JP2013205311A - Liquid level measurement system and marine vessel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the height of a liquid level in the circumference of a structure existing on the surface of a liquid with a simple configuration without affecting an original waveform.SOLUTION: A liquid level measurement system includes: multiple electrode pairs; and a measurement unit 20 connected to them. Four sets of vertically elongate and thin film shape electrodes 11, 12 are paired (electrode pairs) and arranged on a side surface of a marine vessel body 100. A voltage is applied to the respective electrode pairs, and characteristic changes between the electrodes 11, 12 are detected by the measurement unit 20, so that the heights of a sea level 201 at places of the respective electrode pairs are measured. The measurement unit 20 includes a detection control circuit 30 and a calculation circuit 40. The electrodes 11, 12 are arranged to partially sink into the water in the length direction, i.e. to allow the sea level 201 to enter within the range of respective lengths in a vertical direction (a depth direction).

Description

  The present invention relates to a liquid level measurement system that measures the height of a liquid surface around a structure that exists on the liquid surface, such as a ship, or the spatial and temporal distribution (liquid surface wave) of this height. Moreover, it is related with the ship mounted with this liquid level measurement system.

  When a ship exists on the water (the sea), it is important for the operation of the ship and the weather observation to actually measure the shape (waveform) and wave height of the waves on the sea. For example, the wave height distribution around the hull greatly affects the wave resistance, so this measurement is important data for designing the shape of the hull. In this case, it is necessary to measure the waveform and wave height on the side surface (ship side) of the ship. In this case, it is necessary to perform this measurement regardless of whether the ship is stopped or moving, or whether the ship is near or far from the land. Also, this measurement may be performed using a model ship instead of an actual ship. In this case, this measurement may be performed not in the sea but in the water tank.

  As this ship side wave measuring method, for example, Patent Document 1 describes a technique of observing the ship side using a video camera and recognizing a gas-liquid interface (interface of air and water) from the image. According to this method, the waveform and the wave height can be accurately measured, and the time change can be easily checked. A method of observing the water surface using laser light instead of obtaining an image with a video camera is also known.

  Further, sensors (liquid level sensors) for measuring a gas-liquid interface using a liquid level detector are used in various industrial fields. For example, Patent Documents 2 and 3 describe a liquid level sensor that uses three electrodes to calculate the height of the liquid level from the conductivity and capacitance between them. These are not used for ship side wave measurement, but it is clear that if you install many of these liquid level sensors on the ship side and measure the water level on the ship side, you can measure the wave of the ship side wave. is there.

JP 2001-356015 A JP 2004-347331 A Utility Model Registration No. 3162032

  In the technique described in Patent Document 1, it is necessary to install a video camera at a location away from the ship side. For this reason, this video camera needs to be provided on another ship for measurement, or provided so as to protrude from the ship side in this ship itself. In the former case, it is necessary to prepare a ship for measurement separately, and in the latter case, it is necessary to provide a structure that obstructs the operation of the ship. For this reason, it has been difficult to easily measure ship side waves using this technique. Even in the case where laser light is used, the same problem occurs in the place where the laser light source is installed.

  When measuring a ship side wave using the liquid level sensor described in Patent Documents 2 and 3, no other ship for measurement is required, and the liquid level sensor can be easily installed. However, since the liquid level sensor itself is a structure, the waveform and wave height of the ship side wave are affected by the presence of the liquid level sensor itself. For this reason, it has been difficult to accurately measure the original ship side wave waveform and wave height. Furthermore, when this liquid level sensor is fixed to a ship, the liquid level sensor may affect the navigation of the ship (or a model ship) itself and may affect the navigation.

  Therefore, it has been difficult to measure a ship side wave with a simple configuration without affecting the original waveform. This is not limited to ship side waves, and the same applies to the overall measurement of the liquid level around the structure existing on the liquid level.

  The present invention has been made in view of such problems, and an object thereof is to provide an invention that solves the above problems.

