Control device
The control device adjusts antenna direction to ensure the electric field vector of horizontally polarized waves is perpendicular to the target plane, addressing the uncontrolled rotation issue in existing systems and enabling consistent observation conditions.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- MITSUBISHI ELECTRIC CORP
- Filing Date
- 2026-02-26
- Publication Date
- 2026-05-19
AI Technical Summary
Existing beam direction control systems for spacecraft observations fail to control the rotation around the beam direction, leading to uncontrolled fluctuation of the electric field vector of electromagnetic waves, making it impossible to observe targets under desired electric field vector incidence conditions.
A control device installed at a ground station sets target information for a flying object, adjusting the antenna's direction to match the normal direction of the observation target's plane, ensuring the electric field vector of horizontally polarized waves is perpendicular to the target plane, using antenna and beam control devices to maintain this orientation.
The solution enables precise control of the electric field vector direction relative to the target plane, allowing consistent observation under desired conditions, regardless of the target's location or movement relative to the flying object.
Smart Images
Figure 2026083149000001_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to beam direction control for observing an observation target.
Background Art
[0002] Conventionally, observations using spacecraft have been carried out. Non-Patent Document 1 discloses rotationally controlling a beam so that the beam is directed at an observation target.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Patent Document 2
Non-Patent Documents
[0004]
Non-Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0005] In Non-Patent Document 1, the beam direction (vector) is adjusted to the direction of the observation target, but the rotation around the beam direction is not defined. Therefore, the fluctuation direction of the electric field vector of the electromagnetic wave irradiated on the observation target cannot be controlled in the intended direction, and the observation target cannot be observed under the desired electric field vector incidence conditions.
[0006] The purpose of this disclosure is to enable the direction of variation of the electric field vector of horizontally polarized waves irradiated onto the object being observed to be fixed perpendicular to the normal direction of the plane in which the object is located. [Means for solving the problem]
[0007] The control device of this disclosure, A control device installed at a ground station, which sets target information for a flying object from the ground station. The aforementioned flying body, An antenna for emitting a beam and receiving the beam reflected from an observation target located on the Earth's surface, An antenna control device that adjusts the direction of the antenna in accordance with the movement of the flying object so that the azimuth direction of the antenna matches the normal direction of a specific plane defined based on the normal direction of the target plane at the position of the observation target, and so that the boresight direction of the antenna points towards the observation target. A beam control device that irradiates the antenna in the direction of the boresite, A receiving device that uses the aforementioned antenna to receive the beam reflected from the object being observed, Equipped with, The observed object is located in a direction that is forward of the flying object or in a direction that is backward of the flying object. The aforementioned specific plane is the plane formed by the relative direction of the antenna with respect to the observation object and the normal direction of the target plane. The aforementioned target plane is the ground surface at the location of the observation target, The aforementioned target information indicates the position or normal direction of the observed target. The control device transmits the target information to the flying object using the communication device of the ground station and sets the target information on the flying object. [Effects of the Invention]
[0008] According to this disclosure, it is possible to fix the direction of variation of the electric field vector of the horizontally polarized waves irradiated onto the object being observed at a right angle to the normal direction of the plane in which the object is located. [Brief explanation of the drawing]
[0009] [Figure 1] Configuration diagram of the satellite observation system 100 in Embodiment 1. [Figure 2] Configuration diagram of the observation satellite 200 in Embodiment 1. [Figure 3] Schematic diagram of the observation method in Embodiment 1. [Figure 4] Flowchart of the observation method in Embodiment 1. [Figure 5] Schematic diagram of the conventional observation method. [Figure 6] Schematic diagram of the first embodiment in Embodiment 1. [Figure 7] Schematic diagram of the second embodiment in Embodiment 1. [Figure 8] Schematic diagram of the third embodiment in Embodiment 1. [Figure 9] Schematic diagram of the fourth embodiment in Embodiment 1. [Figure 10] Schematic diagram of the observation method in Embodiment 2. [Figure 11] Schematic diagram of the observation method in Embodiment 3.
Modes for Carrying Out the Invention
[0010] In the embodiments and drawings, the same elements or corresponding elements are denoted by the same reference numerals. The description of the elements denoted by the same reference numerals as the described elements will be omitted or simplified as appropriate. The arrows in the figures mainly indicate the flow of signals, data, or processes.
[0011] Embodiment 1. The satellite observation system 100 will be described based on FIGS. 1 to 9.
