JPH05272977A - Underwater buoy waves meter - Google Patents

Abstract

PURPOSE:To maintain measurement accuracy and achieve an accurate measurement by mounting an ultrasonic wave-height meter on an artificial horizontal stand which is mounted to an underwater buoy which is retained at one underwater point in tension. CONSTITUTION:This meter measures waves of water surface in a water region with a relatively deep part, an artificial horizontal stand 5 is mounted to an underwater buoy 3 which is connected to the top of a bridle 2 which is extended to an anchor 1 which is installed at a water bottom B, and then an ultrasonic wave-height meter 10 is mounted on the stand. The underwater buoy 3 which is retained at one point in tension under sea can cope with any water depth by changing the length of the bridle 2. Also, since the reception part of the ultrasonic wave-height meter 10 is located on the horizontal stand 5, the distance in vertical direction can be measured constantly even if the buoy 3 is inclined. When the buoy 3 is retained at a relatively deep position in tension, the buoy 3 does not rock even if waves approach a point on the water surface, thus minimizing influence to the measurement accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to an underwater buoy type wavemeter capable of measuring a wave height while maintaining high accuracy when observing a wave in a deep water region.

[0002]

2. Description of the Related Art Conventionally, as equipment used for wave observation, water pressure wave height meters, buoy type wave height meters such as disc type buoys, spherical buoys, measuring rod type wave height meters, and underwater and airborne types. The ultrasonic wave height meter is classified into four types, and each of these types of equipment has advantages and disadvantages as described below.

First, the water pressure wave height meter is a method of detecting underwater pressure fluctuation due to waves and converting the fluctuation amplitude into the amplitude of the surface waveform to obtain wave characteristics.
Normally, it can be used simply by providing a simple installation base on the seabed. However, this wave height meter has a drawback that a method for converting a pressure waveform into a surface waveform has not been sufficiently established.

That is, generally, the conversion of a water pressure waveform to a surface waveform is performed using a linear theory, but in shallow waters, the linear theory cannot be applied when the wave height is large, and when the water depth is large, it is short. There is also a problem that it is difficult to obtain information such as frequency characteristics of the wave because the wave cannot be detected. Next, the buoy type wave height meter measures the vertical acceleration of the buoy itself floating on the sea surface and obtains the surface waveform by integrating twice, and this wave height meter measures the water particle motion on the water surface. Since it is measured as the vertical response of the buoy, its measurement accuracy depends on the detection accuracy of the vertical response and the response characteristics of the buoy body to the waves. Therefore, it is necessary to make the buoy body have good response characteristics over a wide period range, but in reality it is difficult and the wave measured by the buoy type wave height meter may show different characteristics from the actual one. In addition, this wave height meter has a problem in that many mooring line cutting accidents occur.

That is, normally, the buoy type wave height meter is relaxed and moored so as not to affect the movement of the buoy, but since the buoy is affected by not only waves but also tidal current and wind, abnormal tension is generated in the mooring line. And lead to disconnection. When the mooring line is cut, the buoy may drift, which may cause another accident. If the water depth is shallow, for example, 50m to 100m or less, the catenary effect of the mooring line is sufficiently obtained. The risk of cutting the mooring line is even greater, since it is not possible.

In the above two types, it is necessary to estimate the surface waveform from the measured data by some method, but the measurement rod type and ultrasonic type can directly measure the surface waveform. The measuring rod wave height meter is used by installing the rods with light bulbs arranged at equal intervals on an existing structure or a dedicated observation tower, and this method is the most accurate because it directly detects the surface waveform. It is a device that can obtain various data. However, it is not practical because it requires a large-scale structure for attaching the measuring rod, and since it requires frequent cleaning because seagrass and shellfish adhere to it.

The ultrasonic wave height meter is for measuring the propagation time of an ultrasonic pulse to the sea surface, and there are an underwater discharge type and an air discharge type. In the air discharge type, the observation tower is the same as the measuring rod type. Since such a structure is required, there are few cases of observation by it, and the underwater launch type is general. The submersible ultrasonic wave height meter is used as a standard equipment for wave observation in Japan because it can measure the surface waveform just by installing it on the sea floor. The problem with this type is that it is difficult to apply it to deep water and there are some missing data during high waves.

The problem of applying deep water is due to the nature of ultrasonic waves. In other words, ultrasonic waves have less sound attenuation as the frequency decreases, but they have the property that they have a large spread when they reach the sea surface because of their low directivity. When applied to
Measurement accuracy deteriorates. In addition, during high waves, the sea surface is disturbed due to the breaking of the waves, and a large amount of air bubbles are entrained, which absorbs or scatters the ultrasonic pulse and makes measurement impossible.

This point is unavoidable as long as ultrasonic waves are used, but in recent years, an ultrasonic wave height meter has been incorporated with a water pressure sensor to observe with a compound wave height meter that compensates for each other's drawbacks.
Analytical methods have been developed. Although the problems of each type of wave height meter in the related art have been described above, the inventors of the present invention have made various studies and studies on these problems, and as a result, have reached the following conclusions.

