Synthetic aperture radar reflector and measurement method

Abstract

To provide a synthetic aperture radar reflector capable of controlling the inclination of a reflector plate, and a measurement method using the same.SOLUTION: A synthetic aperture radar reflector includes a support; a reflector constituted to include a reflector plate for reflecting a synthetic aperture radar; and an arm arranged on both sides of the reflector and installed on the support. The reflector is installed on the arm on both sides so as to slide along the arm axis of the arm; a part thereof is pin-connected to the support; and when the reflector slides along the arm axis, the rotation of the reflector changes the inclination thereof.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to technology related to measurements using synthetic aperture radar, and more specifically to a reflector for synthetic aperture radar whose tilt can be easily adjusted, and a measurement method using the same. [Background technology]

[0002] Japan is known as a country prone to earthquakes, and in recent years has experienced major earthquakes such as the 2024 Noto Peninsula Earthquake, the Tohoku Pacific Coast Earthquake, and the Southern Hyogo Prefecture Earthquake, each of which has caused extensive damage. Furthermore, due to global warming, there has been an increase in large-scale wind and flood damage, including unprecedented torrential rains and typhoons.

[0003] When widespread building damage occurs due to earthquakes, typhoons, or other disasters, aerial surveys are conducted to grasp the full extent of the damage. For example, aircraft may fly overhead and take photographs (so-called aerial photography), and the images may be used to confirm the extent of the damage. Techniques for surveying large areas include aerial photography and synthetic aperture radar (SAR). For example, differential interferometric synthetic aperture radar (SAR) analysis, which compares SAR measurement results from two different periods, can reveal displacements on the order of a few centimeters over a wide area. The Advanced Land Observing Satellite-2 (ALOS-2) was launched in May 2014, and the development and launch of privately-run micro-SAR satellites is also underway, further promoting the use of SAR.

[0004] Measurements made using synthetic aperture radar (hereafter simply referred to as "synthetic aperture radar measurements") involve microwaves emitted from a satellite being reflected off the ground, and the position and displacement of a feature being determined from the signal strength and phase of the reflected waves. Synthetic aperture radar measurements sometimes use reflectors that strongly reflect synthetic aperture radar (i.e., microwaves). The waves reflected by a reflector are much stronger than the surrounding area, making them distinguishable from waves reflected by other features, so reflectors (sometimes called corner reflectors) are installed at reference points with known coordinates, for example.

[0005] Typically, once a reflector is installed, the inclination (tilt angle) of the reflector (e.g., a metal plate) included in the reflector is not changed, and once installed, the reflector is not moved for a long period of time. Therefore, when installing a reflector, considerable care is required, such as placing the reflector so that it is always at an appropriate angle and selecting a location that does not create a barrier to others. Therefore, various technologies related to reflectors for synthetic aperture radar have been proposed. For example, Patent Document 1 proposes a "reference point reflector" that is fixed to the ground and is intended to reflect satellite radio waves from various directions. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-220905 Summary of the Invention [Problem to be solved by the invention]

[0007] As mentioned above, the tilt of a reflector's reflector's reflective plate is usually not changed, and so the reflector is manufactured so that the reflector has a planned tilt. Therefore, the tilt of the reflector in conventional reflectors, including the reference point reflector of Patent Document 1, remains fixed, meaning that the tilt of the reflector cannot be changed afterward. However, when a reflector is actually installed on-site, the tilt of the reflector may need to be changed because it is observed by satellites from various directions. Furthermore, the tilt of the reflector may need to be adjusted depending on the surrounding environment and the slope of the installation location. In such cases, conventionally, there was no choice but to manufacture a new reflector.

[0008] The object of the present invention is to solve the conventional problems, that is, to provide a reflector for synthetic aperture radar in which the inclination of the reflector can be adjusted, and a measurement method using the same. [Means for solving the problem]

[0009] The present invention focuses on the fact that the reflector slides along the arm that supports it, thereby making it possible to change the inclination of the reflector, and is an invention based on an idea that has not been seen before.