In order to solve the above problems, the present invention has the following configurations.
A liquid level measurement system according to claim 1 of the present invention is a liquid level measurement system that measures the height of the liquid level with respect to a structure existing on the liquid level so that a part of the level is submerged below the liquid level. An electrode pair formed of two electrodes, at least one of which is formed in a thin film shape so that a part of the electrode is submerged in the liquid below the liquid surface, and the two And a measuring unit for detecting the height of the liquid surface at a location where the electrode pair is formed from the electrical characteristics between the electrodes.
In the present invention, the height of the liquid surface around the structure existing on the liquid surface is measured using an electrode pair composed of two electrodes and a measuring unit.
The liquid level measurement system according to claim 2 of the present invention is characterized in that the structure having a conductive surface is used as the other electrode of the two electrodes.
In the present invention, the structure itself having a conductive surface is used as the other electrode in the electrode pair.
The liquid level measurement system according to claim 3 of the present invention is characterized in that the one electrode is composed of a conductive paint applied to a side surface of the structure.
In the present invention, one electrode of the electrode pair is formed in a thin film shape using a conductive paint on the side surface of the structure.

In the liquid level measurement system according to claim 4 of the present invention, the measurement unit detects the height of the liquid level from a shift in an equilibrium condition caused by a change in electrical characteristics between the two electrodes in a bridge circuit. It is characterized by that.
In the present invention, the height of the liquid level is calculated from a voltage generated due to a shift in equilibrium conditions in a bridge circuit (for example, a Wheatstone bridge circuit).
In the liquid level measurement system according to claim 5 of the present invention, a compensation element having a compensation electrode that is always immersed in the liquid is inserted into the bridge circuit.
In the present invention, a compensation element using a compensation electrode that is always submerged in the liquid is inserted into the bridge circuit. The compensation element reduces the influence of changes in liquid temperature and the like on the balance of the bridge circuit.
In the liquid level measurement system according to claim 6 of the present invention, the measurement unit detects the height of the liquid level between the two electrodes by measuring the electrical resistance between the two electrodes. Features.
In the present invention, the height of the liquid level is calculated from the electrical resistance between the two electrodes.
In the liquid level measurement system according to claim 7 of the present invention, the measurement unit applies an AC voltage between the two electrodes.
In the present invention, an alternating voltage is applied between the two electrodes in order to detect the height of the liquid level.

In the liquid level measurement system according to claim 8 of the present invention, the structure is a ship hull.
In the present invention, the liquid level measurement system is mounted on a ship (actual ship or model ship), and the height of the surrounding liquid level is measured.
In the liquid level measurement system according to claim 9 of the present invention, a plurality of measurement points at which the height of the liquid level is measured using the electrodes are arranged at a plurality of positions in the horizontal direction on the side surface of the hull. It is characterized by.
In the present invention, the liquid level at a plurality of measurement points is calculated. That is, the spatial distribution of the liquid level is measured.
The liquid level measurement system according to claim 10 of the present invention is characterized in that the measurement points are arranged substantially symmetrically on both right and left sides of the hull.
In the present invention, the measurement points are provided substantially symmetrically on both sides of the traveling direction.
In a liquid level measurement system according to an eleventh aspect of the present invention, the measurement points are arranged on the bow portion of the hull, the left and right sides of the stern portion, and the left and right sides of the middle of the bow portion and the stern portion, respectively. It is characterized by that.
In the present invention, measurement points are arranged at a total of five locations: one on the bow, two on the left and right sides of the stern, and two on the left and right sides of the center.
In the liquid level measurement system according to claim 12 of the present invention, the interval between the adjacent measurement points is shorter at the bow and / or stern than at the center of the hull.
In the present invention, the arrangement of the plurality of measurement points is not uniform and is densely arranged at the bow or stern.

In the liquid level measurement system according to claim 13 of the present invention, the one electrode is at least at the height of the water line in the ballast state of the hull and the height of the water line when the hull is fully loaded in the depth direction of the liquid. It is characterized by having a stretched configuration.
In the present invention, at least one of the electrodes is configured to cover a space between the height of the draft line in an empty state and the draft line when fully loaded.
A liquid level measurement system according to a fourteenth aspect of the present invention is characterized in that the detection result of the liquid level is processed to recognize waves.
In the present invention, waves on the liquid level are recognized by recognizing spatial and temporal fluctuations in the liquid level.
A liquid level measurement system according to a fifteenth aspect of the present invention is characterized by recognizing directional waves constituting a multidirectional wave by analyzing temporal changes of the waves.
In the present invention, the direction wave in the waves is further analyzed.
A ship according to claim 16 of the present invention is equipped with the liquid level measurement system.
In the present invention, a ship (an actual ship or a model ship) is equipped with the liquid level measurement system.

