Sensor holding device
The sensor holding device ensures parallel contact of the ultrasonic sensor with the subject's surface using a simplified configuration, addressing the challenge of maintaining sensor alignment during tilted drone propulsion.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- SIDE EFFECT CO LTD
- Filing Date
- 2024-12-17
- Publication Date
- 2026-05-19
AI Technical Summary
Existing methods for remotely pressing an ultrasonic sensor against a subject, such as large structures, often require complex configurations and struggle to maintain the sensor surface parallel to the structure's surface, especially when the drone is tilted during propulsion.
A sensor holding device with a sensor mounting portion, support mounting portion, and multiple connecting members of varying lengths, allowing for rotational adjustment to ensure the sensor surface remains parallel to the subject's surface, even when the drone is tilted.
The device allows for stable and parallel contact of the ultrasonic sensor with the subject's surface, mitigating impact and averaging pressure, enabling effective ultrasonic wave propagation and measurement.
Smart Images
Figure 2026082588000001_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a technique for evaluating the state of a subject using an ultrasonic sensor, and particularly to a technique for remotely evaluating the state of a subject.
Background Art
[0002] In recent years, as one method for evaluating the state of a subject such as a structure, a non-destructive inspection technique using ultrasonic waves has come to be used. As an example of the evaluation of the state of a subject using such a non-destructive inspection technique using ultrasonic waves, measuring the thickness of the wall of the subject has been performed. When measuring the thickness of the wall of the subject, an ultrasonic signal transmitted from an ultrasonic sensor toward the wall of the subject propagates inside the subject, and the ultrasonic signal is reflected by the inner surface of the wall and reaches the ultrasonic sensor. By measuring the time from the transmission to the reception of this ultrasonic signal, the thickness of the wall of the subject can be measured. Also, an ultrasonic signal reflected by an inclusion or a defect inside the subject is received, and the depth of existence of the inclusion or the defect is also measured.
[0003] Thus, when performing non-destructive inspection using ultrasonic waves, the sensor surface of the ultrasonic sensor that transmits and receives ultrasonic signals is pressed against the outer surface (wall surface) of the wall, which is the subject, in a state parallel to the wall surface. This operation of pressing the sensor surface against the wall surface is usually performed by an operator holding the ultrasonic sensor and pressing the sensor surface (ultrasonic sensor) against the wall surface while adjusting the orientation of the ultrasonic sensor held by the operator.
[0004] However, when evaluating the condition of the upper side walls of large structures such as large tanks and chimneys, it is not easy for workers to directly press the ultrasonic sensor against the wall surface at the measurement point. Furthermore, even if the structure is relatively small, depending on its location, it may be difficult for workers to approach the structure. Therefore, a drone equipped with an ultrasonic sensor is used to bring the ultrasonic sensor into contact with the structure, and then the drone is propelled towards the structure to press the ultrasonic sensor against it.
[0005] Thus, when a drone is propelled toward a subject, the drone is generally tilted so that the side in the direction of propulsion faces downward, making it difficult to align the sensor surface of the ultrasonic sensor with the wall surface of the subject. Therefore, various methods have been proposed to support the sensor (ultrasonic sensor) in a flexible manner on an arm extending forward from the drone body, so that the sensor can be brought into direct contact with the wall surface of the subject (i.e., with the sensor surface parallel to the wall surface) (see, for example, Patent Document 1).
[0006] As a method for making the sensor directly face and contact the wall surface of the subject, Patent Document 1 describes connecting a front arm that holds the sensor and a rear arm attached to the drone body with a bending spring, and by bending the bending spring, the sensor cover attached to the front arm and protecting the sensor comes into direct contact with the wall surface of the subject, so that the sensor comes into direct contact with the wall surface of the subject. [Prior art documents] [Patent Documents]
[0007] [Patent Document 1] Japanese Patent Publication No. 2023-170624 [Overview of the project] [Problems that the invention aims to solve]
[0008] However, with the method proposed in Patent Document 1, it is possible to ensure that the direction of the arm that makes contact with the sensor is not initially directly facing the wall surface of the subject, but that the sensor eventually comes into direct contact with the wall surface of the subject. However, the configuration is complex.