[0010] The synthetic aperture radar reflector of the present invention comprises a support, a reflector, and an arm. The reflector includes a reflector plate that reflects synthetic aperture radar, and the arms are disposed on both sides of the reflector and attached to the support. The reflectors are attached to the arms on both sides so that they can slide along the arm axes of the arms, and portions of the reflectors are pin-connected to the support. When the reflector slides along the arm axes, the reflector rotates, changing its tilt.

[0011] The synthetic aperture radar reflector of the present invention may also be one in which the arm is attached so as to rotate around the axis of the support.

[0012] The synthetic aperture radar reflector of the present invention may also be mounted so that the arm is slidable along the axis of the support.

[0013] The synthetic aperture radar reflector of the present invention can also have a reflector consisting of a three-sided reflector. That is, the reflector is formed by a "bottom reflecting surface" located on the bottom surface, a "left reflecting surface" located on one side of the bottom reflecting surface, and a "right reflecting surface" located on the other side of the bottom reflecting surface. In this case, the reflector is attached to a support on the back side where the left and right reflecting surfaces are joined. Furthermore, by inserting the left protruding member on the left reflecting surface into the slide hole and the right protruding member on the right reflecting surface into the slide hole, the reflector becomes slidable, i.e., the reflector becomes rotatable.

[0014] The measurement method of the present invention is a method for performing synthetic aperture radar measurement using the synthetic aperture radar reflector of the present invention, and includes a reflector installation step and an angle adjustment step. In the reflector installation step, the synthetic aperture radar reflector of the present invention is installed at a planned position, and in the angle adjustment step, the reflector is slid along the arm axis to adjust the inclination of the reflector. Then, synthetic aperture radar measurement is performed using the synthetic aperture radar reflector. [Effects of the Invention]

[0015] The reflector for synthetic aperture radar and the measurement method of the present invention have the following advantages. (1) Even after the synthetic aperture radar reflector is installed, the inclination of the reflector can be adjusted, making it easier and more flexible to install than conventional reflectors. (2) The manufacturing cost can be reduced by adopting a relatively simple structure in which the reflector rotates when it slides along the arm axis. (3) Conventional reflectors are, so to speak, dedicated products and cannot be used for other measurement locations. On the other hand, the reflector for synthetic aperture radar of the present invention can be used for other measurement locations. As a result, the overall manufacturing cost of the reflector is actually lower than that of the conventional technology. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a perspective view showing a reflector for a synthetic aperture radar according to the present invention; [Figure 2] FIG. 2 is a side view of the reflector for synthetic aperture radar of the present invention; [Figure 3] FIG. 2 is a front view schematically showing a reflector formed by a bottom reflecting surface, a left reflecting surface, and a right reflecting surface, all of which are triangular. [Figure 4] FIG. 1 is a front perspective view of a reflector for synthetic aperture radar including a reflector formed by triangular reflective surfaces. [Figure 5] FIG. 2 is a front view schematically showing a reflector formed by a bottom reflective surface, a left reflective surface, and a right reflective surface, all of which are rectangular. [Figure 6] (a) is a perspective view showing the synthetic aperture radar reflector as seen from behind the support, and (b) is a plan view showing the arm as seen from above. [Figure 7] (a) is a side view that shows the state before the reflector is rotated, and (b) is a side view that shows the state after the reflector is rotated. [Figure 8] 1 is a flowchart showing the flow of main steps of a measurement method according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] An example of an embodiment of a reflector for synthetic aperture radar and a measurement method according to the present invention will be described with reference to the drawings.

[0018] 1. Measurement System First, we will explain the reflector for synthetic aperture radar of the present invention. Note that the measurement method of the present invention is a method for performing synthetic aperture radar measurement using the reflector for synthetic aperture radar of the present invention. Therefore, we will first explain the reflector for synthetic aperture radar of the present invention, and then explain the measurement method of the present invention.

