JP2019117136A - Position measurement system, and position measurement method - Google Patents

Abstract

To highly accurately obtain position posture data, as suppressing increase in size of an underwater work device.SOLUTION: A position measurement system has: an underwater work device 2 that provides a reflection body 9 reflecting an ultrasonic sound wave caused to stay stationary at a higher position by a prescribed height than a main body so as to recognize a position and posture of the main body; a reflection body identification unit 17 that, when an ultrasonic sound wave sensor 3 with three-dimensional azimuth resolving power receives a reflection wave with respect to an incident ultrasonic sound wave beam, and a height of a reflection position of the reflection wave falls within a height range of the reflection body 9 based on the prescribed height, identifies the reflection wave that is reflected upon the reflection body 9; and a position calculation unit 18 that obtains a position of each reflection body 9 from each reflection wave reflected upon the reflection body 9 identified by the reflection body identification unit 17, and obtains position data and posture data on the underwater work device 2 from the obtained position of each reflection body 9.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a position measurement system and a position measurement method.

There are underwater working devices that measure the thickness of wall surfaces of structures installed on land or sea such as tanks and pools and check the integrity of weld lines in a liquid filled with water (in water). If deposits or the like exist in the pool, the deposits will soar and the liquid may become cloudy as the underwater working device moves. Therefore, since the light is blocked in the turbid liquid, it is difficult to use a general position measurement method used in the air with an optical camera or a laser as it is even in water.
In such a case, measurement with ultrasonic waves having a longer wavelength than light and good permeability in liquid is effective, and in port construction under water, etc., position measurement of the working device with ultrasonic waves is performed. There is.

  Patent Document 1 describes a position measurement system in which an ultrasonic transmitter is mounted on a support ship on the water surface, an ultrasonic receiver is mounted on an underwater work device, and three-point position measurement is performed. Thereby, the position of the working device can be measured.

  In Patent Document 2, an ultrasonic sonar for transmitting an ultrasonic wave toward the seabed is mounted on the bottom outer plate of a support ship on the water surface, and an instruction structure for installing a reflection plate on an underwater work device is installed. A position measurement system is described, in which reflectors are installed at two places on the structure. The shape of the reflecting plate has a plurality of reflecting surfaces of an upper concave spherical surface. The diameter of the reflection plate is equal to or greater than the spread of the ultrasonic wave, and a step greater than the distance resolution of the ultrasonic wave is provided in the vertical direction.

JP, 2013-23892, A Japanese Patent Application Laid-Open No. 07-062684

By providing a reflection plate on the surface of the main body of the underwater working device, the ultrasonic waves of the measurement signal can be appropriately reflected in the direction of the ultrasonic sonar without a great deal of attenuation. This makes it possible to distinguish the underwater working device in which the reflecting plate is present from other structures such as rocks and to make it easy to detect the position.
Here, in various inspections performed by the underwater working device, it may be insufficient to just specify at which position the underwater working device is present. For example, in the case where a camera attached to the underwater working apparatus shoots the front and remotely transmits the photographed image to the examiner, not only from which position but also from which direction it was photographed It is important to let inspectors know

  However, in the prior art, although the device for improving the accuracy of the position data of the underwater working device is mentioned, the device for detecting the posture data of the underwater working device with high accuracy is not considered. Furthermore, the space of the structure searched by the underwater working device may have a narrow passage due to an obstacle or the like, and there is also a restriction that the underwater working device can not be physically increased in size.

  Then, this invention makes it a main subject to obtain | require position and orientation data with high precision, suppressing the enlargement of the underwater working apparatus.

In order to solve the above-mentioned subject, a position measurement system of the present invention has the following features.
The present invention is provided with a reflector that has an main body and moving means and reflects ultrasonic waves fixed at a position higher than the main body by a predetermined height so that the position and attitude of the main body can be recognized. Underwater work equipment,
An ultrasonic sensor having a three-dimensional azimuthal resolution receives a reflected wave to the incident ultrasonic beam, and the height of the reflected position of the reflected wave is within the range of the height of the reflector based on the predetermined height. A reflector identification unit that identifies that the reflected wave is reflected by the reflector when
The position of each of the reflectors is determined from each reflected wave that the reflector identification unit has identified as reflected by the reflector, and the position data and posture data of the underwater working device are calculated from the determined position of each of the reflectors. And a position calculation unit to be determined.
Other means will be described later.