[0009] The present invention has been made to solve the above-mentioned conventional problems, and aims to provide a technology that enables remotely pressing an ultrasonic sensor against a subject so that the sensor surface of the ultrasonic sensor is parallel to the surface of the subject, with a simpler configuration. [Means for solving the problem]
[0010] The invention described in claim 1 of the present invention is a sensor holding device for remotely pressing an ultrasonic sensor for evaluating the condition of a subject onto the subject, comprising: a sensor mounting portion to which the ultrasonic sensor is attached; a support mounting portion to which a support for remotely supporting the sensor holding device is attached; and N (N is an integer of 3 or more) connecting members connected to both the sensor mounting portion and the support mounting portion, wherein the distance from the axis of the sensor holding device to the sensor-side connecting portion to which each of the N connecting members is connected to the sensor mounting portion and the distance from the axis of the support-side connecting portion to which each of the N connecting members is connected are set to be different from each other, and each of the N connecting members is rotatable about the sensor-side connecting portion and the support mounting portion, respectively, in a plane including the axis.
[0011] The invention described in claim 2 is characterized in that, in the sensor holding device described in claim 1, the distance of the sensor-side connection portion from the axis is set to be shorter than the distance of the support-side connection portion from the axis.
[0012] The invention described in claim 3 is characterized in that, in the sensor holding device described in claim 1 or 2, the connecting member is formed of a flexible wire.
[0013] The invention described in claim 4 is characterized in that, in the sensor holding device described in claim 1 or 2, the support body has a rod that extends from the drone in the direction in which the drone can move. [Effects of the Invention]
[0014] According to the sensor holding device of claim 1, when the inclination of the axis with respect to the pressing direction is small, the load applied to the ultrasonic sensor from the subject causes the sensor surface of the ultrasonic sensor to become parallel to the surface of the subject. The sensor holding device mainly consists of a sensor mounting part to which the ultrasonic sensor is attached, a support mounting part to which a support that remotely supports the sensor holding device is attached, and N connecting members (where N is an integer of 3 or more) connected to both the sensor mounting part and the support mounting part. Therefore, it is possible to remotely press the ultrasonic sensor against the subject with a simpler configuration so that the sensor surface of the ultrasonic sensor becomes parallel to the surface of the subject.
[0015] According to the sensor holding device of claim 2, even when the inclination of the axis with respect to the pressing direction becomes large, the sensor surface of the ultrasonic sensor can be made parallel to the surface of the subject.
[0016] According to the sensor holding device of claim 3, when the ultrasonic sensor comes into contact with the surface of the object to be examined, the impact applied to the ultrasonic sensor can be mitigated, and when the ultrasonic sensor is pressed against the object to be examined, the pressure of the ultrasonic sensor can be averaged across the entire sensor surface, allowing for more stable propagation of ultrasonic waves.
[0017] According to the sensor holding device of claim 4, the ultrasonic sensor can be pressed against the subject even when the subject is at a high height or when it is difficult to see the subject in a straight line.
[0018] Incidentally, the present invention can be implemented in various modes. For example, it can be implemented in modes such as a sensor holding device, a subject state evaluation device using the sensor holding device, a subject state evaluation method using those holding devices and state evaluation devices, and the like.
Brief Description of the Drawings
[0019] [Figure 1] It is an explanatory diagram showing a state of measuring the thickness of an upper side wall of a large structure by applying the first embodiment of the present invention. [Figure 2] It is an explanatory diagram showing a state of measuring the thickness of an upper side wall of a large structure by applying the first embodiment of the present invention. [Figure 3] It is an external perspective view showing the configuration of a drone system to which the first embodiment is applied. [Figure 4] It is an explanatory diagram showing the configuration of a sensor unit. [Figure 5] It is an explanatory diagram showing the operation of a link mechanism deformable in the X-Z plane. [Figure 6] It is an explanatory diagram showing a state where an ultrasonic sensor contacts the surface of a subject. [Figure 7] It is an explanatory diagram showing a state where the surface of an ultrasonic sensor is pressed against the surface of a subject by a conventional drone equipped with an ultrasonic sensor. [Figure 8] It is an explanatory diagram showing a state where the surface of an ultrasonic sensor is pressed against the surface of a subject by a conventional drone equipped with an ultrasonic sensor. [Figure 9] It is an explanatory diagram showing the operation of a link mechanism deformable in the X-Z plane. [Figure 10] It is an explanatory diagram showing the operation of a link mechanism deformable in the X-Z plane. [Figure 11] It is an explanatory diagram showing the operation of a link mechanism deformable in the X-Z plane. [Figure 12] It is an explanatory diagram showing a state where the surface of an ultrasonic sensor is pressed against the surface of a subject by a conventional drone equipped with an ultrasonic sensor. [Figure 13] It is an explanatory diagram showing the configuration of a sensor unit in the second embodiment. [Modes for carrying out the invention]
[0020] Hereinafter, embodiments for carrying out the present invention will be described in the following order. A. First Embodiment: A1. Measuring the thickness of walls in large structures: A2. Drone system configuration: A3. Sensor unit configuration: A4. Operation of the linkage mechanism: B. Second Embodiment: C. Variant:
[0021] A. First Embodiment: A1. Measuring the thickness of walls in large structures: Figures 1 and 2 are explanatory diagrams showing how to measure the thickness of the upper side wall of a large structure such as a large tank or chimney (in the example of Figures 1 and 2, a large tank) LST by applying the first embodiment of the present invention. In Figures 1 and 2, and other figures, the X and Y directions represent two orthogonal horizontal directions set as appropriate, and the Z direction represents the vertical direction.