[0012] ***Description of the Configuration*** Based on FIG. 1, the configuration of the satellite observation system 100 as an observation system will be described. The satellite observation system 100 has an observation satellite 200 as a flying object and a ground station 110. The satellite observation system 100 is an example of an observation system that uses a flying object for observation. The flying object can be an artificial satellite or an aircraft, etc. Observation satellite 200 is an artificial satellite that observes observation target 102. Observation is performed by emitting a beam and receiving the beam reflected from observation target 102, which is located on the Earth's surface. An artificial satellite is also called a spacecraft. Antenna 201 is also called an antenna. The target 101 is the point pointed to by the antenna 201. Specifically, the observation target 102 becomes the target 101. Observation object 102 is something that is observed. Specifically, observation object 102 is something that is fixed to the Earth's surface. Ground station 110 communicates with observation satellite 200.
[0013] The dashed arrow passing through observation satellite 200 represents the orbit of observation satellite 200. An orbit is also called a path.
[0014] The dashed-dotted arrow from observation satellite 200 to target 101 represents the beam direction. The beam direction, specified by "Beam," is the direction in which the beam emitted from antenna 201 is directed. The beam is an electromagnetic wave.
[0015] Satellite position Psat is the position of observation satellite 200. Satellite position Psat corresponds to the position of antenna 201. The three arrows attached to observation satellite 200 indicate the boresite direction (Boa), the azimuth direction (Az), and the elevation direction (El). The bore sight direction Boa is the bore sight direction of antenna 201. The azimuth direction Az corresponds to the horizontal polarization excitation direction of antenna 201. The elevation direction El is the elevation direction of 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-pointing arrow attached to observation target 102 represents the normal direction N. The normal direction N is the normal direction of the target plane at the position of the observation target 102. The reference plane is the plane based on the position of the observation target 102. Specifically, the reference plane is the Earth's surface. If the observed object 102 is a building, the normal direction N corresponds to the building's floor direction.
[0017] Based on Figure 2, the configuration of observation satellite 200 will be explained. Observation satellite 200 is equipped with antenna 201S, antenna 201R, position sensor 202, and attitude sensor 203. Antenna 201S is the same antenna 201 used for transmission. Antenna 201R is the receiving antenna 201. The position sensor 202 is a sensor used to determine the position of the observation satellite 200. A specific example of the position sensor 202 is GPS. GPS is an abbreviation for Global Positioning System. The attitude sensor 203 is a sensor used to measure the attitude of the observation satellite 200. A specific example of the attitude sensor 203 is a star tracker.
[0018] The observation satellite 200 is equipped with devices (computers) such as a communication device 211 and a target recording device 212. Observation satellite 200 is equipped with a direction control system 220. The direction control system 220 includes devices such as a direction control device 221, an antenna control device 222, and a beam control device 223. The observation satellite 200 is equipped with devices such as a receiving device 231 and an observation result recording device 232. The device is equipped with a processing circuit. The processing circuit may be dedicated hardware, or it may be a processor that executes a program stored in memory. When the processing circuit is dedicated hardware, the processing circuit may be, for example, a single circuit, a composite 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 is equipped with a communication device 111.
[0020] ***Explanation of operation*** The operating procedures for observation satellite 200 correspond to the observation methods.
[0021] Based on Figure 3, the characteristics of the observation method will be explained. The solid arrow from observation target 102 to antenna 201 indicates the relative direction of antenna 201 to observation target 102. The shaded plane is the plane where the electric field vector of the beam's horizontal polarization exists. In the shaded plane, the dashed arrows attached to the observation target 102 indicate the direction in which the electric field vector of the horizontal polarization of the beam incident on the observation target 102 fluctuates. 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 instruments on observation satellite 200 operate as follows: The antenna control device 222 adjusts the direction of the antenna 201 so that its azimuth direction Az coincides with the normal direction of a specific plane, and its boresight direction Boa points towards the target 101. The antenna control device 222 also adjusts the direction of the antenna 201 in accordance with the movement of the observation satellite 200. The specific plane is the 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 location of the observation target 102. The beam control device 223 directs the beam in the direction of the antenna 201S's orientation. However, since the antenna 201S is directed towards the observation target 102, the beam control device 223 does not need to adjust the beam direction from the direction of the antenna 201S's orientation by electronic scanning. The receiving device 231 uses antenna 201R to receive the beam reflected from the observation target 102.
[0023] The procedure for the observation method will be explained based on Figure 4. In step S110, the observation satellite 200 receives one or more pieces of target information. The target information includes the target position Pg, the normal direction N, and the observation conditions. Observation conditions specify the observation orbit and satellite observation points. The observation orbit is the orbit in which the observation will be conducted. The satellite observation point is the location where the observation will be conducted. Observation satellite 200 will observe the target object 102 from the satellite observation point in its observation orbit.