  According to the present invention, it is possible to obtain position and orientation data with high accuracy while suppressing an increase in the size of the underwater working device.

BRIEF DESCRIPTION OF THE DRAWINGS It is a whole block diagram of the position measurement system of the underwater working apparatus regarding one Embodiment of this invention. FIG. 1 is a block diagram of an ultrasonic transmitter-receiver according to an embodiment of the present invention. FIG. 1 is an XY plan view of a position measurement system according to an embodiment of the present invention. FIG. 1 is a side view of a position measurement system according to an embodiment of the present invention. FIG. 1 is a side view of a position measurement system according to an embodiment of the present invention. FIG. 7 is a side view showing the relationship between the signal intensity of an ultrasonic beam and the size of a reflector according to an embodiment of the present invention. FIG. 7 is an enlarged view of the vicinity of a reflector in the side view of FIG. 6 according to an embodiment of the present invention. It is a graph which shows waveform data which a waveform generation part concerning one embodiment of the present invention generates. It is a top view which shows the attitude | position detection process of the reflector regarding one Embodiment of this invention. FIG. 5 is a plan view of a reflector tracking process according to an embodiment of the present invention.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an overall configuration diagram of a position measurement system of the underwater working device.
The underwater working device 2 performs inspection while traveling on the pool floor 8 of the pool 1. Hereinafter, as a coordinate system in a three-dimensional bird's-eye view, a traveling direction of the underwater working device 2 is taken as a Y axis, a side direction of the underwater working device 2 is taken as an X axis, and a height direction of the pool 1 is taken as a Z axis.

  The underwater working device 2 is remotely controlled by wired control or wireless communication from a control unit (not shown) on the ground. The inspection means of the underwater working device 2 is, for example, an ultrasonic sensor (not shown) or an eddy current sensor (not shown) for measuring the thickness of the wall of the tank or pool 1 or checking the integrity of the weld line. The moving means of the underwater working device 2 is, for example, a means provided with a pair of left and right traveling wheels driven by a motor at the front and back of the device, or a pair of left and right crawlers.

A reflector 9 (9A, 9B, 9C) for reflecting ultrasonic waves is installed at a position higher by a predetermined height than the main body of the underwater working device 2 so that the position and attitude of the main body can be recognized. There is. In order to be able to reliably reflect an incident wave from any direction, it is desirable that the shape of the reflector 9 be a sphere.
Each reflector 9 may be configured to be able to recognize the position and attitude of the main body. For example, it is desirable that at least three reflectors 9 be installed at mutually different positions on the XY plane. Further, by setting the positions of the reflectors 9 at a large distance from each other, the accuracy of the attitude detection of the underwater working device 2 is enhanced.

The ultrasonic sensor 3 measures the position of each reflector 9 by reflecting the incident ultrasonic beam on the reflector 9 (indicated by the broken arrow in the drawing). As the ultrasonic sensor 3, a matrix array in which transducers are two-dimensionally arranged or a cross or T-shaped array sensor in which two one-dimensional arrays are orthogonally used are used. The ultrasonic sensor 3 transmits an ultrasonic beam based on a signal from the sensor transmission unit 12 described later in FIG. 2 and transmits a signal based on the received reflected wave to a sensor reception unit 14 described later.
Since the ultrasonic sensor 3 has a three-dimensional azimuthal resolution, the three-dimensional (X, Y, Z) position of each reflector 9 can be measured. Although the installation position of the ultrasonic sensor 3 is illustrated in the upper part of the pool 1 in FIG. 1 in general, the inside of the pool 1 is generally selected in order to search for an object in water in the pool 1 by suppressing reflection by the water surface. Installed in the water.

An ultrasonic sensor 3 is attached to the ultrasonic sensor drive unit 4. The ultrasonic sensor 3 and the ultrasonic sensor drive unit 4 are connected to the ultrasonic transmitter / receiver 6 via the cable 5.
The monitor 7 displays inspection result data such as waveform data by the inspection means of the underwater working device 2 and position / posture data of the underwater working device 2 based on the measured positions of the reflectors 9.

