving device that receives a beam reflected by the target using the antenna; A flying object comprising: the specific plane is a plane formed by the relative direction of the antenna with respect to the observation target and the normal direction of the ground surface at the position of the observation target, and is rotated around the normal direction of the ground surface at the position of the observation target according to a plane rotation angle, the plane rotation angle is set as an angle around a normal direction of the ground surface, The deflection angle is the angle in the elevation direction of the antenna. Flying object.

[0092] (Appendix 16) the antenna is directed to a target that is farther than the observation target, The beam is directed to the observation target that is closer than the target. 16. A flying object as described in Appendix 15.

[0093] (Appendix 17) the antenna is directed to a target closer than the observation target, The beam is directed to the observation target that is farther away than the directed target. 16. A flying object as described in Appendix 15.

[0094] (Appendix 18) 18. A pointing control system mounted on the flying object according to any one of claims 15 to 17, the antenna control device; the beam control device; A pointing control system comprising:

[0095] (Appendix 19) adjusting the pointing direction of the antenna so that the azimuth direction of the antenna coincides with the normal direction of the specific plane and so that the boresight direction of the antenna points in a direction deviated from the direction pointing at the observation target according to a deviation angle; irradiating a beam in a direction deviated from the pointing direction of the antenna according to the deflection angle by electronic scanning; Using the antenna, receive the beam reflected from the target. It is an observation method, the specific plane is a plane formed by the relative direction of the antenna with respect to the observation target and the normal direction of the ground surface at the position of the observation target, and is rotated around the normal direction of the ground surface at the position of the observation target according to a plane rotation angle, The plane rotation angle is set as an angle around the normal direction of the ground surface. Observation method. [Explanation of symbols]

[0096] 100 satellite observation system, 101 pointing target, 102 observation target, 110 ground station, 111 communication equipment, 200 observation satellite, 201 antenna, 202 position sensor, 203 attitude sensor, 211 communication equipment, 212 target recording device, 220 pointing control system, 221 pointing control device, 222 antenna control device, 223 beam control device, 231 receiving device, 232 observation result recording device, Az azimuth direction, Beam beam pointing direction, Boa boresight direction, El elevation direction, N normal direction, Pg target position, Psat satellite position, θ deflection angle, φ plane rotation angle.

Claims

1. an antenna for emitting a beam and receiving the beam reflected by an observation target located on the Earth's surface; an antenna control device that adjusts the direction of the antenna so that the azimuth direction of the antenna coincides with the normal direction of a specific plane defined based on the normal direction of a target plane at the position of a specified observation target, and so that the boresight direction of the antenna is directed toward the observation target; a beam control device that irradiates a beam in the boresight direction of the antenna; a receiving device that receives a beam reflected by the target using the antenna; A flying object comprising: the observation target is present in a forward looking direction as seen from the flying body or a backward looking direction as seen from the flying body, the specific plane is a plane formed by a relative direction of the antenna with respect to the observation target and a normal direction of the target plane, the target plane is the ground surface at the position of the observation target, The antenna control device adjusts the direction of the antenna in accordance with the movement of the flying object.

2. an antenna for emitting a beam and receiving the beam reflected by an observation target located on the Earth's surface; an antenna control device that adjusts the direction of the antenna so that the azimuth direction of the antenna coincides with the normal direction of a specific plane defined based on the normal direction of a target plane at the position of a specified observation target, and so that the boresight direction of the antenna is directed toward the observation target; a beam control device that irradiates a beam in the boresight direction of the antenna; a receiving device that receives a beam reflected by the target using the antenna; A flying object comprising: the specific plane is a plane formed by a relative direction of the antenna with respect to the observation target and a normal direction of the target plane, the observation target is a building that is present in a forward looking direction as seen from the flying object or a backward looking direction as seen from the flying object, the normal direction of the target plane is the story direction of the building, The antenna control device adjusts the direction of the antenna in accordance with the movement of the flying object.