[0024] The information to be submitted can be submitted as follows: The operator inputs the target information into the control device at ground station 110. The communication device 111 transmits the target information input to the control device. The communication device 211 receives the target information. The target recording device 212 is equipped with a storage device such as memory and records the received target information. The target recording device 212 stores a target list. The target list indicates one or more target information.
[0025] In step S120, the direction control device 221 calculates the direction of the antenna 201 (Boa, Az, El) and the beam direction Beam based on the target information.
[0026] The directivity direction and beam direction (Beam) of antenna 201 are calculated using the following procedure. The position sensor 202 determines 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 direction control device 221 selects target information from the target list that indicates observation conditions that match the satellite position Psat. The direction control device 221 calculates the direction of the antenna 201 and the beam direction Beam 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 shown in the selected target information.
[0027] The details of calculating the direction of antenna 201 (Boa, Az, El) and beam direction (Beam) will be described later.
[0028] In step S130, the antenna control device 222 directs the antenna 201 in the direction of direction.
[0029] Antenna 201 is directed in the following direction. The antenna direction control device 221 outputs an antenna direction command. The antenna direction command indicates the direction in which the antenna 201 should be directed. The output antenna direction command is input to the antenna control device 222. The antenna control device 222 directs the antenna 201 in the direction indicated by the antenna direction command. At this time, the antenna control device 222 directs the antenna 201 in the direction indicated by the antenna direction command by adjusting the attitude of the observation satellite 200 or the attitude of the antenna 201. However, the antenna control device 222 may also direct the antenna 201 in the direction indicated by the antenna direction by adjusting the attitude of both the observation satellite 200 and the antenna 201. Alternatively, the antenna control device 222 may direct the antenna 201 in the direction indicated by the antenna direction command by adjusting only the attitude of the observation satellite 200. Alternatively, the antenna control device 222 may direct the antenna 201 in the direction indicated by the antenna direction command by adjusting only the attitude of the antenna 201. The attitude of observation satellite 200 is adjusted by controlling the attitude control devices installed on observation satellite 200. Examples of attitude control devices include reaction wheels, control moment gyros, and thrusters. Furthermore, the antenna 201 may be equipped with a drive mechanism. The attitude of the antenna 201 is adjusted by controlling the drive mechanism provided in the antenna 201. An example of a drive mechanism is a gimbal. The antenna control device 222 performs feedback control or forward 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 the beam from the antenna 201 in the beam direction Beam.
[0031] The beam is irradiated as follows: The beam direction control device 221 outputs a beam direction command. The beam direction command specifies the beam direction, Beam. The output beam direction command is input to the beam direction control device 223. The beam control device 223 uses the antenna 201S to irradiate the beam in the beam direction Beam specified by the beam direction command.
[0032] In step S150, the observation satellite 200 obtains observation results for the observation target 102. The observation results are data obtained from observing 102 observation targets.
[0033] The observation results are as follows: The beam (transmitted wave) emitted from antenna 201S is reflected by the observation target 102. The beam (reflected wave) reflected from the observation target 102 is incident on antenna 201R. The receiving device 231 receives the beam from antenna 201R and processes the received beam. This allows observation results to be obtained. The observation result recording device 232 is equipped with a memory or other storage device and records the observation results.
[0034] The details of the calculation of the directivity direction in step S120 will be explained. The direction control device 221 calculates the following equation. This calculates the direction of the antenna 201 (Boa, Az, El) and the beam direction Beam.
[0035]
number
[0036] The arrows above each sign indicate vectors.
[0037] The boresight direction Boa corresponds to the relative direction of the satellite position Psat to the target position Pg. The boresight direction Boa is calculated by performing equation (1-1). The azimuth direction Az corresponds to the normal direction of the plane (specific plane) formed by the boresight direction Boa and the normal direction N. When the observation target 102 is located to the right of the satellite's basoplanet trajectory as viewed from observation satellite 200, the azimuth direction Az is calculated by equation (1-2R). When the observation target 102 is located to the left of the satellite's basoplanet trajectory as viewed from observation satellite 200, the azimuth direction Az is calculated by equation (1-2L). The satellite's basoplanet trajectory is the trajectory of the point directly below observation satellite 200. In other words, the satellite's basoplanet trajectory corresponds to the orbit of 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 by performing equation (1-3). The beam direction Beam is equal to the boresite direction Boa, as shown in equation (1-4).
[0038] Each direction may be represented in vector form or in angular form, indicating an angle from the reference direction.