In other words, judging from the observation of economic efficiency and measurement accuracy, the ultrasonic wave height meter, which does not require a large-scale structure and can directly measure the surface waveform, is excellent among the current devices, and particularly, It can be said that the composite wave height meter is more excellent. However, it is difficult to apply the ultrasonic wave crest meter in the deep water region, and the buoy type crest meter is unavoidable. From the above conclusion, the present inventors arrived at the present invention by paying attention to the combined use of the advantages of both the buoy type wave height meter and the ultrasonic wave type height meter.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the problems in the conventional wave height meter for wave observation, and maintains the measurement accuracy even when applied to a large depth of water. The problem to be solved is to provide an underwater buoy type wavemeter using an ultrasonic wave heightmeter which does not require a large-scale structure.

[0012]

As a means for solving the above-mentioned problems, the underwater buoy type wave meter of the present invention is a super-horizontal platform mounted on an underwater buoy tensioned and moored at a single point in the water. It is configured by mounting a sonic wave height meter, but it is possible to detachably mount a composite wave height meter that incorporates an ultrasonic wave height meter and a water pressure sensor on the artificial horizontal table. This is a more excellent configuration because it is possible to correct the mutual error between the measurement value at the ultrasonic wave height value and the measurement value at the ultrasonic wave height meter.

[0013]

[Operation] The underwater buoy type wavemeter with the above configuration has a wave height meter mounted on a horizontal mount attached to the underwater buoy, so the distance from the wave height meter to the water surface is short even in deep water. Measurement accuracy is maintained even with an ultrasonic wave height meter with low directivity, and since the wave height meter is mounted on a horizontal pedestal, it always faces the water surface, and accurate measurement is performed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic side view of the underwater buoy type wave meter according to the first embodiment of the present invention. This underwater buoy wave meter is provided to measure a wave meter on the water surface in a water area with a relatively large water depth, and the anchor 1 installed on the bottom B of the water
The artificial horizontal stand 5 is attached to the underwater buoy 3 connected to the top of the mooring line 2 which is tense, and the ultrasonic wave height meter 10 is mounted on the artificial horizontal stand 5.

As described above, the underwater buoy 3 tensioned and moored at one point in water can be adjusted to any water depth by changing the length of the mooring line 2, and the ultrasonic wave transmitter / receiver of the ultrasonic wave height meter 10 can be used. Is on the artificial horizontal table 5, so underwater buoy 3
Even if is tilted, it always measures the vertical distance. It should be noted that the inventors of the present invention, if such an underwater buoy 3 is tensioned and moored at a position where the water depth is deep to some extent, the underwater buoy 3 will hardly be shaken even if a wave comes on the water surface, It has been confirmed using an experimental model that the sway in the direction of movement has a very small effect on the measurement accuracy.

Further, when the inclination angle of the artificial horizontal base 5 is large, the influence of the vertical displacement appears, but it has been confirmed that this case can be easily corrected. Next, FIG. 2 is a schematic side view of the underwater buoy type wave height meter of the second embodiment, and in this case also, similarly to the first embodiment of FIG. 1, the underwater buoy 3 tensioned and moored at one point in the water. On the artificial horizontal table 5 attached to the above, a wave observation unit is provided in which a composite wave height meter 11 incorporating an ultrasonic wave height meter and a pressure sensor is detachably attached.

This unit also incorporates a motion measuring device such as an inclination measuring device and an azimuth measuring device, a control device, and a power supply unit for each of these devices. The composite wave height meter 11 is operated by the underwater buoy 3. By placing it underwater, the ultrasonic wave height meter can be applied to deep water. In addition, in FIG. 2, a data recording device and a power supply unit for driving for the purpose of short-term measurement are built in a wave observation unit equipped with the composite wave height meter 11, but in FIG. It is also possible to use the indicator buoy 6 moored to the water surface via the mooring line 3 to the anchor 1 to transmit data by a telemeter system, or to extend the cable for power supply and signal transmission from the land area. is there.

The underwater buoy wavemeter having the above-mentioned structure can be adapted to any water depth by changing the length of the mooring line 2, and the underwater buoy 3 and the composite type wave height meter 11 can be detached. Moreover, since each has a water resistant structure, installation, inspection, and removal work are extremely easy. That is, in the installation work, after the underwater buoy 3 is thrown into the water from the sea at a predetermined position, the body of the composite wave height meter 11 can be set on the underwater buoy 3 by the diver.

The underwater buoy 3 is set at a water depth where the diver can secure a sufficient dive time, for example, at an underwater position of 10 to 20 m below the sea level, and the main body of the combined wave height meter 11 is lightweight and the underwater weight is almost zero. ing. In addition, compound wave height meter 11
Since the ultrasonic wave transmitter / receiver of the ultrasonic wave height meter built in is located on the artificial horizontal stand 5, the vertical distance is always measured even if the underwater buoy 3 is tilted.

Next, the motion of the underwater buoy 3 can be modeled as an underwater inverted pendulum, and its motion characteristics in waves can be estimated by a relatively simple theory. The natural period of the underwater buoy 3 is the length of the mooring line 2 and the marginal buoyancy of the underwater buoy 3 (that is, buoyancy −
Although it depends on its own weight, they can be changed, so that the natural period can be adjusted so that the motion of the underwater buoy 3 becomes small with respect to the target wave period range.

