JPH0140924B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a wave measuring device that measures both wave height and wave direction, and in particular, has a simpler structure and can be made more compact than conventional devices, and has stable accuracy. This invention relates to a wave measurement device that can obtain the following.

Wave height and wave direction can be obtained by measuring the water surface displacement and water surface slope caused by waves, respectively. In conventional wave meters, water surface displacement can be measured using accelerometers or hanging pressure gauges.

The former method measures the vertical acceleration of a buoy by attaching an accelerometer to a gimbal or vertical gyroscope, and then integrates the acceleration signal twice to determine water surface displacement.

The latter method involves suspending a pressure gauge from a buoy, measuring pressure changes by moving the pressure gauge up and down in the same way as the buoy, and determining water surface displacement from the changes. As shown from the above explanation, when determining water surface displacement, the method using a hanging pressure gauge has the disadvantage, compared to the method using an accelerometer, that the pressure gauge must be suspended to a depth where it is relatively less affected by waves. However, it has the advantages of being a simpler device, having almost no noise due to wave pressure, and being able to be processed with relatively simple analysis.

On the other hand, there are two ways to measure water surface slope: a vertical gyroscope and a gravity-based inclinometer.

The former has excellent measurement accuracy, but has the drawback of requiring relatively large amounts of power and being expensive, while the latter is often used with relatively simple devices such as pendulum type devices. , it is susceptible to noise caused by the horizontal movement of waves and wave pressure, and has not yet achieved sufficient stability and accuracy.

From the above, it can be said that the currently commonly used wave meters that can accurately measure both wave height and wave direction are those that combine an accelerometer and a vertical gyroscope, and the typical example is the pitcherol type buoy. There is a clover shaped buoy.

However, as already mentioned, this method requires integrating the acceleration signal twice to determine the water surface displacement, is susceptible to low-frequency noise, and uses a gyroscope, making the structure complicated and expensive. It has disadvantages such as becoming a thing.

It is an object of the present invention to provide a wave measuring device that eliminates these drawbacks as much as possible.

In order to achieve this objective, the wave measuring device of the present invention employs a hanging pressure gauge for wave height measurement, and connects the other end of the cable that suspends this pressure gauge to two
By attaching it to a buoy that closely follows the wave surface via an axial gimbal, the water surface displacement and water surface slope of waves can be measured simultaneously.

Next, embodiments of the present invention will be specifically described with reference to the drawings.

In the figure, 2 is a disc-shaped buoy, and a 2-axis gimbal 3 is installed in a recess 9 provided at the center of the bottom, a cable 6 is suspended from the center of the 2-axis gimbal 3, and a weight 7 and a pressure gauge 8 are attached to the tip of the buoy. and attach it.

Each axis of the two-axis gimbal 3 is provided with a tilt detector consisting of a potentiometer. A bellows-shaped waterproof membrane 5 is disposed between the recess 9 of the buoy 2 and the cable 6 to prevent seawater from entering the gimbal section. 4 is a compass provided on the top surface of the buoy 2.

Next, to explain the action, the buoy 2 moves up and down due to changes in the wave front, and the gimbal 3 and cable 6
The pressure gauge 8 also moves up and down. Therefore, water surface displacement can be measured by pressure measurement using the pressure gauge 8.

In addition, the cable 6 is vertical, and the buoy 2
Since its horizontal plane is parallel to wavefront 1,
The angle between the axis of the cable 6, that is, the vertical line, and the wave surface 1, that is, the horizontal plane of the buoy 2, can be measured by a tilt detector consisting of a potentiometer provided on each axis of the two-axis gimbal 3.

As described above, the present invention takes advantage of the fact that the cable of a hanging pressure gauge has stable verticality even when the water surface is displaced by waves.
It measures the water surface inclination, and by attaching a cable with a pressure gauge suspended to a buoy that closely follows the wave surface via a two-axis gimbal and simultaneously measuring both the wave height and wave direction, it is possible to determine the water surface displacement. There is no need to integrate twice, the influence of noise due to wave pressure is small, and the structure is simple and inexpensive because a commonly used two-axis gimbal mechanism is used for water surface inclination.

Note that the measurement of water surface slope according to the present invention is also affected by noise caused by the horizontal motion of waves and wave pressure, but according to laboratory tank experiments, the effects of these noises can be reduced by the following measures. can be reduced.

First, by attaching a weight to the pressure gauge to provide more stable verticality, high-frequency rolling and pitching buoys are reduced, and it is more effective than conventional disc-shaped pitcherol type buoys. It becomes a stable buoy.

Second, by mooring the wave meter's buoy to a drifting ship or a buoy anchored to the seabed, the wave meter's buoy will almost always flow in the direction of the waves, and the mooring rope will be loose. First, it is always tensioned, and as a result, the horizontal movement of the wave gauge buoy due to waves is suppressed.

[Brief explanation of drawings]

The drawing is a schematic front view illustrating an embodiment of the present invention. 1...Wave surface of waves, 2...Disc-shaped buoy body, 3...2
Axial gimbal, 4... Compass, 5... Bellows-shaped waterproof membrane, 6... Pressure gauge hanging cable, 7... Weight, 8...
Pressure gauge, 9... recess.

Claims (1)

[Claims] 1 A cable is attached to the buoy via a two-axis gimbal, and a pressure gauge is hung from the tip of the cable, a compass is attached to the buoy, and an inclination detector is attached between each axis of the two-axis gimbal and the cable. wave measurement device.