[0022] The thickness of a structural wall can be measured by various methods, but it is common to use an ultrasonic sensor. Specifically, the ultrasonic sensor is pressed against the surface of the wall, and an ultrasonic signal is emitted from the sensor in the direction of the wall's thickness. After the emitted ultrasonic signal enters the wall, it propagates through the wall at a constant propagation speed (speed of sound). The ultrasonic signal that has propagated through the wall is reflected by the inner wall surface. The reflected ultrasonic signal is emitted from the outer wall surface and returns to the ultrasonic sensor. At this time, the thickness of the wall is measured by measuring the time (propagation time) from when the ultrasonic sensor emits an ultrasonic signal toward the wall until the ultrasonic signal is reflected by the inner wall surface and returns to the ultrasonic sensor.
[0023] Thus, when measuring the thickness of a wall using an ultrasonic sensor, the thickness of the wall is determined by the propagation time, so the ultrasonic signal needs to be incident in the direction of the wall's thickness. For this reason, the sensor surface of the ultrasonic sensor, which transmits and receives ultrasonic signals, is pressed against the wall surface of the wall being measured, parallel to the wall surface. This operation of pressing the sensor surface against the wall surface is usually performed by an operator holding the ultrasonic sensor and adjusting the orientation of the ultrasonic sensor while pressing the ultrasonic sensor (sensor surface) against the wall surface.
[0024] When an ultrasonic sensor is pressed against a wall surface to measure the thickness of a wall, the sensor surface of the ultrasonic sensor is naturally pressed against the wall surface. Therefore, pressing an ultrasonic sensor against a wall is equivalent to pressing the sensor surface of the ultrasonic sensor against the wall surface, and in this specification, unless specifically necessary, these distinctions are not made. Similarly, unless specifically necessary, no distinction is made between a wall and a wall surface as objects against which the ultrasonic sensor is pressed.
[0025] Generally, as described above, an ultrasonic sensor is pressed against the wall of the object to be measured by an operator. However, when measuring the thickness of the upper side wall of a large structure such as a LST, as shown in Figures 1 and 2, it is not easy for an operator to directly press the ultrasonic sensor against the wall surface at the measurement point. Furthermore, even with relatively small structures, depending on the installation location, it may be difficult for an operator to approach the structure. Therefore, as shown in Figures 1 and 2, by using a drone system 100 equipped with an ultrasonic sensor, it becomes possible to remotely press the ultrasonic sensor against the wall surface at the measurement point. The specific configuration of the drone system 100 to which the first embodiment is applied will be described later.
[0026] When measuring the thickness of the upper side wall of a large structure LST using the drone system 100, the drone system 100 is controlled to approach the large structure LST by flight control, as shown in Figure 1. In the example in Figure 1, the drone system 100 is positioned on the -X side of the large structure LST. After positioning the drone system 100 on the -X side of the large structure LST, the drone system 100 is propelled in the +X direction as shown by the three-dimensional arrow.
[0027] As a result, as shown in Figure 2, the ultrasonic sensor attached to the tip of the drone system 100 comes into contact with the large structure LST. Then, with the tip of the drone system 100 in contact with the large structure LST, the drone system 100 is further propelled in the +X direction as shown by the 3D arrow, causing the sensor surface of the ultrasonic sensor attached to the tip of the drone system 100 to be pressed against the wall surface of the large structure (large tank) LST.
[0028] As shown in Figures 1 and 2, when the drone system 100 is propelled in the +X direction, the drone system 100 tilts so that the propulsion direction side (+X direction side) is directed vertically downward (-Z direction). However, as will be described in more detail later, even when the drone system 100 is tilted in this way, by using the drone system 100 to which the first embodiment is applied, the ultrasonic sensor can be pressed against the wall of the large structure LST in the direction of propulsion, with its sensor surface parallel to the wall. In this way, the propulsion direction is the direction in which the ultrasonic sensor is pressed, so it can also be called the "pressing direction".