Since the liquid level measurement system of the present invention is configured as described above, the influence of the liquid level measurement system itself on the liquid level is reduced, and the height of the liquid level or its change with time can be reduced with a simple configuration. It can be measured. At this time, if the detection is performed using a bridge circuit or the electrical resistance between the electrodes is measured, this measurement can be performed with a precise and simple configuration.
Further, if only one electrode in the electrode pair is formed into a thin film and a structure (such as a hull) whose surface is made conductive is used as the other electrode, the number of electrodes to be used can be reduced.
Further, if the thin film electrode is made of a conductive paint, its formation is particularly easy, and the influence of the electrode itself on the liquid level (wave) to be measured can be minimized.
In addition, if the compensation element (compensation resistor or the like) is used in a bridge circuit, stable measurement can be performed even when the environment changes (liquid temperature change or the like). This compensation element can be easily formed.
Further, if the voltage applied between the two electrodes during measurement is an alternating current, the life of the electrodes can be extended. This is particularly effective when measuring the sea level or waves.

Moreover, since the height distribution of the liquid level can be measured by using a large number of measurement points arranged and being arranged substantially symmetrically with respect to the traveling direction, it is possible to accurately observe waves. Due to the nature of general wave hulls, it is possible to accurately measure ship side waves without using many measurement points (electrodes) if the measurement points are not evenly spaced but close at the bow or stern. it can.
Alternatively, when the measurement points are installed at the five locations, the attitude of the hull or the like (structure) can be detected with high accuracy while the number of electrodes is reduced.
Such an arrangement of measurement points can be easily realized in any case.
In addition, if at least one of the two electrodes constituting the electrode pair covers between the height of the draft line in an empty state and the draft line at the time of full load, attitude detection of the hull, etc. and detection of waves can be performed. It can be done sufficiently.
In addition, the above-described liquid level measurement system can accurately measure the temporal and spatial distribution of the liquid level, so that it is possible to recognize waves or analyze waves in a particularly precise manner. It is.
In addition, the liquid level measurement system can be easily mounted on an actual ship, a model ship, or another floating body. When mounted on an actual ship, the electrodes and the like used in this liquid level measurement system do not adversely affect the frictional resistance and the like when navigating the ship.

It is a figure which shows the structure of the ship side wave measuring system used as embodiment of this invention. It is a figure which shows the structure of the electrode pair and detection control circuit in the ship side wave measurement system used as embodiment of this invention. It is the top view (a) and sectional drawing (b) of the 1st example which use the ship body side as the other electrode of an electrode pair. It is a top view (a) and a sectional view (b) of the 2nd example using the hull side as the other electrode of an electrode pair. It is the top view (a) and sectional drawing (b) of the 3rd example which uses a ship body side as the other electrode of an electrode pair. It is a side view which shows an example of the arrangement configuration of the several electrode pair in the ship side wave measurement system used as embodiment of this invention. It is a top view which shows another example of the arrangement configuration of the several electrode pair in the ship side wave measurement system used as embodiment of this invention. It is the 1st example of composition using compensation resistance in a ship side wave measuring system used as an embodiment of the invention. It is the 2nd example of the composition using compensation resistance in the ship side wave measuring system used as an embodiment of the invention. It is a 3rd example of the structure using the compensation resistance in the ship side wave measuring system used as embodiment of this invention. It is a 4th example of composition using compensation resistance in a ship side wave measuring system used as an embodiment of the invention. It is the result of having actually measured the resistance value and water surface height between two electrodes in an Example. It is the result of having measured the ship side wave by attaching the ship side wave measurement system of an Example to a Wigley model. It is the result of having measured the change of the height of the water surface accompanying the movement of a hull at the time of attaching the ship side wave measurement system of an Example to a Wigley model. It is the result of having actually measured the attitude | position (heave, pitch) change of the hull at the time of generating a wave when attaching the ship side wave measurement system of an Example to a VALQUA ship model.

  Hereinafter, a liquid level measurement system as an embodiment for carrying out the present invention will be described. With this liquid level measurement system, the positional relationship (the height of the liquid level) between the liquid surface and the structure around the structure existing on the liquid surface can be measured. Moreover, the state of the wave (liquid surface wave) formed on the liquid surface can be measured by measuring the spatial and temporal changes in the height of the liquid surface. Hereinafter, a case will be described in which this liquid level measurement system is mounted on a ship or the like existing on the water surface and becomes a ship side wave measurement system that measures the state of waves (ship side waves) formed around the ship or the like. Here, the presence of a ship or the like (structure) on the water surface (liquid surface) means that a part of the ship exists so as to be submerged below the water surface (liquid surface).