[0039] ***Supplement to Embodiment 1*** Embodiment 1 relates to beam directing control for maintaining a constant direction of fluctuation in the electric field vector of the beam irradiating the observation target 102 in observations using SAR (Synthetic Aperture Radar). The antenna control device 222 controls the rotational 2 degrees of freedom of the antenna 201 to make the azimuth direction of the antenna 201 coincide with the normal vector of a specific plane. The rotational 2 degrees of freedom are rotations around any two axes. The specific plane is the 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. The antenna control device 222 directs the boresight direction of the antenna 201 toward the observation target 102 by controlling the remaining rotational degree of freedom of the antenna 201. The rotational degree of freedom is the rotation of the antenna 201 around the axis in the azimuth direction. Through this series of controls, the beam is directed towards the observation target 102. Furthermore, the angle between the direction of variation of the electric field vector of the horizontally polarized waves irradiating the observation target 102 and the surface normal vector of the observation target 102 is fixed at a right angle.
[0040] ***Effects of Embodiment 1*** Figure 5 illustrates beam direction control in conventional spacecraft observations. Spacecraft are equipped with antennas. "Intersection" refers to the point where the direction of the antenna's boresight intersects with the ground surface. The two solid arrows at the intersection represent the direction in which the elevation direction of the antenna is projected onto the ground surface, and the direction in which the azimuth direction of the antenna is projected onto the ground surface. Traditionally, beam rotation control was used to direct the beam towards the observation target. This beam rotation control was achieved through electronic scanning or mechanical drive. However, while the beam direction (vector) is aligned with the direction of the object being observed, rotation around the beam direction is not defined. Furthermore, the direction of variation of the electric field vector of the electromagnetic waves irradiating the object being observed is not controlled in the intended direction. As a result, there was a problem in that it was not possible to observe the object under the desired electric field vector incidence conditions.
[0041] Embodiment 1 makes it possible to fix the direction of fluctuation of the electric field vector of the horizontally polarized waves irradiated onto the object being observed to be perpendicular to the direction of the Earth surface normal to the object being observed.
[0042] ***Description of the Example*** The target position Pg may be set from the ground station 110 to the observation satellite 200, or it may be set on the observation satellite 200 based on the conditions of the target 101. The satellite position Psat may be determined by the observation satellite 200, or it may be calculated by the ground station 110 and set on the observation satellite 200. For example, at the ground station 110, the distance from each of the multiple radars to the observation satellite 200 is measured, and the satellite position Psat is calculated by triangulation. The normal direction N may be set from the ground station 110 to the observation satellite 200, or it may be calculated based on the target position Pg at the observation satellite 200.
[0043] The following describes an example for observation target 102.
[0044] The first embodiment will be described based on Figure 6. Observation target 102 is a point trajectory located on the Earth's surface in a direction that coincides with the direction of movement of observation satellite 200. The direction of movement of observation target 102 corresponds to the direction in which the direction of movement of observation satellite 200 is projected onto the Earth's surface. Observation target 102 moves in accordance with the movement of observation satellite 200. The antenna control device 222 adjusts the direction of the antenna 201 in accordance with the movement of the object being observed 102 and the movement of the observation satellite 200.
[0045] A second embodiment will be described based on Figure 7. Observation target 102 is a point trajectory located on the Earth's surface in a direction that does not coincide with the direction of movement of observation satellite 200. Observation target 102 moves within the observation area independently of the movement of observation satellite 200. The antenna control device 222 adjusts the direction of the antenna 201 in accordance with the movement of the object being observed 102 and the movement of the observation satellite 200.
[0046] A third embodiment will be described based on Figure 8. The observation target 102 may be a representative point on the path of a point trajectory located on the Earth's surface in a direction that coincides with the direction of travel of the observation satellite 200. The position of the observation target 102 at any time during the observation period is the representative point. The antenna control device 222 calculates the direction of direction when the representative point at the satellite observation point is the observation target 102. The direction of direction is maintained throughout the observation period. The relationship between the direction of antenna 201 and the spatial coordinate system is fixed. Maintaining this relationship between the direction of antenna 201 and the spatial coordinate system throughout the observation period yields the following effects: 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 ground surface and the ground surface normal vector of the radio wave irradiation point is fixed to approximately a right angle. The radio wave irradiation point is the intersection of the beam direction and the ground surface. The spatial coordinate system may be an orbital coordinate system or an inertial coordinate system.
[0047] A fourth embodiment will be described based on Figure 9. Observation target 102 is a point located underground. The point of radio wave irradiation is the intersection of the beam direction and the Earth's 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 location Pg. The normal direction of the target plane is the same as the normal direction N.