[0029] A2. Drone system configuration: Figure 3 is an external perspective view showing the configuration of the drone system 100 to which the first embodiment is applied. Note that Figure 3 shows the drone system 100 placed on a horizontal plane (XY plane) which is not shown.
[0030] The drone system 100 includes a drone body 110, a camera 120, mounting members 131 and 132 for attaching various devices to the drone body 110, a rod 201, and a sensor unit 200. The drone system 100 also includes means for supplying an ultrasonic transmission medium to be injected between the ultrasonic sensor and the wall (subject), and wiring for connecting the ultrasonic sensor and the drone body 110, but these are omitted from the illustration in Figure 3.
[0031] The rod 201 is a cylindrical member extending from the mounting member 132 toward the tip (+X direction). The sensor unit 200 is attached to the tip side (+X direction side) of this rod 201, so that it is positioned away from the drone body 110 toward the tip. This prevents interference between the subject (in the example in Figure 2, the wall of a large structure LST) and the drone body 110 when the ultrasonic sensor comes into contact with the subject.
[0032] By attaching the sensor unit 200 to the rod 201 in this way, the ultrasonic sensor is remotely pressed against the wall surface of the subject. Therefore, the rod 201 can be considered a "support" that remotely supports the sensor unit 200 in order to remotely press the ultrasonic sensor against the subject.
[0033] Figure 3 shows an example of the drone system 100, but the drone body, camera, and mounting components that make up the drone system can be changed in various ways. For example, in the example in Figure 3, the drone body 110 and the camera 120 are separate, but a drone body with a built-in camera can be used.
[0034] A3. Sensor unit configuration: Figure 4 is an explanatory diagram showing the configuration of the sensor unit 200. Figure 4(a) is an external perspective view showing the sensor unit 200 and the tip of the rod 201 (hereinafter also referred to as the "rod tip"). Figure 4(b) is a partial cross-sectional view of the sensor unit 200 and the rod tip, cut along the cutting plane A (the XZ plane passing through the axis C) in Figure 4(a). In Figures 4(a) and 4(b), the dashed line C represents the axis C of the sensor unit 200. The direction perpendicular to the axis C and away from the axis C is also called the "outward direction".
[0035] As shown in Figure 4, the sensor unit 200 includes a rod mounting portion 210, four extension arms 220, four link members 230, four link connection tabs 240, a sensor mounting portion 250, and an ultrasonic sensor 260.
[0036] Furthermore, the sensor unit 200, excluding the ultrasonic sensor 260, consists of the rod mounting portion 210, extension arm 220, link member 230, link connection tab 240, and sensor mounting portion 250, and is configured as a whole to hold the ultrasonic sensor 260, so it can also be called a "sensor holding device".
[0037] The rod mounting portion 210 is a substantially cylindrical member, and a rod mounting hole 219 is provided at its rear end (-X direction side) into which the tip of the rod 201 is inserted. In addition, four arm insertion holes 218 are provided on the side of the rod mounting portion 210, which are arranged at equal angles around the axis C into which the extension arm 220 is inserted.
[0038] The extension arm 220 is a flat bar-shaped member, one end of which is inserted into the arm insertion hole 218 of the rod mounting portion 210. The other end of the extension arm 220 is provided with a link connection hole 229 for connecting the link member 230. As shown in Figure 4(b), in the first embodiment, the arm insertion hole 218 of the rod mounting portion 210 is formed so that the tip side (+X direction side) faces outward, so the extension arm 220 is positioned so that the tip side faces outward.
[0039] The sensor mounting portion 250 is a substantially annular member provided with a sensor mounting hole 259 and four tab insertion holes 258 arranged at equal angles around the axis C. The sensor mounting hole 259 is designed to match the shape of the ultrasonic sensor 260 described later, with a smaller inner diameter at the rear end and a tapered shape at the front end where the inner diameter decreases towards the front.
[0040] The link connection tab 240 is a flat bar-shaped member, one end of which is inserted into the tab insertion hole 258 of the sensor mounting portion 250. The other end of the link connection tab 240 is provided with a link connection hole 249 for connecting the link member 230. As shown in Figure 4(b), in the first embodiment, the tab insertion hole 258 of the sensor mounting portion 250 is formed to face outward, so the link connection tab 240 is positioned to extend outward.