[0019] Fig. 1 is a perspective view showing a synthetic aperture radar reflector 100 of the present invention, and Fig. 2 is a side view of the synthetic aperture radar reflector 100 of the present invention. As shown in these figures, the synthetic aperture radar reflector 100 of the present invention is configured to include a support 110, a reflector 120, and an arm 130, and can also be configured to include a base member 140, a reflector connecting jig 150, an arm connecting jig 160, etc. For convenience, as shown in Fig. 2, the direction away from the support 110 will be referred to as the "front," and the direction approaching the support 110 will be referred to as the "rear." Furthermore, when referring to the "left side" and "right side," these refer to the left and right sides when looking forward from the rear.

[0020] The support 110 constituting the synthetic aperture radar reflector 100 is a tubular or rod-shaped member that is long in the direction of its axis (hereinafter referred to as the "column axis"), and is installed with its column axis oriented in a substantially vertical (including vertical) direction during use. This support 110 supports the reflector 120 and the arm 130, and for example, the arm 130 is attached to the support 110 by an arm connecting jig 160. Meanwhile, a reflector connecting jig 150 is installed on the support 110, and a connecting member 124 provided on the reflector 120 and this reflector connecting jig 150 are pin-connected. The reflector connecting jig 150 is installed on the support 110 at a position higher than the arm 130. In addition, arm 130 is provided with a slide hole 130H along its axis (hereinafter referred to as the "arm axis"), and reflector 120 is also attached to arm 130 by inserting a portion of protrusion 120B provided on reflector 120 into this slide hole 130H.

[0021] The synthetic aperture radar reflector 100 can be fixed to a foundation frame BS prepared in advance as shown in Fig. 1, or to a concrete foundation BC as shown in Fig. 2. Of course, the synthetic aperture radar reflector 100 can be fixed to various foundations, not just the foundation frame BS or concrete foundation BC, such as directly to the ground.

[0022] The reflector 120 constituting the synthetic aperture radar reflector 100 includes a reflector. This reflector is a plate-shaped member made of a material that strongly reflects synthetic aperture radar (i.e., microwaves), such as a metal such as iron or copper, and various conventional reflectors can be used. The reflector 120 can be a corner reflector made of a three-sided reflector. For example, the reflector 120 shown in FIG. 3 is configured by joining triangular reflectors. More specifically, a reflector disposed on the bottom surface (hereinafter referred to as the "bottom reflecting surface 121"), a reflector disposed on the left side of the bottom reflecting surface 121 (hereinafter referred to as the "left reflecting surface 122"), and a reflector disposed on the right side of the bottom reflecting surface 121 (hereinafter referred to as the "right reflecting surface 123") are joined at their adjacent sides. Then, a part (connecting material 124) of the reflector 120 shown in FIG. 3 is connected to the reflector connecting jig 150, and the reflector 120 is attached to the arm 130, thereby forming the synthetic aperture radar reflector 100 shown in FIG.

[0023] 5, the reflector 120 can be formed by a bottom reflecting surface 121, a left reflecting surface 122, and a right reflecting surface 123, all of which are rectangular. Alternatively, the reflector 120 can be formed by a reflecting plate of another shape, or by one or more reflecting plates.

[0024] Fig. 6(a) is a perspective view showing the synthetic aperture radar reflector 100 as seen from behind the support pillar 110, and Fig. 6(b) is a plan view schematically showing the arm 130 as seen from above. As shown in this figure, the arm 130 is roughly U-shaped in plan view, and is formed by a central arm 131, a left arm 132, and a right arm 133. The arm 130 can be formed by joining the central arm 131, the left arm 132, and the right arm 133, which are each separate bodies, or it can be formed as a single body from the beginning.

[0025] Arm 130 is attached to support 110 with central arm 131 in a substantially horizontal (including horizontal) position that is substantially perpendicular (including vertical) to the axis of support 110, and further arranged so that the center of central arm 131 is located near support 110. At this time, left arm 132 and right arm 133 are arranged substantially perpendicular (including vertical) to central arm 131, so that left arm 132 is arranged to extend forward on the left side, and right arm 133 is arranged to extend forward on the right side.