[0048] Embodiment 2. The main differences from Embodiment 1 regarding the configuration in which the beam is irradiated while being diverted from the direction of direction of antenna 201 will be explained with reference to Figure 10.
[0049] ***Explanation of the structure*** The configuration of the satellite observation system 100 is the same as the configuration in Embodiment 1. However, the target object 101 does not have to be the same as the observation object 102.
[0050] ***Explanation of operation*** Based on Figure 10, the characteristics of the observation method will be explained. The antenna control device 222 adjusts the 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 the boresight direction Boa of the antenna 201 points in a direction deviated by a deviation angle θ from the direction pointing to the observation target 102. The specific plane is the 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 location of the observation target 102. The beam control device 223 irradiates the antenna 201S with a beam deflected from its directing direction according to the deflection angle θ by electronic scanning. The deflection angle θ is the angle in the elevation direction El of antenna 201. The antenna 201 points towards the target 101 which is further away from the observation target 102, while the beam points towards the observation target 102 which is closer than the target 101. Alternatively, the antenna 201 may point towards a target 101 that is closer than the observation target 102, while the beam may point towards an observation target 102 that is further away from the target 101.
[0051] The procedure for the observation method is the same as the procedure in Embodiment 1 (see Figure 4). However, the target information received in step S110 further indicates the deflection angle θ. Furthermore, the formula for calculating the directional direction in step S120 is as follows:
[0052]
number
[0053] The operation `rotation{X,Y,Z}` means rotating the unit vector X by Z degrees in a right-handed direction around the 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 object 102 is located to the right of the satellite's basoplanet as viewed from the observation satellite 200, the azimuth direction Az is calculated by equation (2-1R). When the observed object 102 is located to the left of the satellite's basoplanet as viewed from the observation satellite 200, the azimuth direction Az is calculated by equation (2-1L). The elevation direction El corresponds to the direction obtained by deflecting the relative direction of the satellite position Psat with respect to the target position Pg around the axis of the azimuth direction Az and rotating it according to the angle θ. The elevation direction El is calculated by performing equation (2-2). The boresight direction Boa corresponds to the cross product of the azimuth direction Az and the elevation direction El. The boresight direction Boa is calculated by performing equation (2-3). The beam direction, Beam, corresponds to the relative direction of the target position Pg to the satellite position Psat. The beam direction, Beam, is calculated by performing equation (2-4).
[0055] ***Supplement to Embodiment 2*** The antenna control device 222 controls the rotational 2 degrees of freedom 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 the 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. The antenna control device 222 controls the remaining rotational degree of freedom of the antenna 201, thereby directing the boresight direction of the antenna 201 to the targeting target 101 (a position deviated in the elevation direction El projected onto the ground surface) which is deviated from the observation target 102, according to the deflection angle θ. The beam control device 223 directs the beam towards the observation target 102 by electronic scanning. Through this series of controls, the beam is directed towards the observation target 102. Furthermore, the angle between the direction of variation of the electric field vector of the horizontally polarized waves irradiating the observation target 102 and the surface normal vector 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 antenna 201 around the boresight axis.
[0056] When the deflection angle θ is zero, Embodiment 2 is equivalent to Embodiment 1.
[0057] ***Effects of Embodiment 2*** Embodiment 2 makes it possible to fix the direction of variation of the electric field vector of the horizontally polarized waves irradiated onto the observation target at a right angle to the direction of the ground surface normal to the observation target, without significantly increasing the rotation rate of the platform antenna around the boresight axis.
[0058] ***Description of the Example*** The deflection angle θ may be set from the ground station 110 to the observation satellite 200, or it may be set on the observation satellite 200.
[0059] The deflection angle θ is set as the angle around the axis of the azimuth direction Az. Due to the deflection angle θ, the point of focus will deviate from the observed object in the elevation direction El. This is an embodiment that takes into account the fact that the adjustment range by electronic scanning is usually large in the elevation direction (El).
[0060] The embodiment of Embodiment 1 may also be applied to Embodiment 2.
[0061] Embodiment 3. The main differences from Embodiment 1 regarding the configuration in which the beam is irradiated while being diverted from the direction of direction of antenna 201 will be explained with reference to Figure 11.
[0062] ***Explanation of the structure*** The configuration of the satellite observation system 100 is the same as the configuration in Embodiment 1. However, the target object 101 does not have to be the same as the observation object 102.