This ship side wave measurement system is installed in a ship or the like, and can measure the positional relationship between this object and the water surface around it. Below, the case where the height of the water surface in side surfaces (ship side), such as a ship, is measured is demonstrated. A ship or the like includes a floating body, a buoy on the water, and the like, but a system that measures the height of the surrounding water surface is also referred to as a ship side wave measurement system. With this ship side wave measurement system, the height and shape of waves (ship side waves) at a place where a ship or the like is sailing or floating can be measured. Alternatively, the attitude of the hull or the like relative to the water surface can also be measured by this ship side wave measurement system.

  Here, this ship side wave measurement system shall be installed in the hull of a ship. The lower side of the hull is submerged in seawater, and the upper side appears on the sea. FIG. 1 conceptually shows a configuration viewed from the side of the hull 100. Further, as shown in the drawing, the sea surface 201 of the seawater 200 has a wavy shape around the waterline 202, that is, a ship side wave is generated. Further, the shape of the sea surface 201 (the shape of the ship side wave) changes with time.

  This ship side wave measurement system includes a plurality of electrode pairs and a measurement unit 20 connected thereto. As shown in FIG. 1, four pairs of thin film-like electrodes 11, 12 elongated in the vertical direction are provided on the side surface of the hull 100 as a pair (electrode pair). A voltage is applied to each electrode pair, and a change in characteristics between the electrodes 11 and 12 is detected by the measurement unit 20, whereby the height of the sea surface 201 at the location of each electrode pair is measured. The measurement unit 20 includes a detection control circuit 30 and a calculation circuit 40.

  The electrodes 11 and 12 are installed so that the length direction thereof is partially submerged, that is, the sea surface 201 enters the range of the length in the respective vertical direction (depth direction). A detection control circuit 30 is connected to the pair of electrodes 11 and 12 (electrode pair). Each detection control circuit 30 is connected to a calculation circuit 40 configured using, for example, a personal computer.

  The thin film electrodes 11 and 12 can be formed on the side surface of the hull 100 by, for example, applying a conductive paint in a strip shape on an insulating coating film. As the conductive paint in this case, a silver paste or various conductive paints can be used. The wiring connected to the electrodes 11 and 12 can be taken out from the upper part in FIG. 1 (the part that is always above the sea surface 201).

FIG. 2 is a diagram showing in detail the configuration of the pair of electrodes 11 and 12 and the detection control circuit 30 connected thereto. The resistance R between the electrodes 11 and 12 is _one of bridge circuits (Wheatstone bridge circuits) configured using fixed resistors 31 to 33 (respective resistance values are R ₁ , R ₂ , and R ₃ ). An AC power supply is connected between the nodes A and B, the voltage between the nodes C and D is amplified and detected by the amplifier circuit 35, and the output is output to the calculation circuit 40.

In general, it can be considered that the resistivity of air is infinite and the resistivity of water (seawater) is a finite value. In this case, the resistance R between the electrodes 11 and 12 is proportional to the distance D between the electrodes 11 and 12, and is inversely proportional to the length H that the electrodes 11 and 12 are submerged. Accordingly, if the interval D is constant, R changes according to the fluctuation of H. If the reference value of R is set to R ₀ , the voltage across the node AB becomes zero if R ₀ R ₁ = R ₂ R ₃ is set. Here, the resistance value when the sea surface 201 is equal to the water line 202 in FIG. 1 (when H = H ₀ ) can be used as the reference value R ₀ . For example, when the height of the sea surface 201 fluctuates and the length in which the electrodes 11 and 12 are submerged becomes H (H ₀ <H), R <R ₀ is satisfied, and the equilibrium condition of the Wheatstone bridge circuit is lost. A voltage is generated between the nodes CD. By detecting this voltage with the amplifier circuit 35, it is possible to calculate R, and the calculation circuit 40 can thereby calculate H corresponding to each electrode pair.

  That is, the length H in which each electrode pair is submerged can be calculated by the configuration of FIG. Since the position where the electrode pair is installed on the hull 100 is fixed, the positional relationship between the hull 100 and the sea surface 201 at the location where this electrode pair is installed can be recognized. In the configuration of FIG. 1, since four sets of the electrodes 11 and 12 are provided in the horizontal direction, the height of the sea surface 201 at four measurement points on the ship side can be calculated. Thereby, the shape of the sea surface 201 around the hull 100 (the space shape of the ship side wave) can be recognized. It is also possible to monitor this shape from moment to moment. Accordingly, it is possible to monitor the progress of the ship side wave in the direction in which the pair of electrodes 11 and 12 are arranged (in FIG. 1, the left-right direction: the traveling direction of the hull 100).