However, depending on the observation depth, the underwater buoy 3
It is conceivable that the natural period of is close to the wave period range and the motion of the underwater buoy 3 becomes large. In that case, the measurement data may include a measurement error due to the movement of the underwater buoy 3. Therefore, the present inventors carry out a numerical simulation of the measurement data by the composite wave height meter 11 to determine the error. As a result of the examination, it was confirmed that there is no problem in practical use at a water depth of 20 m or more, which is the object of observation of the composite wave height meter 11.

Further, when the horizontal movement is large, the underwater buoy 3 will sink, and as a result, the underwater buoy 3 will also move in the vertical direction, but when the underwater buoy 3 largely sinks, it will reach the water surface. Since the distance is measured longer than the stationary position, the water surface fluctuation will be greatly evaluated. However, in the second embodiment, since the motion measuring device is mounted on the underwater buoy 3, the measurement data can be easily corrected.

Further, since the motion characteristics of the underwater buoy 3 can be easily estimated, the response characteristics of the artificial horizontal base 5 of the underwater buoy 3 can be easily designed and easily realized. That is, the movement of the underwater buoy 3 under tension mooring is large near the natural period, but is very small in the period range shorter than that. Therefore, the underwater buoy 3 like the diagram showing the response to the wave period in FIG. The response characteristic of the artificial horizontal base 5 may be obtained.

Furthermore, since the wave direction and the predominant direction of the motion of the underwater buoy 3 coincide with each other, the wave direction can be estimated by measuring the motion of the underwater buoy 3. Next, the motion measuring device mounted on the underwater buoy 3 will be described. The underwater buoy 3 moves in the horizontal direction and the rotating direction, and for measuring the horizontal motion of the underwater buoy 3, an accelerometer or an inclinometer, Although it is possible to use a vertical gyro, since the accelerometer is affected by the inclination, it is necessary to mount the accelerometer on the artificial horizontal base 5, and the equipment becomes large-scale.

On the contrary, the inclinometer is affected by the horizontal acceleration, and the vertical gyro cannot be used for a long time. Therefore, here, by detecting the inclination angle of the artificial horizontal table 5 equipped with the ultrasonic transmitter / receiver,
The movement of the underwater buoy 3, that is, the tilt angle in two directions can be measured.

The tilt angle is detected by a method of measuring the rotation angle of the gimbal shaft with a potentiometer or the like,
As shown in FIG. 4, a method is conceivable in which a light source 13 is placed below the shaft 14 of a universal joint of a gimbal 5A, which is an artificial horizontal base 5, and its movement is detected by a CCD image sensor 15. An azimuth compass can be used to measure the rotational movement of the underwater buoy 3.

[0027]

INDUSTRIAL APPLICABILITY Since the underwater buoy type wave meter of the present invention described above is mounted on an underwater buoy in which an ultrasonic wave height meter is tensioned and moored, even if it is applied in a deep water region, the characteristics of ultrasonic waves. As a result, the measurement accuracy is not deteriorated, the measurement accuracy is maintained, and since the underwater buoy is used, there is an effect that it does not require a large-scale structure and is economical.

Further, by mounting the composite wave height meter in which the ultrasonic wave height meter and the pressure sensor are incorporated in the underwater buoy in a detachable manner, the ultrasonic wave height meter and the water pressure sensor can prevent the error between them. Since it is corrected, more practical measurement can be performed, and since the underwater buoy is at a relatively shallow position where the diver can reach from the surface of the water, there is an advantage that the crest meter can be easily installed, inspected, and removed.

[Brief description of drawings]

FIG. 1 is a schematic side view of an underwater buoy type wave meter according to a first embodiment of the present invention.

FIG. 2 is a schematic side view of an underwater buoy type wave meter according to a second embodiment of the present invention.

3 is a diagram showing respective response characteristics of an underwater buoy and an artificial horizontal base of the wave meter of FIG.

4 is a side sectional view of a motion measuring device using an artificial horizontal base applied to the wavemeter of FIG.

[Explanation of symbols]

1 Anchor 2 Mooring cable 3 Underwater buoy 5 Artificial horizontal stand 10 Ultrasonic wave crest meter 11 Combined crest meter

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Teruhiko Ido 2-28-19 Minami Tsukushino, Machida-shi, Tokyo Within Aiotech Limited Ltd. (72) Inventor Akira Otani 2-28-19 Minami Tsukushino, Machida-shi, Tokyo Yes Limited company Aio Technique

Claims (2)

[Claims] 1. An underwater buoy type wave meter in which an ultrasonic wave height meter is mounted on an artificial horizontal stand mounted on an underwater buoy tensioned and moored at one point in water. 2. An underwater buoy type in which a composite wave height meter incorporating an ultrasonic wave height meter and a water pressure sensor is removably mounted on an artificial horizontal platform attached to an underwater buoy tensioned and moored at one point in water. Wave total.