JPH0989557A - Floating structure body with wave direction follow-up ability - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remotely measure the direction of waves from the land by mounting an azimuth detecting circuit on a structure body that keeps its attitude automatically in the direction of waves on the sea level. SOLUTION: In a T-shape support means formed by fixing one end of one support bar vertically to a center point O of the other support bar, floats A, B are provided at both ends of the horizontal support bar, and a weight C is provided at the lower end of the vertical support bar. In such a structure body, buoyancy is adjusted so that floats partially come out to the water surface when this structure body is placed in the water.

Description

Detailed Description of the Invention

[0001]

This invention relates to a floating body for measuring the direction of waves in the ocean or lakes.

[0002]

2. Description of the Related Art The wave direction observation method known so far is
It can be roughly divided as follows. (1) Method of visually observing the sea surface ・ ・ ・ Visually or by radar for ocean observation. (2) Instrument observation at a fixed point: Stationary wave direction meter, buoy type wave direction meter, wave height meter group method. (3) Remote sensing method: By analyzing image information from artificial satellites and aircraft. Among them, the present invention (2) relates to instrument observation at a fixed point and instrument observation at a moving point, and provides a new component of the buoy type wave direction meter.

The conventional principle of the buoy type wave direction measurement is to calculate the wave direction by measuring the direction and the magnitude of the inclination of the water surface. The water surface inclination can be calculated from two orthogonal components of the inclination of the floating type buoy, and the buoy type wave direction meter has been used since around 1960 and is called a pitch roll buoy. further,
A clover buoy is also used, which not only measures the inclination of the water surface but also measures the curvature of the water surface to improve the observation accuracy. One technical problem with buoy wave direction meters is that the majority of instruments that measure tilt angle use the principle of the pendulum, so when they are subjected to horizontal acceleration, they appear to record the same effect as tilt. Is to do. In horizontal motions caused by waves, the effects of water surface inclination and horizontal acceleration act so as to cancel each other out, so the wave direction cannot be observed simply by mounting an ordinary inclinometer on the buoy. For buoys for ocean research, a gyroscope is used for the purpose of observation in a relatively short time, and the tilt angle of the buoy is determined by measuring the tilt angle between its rotation axis (holding vertical) and the buoy. I have to.

On the other hand, in a wave direction meter for the purpose of steady observation for several months to one year or more, it is difficult to use the gyroscope in terms of power consumption and durability of the bearing portion, and another method has been devised. There is. One of them is a system that uses an inclinometer with a very long natural period by combining an electromagnetic circuit and a mechanical damping mechanism and mounts it on a large or medium buoy. The other method uses a mooring fulcrum near the center of a rod-shaped vertical buoy and incorporates an inclinometer at the lower end of the buoy. Since the buoy makes a pendulum motion around the mooring point, the tilt angle at the bottom of the buoy and the horizontal acceleration exert the same effect on the inclinometer, and the direction of the water surface tilt can be known.

[0005]

The conventional buoy type wave direction detector has the following drawbacks. (A) A mechanically precise inclinometer is used, and a gyroscope or an electromagnetic sensor for increasing the natural period is used.
Since a complicated mechanism such as a mechanical damping mechanism is used together, the cost of the measurement system is high. (B) Since it is a precise and complicated measurement system, the frequency of failure is high and maintenance costs are high. The present invention has been made to eliminate these drawbacks.

[0006]

In the conventional wave direction measurement, a method of measuring the inclination of a buoy caused by a wave is adopted. On the other hand, the present invention eliminates the need for a precise and complicated measurement system by positively introducing the floating structure having the characteristic that the floating direction matches the wave direction. As a means for achieving this, a float is provided at both ends of the horizontal support rod of the T-shaped support, and a weight is provided at the lower end of the vertical support rod. When this is placed in water, a part of the float is above the water surface. A floating structure is used that has wave-following capability and buoyancy adjusted so that By mounting an azimuth angle detection circuit on this floating structure, it becomes possible to measure the wave direction.

As an azimuth angle detection circuit, a circuit for detecting the azimuth angle of the flat plate with respect to the direction of the geomagnetism (north or south) by three geomagnetic detection coils arranged on the flat plate is already known. (Mikio Takamoto, Transistor Technology, Apr
il 1992, pp296-309) In the floating structure having the wave direction followability of the present invention, through the horizontal maintaining mechanism,
By attaching this azimuth detecting circuit, the azimuth of the floating structure with respect to the geomagnetic direction, that is, the azimuth of the wave with respect to the geomagnetic direction can be obtained.

[0008]

The floating structure having the wave direction followability is abbreviated as a wave direction buoy here. As shown in FIG. 1, the wave-direction buoy joins floats A and B having equal buoyancy to both ends of a horizontal support rod (hereinafter abbreviated as horizontal rod) having a length of 2a, and from the center of the horizontal rod. It has a structure in which a vertical support rod (hereinafter referred to as a vertical rod) having a length of c is extended at a right angle and a weight C is joined to the tip of the vertical rod. The buoyancy of the float and the weight of the weight are adjusted so that the part appears above the water surface.