3. The observation target is fixed to the earth's surface. The flying object according to claim 1 or 2.

4. the observation target is traveling on the ground surface in a direction that matches the traveling direction of the flying object, The antenna control device adjusts the pointing direction of the antenna in accordance with the progress of the observation target and the progress of the flying object. The flying object according to claim 1 or 2.

5. the observation target is traveling on the ground surface in a direction that does not match the traveling direction of the flying object, The antenna control device adjusts the pointing direction of the antenna in accordance with the progress of the observation target and the progress of the flying object. The flying object according to claim 1 or 2.

6. the observation target is a representative point of a path of travel that travels on the ground surface in a direction that coincides with the traveling direction of the flying object, The antenna control device adjusts the pointing direction of the antenna in accordance with the movement of the flying object. The flying object according to claim 1 or 2.

7. the observation target is an underground point, The normal direction of the target plane is the same as the normal direction of the earth's surface at the latitude and longitude of the observation target. The flying object according to claim 1 or 2.

8. A pointing control system mounted on the flying object according to claim 1 or 2, the antenna control device; the beam control device; A directional control system comprising:

9. adjusting the direction of the antenna in accordance with the flight vehicle's movement so that the azimuth direction of the antenna coincides with the normal direction of a specific plane defined based on the normal direction of the target plane at the position of the specified observation target, and so that the boresight direction of the antenna is directed toward the observation target; irradiating a beam in the boresight direction of the antenna; The antenna is used to receive the beam reflected from the target. It is an observation method, the observation target is present in a forward looking direction as seen from the flying body or a backward looking direction as seen from the flying body, the specific plane is a plane formed by a relative direction of the antenna with respect to the observation target and a normal direction of the target plane, The target plane is the ground surface at the position of the observation target. Observation method.

10. adjusting the direction of the antenna in accordance with the flight vehicle's movement so that the azimuth direction of the antenna coincides with the normal direction of a specific plane defined based on the normal direction of the target plane at the position of the specified observation target, and so that the boresight direction of the antenna points toward the observation target; irradiating a beam in the boresight direction of the antenna; The antenna is used to receive the beam reflected from the target. It is an observation method, the specific plane is a plane formed by a relative direction of the antenna with respect to the observation target and a normal direction of the target plane, the observation target is a building that is present in a forward looking direction as seen from the flying object or a backward looking direction as seen from the flying object, The normal direction of the target plane is the story direction of the building. Observation method.

11. an antenna for emitting a beam and receiving the beam reflected by an observation target located on the Earth's surface; an antenna control device that adjusts the pointing direction of the antenna so that the azimuth direction of the antenna coincides with the normal direction of a specific plane defined in accordance with the position of the observation target; a beam control device that irradiates a beam in the direction of the antenna; a receiving device that receives a beam reflected by the target using the antenna; A flying object comprising: the observation target is present in a forward looking direction as seen from the flying body or a backward looking direction as seen from the flying body, the specific plane is a plane formed by a relative direction of the antenna with respect to the observation target and a normal direction of an object plane at the position of the observation target, the target plane is the earth's surface at the latitude and longitude of the observation target, The antenna control device adjusts the pointing direction of the antenna in accordance with the movement of the flying object. Flying object.

12. The antenna control device adjusts the pointing direction of the antenna so that the azimuth direction of the antenna coincides with the normal direction of the specific plane and so that the boresight direction of the antenna points toward the observation target. The flying object according to claim 11.

13. the target plane is the ground surface, the observation target is fixed to the ground surface, The antenna control device adjusts the pointing direction of the antenna in accordance with the movement of the flying object. The flying object according to claim 11 or 12.

14. the target plane is the ground surface, the observation target is traveling on the ground surface in a direction that matches the traveling direction of the flying object, The antenna control device adjusts the pointing direction of the antenna in accordance with the progress of the observation target and the progress of the flying object. The flying object according to claim 11 or 12.