[0041] The ultrasonic sensor 260 has a large-diameter portion 261 at the tip and a small-diameter portion 262 at the rear end. A tapered portion 269 is formed at the tip of the large-diameter portion 261, with its outer diameter decreasing towards the tip. The tip surface 265 of the large-diameter portion 261 is the sensor surface (hereinafter also referred to as "sensor surface 265") that transmits and receives ultrasonic signals in the ultrasonic sensor 260.
[0042] As described above, the sensor mounting portion 250 is provided with a sensor mounting hole 259 formed to match the shape of the ultrasonic sensor 260. By fitting the ultrasonic sensor 260 into this sensor mounting hole 259, the ultrasonic sensor 260 is fixed to the sensor mounting portion 250. Furthermore, as shown in Figure 4, when the ultrasonic sensor 260 is fitted into the sensor mounting portion 250, the sensor surface 265 and the tip surface of the sensor mounting portion 250 are aligned on a substantially single plane. Therefore, the sensor mounting portion 250 also has the function of protecting the ultrasonic sensor 260.
[0043] The link member 230 is a flat bar-shaped member, with an arm connection hole 239 at its rear end for connecting to the extension arm 220, and a tab connection hole 238 at its front end for connecting to the link connection tab 240. The arm connection hole 239 at the rear end is fixed to the position of the link connection hole 229 of the extension arm 220 using a connecting pin (not shown) or a bolt and nut. Similarly, the tab connection hole 238 at the front end is fixed to the position of the link connection hole 249 of the link connection tab 240 using a pin (not shown) or a bolt and nut.
[0044] The arm connection hole 239 and tab connection hole 238 provided in the link member 230 are fixed to the positions of the link connection holes 229 and 249 of the extension arm 220 and link connection tab 240, respectively. However, the link member 230 itself is attached to the extension arm 220 and link connection tab 240 so that it can rotate within a plane containing the axis C, centered on the link connection holes 229 and 249.
[0045] Thus, in the sensor unit 200 of the first embodiment, the link member 230 is configured to be rotatable around the link connection holes 229 and 249. Therefore, the two link members 230 facing each other in the Z direction, the rod mounting portion 210 and the two extension arms 220 facing each other in the Z direction, and the sensor mounting portion 250 and the two link connection tabs 240 facing each other in the Z direction each act as a link, forming a deformable link mechanism in the XZ plane. Similarly, the two link members 230 facing each other in the Y direction, the rod mounting portion 210 and the two extension arms 220 facing each other in the Y direction, and the sensor mounting portion 250 and the two link connection tabs 240 facing each other in the Y direction each act as a link, forming a deformable link mechanism in the XY plane.
[0046] As is clear from Figure 4(b), in the first embodiment, in such a link mechanism, the distance from the axis C of the link connection hole 229 that forms the rear end joint is set to be longer than the distance from the axis C of the link connection hole 249 of the link connection tab 240 that forms the front end joint.
[0047] Therefore, in the first embodiment, the front end link formed by the sensor mounting portion 250 and the two opposing link connection tabs 240 is set to be shorter than the rear end link formed by the rod mounting portion 210 and the two opposing extension arms 220.
[0048] As can be seen from the above explanation, the rod mounting section 210 and extension arm 220, and the sensor mounting section 250 and link connection tab 240 each function as links that constitute a link mechanism. Therefore, the rod mounting section 210 and extension arm 220 can be considered together as a single component and referred to as the "support mounting section" to which the support is attached. Similarly, the sensor mounting section 250 and link connection tab 240 can be considered together as a single component and referred to as the "sensor mounting section" to which the ultrasonic sensor is attached.
[0049] In this case, the link member 230 connects the support mounting portion and the sensor mounting portion, so it can also be called a "connecting member." The link connection hole 229 of the extension arm 220 or the arm connection hole 239 on the rear end side of the link member 230 is the part where the connecting member, the link member 230, is connected to the support mounting portion (rod mounting portion 210 and extension arm 220), so it can also be called a "support connection portion." Similarly, the link connection hole 249 of the link connection tab 240 or the tab connection hole 238 on the tip side of the link member 230 can also be called a "sensor-side connection portion."
[0050] A4. Explanation of the operation of the link mechanism of the sensor holding device (sensor unit 200): In the sensor holding device (sensor unit 200) of the first embodiment configured as described above, the ultrasonic sensor (260) is fixed in a manner partially submerged in the holding ring (sensor mounting part 250) that holds it, as shown in Figure 5(a). Furthermore, the contact surface (sensor surface 265) of the ultrasonic sensor (260) with respect to the object is adjusted to be almost the same plane as the contact surface (255) of the holding ring (sensor mounting part 250) (see Figure 4). In addition, the main rod (rod 201) is attached to the drone body 110 at an arbitrary angle. Moreover, the main rod support arm mounting part (rod mounting part 210) is fixed to the main rod (rod 201).
