JPH10148524A - Buoy-type wave-height meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the durability and handling property and realize highly accurate measurement. SOLUTION: The natural frequency period of a buoy 1 is made shorter than the shortest cycle of a wave to be measured for wave height. Two angular velocity sensors 2x and 2y for measuring rotary angular velocity against the horizontal axis mutually crossing at right angles are built in and fixed to the buoy 1. Further, the buoy 1 contains digital filters 31x and 31y which have a specified logical correction property in a range of measuring wave height and remove elements outside the range, and a wave height calculation part 3 is provided to calculate the wave height value within a range of wave height according to the information on rotary angular velocity from the sensors 2x and 2y. Furthermore, a communication device 4 is provided to radiate the information on wave height value from an antenna 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a buoy-type wave height meter, and more particularly to a buoy-type wave height meter used for safety management at the time of harbor construction work, safety management of a beach, and the like.

[0002]

2. Description of the Related Art A wave height meter used for acquiring design conditions of a harbor structure or for safety management during harbor construction work, a wave height meter used for safety management of a beach, and the like are usually buoys. A wave height meter is used. FIGS. 7A and 7B show a typical conventional example of such a buoy-type wave height meter. FIG.
FIG. 7A is a schematic diagram of a main configuration showing moored buoys floating on the sea surface and main components inside the buoy, and FIG. 7B is a block diagram mainly illustrating an electronic circuit portion of the buoy type wave height meter. This buoy-type wave gauge is composed of an anchor 11 and a mooring line 10.
Buoy 1a moored by the sea and floating on the sea surface, and this buoy 1a
A gimbal 8 is disposed at a predetermined position inside the gimbal 8 to keep the measuring instrument mounting surface horizontal, and is fixed and mounted on the measuring instrument mounting surface of the gimbal 8 to measure the vertical fluctuation of the buoy 1a as vertical acceleration. The accelerometer 9, a crest value calculator 3 a including an integration circuit 34 for calculating a crest value from the vertical acceleration measured by the accelerometer 9, and the information of the crest value calculated by the crest value calculator 3 a to the antenna 5. And a communication device 4 that radiates the air as radio waves through the air.

In this buoy-type wave height meter, an accelerometer 9
Has a vertical measurement direction, and measures a gravitational acceleration of 1 g in a stationary state. When the buoy 1 a fluctuates in the vertical direction, the measurement value changes in accordance with the fluctuation. Therefore, the gravitational acceleration 1 g is subtracted from this measured value, and the integration circuit 34 calculates
By performing the time integration, the fluctuation amount of the buoy 1a can be calculated as the peak value. If the measuring direction of the accelerometer 9 rotates or tilts, the 1 g in the stationary state is measured low and an error occurs. Therefore, the gimbal 8 is used to maintain the measuring direction vertical, and the gimbal 8 itself shakes. This is soaked in oil to hold down.

[0004]

In this conventional buoy type wave height meter, a gimbal 8 is used to keep the mounting surface of the accelerometer 9 horizontal, and the gimbal 8 is immersed in oil to suppress the movement of the gimbal 8 itself. However, if the buoy 1a is rotationally swayed or tilted, the gimbal 8 itself is not always immediately horizontal, causing a phase delay, and the acceleration measured by the accelerometer 9 includes an error due to swaying, etc. There is a problem that high-precision wave height measurement cannot be performed. Since this error appears as an error having a long cycle when integrated twice, there is a filter provided with a filter for removing a component having a long cycle. , The wave component having a long period is also removed, and it is impossible to measure the peak value of that portion, which also makes it impossible to measure the peak value with high accuracy There is a problem point.

Further, since the gimbal 8 has a mechanically movable portion, maintenance is required for a short period of time, and a clamp for suppressing the movement of the gimbal 8 is required during movement, so that durability and handleability are required. Is bad. Furthermore, since the mooring line 10 mooring the buoy 1a impedes the ability of the buoy 1a to follow up and down, there is a problem in that the accuracy of wave height measurement is reduced. Furthermore, since the measurement results of the accelerometer 9 do not include the physical specifications required for calculating the direction of the wave with respect to the buoy, the direction of the wave required for safety management in ports and beaches, etc. Is difficult to measure.

An object of the present invention is to provide a buoy-type crest meter which is excellent in durability and handleability and can obtain a high-precision wave height measurement, and can be easily achieved by adding only a few components. It is an object of the present invention to provide a buoy-type wave gauge capable of measuring the direction of a wave.