FIG. 2 is a block diagram of the ultrasonic transmitter-receiver 6. The ultrasonic transmitter / receiver 6 includes a drive signal generator 11, a sensor transmitter 12, a transmission signal generator 13, a sensor receiver 14, a waveform generator 15, a sensor position calculator 16, and a reflector identifier. A position calculation unit 18 and a position storage unit 18 are provided.
The ultrasound transmitter / receiver 6 is configured as a computer having a CPU (Central Processing Unit), a memory, a storage unit (storage unit) such as a hard disk, and a network interface.
The computer operates a control unit (control means) configured of each processing unit by the CPU executing a program (also called an application or an abbreviation of the application) read into the memory.

The drive signal generation unit 11 transmits a command signal of the ultrasonic sensor drive unit 4. The sensor transmission unit 12 transmits a pulse signal to each transducer of the ultrasonic sensor 3 to vibrate the transducer and transmit an ultrasonic beam.
The transmission signal generator 13 determines the transmission pattern of the ultrasonic beam. The sensor reception unit 14 converts signals (analog electric signals based on the vibration of the vibrator) received by the vibrators of the ultrasonic sensor 3 into digital signals.
The waveform generation unit 15 generates waveform data based on the digital signal from the sensor reception unit 14 and the transmission pattern from the transmission signal generation unit 13. That is, the transmission pattern from the transmission signal generation unit 13 is added to the generated waveform data.

The sensor position calculation unit 16 calculates the height Zc, the depression angle θv, and the like of FIG. 4 based on the arrangement of the ultrasonic sensor 3 as setting information of the ultrasonic sensor 3 or receives an input.
The reflector identification unit 17 identifies the reflection wave from the reflector 9 and the reflection wave from other objects by measuring the reflection position of the reflection wave of the ultrasonic sensor 3 from the waveform data of the waveform generation unit 15 Do.
The position calculation unit 18 calculates the position of the reflector 9 based on the reflected wave of the reflector 9 extracted by the reflector identification unit 17. Then, the position calculation unit 18 calculates position and orientation data of the underwater working device 2 from the calculated positions of the reflectors 9. The calculated position and orientation data is displayed via the monitor 7.
The position storage unit 19 stores the calculation result of the position calculation unit 18.

FIG. 3 is an XY plan view of the position measurement system.
An incident wave 30A traveling from the ultrasonic sensor 3 to the reflector 9A is transmitted at an azimuth angle θh1 to the left around the Y axis.
The incident wave 30B traveling from the ultrasonic sensor 3 to the reflector 9B is transmitted at an azimuth angle θh2 on the clockwise side with respect to the Y axis.
An incident wave 30C traveling from the ultrasonic sensor 3 to the reflector 9C is transmitted at an azimuth angle θh3 on the clockwise side with respect to the Y axis.

FIG. 4 is a side view of a position measurement system. In this side view, the azimuth (θ h3 in FIG. 3) of the incident wave 30C passing through the reflector 9C is taken as the horizontal axis, and the Z axis in the height direction is taken as the vertical axis.
The depression angle θv is a set angle at which the ultrasonic beam is incident on the pool floor 8 to scan the position of the underwater working device 2 by the ultrasonic sensor 3.
The height Zc of the monitoring position is the Z-axis distance from the pool floor 8 to the surface center of the ultrasonic sensor 3. The sensor position calculation unit 16 sets the depression angle θv of the ultrasonic sensor 3 vertically downward and then applies the ultrasonic beam to the pool floor surface 8 to obtain the height Zc.

Hereinafter, the fact that the ultrasonic beam from the ultrasonic sensor 3 is reflected to various objects by various transmission angles θv1 to θv3 will be described.
First, since the incident wave 31C of the transmission angle θv3 hits the reflector 9C, the reflected wave returns toward the ultrasonic sensor 3. Therefore, when the ultrasonic wave sensor 3 receives the reflected wave, the position of the reflector 9C can be obtained.
On the other hand, since the incident wave 32C of the transmission angle θv2 hits the case of the underwater working device 2, the reflected wave becomes noise when the position of the reflector 9 is determined. Since the incident wave 33C of the transmission angle θv1 strikes the pool floor 8, its reflected wave also becomes noise when the position of the reflector 9 is determined.