[0063] ***Explanation of operation*** Based on Figure 11, the characteristics of the observation method will be explained. The dashed line attached to 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 object 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 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 the boresight direction Boa of the antenna 201 points in a direction deviated by a deviation angle θ from the direction pointing to the observation target 102. 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 location of the observation target 102, and is rotated around the normal direction of the ground surface at the location of the observation target 102 according to the 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 procedure for the observation method is the same as the procedure in Embodiment 1 (see Figure 4). However, the target information received in step S110 further indicates the surface rotation angle φ and the deflection angle θ. Furthermore, the formula for calculating the directional direction in step S120 is as follows:
[0066]
number
[0067] The operation `rotation{X,Y,Z}` means rotating the unit vector X by Z degrees in a right-handed direction around the 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 object 102 is located to the right of the satellite's basoplanet as viewed from the observation satellite 200, the azimuth direction Az is calculated by equation (3-1R). When the observed object 102 is located to the left of the satellite's basoplanet as viewed from the observation satellite 200, the azimuth direction Az is calculated by equation (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, according to the plane rotation angle φ around the axis of the normal direction N, and then rotating that direction according to the deflection angle θ around the axis of the azimuth direction Az. The boresight direction Boa is calculated by performing 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 by performing equation (3-4). The beam direction, Beam, corresponds to the relative direction of the target position Pg to the satellite position Psat. The beam direction, Beam, is calculated by applying equation (3-5).
[0069] ***Supplement to Embodiment 3*** The antenna control device 222 controls the rotational 2 degrees of freedom 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 the 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 direction of the ground surface normal at the position of the observation target 102 according to the plane rotation angle φ. The antenna control device 222 directs the boresight direction of the antenna 201 in a direction corresponding to the deflection angle θ by controlling the remaining rotational degree of freedom of the antenna 201. The beam control device 223 directs the beam towards the observation target 102 by electronic scanning. Through this series of controls, the beam is directed towards the observation target 102. Furthermore, the angle between the direction of variation of the electric field vector of the horizontally polarized waves irradiating the observation target 102 and the surface normal vector 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 antenna 201 around the boresight axis.
[0070] When the surface rotation angle φ is zero and the deflection angle θ is zero, Embodiment 3 is equivalent to Embodiment 1. When the surface rotation angle φ is zero, Embodiment 3 is equivalent to Embodiment 2.
[0071] ***Effects of Embodiment 3*** Embodiment 3 makes it possible to fix the direction of fluctuation of the electric field vector of the horizontally polarized waves irradiated onto the observation target at a right angle to the direction of the ground surface normal to the observation target, without significantly increasing the rotation rate of the platform antenna around the boresight axis.
[0072] ***Description of the Example*** The plane rotation angle φ and the deflection angle θ may be set from the ground station 110 to the observation satellite 200, or they may be set on the observation satellite 200.
[0073] The plane rotation angle φ is set as the angle around the normal direction of the ground surface of the object being observed. Due to the plane rotation angle φ, the point of focus will deviate from the object of observation in the azimuth direction Az. The deflection angle θ is set as an angle around the azimuth axis (Az). Depending on the deflection angle θ, the point of focus will be deflected from the object of observation in the elevation direction (El).
[0074] The embodiment of Embodiment 1 may also be applied to Embodiment 3.
[0075] ***Supplementary Information on the Embodiment*** Each embodiment is an example of a preferred form and is not intended to limit the technical scope of this 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] The word "device" can be replaced with "part," "processing," "circuit," or "circuit."
[0077] The various aspects of this disclosure are described below as appendices. (Note 1) An antenna for emitting a beam and receiving the beam reflected from 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, A beam control device that irradiates a beam in the direction of the antenna, A receiving device that uses the aforementioned antenna to receive the beam reflected from the object being observed, It is a flying object equipped with, The aforementioned 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 at the position of the observation target. The aforementioned target plane is the plane on which the observed object is located. Flying object.
[0078] (Note 2) The antenna control device adjusts the antenna's pointing direction such that the antenna's azimuth direction coincides with the normal direction of the specific plane, and the antenna's boresight direction points towards the object being observed. The flying object described in Appendix 1.
[0079] (Note 3) The aforementioned target plane is the ground surface, The object of observation is fixed to the ground surface, The antenna control device adjusts the direction of the antenna in accordance with the movement of the flying object. The projectile described in Appendix 1 or Appendix 2.
[0080] (Note 4) The aforementioned target plane is the ground surface, The object being observed moves across the ground surface in a direction that coincides with the direction of travel of the flying object. The antenna control device adjusts the direction of the antenna in accordance with the movement of the observed object and the movement of the flying object. The projectile described in Appendix 1 or Appendix 2.