[0051] Furthermore, the support arm (extension arm 220) is fixed to the main rod support arm mounting part (rod mounting part 210). In addition, the movable arm (link member 230) is connected to the support arm (extension arm 220) via a movable arm axis pin (axis pin passing through the arm connection hole 239), and is able to rotate around the movable arm axis pin (axis pin passing through the arm connection hole 239) as an axis. On the other hand, the sensor retaining ring mounting tab (link connection tab 240) is fixed to the sensor retaining ring (sensor mounting part 250). Furthermore, the movable arm (link member 230) and the sensor retaining ring mounting tab (link connection tab 240) are connected via a tab pin (axis pin passing through the link connection hole 249), and are able to rotate around the tab pin (axis pin passing through the link connection hole 249) as an axis.
[0052] Furthermore, in order to explain the operating mechanism of the ultrasonic sensor mounted on the sensor holding device (sensor unit 200) configured as described above, the structure directly involved in the operating mechanism is schematically represented as shown in Figure 5(b). The virtual structural line (235) in Figure 5(b) is a virtual line segment that represents a single rigid body structure, as the main rod (rod 201), the main rod support arm mounting part (rod mounting part 210), and the support arm (extension arm 220) are fixed together. In Figure 5(b), the lengths of each schematic line segment 230a (link member), 230b (link member), 235, and 265 are all fixed (unchanging). Also, the line segments 230a, 230b, 235, and 265 are connected at the connection points 239a, 239b, 249a, and 249b, as shown in the figure. Furthermore, the pressing direction (V) represents the direction of the force exerted by the main rod (rod 201) to press the entire mechanism against the object, and for the purposes of this explanation, it is assumed to be parallel to the Z-axis direction. The contact pressure direction (P) represents the direction of the contact pressure generated at the contact surface between the sensor contact surface (sensor surface 265) and the object surface (WL).
[0053] In an ideal state, the surface of the subject (WL) and the direction of pressure (V) are perpendicular, and the same force strength and direction as the force applied in the direction of pressure (V) acts on the sensor contact surface (sensor surface 265), resulting in correct contact. However, in reality, especially when attaching an ultrasonic sensor to an aircraft with an unstable attitude such as a drone, it is difficult to maneuver the drone so that the direction of pressure is perpendicular to the surface of the subject. Therefore, as often as shown in Figure 6, a contact angle (θp) is created between the sensor contact surface and the surface of the subject, resulting in a gap between the surface of the subject and the sensor contact surface. When such a gap exists, ultrasound cannot propagate, and therefore measurement of the subject is not possible.
[0054] To prevent such gaps from forming, a common practice is to use flexible joints or springs on the ultrasonic probe, as shown in Figures 7(a) and (b), to ensure the sensor contact surface is in close contact with the surface of the object being examined. However, when flexible joints or springs are used, as shown in Figures 8(a) and (b), if the pressing center axis extends beyond the edge of the sensor contact surface, the lateral stress generated in the rotating part of the flexible joint can cause the sensor to tip over, resulting in a loss of contact between the sensor and the object being examined.
[0055] The sensor holding device (sensor unit 200) of the first embodiment, configured as described above, can maintain correct contact between the surface of the object being examined and the sensor contact surface due to its mechanical structure, even when the pressing direction is not perpendicular to the surface of the object being examined. This will be explained using Figure 9. Figure 9 shows the schematic diagram of Figure 5(b) with the pressing direction changed. As mentioned earlier, the lengths of the line segments 230a (link member), 230b (link member), 235, and 265 are the same as the lengths in Figure 5(b). In accordance with the change in the pressing direction, only the connection angles of each line segment change at the connection points of 239a, 239b, 249a, and 249b.
[0056] Furthermore, as described above, the situation of the pressure applied from the main rod (rod 201) to the ultrasonic sensor 260 and the surface of the specimen when the pressing direction is changed will be explained using Figure 10. In order to explain the situation of the pressure, it is necessary to represent the action of stress, so the force initially applied from the main rod (rod 201) is expressed as a pressure vector. Also, since the main rod (rod 201) to the main rod support arm mounting part (rod mounting part 210) and the support arm (extension arm 220) are a single unit, they are conveniently represented by a virtual structural line (235), and the pressure vector is applied to the main rod (rod 201) as well as the virtual structural line.