  In the following description, the height of the submersible working apparatus 2 case is h, and the length g of the reflector support from the top of the case to the bottom of the reflector 9 is h. Here, the reflector support is, for example, a rod-like member for supporting the reflector 9 from below, and the reflector support itself is small in volume or hard to reflect so as not to reflect the ultrasonic beam as much as possible. It is desirable to be composed of materials.

FIG. 5 is a side view of a position measurement system.
The reflector identification unit 17 can measure the Z-axis height of the reflection position of the reflected wave of the ultrasonic sensor 3 according to the following equation.
(Z-axis height of reflection position of reflection wave) = (propagation time of reflection wave) × (sound velocity of liquid) × cos (transmission and reception azimuth θv2 of ultrasonic beam)
When the Z-axis height of this reflection position is in the range from the depth Zd to the depth Zu where the reflector 9 is present, the reflected wave can be regarded as the reflection from the reflector 9.
The height (depth) Zc from the ultrasonic sensor 3 to the pool floor 8 is acquired by the sensor position calculator 16 as described above.
The depth Zd from the ultrasonic sensor 3 to the lower part of the reflector 9 is (depth Zc)-(height h of the submersible working device 2 case) + (length g of the reflector support).
The depth Zu from the ultrasonic sensor 3 to the upper portion of the reflector 9 is (depth Zc) − (diameter φ of the reflector 9).

First, when the reflection position of the reflected wave is deeper than the depth Zd (lower than the pool floor 8) as in the position R1, the reflected wave is from the case of the underwater working device 2 or the pool floor 8 Since it can be regarded as reflection, the reflector identification unit 17 rejects the reflected wave.
Next, as in the case of the position R2, when the reflection position of the reflected wave is in the range from the depth Zd to the depth Zu, the reflector identification unit 17 is used as data for specifying the position and orientation of the underwater working device 2 adopt.
Furthermore, when the reflection position of the reflected wave is shallower than the depth Zu (high from the pool floor 8) as in the position R3, the reflected wave may be regarded as the reflection from the piping or the like of the structure Since it is possible, the reflector identification unit 17 rejects the reflected wave.

FIG. 6 is a side view showing the relationship between the signal intensity of the ultrasonic beam and the size of the reflector 9.
The ultrasonic beam transmitted toward the reflector 9 is attenuated in signal intensity as it goes away from the central sound axis 42 where the signal intensity is the strongest. In FIG. 6, peripheral sound axes 41 and 43 having a signal strength that is 1⁄2 times the signal strength (reference strength) of the central sound axis 42 are also described.

FIG. 7 is an enlarged view of the vicinity of the reflector 9 in the side view of FIG.
The width between the peripheral sound axes 41 and 43, which is a signal intensity equal to or more than half the reference intensity, is referred to as “sound wave arrival width w”. That is, when the reflector 9 is present within the range of the sound wave arrival width w, the signal intensity of the reflected wave from the reflector 9 is sufficiently strong, so that the ultrasonic wave sensor 3 can detect the reflected wave.

Here, as described in FIG. 5, the length g of the reflector supporting portion and the diameter φ of the reflector 9 are important parameters for determining the accuracy with which the underwater working device 2 and the reflector 9 are distinguished. , It is desirable to be in the following range.
It is desirable that the lower limit of the length g (predetermined height) of the reflector support be a sound wave arrival width w. As a result, it is possible to prevent the ultrasonic sensor 3 from mixing the reflected wave from the main body of the underwater working device 2 and the reflected wave from the reflector 9 when the underwater working device 2 and the reflector 9 are too close to each other.
The upper limit of the length g of the reflector support is preferably three times the diameter φ of the reflector 9. As a result, when the underwater working device 2 and the reflector 9 are separated too much, it is possible to suppress the reflector 9 from colliding with an obstacle while traveling inside a narrow space inside a structure where deposits and the like are present. That is, the size when the underwater working device 2 and the reflector 9 are regarded as one can be miniaturized.
The lower limit of the diameter φ of the reflector 9 is preferably the sound wave arrival width w. As a result, when the reflector 9 itself is too small, the range in which the incident wave can be reflected is suppressed from being too narrow, and the incident wave can be appropriately reflected.