[0081] (Note 5) The aforementioned target plane is the ground surface, The object being observed is moving across the ground surface in a direction that does not coincide with the direction of travel of the flying object. The antenna control device adjusts the direction of the antenna in accordance with the movement of the observed object and the movement of the flying object. The projectile described in Appendix 1 or Appendix 2.
[0082] (Note 6) The aforementioned target plane is the ground surface, The observed object is a representative point on the path of the projectile traveling across the ground surface in a direction that coincides with the direction of the projectile's movement. The antenna control device adjusts the direction of the antenna in accordance with the movement of the flying object. The projectile described in Appendix 1 or Appendix 2.
[0083] (Note 7) The aforementioned observation target is a point underground, The normal direction of the aforementioned target plane is the same as the normal direction of the Earth's surface at the latitude and longitude of the observed object. The projectile described in Appendix 1 or Appendix 2.
[0084] (Note 8) A directional control system mounted on a flying object described in any one of the items from Appendix 1 to Appendix 7, The antenna control device and, The beam control device and, A directional control system equipped with the following features.
[0085] (Note 9) The direction of the antenna is adjusted so that the azimuth direction of the antenna coincides with the normal direction of a specific plane. The beam is irradiated in the direction of the antenna, The aforementioned antenna is used to receive the beam reflected from the object being observed. It is an observation method, The aforementioned 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 at the position of the observation target. The aforementioned target plane is the plane on which the observed object is located. Observation method.
[0086] (Note 10) An antenna for emitting a beam and receiving the beam reflected from 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 the boresight direction of the antenna points in a direction deviated from the direction pointing to the observation target according to the deflection angle, A beam control device that, by electronic scanning, irradiates the antenna in a direction deflected from the direction of direction according to the deflection angle, A receiving device that uses the aforementioned antenna to receive the beam reflected from the object being observed, It is a flying object equipped with, The aforementioned 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 location of the observation target. The deflection angle is the angle in the elevation direction of the antenna. Flying object.
[0087] (Note 11) The antenna points towards a target that is further away than the observed object. The beam is directed towards the observation target which is closer than the target being directed. The flying object described in Appendix 10.
[0088] (Note 12) The aforementioned antenna points towards a target closer than the observed object, The beam is directed towards the observation target which is further away from the target being directed. The flying object described in Appendix 10.
[0089] (Note 13) A directional control system mounted on a flying object described in any one of the appendices 10 to 12, The antenna control device and, The beam control device and, A directional control system equipped with the following features.
[0090] (Note 14) The antenna's azimuth direction is adjusted so that it coincides with the normal direction of a specific plane, and the antenna's boresight direction points in a direction deviated from the direction pointing to the observation target according to the angle of deviation. By electronic scanning, the beam is irradiated in a direction deflected from the direction of the antenna according to the deflection angle, The antenna is used to receive the beam reflected from the object being observed. It is an observation method, The aforementioned specific plane is the 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 location of the observation target. Observation method.
[0091] (Note 15) An antenna for emitting a beam and receiving the beam reflected from 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 the boresight direction of the antenna points in a direction deviated from the direction pointing to the observation target according to the deflection angle, A beam control device that, by electronic scanning, irradiates the antenna in a direction deflected from the direction of direction according to the deflection angle, A receiving device that uses the aforementioned antenna to receive the beam reflected from the object being observed, It is a flying object equipped with, The aforementioned specific plane is a plane obtained by rotating the 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, around the normal direction of the ground surface at the position of the observation target, according to the plane rotation angle. The aforementioned surface rotation angle is set as an angle around the normal direction of the ground surface, The deflection angle is the angle in the elevation direction of the antenna. Flying object.
[0092] (Note 16) The antenna points towards a target that is further away than the observed object. The beam is directed towards the observation target which is closer than the target being directed. The flying object described in Appendix 15.
[0093] (Note 17) The aforementioned antenna points towards a target closer than the observed object, The beam is directed towards the observation target which is further away from the target being directed. The flying object described in Appendix 15.
[0094] (Note 18) A directional control system mounted on a flying object described in any one of the appendices 15 to 17, The antenna control device and, The beam control device and, A directional control system equipped with the following features.