[0057] The pressure vector applied to the virtual structural line is transmitted to the sensor contact area (sensor surface 265) via the movable arms (link members 230a and 230b). However, since it does not come into contact with other objects during the propagation process, the pressure vector remains unchanged until it reaches the sensor contact area (sensor surface 265). Upon reaching the sensor contact area (sensor surface 265), this pressure vector is decomposed into contact pressure and lateral pressure. The contact pressure then acts as the pressure required to keep the ultrasonic sensor in close contact with the object being tested. On the other hand, the lateral pressure is a force that pushes the ultrasonic sensor sideways, but since it occurs at the contact surface, it does not cause the ultrasonic sensor to tip over, and is absorbed by the static friction force between the sensor contact surface and the object's surface.
[0058] Furthermore, the link structure of the sensor holding device (sensor unit 200) of the first embodiment configured as described above is structured to always point towards the center of the contact surface even if the pressing center line is tilted, as shown in Figure 11, so it is easy to obtain good contact pressure even if the pressing direction is tilted significantly. On the other hand, in conventional sensor holding using flexible joints or springs as shown in Figure 12, if the pressing center is tilted, it points in a direction away from the center of the contact surface, so the stability of the contact deteriorates as the tilt in the pressing direction increases.
[0059] In the first embodiment, the sensor holding device (sensor unit 200) has a link structure in operation as described above, so even if the pressing direction is significantly tilted, the sensor surface 265 of the ultrasonic sensor 260 can be pressed against the wall surface so that it is parallel to the wall surface of the object being examined.
[0060] B. Second Embodiment: Figure 13 is an explanatory diagram showing the configuration of the sensor unit 200a in the second embodiment. The sensor unit 200a in the second embodiment differs from the sensor unit 200 in the first embodiment in that a link member 230a made of a flexible wire is used instead of the flat bar-shaped link member 230. Other points are the same as in the first embodiment, so the explanation of matters common to the first embodiment will be omitted as appropriate.
[0061] Loops 231a and 232a are formed at the rear and front ends of the link member 230a, respectively. The rear end loop 231a is fixed to the link connection hole 229 of the extension arm 220 using bolts and nuts (not shown). Similarly, the front end loop 232a is fixed to the link connection hole 249 of the link connection tab 240 using bolts and nuts (not shown).
[0062] The loops 231a and 232a formed on the link member 230a are fixed to the positions of the link connection holes 229 and 249 of the extension arm 220 and the link connection tab 240, respectively. However, the link member 230a itself is attached to the extension arm 220 and the link connection tab 240 so that it can rotate within a plane containing the axis C, centered on the link connection holes 229 and 249.
[0063] Therefore, in the sensor unit 200a of the second embodiment, the two link members 230a facing each other in the Z direction, the rod mounting portion 210 and the two extension arms 220 facing each other in the Z direction, and the sensor mounting portion 250 and the two link connection tabs 240 facing each other in the Z direction constitute a deformable link mechanism in the XZ plane. Similarly, the two link members 230a facing each other in the Y direction, the rod mounting portion 210 and the two extension arms 220 facing each other in the Y direction, and the sensor mounting portion 250 and the two link connection tabs 240 facing each other in the Y direction constitute a deformable link mechanism in the XY plane.
[0064] Therefore, in the second embodiment as well, even when the sensor unit 200a is pressed against the wall surface of the subject with the axis C tilted in the vertical or horizontal direction, it is possible to press the sensor surface 265 of the ultrasonic sensor 260 against the wall surface so that the sensor surface 265 is parallel to the wall surface of the subject.
[0065] Furthermore, in the second embodiment, by forming the link member 230a with a flexible wire, the impact applied to the ultrasonic sensor 260 when it comes into contact with the wall surface of the specimen can be mitigated. In addition, when the ultrasonic sensor 260 is pressed against the wall surface of the specimen, the pressure of the ultrasonic sensor 260 is averaged across the entire sensor surface 265, so that the ultrasonic signal emitted by the ultrasonic sensor 260 can be propagated more stably into the inside of the specimen.
[0066] In the second embodiment, as shown in Figure 13, the sensor unit 200a is composed of a rod mounting portion 210, an extension arm 220, a link member 230a made of wire, a link connection tab 240, a sensor mounting portion 250, and an ultrasonic sensor 260. However, the extension arm 220 can be omitted. In this case, a longer wire is attached to the rod mounting portion with its tip facing outward. Then, with the wire bent, the loop provided on the tip side of the wire is rotatably attached to the link connection hole of the link connection tab, similar to the second embodiment.