In the wave direction buoy, when the buoy is placed on the inclined water surface, that is, the wave surface, the two floats are automatically arranged on the contour line of the wave surface by the restoring force of the weight at the tip of the vertical bar. Have a certain property. The operation principle of the wave direction buoy will be described below with reference to FIGS. 2 and 3.

FIG. 2 shows the situation of a wave direction buoy on a tilted water surface. In this figure, for the sake of simplification, the two floats and the weights are omitted, and buoys are represented by horizontal and vertical bars. The wavefront W is inclined by an angle α with respect to the horizontal plane H, and the horizontal bar of the buoy lies on the wavefront W. Further, for simplification, the horizontal bar and the vertical bar are on the vertical plane V orthogonal to the horizontal plane H. This vertical plane is drawn as having an inclination of an angle β with respect to the projection line u-v of the contour line s-t on the inclined wave front onto the horizontal plane H.

The angle γ formed by the horizontal bar of the wave direction buoy having such a positional relationship with the horizontal plane H is as follows. When the horizontal bar of the buoy is on an arbitrary contour line, that is, when β is 0, γ becomes 0, and when the horizontal bar of the buoy is orthogonal to the contour line, that is, when β is π / 2, γ Becomes α,
In general, the relationship between γ, α, and β can be expressed by the following mathematical formula 1.

[Equation 1]

Next, referring to FIG. 3, let us consider the balance of forces in the vicinity of the weight C and in the vicinity of the center point O of the buoy. When there is a weight C with a specific gravity ρ and a volume v, the acceleration of gravity is g
If it is expressed by, the apparent gravity (ρ−1) vg in water works downward along the vertical plane V. The component force of this gravity in the vertical bar direction is (ρ-1) vg · cosγ. On the other hand, the component force (ρ-1) vg · sinγ of the weight in the direction orthogonal to the vertical bar is the vertical plane V
Work above, towards a perpendicular OZ through O. In the example of FIG. 3, this component force acts to rotate the buoy clockwise in the vertical plane V and deeply sinks the float B in the high position. Therefore, the buoyancy of the float B is larger than that of the float A. Therefore, the point of action of the resultant force of the buoyancy of the floats A and B (composite buoyancy) is set to the point M closer to the float B than the center point O.

Since buoyancy acts in a direction orthogonal to the water surface W,
An orthogonal plane P passing through the point of buoyancy action M and along the contour line of the water surface is assumed and displayed in the figure. Synthesis buoyancy -f p _(a direction against the force of gravity - the display) is on a perpendicular plane P, and acts on M points. Now, the combined buoyancy -f _p acting on the M point, and be divided into a component force f _w along the component force -f _v and the wavefront W toward the on and parallel to the vertical bar along the vertical plane V, acting on the M point The upward component force −f _v in the vertical direction is the downward component force (ρ in the vertical direction due to the weight C.
-1) It has a function of rotating the float counterclockwise in the vertical plane in combination with vg · cosγ, while the component force (ρ-1) vg of the weight C in the direction orthogonal to the vertical bar.・ Sine γ has the effect of rotating the float clockwise. After all, these component forces are balanced in the vertical plane V. Therefore, only the component force f _w of Md direction along the wavefront W remains in the M point.

The component force f _w along the wave front W causes a fluid resistance in the wave direction buoy, as shown in FIG. The action point of the fluid resistance R of the buoy is near the point O on the vertical bar axis and is below (point s in FIG. 4), and the fluid resistance R and the component force f along the wave front W are
_The rotational force due to _w becomes the driving force that moves the horizontal bar of the buoy in the direction of the contour line of the wave front. Therefore, the wave buoy placed on the inclined water surface (wave surface) moves in a direction parallel to the contour line.

Up to now, the relationship of the force acting on the wave direction buoy having a specific positional relationship with the inclined water surface has been described, but it is as follows from the viewpoint of potential energy. . Now, in FIG. 2, when the weight C is on the vertical line OZ of the center point O of the horizontal bar of the buoy, the potential energy is zero with the center point O as a reference point. In the general case where the horizontal bar of the buoy is not parallel to the contours on the wavefront,
Since the horizontal bar of the wave direction buoy is adjusted to be located near the water surface by the buoyancy of the left and right floats, the vertical bar has an inclination angle γ with respect to the vertical line as shown in FIGS. 2 and 3. It will be. This gives the potential energy of the weight C to c (1-cos
γ) (ρ-1) vg. This potential energy becomes drive energy for changing the posture of the buoy.
As already explained, as long as the vertical bar of the buoy has the inclination angle γ with respect to the vertical line passing through the center point O, the force f _w that tries to rotate the buoy along the wavefront W is generated, so the potential energy is It will continue to decrease. As described in detail above, the wave direction buoy placed on the inclined water surface (wave surface) has a characteristic of automatically maintaining a posture parallel to the contour line on the wave surface.