[0026] As described above, the arm 130 is attached to the support 110 by the arm connecting jig 160. This arm connecting jig 160 can be a member that is wrapped around the support 110 and connected to the arm 130, such as a U-bolt or a ring band. In this case, the arm connecting jig 160 is rotatable around the axis of the support 110 and is also slidable up and down relative to the support 110. As a result, the arm 130 attached to the support 110 by the arm connecting jig 160 is also rotatable around the axis of the support 110 and is also slidable up and down relative to the support 110.

[0027] 6(b), a slide hole 130H (hereinafter, particularly referred to as the "left slide hole 132H") that is an elongated hole along the arm axis is formed in the left arm 132 of the arm 130, and a slide hole 130H (hereinafter, particularly referred to as the "right slide hole 133H") that is also formed in the right arm 133 along the arm axis. Meanwhile, a left protrusion 122B extending to the left is provided on the left reflecting surface 122 of the reflector 120, and a right protrusion 123B extending to the right is provided on the right reflecting surface 123. A portion of the tip end of the left protrusion 122B is inserted into the left slide hole 132H, and a portion of the tip end of the right protrusion 123B is inserted into the right slide hole 133H. As a result, the reflector 120 is supported by the support 110 (reflector connecting jig 150) and also by the arm 130, and is slidable along the arm axis.

[0028] As described above, reflector 120 is attached to arm 130 so as to be slidable along the arm axis, but it is not limited to the slide mechanism consisting of overhang member 120B and slide hole 130H, and various other conventional slide mechanisms can also be used. For example, various slide mechanisms can be used, such as a rack-and-pinion slide mechanism in which a rack is provided on one of reflector 120 or arm 130 and a pinion is provided on the other, or a rail-type slide mechanism in which a rail is provided on one side and a rotating body (such as a wheel) on the other.

[0029] As shown in FIG. 7 , the reflector 120 is attached to the support 110 via a reflector connecting jig 150. More specifically, the reflector 120 is attached to the support 110 by pin-connecting the reflector connecting jig 150, which is installed on the support 110, to a part of the reflector 120 (connecting member 124). In other words, the reflector 120 is attached to the support 110 so as to be rotatable within a substantially vertical (including vertical) plane that includes the support 110. Note that, like the arm connecting jig 160, a U-bolt, a ring band, or the like can be used for the reflector connecting jig 150. In this case, the reflector connecting jig 150 is rotatable around the axis of the support 110 and is slidable up and down relative to the support 110. As a result, the reflector 120, which is pin-connected to the reflector connecting jig 150, is also rotatable around the axis of the support 110 and is slidable up and down relative to the support 110.

[0030] The mechanism by which the reflector 120 rotates will be described below with reference to Fig. 7. Fig. 7(a) is a side view that schematically shows the state before the reflector 120 rotates, and Fig. 7(b) is a side view that schematically shows the state after the reflector 120 has rotated. Note that this figure depicts the right side of the synthetic aperture radar reflector 100.

[0031] In the state shown in FIG. 7(a), the right protrusion 123B of the right reflecting surface 123 is placed in front of the right slide hole 133H, and similarly, the left protrusion 122B of the left reflecting surface 122 is placed in front of the left slide hole 132H. In this case, the reflector 120 and the connecting member 124 are both inclined at a "gentle slope" close to a horizontal plane. On the other hand, when the right protrusion 123B and the left protrusion 122B are slid backward from the state shown in FIG. 7(a), the connecting member 124, which is pin-connected to the reflector connecting jig 150, rotates forward (clockwise in the figure) in a substantially vertical plane, and the reflector 120 also rotates forward accordingly. As a result, the reflector 120 and the connecting member 124 shown in FIG. 7(b) are both inclined at a "steep slope" close to a vertical plane compared to FIG. 7(a).