[0067] Even in this configuration, the position of the link connection hole is closer to the axis of the sensor unit than the part of the wire that bulges outward the most. Therefore, as in the second embodiment, it is possible to press the sensor surface of the ultrasonic sensor against the wall so that the sensor surface is parallel to the wall surface of the object being examined.
[0068] C. Variant: The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from its spirit, for example, the following modifications are also possible.
[0069] C1. Variation 1: In each of the above embodiments, the support mounting section (rod mounting section 210 and extension arm 220) and the sensor mounting section (sensor mounting section 250 and link connection tab 240) are connected by four connecting members (link members 230, 230a), but the number of connecting members connecting the support mounting section and the sensor mounting section only needs to be three or more.
[0070] C2. Variation 2: In each of the embodiments described above, the rod attachment portion 210, which constitutes the support attachment portion, is attached to the tip of the rod 201 that is attached to the drone body 110 via attachment members 131 and 132. However, it is also possible to attach the connecting member to the tip of the drone body (for example, the cylindrical portion below the propeller on the +X direction side in Figure 3). In this case, the tip of the drone body to which the connecting member is attached corresponds to the support attachment portion.
[0071] C3. Modification 3: In each of the above embodiments, as shown in Figure 2, a drone system 100 equipped with an ultrasonic sensor is used to remotely press the ultrasonic sensor against the subject (large structure LST). However, generally, it is sufficient as long as the ultrasonic sensor can be remotely pressed against the subject. For example, the sensor units 200, 200a of the above embodiments (see Figure 3 or Figure 4, Figure 13) may be attached to the tip of a rod of sufficient length, or a rod 201 with the sensor units 200, 200a attached may be attached to the tip of a rod of sufficient length.
[0072] However, it is preferable to use a drone system 100 equipped with an ultrasonic sensor, as it can press the ultrasonic sensor against the object even when the large structure being tested is tall or when it is difficult to see the object in a straight line.
[0073] C4. Modification 4: In the embodiments described above, the present invention is used to measure the thickness of the wall of a large structural LST (see Figure 1 or Figure 2), which is the subject of the test. However, the present invention can also be used to evaluate various conditions of the subject. For example, the present invention can be applied to detect cracks, defects, etc., that may occur in the subject. In this case, in addition to chimneys and large tanks, buildings such as steel towers and bridges can also be used as subjects for condition evaluation. [Industrial applicability]
[0074] As described above, the sensor holding device of the present invention exhibits excellent effects and can therefore be suitably used to remotely evaluate the condition of a subject using an ultrasonic sensor. [Explanation of symbols]
[0075] 100... Drone system 110... Drone body 120... Camera 131, 132... Mounting parts 201... Rod 200,200a... Sensor Unit 210... Rod mounting section 218... Arm insertion hole 219... Rod mounting hole 220... Extension Arm 229... Link connection hole 230, 230a... Link members 231a, 232a... loop 238... Tab connection hole 239...Arm connection hole 240... Link Connection Tab 249... Link connection hole 250... Sensor mounting section 258... Mounting member insertion hole 259...Sensor mounting hole 260... Ultrasonic sensor 261...Large diameter section 262‥Small diameter part 265...Sensor surface 269...Tapered section JA1, JA2... Joint JB1, JB2... Joint JC1, JC2... Joint JD1, JD2... Joint LF1, LF2... Leading links LR1, LR2... Rear end links LST‥Large structure LU1, LD1... Connection links LU1, LU2, LD1, LD2... Connection links WL‥Wall
Claims
1. A sensor holding device for remotely pressing an ultrasonic sensor, which is used to evaluate the condition of a subject, against the subject, The sensor mounting portion to which the ultrasonic sensor is attached, A support mounting portion to which a support for remotely supporting the sensor holding device is attached, N connecting members (where N is an integer of 3 or more) are connected to both the sensor mounting portion and the support mounting portion, Equipped with, The distance from the axis of the sensor holding device to the sensor-side connection portion to which each of the N connecting members is connected to the sensor mounting portion, and the distance from the axis of the support-side connection portion to which each of the N connecting members is connected to the support mounting portion, are set to be different from each other. Each of the N connecting members is rotatable within a plane containing the axis, with respect to the sensor-side connecting portion and the support mounting portion, respectively. Sensor holding device.
2. The sensor holding device according to claim 1, wherein the distance of the sensor-side connection portion from the axis is set to be shorter than the distance of the support-side connection portion from the axis.
3. The sensor holding device according to claim 1 or 2, wherein the connecting member is formed of a flexible wire.
4. The sensor holding device according to claim 1 or 2, wherein the support has a rod extending from the drone in the direction from which the drone can move.