15. the target plane is the ground surface, the observation target is traveling on the ground surface in a direction that does not match the traveling direction of the flying object, The antenna control device adjusts the pointing direction of the antenna in accordance with the progress of the observation target and the progress of the flying object. The flying object according to claim 11 or 12.

16. the target plane is the ground surface, the observation target is a representative point of a path of travel that travels on the ground surface in a direction that coincides with the traveling direction of the flying object, The antenna control device adjusts the pointing direction of the antenna in accordance with the movement of the flying object. The flying object according to claim 11 or 12.

17. the observation target is an underground point, The normal direction of the target plane is the same as the normal direction of the earth's surface at the latitude and longitude of the observation target. The flying object according to claim 11 or 12.

18. 12. A pointing control system mounted on the flying object according to claim 11, the antenna control device; the beam control device; A directional control system comprising:

19. adjusting the direction of the antenna in accordance with the flight vehicle's movement so that the azimuth direction of the antenna coincides with the normal direction of a specific plane defined according to the position of the observation target; irradiating a beam in the direction of the antenna; The antenna is used to receive the beam reflected from the target. It is an observation method, the observation target is present in a forward looking direction as seen from the flying body or a backward looking direction as seen from the flying body, the specific plane is a plane formed by a relative direction of the antenna with respect to the observation target and a normal direction of an object plane at the position of the observation target, The target plane is the earth's surface at the latitude and longitude of the observation target. Observation method.

20. an antenna for emitting a beam and receiving the beam reflected by an observation target located on the Earth's surface; an antenna control device that adjusts the direction of the antenna so that the azimuth direction of the antenna coincides with the normal direction of a specific plane defined in accordance with the position of an observation target; a beam control device that irradiates a beam in the direction of the antenna; a receiving device that receives a beam reflected by the target using the antenna; A flying object comprising: the observation target is present in a forward looking direction as seen from the flying body or a backward looking direction as seen from the flying body, the specific plane is a plane formed by a relative direction of the antenna with respect to the observation target and a floor direction of a building at the latitude and longitude of the observation target, The antenna control device adjusts the pointing direction of the antenna in accordance with the movement of the flying object. Flying object.

21. The antenna control device adjusts the pointing direction of the antenna so that the azimuth direction of the antenna coincides with the normal direction of the specific plane and so that the boresight direction of the antenna points toward the observation target. The flying object according to claim 20.

22. the observation target is fixed to the ground surface, The antenna control device adjusts the pointing direction of the antenna in accordance with the movement of the flying object.

22. The flying object according to claim 20 or claim 21.

23. the observation target is traveling on the ground surface in a direction that matches the traveling direction of the flying object, The antenna control device adjusts the pointing direction of the antenna in accordance with the progress of the observation target and the progress of the flying object.

22. The flying object according to claim 20 or claim 21.

24. the observation target is traveling on the ground surface in a direction that does not match the traveling direction of the flying object, The antenna control device adjusts the pointing direction of the antenna in accordance with the progress of the observation target and the progress of the flying object.

22. The flying object according to claim 20 or claim 21.

25. the observation target is a representative point of a path of travel that travels on the ground surface in a direction that coincides with the traveling direction of the flying object, The antenna control device adjusts the pointing direction of the antenna in accordance with the movement of the flying object.

22. The flying object according to claim 20 or claim 21.

26. The observation target is an underground point 22. The flying object according to claim 20 or claim 21.

27. 21. A pointing control system mounted on the flying object according to claim 20, the antenna control device; the beam control device; A directional control system comprising:

28. adjusting the direction of the antenna in accordance with the flight vehicle's movement so that the azimuth direction of the antenna coincides with the normal direction of a specific plane defined according to the position of the observation target; irradiating a beam in the direction of the antenna; The antenna is used to receive the beam reflected from the target. It is an observation method, the observation target is present in a forward looking direction as seen from the flying body or a backward looking direction as seen from the flying body, The specific plane is a plane formed by the relative direction of the antenna with respect to the observation target and the floor direction of the building at the latitude and longitude of the observation target. Observation method.

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