  FIG. 8 is a graph showing waveform data at the transmission angle θv2 generated by the waveform generation unit 15. The horizontal axis is the time from transmission to reception of the ultrasonic wave, and the vertical axis is the signal strength. The reflector identifying unit 17 determines that the reflected wave is a reflected wave when the signal intensity is equal to or greater than the set threshold (at).

FIG. 9 is a plan view showing the process of detecting the attitude of the reflector 9.
The position calculation unit 18 uses the transmission angles of the ultrasonic beam (θh1 to θh3 in FIG. 3, θv1 to θv3 in FIG. 4) based on the reflected wave of the reflector 9 extracted by the reflector identification unit 17. The position of the reflector 9 is calculated.
For example, even if the main body of the underwater working device 2 is present at the same position, it may be a downward position and orientation as denoted by reference numeral 101, or may be a left orientation and position as denoted by reference numeral 102. Therefore, for example, in the position calculation unit 18, “The line connecting the reflectors 9A and 9B is the front of the main body of the underwater working device 2, and the line connecting the reflectors 9B and 9C is the left side of the main body of the underwater working device 2. The positional relationship of each reflector 9 corresponding to the main body such as "" is stored in advance. Then, the position calculation unit 18 specifies the position and orientation of the underwater working device 2 with respect to the pool floor surface 8 from the position data of the at least three reflectors 9 detected by the ultrasonic beam with reference to the stored positional relationship. Do.

FIG. 10 is a plan view showing the tracking process of the reflector 9.
For example, it is assumed that the position of the reflector 9A1 one second ago has moved to the position of the reflector 9A2 at present. Similarly, it is assumed that the reflector 9B1 → 9B2 is moved and the reflector 9C1 → 9C2 is moved.
The position calculation unit 18 may sequentially track the position of each reflector 9 identified at the time of initial setting when moving. The result of the tracking process may be displayed, for example, as a movement trajectory line at the position of the underwater working device 2 displayed on the monitor 7.
Alternatively, the result of the tracking process may be used when the reflector identification unit 17 narrows the reflected waves of the reflector 9 from the set of received reflected waves. For example, the position calculation unit 18 may regard current position information that causes the movement amount from a position one second before (immediately before) to the current position to be longer than a predetermined distance (for example, 100 m or more) as noise.

In the embodiment described above, as a device to be detected using the ultrasonic sensor 3, the reflector 9 is fixed at a distance from the main body of the underwater working device 2 by the reflector supporting portion of the length g. .
Accordingly, the ultrasonic sensor 3 can easily distinguish the reflected wave from the main body of the underwater working device 2 and the reflected wave from the reflector 9 based on the difference in height of the reflection position. Therefore, it is not sufficient to roughly detect only the main body position of the underwater working device 2, and the ultrasonic transmitter-receiver 6 can also be used in inspection work where posture data from the main body position also needs to be detected with high accuracy. The position / posture data of the underwater working device 2 can be obtained appropriately.

Hereinafter, the comparison with the prior art will be made. In the prior art, the configuration is such that position detection is performed by increasing the size of the underwater working apparatus itself, so it is not suitable for the purpose of the present embodiment in which the inside of a structure where deposits etc. are present inspects a narrow space. .
For example, in the configuration of Patent Document 1, the underwater working apparatus is equipped with an ultrasonic receiver different from the purpose of the underwater work such as measurement of wall thickness and soundness inspection of welding lines. The size of the work device increases.
In the configuration of Patent Document 2, the underwater working device becomes large in size, and the ultrasonic sonar and the working device need to be constantly arranged at the top and bottom, so it is difficult to move underwater if the inside of the structure is a narrow space. turn into.
On the other hand, in the present embodiment, by increasing the distance between the underwater working device 2 and the reflector 9 via the reflector supporting portion, the detection accuracy of the reflector 9 is improved, and the enlargement of the underwater working device 2 is suppressed. it can.