[0007]

The present invention has the following means in order to achieve the above object. That is, the buoy-type wave height meter of the present invention has a natural oscillating cycle shorter than the shortest cycle of a wave to be measured and is moored to an anchor by a mooring line at a predetermined position. First and second angular velocity sensors for measuring rotational angular velocities with respect to each of the horizontal axes, and a peak value for calculating a peak value within a pulse height measuring range from information on rotational angular velocities from the first and second angular velocity sensors. It has a calculating unit and a communication device that radiates the peak value information from the peak value calculating unit to the air as radio waves via an antenna.

[0008] The center of the buoy pitching and rolling sway is referred to as the buoy mooring cable attachment position, and the crest value calculating section transmits information on the rotational angular velocity from the first and second angular velocity sensors. Is provided with a filter that removes the component of the natural oscillation period of the buoy included in
Furthermore, in addition to the characteristic of removing the component of the natural oscillation period of the buoy, the filter has a characteristic of removing a component of a long period outside the peak height measurement range and a predetermined logic correction characteristic for the peak height measurement range. And the filter is configured as a digital filter.

An azimuth compass for measuring the azimuth is fixed in the buoy, and the wave information is obtained from the azimuth information from the azimuth compass and the rotational angular velocity information from the first and second angular velocity sensors. Wave direction calculation means for calculating the direction is provided.

[0010]

Next, an embodiment of the present invention will be described. First, two angular velocity sensors are used as sensors for measuring physical parameters necessary for calculating a peak value, and the physical parameters measured by these two angular velocity sensors are measured for each horizontal axis orthogonal to each other. Let it be the rotational angular velocity. By doing so, the angular velocity sensor has a characteristic that is not affected by acceleration in the vertical and horizontal directions including gravitational acceleration caused by buoyancy of the buoy, so that it is possible to completely measure the rotational angular velocity of only the rotational component. By calculating the peak value from the above information, even if the buoy has a rotational fluctuation, the calculated peak value does not include an error, and the peak value can be measured with high accuracy.

Next, the principle of calculating the peak value from the information on the rotational angular velocity will be described. When the buoy's own rolling and pitching natural frequency is sufficiently higher than the frequency of the wave, the buoy follows the wave surface gradient of the wave and causes rolling and pitching fluctuations. Therefore, the rolling angle and the pitching angle match the water surface gradient. Furthermore, the temporal change rate of the water surface gradient of the wave (the derivative of the water surface gradient of the wave with respect to time) matches the temporal change rate (rotational angular velocity) of the rolling angle and the pitching angle. That is, the rotational angular velocity of the buoy matches the temporal change rate of the water surface gradient. The relationship between the wave height and the rotational angular velocity of the buoy (the rate of change of the water surface gradient over time) is as follows. ω _x (t) = − σ · k (σ, h) · cos (θ) · H (t) (1) ω _y (t) = − σ · k (σ, h) · sin (θ) H (t) (2) θ = tan ⁻¹ (ω _y (t) / ω _x (t)) (3) where, wave height: H (t) wave angular frequency: σ (= 2π / T, T is the cycle of the wave) Rotational angular velocity in the x direction (rolling): ω _x (t) Rotational angular velocity in the y direction (pitching): ω _y (t) Direction of the wave direction with respect to the buoy reference axis: θ Wave number : K (σ, h) = 2π / L, where L is a wavelength and is obtained from the following equation.

L = (2πg / σ ² ) tanh (2πh / L) (4) where h is water depth and g is gravitational acceleration. After all, the wave number k is a function of the water depth h and the angular frequency σ. Here, if G is defined as follows, the following equation is obtained. G (σ, h) = − [σ · k (σ, h)] ⁻¹ (5) Equations (1) and (2) can be expressed by the following equations. H (t) · cos (θ) = G (σ, h) · ω _x (t) (6) H (t) · sin (θ) = G (σ, h) · ω _y (t) … (7)

Here, G (σ, h) is also a function of the water depth h, but generally the installed water depth does not change. Therefore, it is a function of the angular frequency σ of the wave. G in advance according to the installation water depth
When a digital filter having the characteristic of (σ, h) is created and ω _x and ω _y measured by the angular velocity sensor are passed through this filter, H (t) · cos (θ) and H (t) · sin
(Θ) is obtained, the wave direction θ can be calculated by the equation (3), and finally the wave height H (t) is obtained.

As can be seen from the above equations, these equations include the direction θ of the wave direction with respect to the buoy.
Therefore, by installing an azimuth compass such as a magnetic compass in the buoy and measuring this θ, the direction of the wave can be easily calculated from the above equation.