  Even when the liquid level sensors described in Patent Documents 2 and 3 are used, it is possible to detect a change in electrical resistance or capacitance according to the height of the sea level 201 in the same manner. However, as described above, in these configurations, it is necessary to arrange the three electrodes made of metal or the like so as to be partially immersed in water. For this reason, the ship side wave measured in this case is influenced by these liquid level sensors (electrodes) themselves. On the other hand, in the configuration of FIGS. 1 and 2, the thin-film electrodes 11 and 12 are made of a conductive paint, or the electrodes 11 and 12 have an influence on the ship side wave by being made of a conductive thin film. Can be minimized. Also, ship paint is generally formed on the ship side for rust prevention, antifouling and the like. In this case, the electrodes 11 and 12 are formed by applying a conductive paint, and by applying a normal insulating hull paint to a place other than the electrodes 11 and 12, a step due to the electrodes 11 and 12 is formed on the ship side. It is also possible to adopt a configuration that is not formed at all. In this case, the influence on the ship side wave can be particularly reduced. In addition, if a transparent conductive paint using a conductive polymer is used, by applying this on the hull paint, the structure is the same as that of a normal ship in which the electrodes 11 and 12 are not formed. It is also possible.

  Furthermore, in the example of FIGS. 1 and 2, an example using two electrodes (electrode pairs) was described in order to measure the water level at each location, but one of these electrodes was formed into a thin film as described above. By providing and using the surface of the hull as the other electrode, it is possible to use substantially only one electrode (one electrode). FIGS. 3 and 4 show two examples of the structure around the electrode in this case.

  FIG. 3A is a view of a first example using the entire hull 100 as one electrode as viewed from the side, and FIG. 3B is a cross-sectional view in the AA direction. Here, the hull 100 shall be comprised with the steel plate which is a conductor. A conductive paint layer 16 having a thickness of, for example, about 100 μm is formed outside the hull 100, and an insulating paint layer 17 having a thickness of, for example, about 300 μm is further formed thereon. An electrode 15 having a thickness of about 100 μm is formed at the end of the insulating paint layer 17. Since the electrode 15 can be formed of a conductive paint in the same manner as described above, the conductive paint layer 16, the insulating paint layer 17, and the electrode 15 can all be formed thin by painting. Also in this case, the resistance change corresponding to the current path (dotted line in FIG. 3B) below the sea surface 201 indicated by the broken line in FIG. 3A is the hull 100 (conductive paint layer 16). ) And the electrode 15. This can be used to detect the water level.

  FIG. 4A is a side view of the second example using the entire hull 100 as one electrode, and FIG. 4B is a cross-sectional view in the BB direction. As in the example of FIG. 3, a conductive paint layer 16 is formed on the outside of the hull 100, and an insulating paint layer 17 is formed thereon. An insulating paint layer opening 171 is formed in the insulating paint layer 17, and the conductive paint layer 16 is exposed therein. A thin-film electrode 18 is formed so as to cover and cover the insulating paint layer opening 171, and the electrode 18 is provided with a plurality of electrode openings 181. In this configuration, the conductive paint layer 16 and the insulating paint layer 17 can be easily formed by painting, as in the example of FIG. As the electrode 18, a metal foil in which the electrode opening 181 is formed can be attached and used, so that a step on the surface can be reduced. With this configuration, since the seawater 200 freely enters the insulating paint layer opening 171 covered with the electrode 18 through the electrode opening 181, the gap between the electrode 18 and the conductive paint layer 16 corresponding to the height of the sea surface 201 is obtained. Can be measured. As a result, the water level can be detected as described above.

  FIG. 5A is a side view of a third example using the entire hull 100 as one electrode, and FIG. 5B is a cross-sectional view in the CC direction. As in the example of FIG. 3, a conductive paint layer 16 is formed on the outside of the hull 100, and a common electrode 19 connected thereto is exposed. An insulating paint layer 17 is formed so as to cover the periphery of the common electrode 19, and an electrode 18 is formed on the surface of the insulating paint layer 17 as in FIG. 3. In the configuration of FIG. 5, the water levels at two locations between the common electrode 19 and the left and right electrodes 18 are measured. In this case, it is possible to adopt a configuration in which a step on the surface composed of the electrode 18, the common electrode 19, and the insulating paint layer 17 does not occur. The common electrode 19 can be composed of a metal foil, a metal piece, a conductive paint, or the like.