The present invention is not limited to the embodiments described above, but includes various modifications. For example, the above-described embodiments are described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the described configurations.
Also, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment.
In addition, with respect to a part of the configuration of each embodiment, it is possible to add, delete, and replace other configurations. Further, each of the configurations, functions, processing units, processing means, etc. described above may be realized by hardware, for example, by designing part or all of them with an integrated circuit.
Further, each configuration, function, and the like described above may be realized by software by a processor interpreting and executing a program that realizes each function.

Information such as programs, tables, and files that realize each function is a memory, a hard disk, a recording device such as a solid state drive (SSD), an integrated circuit (IC) card, an SD card, a digital versatile disc (DVD), etc. Can be placed on the
Further, control lines and information lines indicate what is considered to be necessary for the description, and not all control lines and information lines in the product are necessarily shown. In practice, almost all configurations may be considered to be mutually connected.
Furthermore, the communication means connecting the respective devices is not limited to the wireless LAN, and may be changed to a wired LAN or other communication means.
Moreover, the place where the pool 1 is installed on land or the sea does not matter. Furthermore, the installation place of the ultrasonic transmitter-receiver 6 which is an apparatus which controls the ultrasonic sensor 3 and the ultrasonic sensor drive part 4 does not matter.

DESCRIPTION OF SYMBOLS 1 pool 2 underwater working apparatus 3 ultrasonic sensor 4 ultrasonic sensor drive part 5 cable 6 ultrasonic transmitter-receiver 7 monitor 8 pool floor surface 9 reflector 11 drive signal generation part 12 sensor transmission part 13 transmission signal generation part 14 sensor reception part 15 waveform generation unit 16 sensor position calculation unit 17 reflector identification unit 18 position calculation unit 19 position storage unit

Claims (7)

An underwater working device provided with a reflector having a main body and moving means and reflecting an ultrasonic wave fixed at a position higher than the main body by a predetermined height so that the position and posture of the main body can be recognized. ,
An ultrasonic sensor having a three-dimensional azimuthal resolution receives the reflected wave to the incident ultrasonic beam, and the height of the reflection position of the reflected wave is within the range of the height of the reflector based on the predetermined height. A reflector identification unit that identifies that the reflected wave is reflected by the reflector when
The position of each of the reflectors is determined from each reflected wave that the reflector identification unit has identified as reflected by the reflector, and the position data and posture data of the underwater working device are calculated from the determined position of each of the reflectors. A position measurement system characterized by having a position calculation unit to be obtained. A reflector provided so as to be able to recognize the position and attitude of the main body of the underwater working device is a sphere provided at three or more different places on an XY plane. Measurement system. The underwater working apparatus is provided, as the predetermined height, longer than a width between peripheral sound axes that attenuates to a signal strength that is 1⁄2 times the signal strength at the central sound axis of the incident ultrasonic beam. The position measurement system according to claim 1. The position measurement system according to claim 1, wherein the underwater working device is provided shorter than three times the diameter of the reflector as the predetermined height. The underwater working device is provided, as a diameter of the reflector, longer than a width between peripheral sound axes which attenuates to a signal strength half the signal strength at the central sound axis of the incident ultrasonic beam. The position measurement system according to claim 1. The position measurement system includes an underwater working device having moving means, a reflector identification unit, and a position calculation unit.
The underwater working apparatus is provided with a reflector that reflects an ultrasonic wave fixed at a position higher than the main body by a predetermined height so that the position and attitude of the main body can be recognized.
The reflector identification unit receives a reflected wave to an ultrasonic beam incident by an ultrasonic sensor having a three-dimensional azimuth resolution, and the reflection position of the reflected wave is based on the predetermined height. When it is within the height of the body, identify the reflected wave as that reflected on the reflector,
The position calculation unit determines the positions of the reflectors from the reflected waves that the reflector identification unit has identified as reflected by the reflectors, and the underwater working device from the positions of the determined reflectors. A position measurement method characterized by obtaining position data and posture data. A reflector provided so as to be able to recognize the position and posture of the main body of the underwater working device is a sphere provided at three or more different places on the XY plane. Measuring method.

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