[0015]

Next, embodiments of the present invention will be described with reference to the drawings. 1A and 1B are a schematic side view showing a moored buoy floating on the sea surface and its internal arrangement according to a first embodiment of the present invention, and a block diagram of an electronic circuit portion.
The first embodiment has a buoy 1 which has a natural oscillation period shorter than the shortest period of the wave to be measured and which is connected to the mooring line 10 at the center of the pitching and rolling rotation and is moored to the anchor 11. An angular velocity sensor 2x, 2y such as an optical gyro or a vibrating gyro, which is built in and fixed to the buoy and measures the rotational angular velocity with respect to each of two horizontal axes orthogonal to each other; an angular velocity sensor including digital filters 31x, 31y and a peak value calculating unit 32 A crest value calculator 3 for calculating a crest value within the crest measurement range of the wave from the rotation angular velocity information from 2x and 2y, and the crest value information from the crest value calculator 3 as radio waves via the antenna 5 And a communication device 4 that radiates into the air.

The buoy 1 has a natural period of oscillation (pitching and rolling) of 1 second or less so that the buoy 1 swings following a wave having a period of 3 seconds or more. This is because there is almost no wave below 3 seconds and there is no need to measure. As a result, the buoy generates a natural oscillation around a natural period of 1 second and is measured by the angle sensors 2x and 2y, but this component is removed by the digital filters 31x and 31y. In this way, the effects of the sway inherent to the buoy 1 are avoided.

FIG. 2 is a layout view of an electronic circuit portion which is built in and fixed to the buoy 1. The angular velocity sensors 2x, 2y
Are arranged to measure the rotational angular velocities with respect to horizontal axes (x axis, y axis) orthogonal to each other.

FIG. 3 is an external view of the peak value calculating section 3. The peak value calculating section 3 includes sensor terminals T31 and T32 for inputting signals from the angular velocity sensors 2x and 2y, and information on the calculated peak value. And the like, and an output connector 322 for serial communication of the RS232C standard for outputting the same, and a water depth setting unit 321 for setting the water depth.

FIG. 4 is a characteristic diagram showing gain characteristics with respect to frequency of the digital filters 31x and 31y included in the peak value calculating section 3, and FIG.
FIG. 9 is a characteristic diagram showing a characteristic of a gain with respect to periods of x and 31y.

The characteristics of the digital filters 31x and 31y are outside the peak height measurement range in the frequency range of section a. Therefore, the gain is reduced in consideration of the drift of the angular velocity sensors 2x and 2y, and the frequency range of section b is set. Is a wave height measurement range, which is a logical correction characteristic determined by the angular frequency of the wave, the water depth, and the like. In the frequency range of the section c, the wave height measurement range is outside the wave height measurement range, and the component of the natural oscillation period of the buoy 1 is removed. , The gain is set to be low.

With such a configuration, the buoy 1
Of the vertical and horizontal accelerations including the gravitational acceleration due to the swaying motion, the natural vibration of the buoy 1, and the angular velocity sensor 2
Since it is possible to prevent the influence of the drift of x and 2y and to eliminate the components within the wave height measurement range, the wave height can be measured with high accuracy, and mechanical movement such as a gimbal can be performed. Since no part is required, a buoy-type crest meter having excellent durability and handleability can be obtained.

Further, since the mooring line mounting position of the buoy 1 is a central portion of the pitching and rolling rotation of the buoy 1, the pulling force of the mooring line 10 has almost no effect on the rotation fluctuation, and the rotation angular velocity is reduced. The measurement accuracy, and thus the wave height measurement accuracy, can be increased.

FIGS. 6A and 6B are a block diagram of an electronic circuit portion and a layout diagram inside the buoy according to a second embodiment of the present invention. The second embodiment is different from the first embodiment in that a magnetic compass 7 as an azimuth compass for measuring a wave direction θ with respect to the buoy 1 is arranged and fixed inside the buoy 1, and the peak value calculation is performed. A wave direction calculating means for calculating the wave direction with respect to the buoy 1 from the information of θ from the magnetic compass 7 and the output signals of the digital filters 31x and 31y to the unit 32 to obtain a crest value / wave direction calculating unit 33; The point is that the peak value calculating section 3 is replaced by a peak value / wave direction calculating section 30.