[0032] 2. Measurement method Next, the measurement method of the present invention will be described with reference to Fig. 8. The measurement method of the present invention is a method for performing synthetic aperture radar measurement using the synthetic aperture radar reflector 100 described up to this point. Therefore, we will avoid any explanation that overlaps with the content explained for the synthetic aperture radar reflector 100, and will mainly explain content that is unique to the measurement method of the present invention. In other words, content not described here is the same as that explained in "1. Synthetic Aperture Radar Reflector."

[0033] Figure 8 is a flow diagram showing the flow of the main steps of the measurement method of the present invention. To perform synthetic aperture radar measurement using the synthetic aperture radar reflector 100 of the present invention, first, as shown in this figure, the synthetic aperture radar reflector 100 is installed at the planned position (Step 201 in Figure 8). Then, the tilt of the reflector 120 is adjusted by sliding the overhanging member 120B back and forth (Step 202 in Figure 8), and synthetic aperture radar measurement is performed using the synthetic aperture radar reflector 100 (Step 203 in Figure 8). [Industrial Applicability]

[0034] The synthetic aperture radar reflector and measurement method of the present invention can be used particularly effectively in places where monitoring of displacement is required, such as structures such as dams, or slopes at risk of landslides or deep collapses. Considering that the use of the present invention enables early reinforcement and repair of large-scale structures and makes it possible to avoid slope disasters by monitoring landslides, etc., it can be said that the invention is not only applicable to industry but is also expected to contribute to society. [Explanation of symbols]

[0035] 100 Reflector for synthetic aperture radar of the present invention 110 (Synthetic aperture radar reflector) support 120 (Synthetic aperture radar reflector) reflector 120B (Reflector) Outrigger 121 (of a reflector) bottom reflective surface 122 (Reflector) Left Reflection Surface 122B Left outrigger (of reflector) 123 Right reflective surface (of reflector) 123B Right outrigger (of reflector) 124 (Reflector) Connector 130 (synthetic aperture radar reflector) arm 130H (Arm) slide hole 131 (of the arms) Central arm 132 (of the arm) left arm 132H (Left arm) Left slide hole 133 Right arm 133H (Right arm) Right slide hole 140 (Synthetic aperture radar reflector) base member 150 Reflector connection jig (for synthetic aperture radar reflectors) 160 (Synthetic aperture radar reflector) arm connecting jig BC Foundation Concrete BS foundation frame

Claims

1. The pillars and a reflector including a reflector that reflects synthetic aperture radar; and arms disposed on both sides of the reflector, The arm is attached to the support, the reflectors are attached to the arms on both sides so as to be slidable along the arm axes of the arms; Furthermore, a portion of the reflector is pin-coupled to the support, When the reflector slides along the arm axis, the tilt changes. A reflector for synthetic aperture radar characterized by:

2. the arm is attached to the support so as to rotate about an axis of the support; 2. The reflector for synthetic aperture radar according to claim 1.

3. the arm is attached to the support so as to be slidable along the axis of the support; 2. The reflector for synthetic aperture radar according to claim 1.

4. The reflector is formed by a bottom reflective surface disposed on a bottom surface, a left reflective surface disposed on one side of the bottom reflective surface, and a right reflective surface disposed on the other side of the bottom reflective surface; the bottom reflective surface, the left reflective surface, and the right reflective surface each comprise a reflective plate; The arm is provided with a slide hole along the arm axis, the reflector is attached to the support at a rear surface where the left and right reflecting surfaces are joined, The left protrusion provided on the left reflective surface is inserted into the slide hole, and the right protrusion provided on the right reflective surface is inserted into the slide hole.

2. The reflector for synthetic aperture radar according to claim 1.

5. a reflector installation step of installing the synthetic aperture radar reflector according to claim 1 at a planned position; an angle adjusting step of adjusting the inclination of the reflector by sliding the reflector along the arm axis, The synthetic aperture radar reflector is used to perform measurement using the synthetic aperture radar. A measuring method characterized by:

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