[0095] (Note 19) The antenna's azimuth direction is adjusted so that it coincides with the normal direction of a specific plane, and the antenna's boresight direction points in a direction deviated from the direction pointing to the observation target according to the angle of deviation. By electronic scanning, the beam is irradiated in a direction deflected from the direction of the antenna according to the deflection angle, The antenna is used to receive the beam reflected from the object being observed. It is an observation method, The aforementioned specific plane is a plane obtained by rotating the 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 location of the observation target, around the normal direction of the ground surface at the location of the observation target, according to the plane rotation angle. The aforementioned surface 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 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 Directional control system, 221 Directional control device, 222 Antenna control device, 223 Beam control device, 231 Receiving device, 232 Observation result recording device, Az Azimuth direction, Beam Beam direction, Boa Boresight direction, El Elevation direction, N Normal direction, Pg Target position, Psat Satellite position, θ Diversion angle, φ Plane rotation angle.
Claims
1. A control device installed at a ground station, which sets target information for a flying object from the ground station. The aforementioned flying body, An antenna for emitting a beam and receiving the beam reflected from an observation target located on the Earth's surface, An antenna control device that adjusts the direction of the antenna in accordance with the movement of the flying object so that the azimuth direction of the antenna matches the normal direction of a specific plane defined based on the normal direction of the target plane at the position of the observation target, and so that the boresight direction of the antenna points towards the observation target. A beam control device that irradiates the antenna in the direction of the boresite, A receiving device that uses the aforementioned antenna to receive the beam reflected from the object being observed, Equipped with, The observed object is located in a direction that is forward of the flying object or in a direction that is backward of the flying object. The aforementioned specific plane is the plane formed by the relative direction of the antenna with respect to the observation object and the normal direction of the target plane. The aforementioned target plane is the ground surface at the location of the observation target, The aforementioned target information indicates the position or normal direction of the observed target. The control device and the ground station's communication device transmit the target information to the flying object and set the target information on the flying object. Control device.
2. A control device installed at a ground station, which sets target information for a flying object from the ground station. The aforementioned flying body, An antenna for emitting a beam and receiving the beam reflected from an observation target located on the Earth's surface, An antenna control device that adjusts the direction of the antenna in accordance with the movement of the flying object so that the azimuth direction of the antenna matches the normal direction of a specific plane defined based on the normal direction of the target plane at the position of the observation target, and so that the boresight direction of the antenna points towards the observation target. A beam control device that irradiates the antenna in the direction of the boresite, A receiving device that uses the aforementioned antenna to receive the beam reflected from the object being observed, Equipped with, The aforementioned specific plane is the plane formed by the relative direction of the antenna with respect to the observation object and the normal direction of the target plane. The observed object is a building located in a direction that is forward of the flying object or in a direction that is backward of the flying object. The normal direction of the aforementioned target plane is the floor direction of the building. The aforementioned target information indicates the position or normal direction of the observed target. The control device and the ground station's communication device transmit the target information to the flying object and set the target information on the flying object. Control device.
3. A control device installed at a ground station, which sets target information for a flying object from the ground station. The aforementioned flying body, An antenna for emitting a beam and receiving the beam reflected from an observation target located on the Earth's surface, An antenna control device that adjusts the direction of the antenna in accordance with the movement of the flying object so that the azimuth direction of the antenna coincides with the normal direction of a specific plane defined according to the position of the object being observed, A beam control device that irradiates a beam in the direction of the antenna, A receiving device that uses the aforementioned antenna to receive the beam reflected from the object being observed, Equipped with, The observed object is located in a direction that is forward of the flying object or in a direction that is backward of the flying object. The aforementioned 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 at the position of the observation target. The aforementioned target plane is the Earth's surface at the aforementioned observation target latitude and longitude, The antenna control device adjusts the direction of the antenna in accordance with the movement of the flying object. The aforementioned target information indicates the position or normal direction of the observed target. The control device and the ground station's communication device transmit the target information to the flying object and set the target information on the flying object. Control device.
4. A control device installed at a ground station, which sets target information for a flying object from the ground station. The aforementioned flying body, An antenna for emitting a beam and receiving the beam reflected from an observation target located on the Earth's surface, An antenna control device that adjusts the direction of the antenna in accordance with the movement of a flying object so that the azimuth direction of the antenna coincides with the normal direction of a specific plane defined according to the position of the object being observed, A beam control device that irradiates a beam in the direction of the antenna, A receiving device that uses the aforementioned antenna to receive the beam reflected from the object being observed, Equipped with, The observed object is located in a direction that is forward of the flying object or in a direction that is backward of the flying object. The aforementioned specific plane is the plane formed by the relative direction of the antenna to the observation target and the floor direction of the building in terms of the latitude and longitude of the observation target. The aforementioned target information indicates the position or normal direction of the observed target. The control device and the ground station's communication device transmit the target information to the flying object and set the target information on the flying object. Control device.