In the second embodiment, the wave direction with respect to the buoy 1 can be calculated only by adding a few components such as the magnetic compass 7 and the wave direction calculating means to the first embodiment. Safety management in harbors and beaches can be further improved. In these embodiments, the electronic circuit portion is arranged and fixed inside the buoy 1. However, the buoy 1 can be replaced with a container having a natural period of pitching and rolling of 1 second or less. For example, a ship having a natural period of 1 second or less can be used as a buoy.

[0025]

As described above, the present invention measures the rotational angular velocities with respect to the horizontal axes orthogonal to each other and is not affected by the gravitational acceleration or the vertical and horizontal accelerations, and calculates the peak value from the rotational angular velocities. , The buoy's natural vibration component is outside the crest height measurement range, and the inside of the crest height measurement range is removed as a predetermined logical correction characteristic to remove the components outside the crest height measurement range, thereby affecting the acceleration due to the buoy's oscillation. The peak value can be calculated without being affected by the natural vibration of the buoy and the drift of the angular velocity sensor, and without removing the components within the peak height measurement range. In addition, since a mechanically movable part such as a gimbal is not required, durability and handleability are improved, and the mooring line mounting position of the buoy can be reduced. Pitching, by a center portion of the rotation upset rolling, it is height measurement precision by eliminating the influence on the rotational upset by the tension force of the mooring lines, there is an effect that. Furthermore, there is an effect that the direction of the wave can be easily calculated only by adding a few components including the azimuth compass, and the safety management in the harbor and the beach can be further improved.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing a moored buoy floating on the sea surface and its internal arrangement according to a first embodiment of the present invention, and a block diagram of an electronic circuit portion.

FIG. 2 is a layout diagram of the inside of the buoy of the embodiment shown in FIG. 1;

FIG. 3 is an external view of a peak value calculating unit of the embodiment shown in FIG.

FIG. 4 is a characteristic diagram of a gain with respect to frequency of a digital filter included in the peak value calculating unit of the embodiment shown in FIG. 1;

FIG. 5 is a characteristic diagram of a gain with respect to a period of a digital filter included in the peak value calculating unit of the embodiment shown in FIG. 1;

FIG. 6 is a block diagram of an electronic circuit portion showing a second embodiment of the present invention and a layout diagram inside the buoy.

FIG. 7 is a schematic diagram of a main configuration showing an example of a conventional buoy-type wavemeter moored and floating on the sea surface and main components inside the buoy, and a block diagram of an electronic circuit portion thereof.

[Explanation of symbols]

 Reference Signs List 1, 1a buoy 2x, 2y angular velocity sensor 3, 3a peak value calculating unit 4 communication device 5 antenna 6 power supply circuit 7 magnetic compass 8 cymbal 9 accelerometer 10 mooring line 11 anchor 30 peak value / wave direction calculating unit 31x, 31y digital filter 32 Crest value calculation unit 33 Crest value / wave direction calculation unit 34 Integration circuit

Claims (6)

[Claims] 1. A buoy having a natural oscillating cycle shorter than the shortest cycle of a wave whose wave height is to be measured and moored at a predetermined position to an anchor by a mooring line, and a rotation built in the buoy about each of two horizontal axes orthogonal to each other. A first and a second angular velocity sensor for measuring an angular velocity, a crest value calculation unit for calculating a crest value within a crest measurement range of the wave from information of the rotational angular velocity from the first and the second angular velocity sensors, A buoy-type crest meter, comprising: a communication device that radiates the crest value information from the crest value calculation unit as radio waves into the air via an antenna. 2. The buoy-type crest meter according to claim 1, wherein a central portion of the pitching of the buoy and the rotational fluctuation of the rolling is a position where the mooring line of the buoy is attached. 3. The buoy-type peak height according to claim 1, wherein the peak value calculating unit is provided with a filter for removing a component of a buoy's natural oscillation period included in the information on the rotational angular velocity from the first and second angular velocity sensors. Total. 4. A filter having a characteristic of removing a component of a natural oscillation period of a buoy, a characteristic of removing a component of a long period outside a peak height measurement range, and a predetermined logical correction characteristic for the peak height measurement range. The buoy-type wave height meter according to claim 3, wherein the buoy-type wave height meter is provided. 5. The buoy-type crest meter according to claim 3, wherein the filter is a digital filter. 6. A buoy has a built-in azimuth compass for measuring an azimuth, and calculates a wave direction from azimuth information from the azimuth compass and rotational angular velocity information from the first and second angular velocity sensors. 2. A wave direction calculating means for calculating a wave direction.
A buoy-type wave height meter as described.