With respect to the size of the wave direction buoy, the inventor clarified the following conditions by experiments. That is, as a result of prototyping several kinds of wave-direction buoys having different dimensions and observing the behavior of the wave-direction buoy for waves having different wavelengths, the horizontal support rod length 2a of the buoy must be smaller than the wavelength λ of the wave,
It has been found that the length of the horizontal support rod is preferably a fraction of the wavelength or less in order to have good wave direction followability.

[0017]

EXAMPLE A first example is shown in FIG. An attitude level maintaining mechanism (a mechanism for maintaining the azimuth angle detection circuit horizontally even when the buoy is tilted) lc is attached to the center point of the horizontal support rod of the buoy, and an azimuth angle detection circuit dd and an automatic wireless communication circuit at are mounted on this. Float the wave buoy on the water. This wave direction buoy can automatically detect the direction of the buoy every moment, that is, the wave direction, and transmit it to the ground station by wireless communication.

A second embodiment is shown in FIG. FIG. 6 shows a floating structure for fixed-point observation, which has wave direction followability. The movable wheel is passed through two positions e and f that sandwich the central point of the horizontal support rod and do not contact the vertical support rod, and both ends of the U (English U) type tractor are fixed to these movable wheels. The mooring line is tied to the central portion uc of the shaped tractor. By mounting an azimuth angle detecting device and an automatic wireless communication device on this floating structure in the same manner as in Example 1 and fixing the mooring line of the U-type towing device to the bottom of the water, automatic observation of the wave direction at a fixed point is possible. It will be possible.

The vertical support rod, which is a component of the tee-shaped support device dealt with in this patent, has a role of transmitting the weight of the weight to the left and right floats via the horizontal support rod, and is not necessarily linear. It does not have to be a rod, and the shape of the supporting rod can be selected depending on the situation.

[Brief description of drawings]

FIG. 1 is a side view of a floating structure having wave direction tracking ability according to the present invention.

[Explanation of symbols]

 A and B Float C Weight O Center point of horizontal support bar (horizontal bar) a and b Length from center point of horizontal bar to each float c Length from center point to weight

[Fig. 2] Positional relationship when a floating structure with wave direction tracking characteristics is placed on an inclined water surface

[Explanation of symbols]

H Horizontal plane V Vertical plane that includes the floating structure in the plane W Wavefront st Contour line uv on the wavefront W passing through the center point O of the floating structure uv Projection line to the horizontal plane H α wavefront and An angle formed by the horizontal plane β An angle between the projection line uv of the contour line st on the horizontal plane and the projection line of the horizontal bar of the floating structure on the horizontal plane γ The vertical support bar (vertical bar) of the floating structure is the central point Angle formed with the vertical line on the V plane passing through O

[Fig. 3] Vector diagram showing the relationship between gravity and buoyancy acting on a floating structure.

[Explanation of symbols]

Perpendicular a point P point M of the vertical line as the wavefront W passing through the center point O of the point Z horizontal support rods M synthesis buoyancy, and, through P faces the plane -f _p synthesis buoyancy (point M parallel to the contour line toward the upper upward vector) component force along the vertical plane of the vector -f _p force on -f _v point M street vertical plane V parallel to the vertical bars through the force (M point acting upwards) f _w vector -f (vector along toward Md direction the point M as the wavefront W) component force along the wavefront W of the _{p (ρ-1)} vg apparent gravity water at weight is subjected (weight C
From the vertical direction) (ρ-1) vg · cosγ Weight component (force from weight C downward in the vertical direction) (ρ-1) vg · sinγ Weight component (weight C from vertical to vertical rod) The force to the perpendicular OZ at a right angle)

FIG. 4 is an action diagram of a force that guides the horizontal bar of the floating structure onto the contour line of the wavefront.

[Explanation of symbols]

M Synthesis force along the center point f _w wavefront W of the point O bars buoyancy (vector exiting M) the point of the fluid resistance s drag R of R buoy (located slightly below the point O on the plane P)

FIG. 5 is a diagram of a floating structure equipped with an azimuth angle detection device and a communication device.

[Explanation of symbols]

 lc posture horizontal maintenance mechanism dd azimuth angle detection device at automatic communication device

FIG. 6 is a side view of a floating structure for fixed point observation.

[Explanation of symbols]

e and f Movable wheels that work so as not to hinder the longitudinal movement of the vertical rods uc Mooring line fastening portion of a U-shaped tractor

Claims (3)

[Claims] 1. In a so-called "T" (alphabet T) type support in which one end of another support rod is vertically fixed to the former at the midpoint of one support rod, it floats at both ends of a horizontal support rod. And a structure in which a weight is provided at the lower end of a vertical support rod, and the buoyancy is adjusted so that a part of the float appears above the water surface when it is placed in water. . 2. In the structure described in the preceding paragraph, the movable ring is passed through two positions which sandwich the midpoint of the horizontal support rod and which do not contact the vertical support rod, and these movable rings are used for mooring. (U) A floating structure having wave-following capability capable of fixed point mooring, in which both ends of the U-shaped tractor are fixed and mooring lines are connected to the central portion of the U-shaped tractor. 3. A wave direction measuring device capable of measuring a wave direction by mounting an azimuth angle detection circuit on the structure according to claim 1 or 2.