  As described above, only one electrode of the electrode pair is provided so as to be partially submerged, and the other electrode is commonly used by using the hull or the conductive paint layer 16 on the hull 100 surface. Thus, it is possible to observe the relative positional relationship between the hull 100 and the sea surface 201 and the waveform of the ship side wave. As long as the resistance value by the seawater 200 between two electrodes can be measured, it is also possible to combine said structure suitably or to use structures other than these.

  In the configuration of FIG. 1, a detection control circuit 30 is provided for each electrode pair. However, an input / output switch is used so that each electrode pair is on the input side and a single detection control circuit 30 is output. The electrode pair connected to the detection control circuit 30 can be switched by causing the calculation circuit 40 to perform the switching operation of the input / output switching device. In this case, the configuration can be further simplified.

  1 shows the configuration of the hull 100 as viewed from one side surface, the other side surface may have the same configuration. As a result, ship side waves can be monitored on both side surfaces of the hull 100, and the progress of waves in the direction perpendicular to the direction of travel of the hull 100 can also be monitored.

  In the configuration shown in FIG. 2, an AC power source is used as a driving power source. However, operation is possible even when a DC power source is used. However, particularly when this ship side wave measurement system is used in seawater, the electrodes 11 and 12 may corrode due to a chemical reaction between impurities (for example, salt) in the seawater and the electrodes 11 and 12. When a DC power source is used, this corrosion proceeds intensively only at one of the electrodes 11 and 12, whereas when an AC power source is used, the influence of this corrosion can be dispersed. . For this reason, the lifetime of the electrodes 11 and 12 can be extended by using an alternating current power supply.

  Further, even when the number of electrode pairs (or one electrode) is one, H can be calculated at the place (measurement point) where the electrode pair is installed. Can be recognized. However, it is more preferable to arrange (measurement points) at a plurality of locations in the horizontal direction and calculate H at each location in order to more accurately measure ship side waves. In addition, it is preferable to arrange them symmetrically on the left and right sides with respect to the traveling direction of the hull 100 because waves traveling from either side can be detected in the same manner.

  In FIG. 1, four pairs of electrode pairs (measurement points) are arranged at equal intervals in the horizontal direction. Actually, however, shortening the interval and increasing the number of the electrode pairs (measurement points) provide more precise ship side waves. This is preferable for measurement. However, this arrangement can be set according to the purpose and the waveform of the ship side wave. FIG. 6 is an example in which 16 pairs of electrodes 120 are provided on the side surface of the hull 110. The wavelength of the ship side wave formed when the hull 110 travels is generally longer at the center than at the tip and stern. For this reason, the space | interval of the arrangement | sequence of the electrode pair 120 is made shorter than the center part in a bow part and a stern part. Thereby, it is possible to accurately measure the waveform of the ship side wave while reducing the total number of electrode pairs 120. Further, as described above, it is preferable that the electrode pairs 120 are provided approximately symmetrically on both the left and right sides with respect to the traveling direction of the hull 110 because ship side waves can be detected equally on the left and right sides of the hull 110.

  On the other hand, when the object is only to detect the attitude of the hull without measuring the wave shape, a simple configuration with a reduced number of electrode pairs can be used. FIG. 7 is a top view showing the arrangement of the electrode pairs in this case. The traveling direction of the hull 140 is indicated by an arrow. In this case, an electrode pair 151 is provided at the bow, electrode pairs 152 and 153 are provided at the left and right sides of the hull center, and electrode pairs 154 and 155 are provided at the left and right sides of the stern. If H can be measured by the electrode pairs 151 to 155 at locations where these are installed, the hull 140 (heave hull up and down), roll (lateral inclination with respect to the traveling direction), pitch (also vertical inclination), etc. Can be measured. That is, this ship side wave measurement system can be used to measure the attitude of the hull 140 using five measurement points.

  Further, as described above, the electrodes 11 and 12 are set so that the longitudinal direction (depth direction) is partially submerged. As a guideline, when a ship equipped with this ship side wave measurement system carries cargo or humans (cargo, etc.), the height of the waterline in its ballast state (empty state) and the full load (of the specified weight) Within the range of the height of the draft line in the case where cargo or the like is loaded), the electrodes 11 and 12 can be configured to extend vertically. In this case, the height of the sea level in most cases can be detected in both cases of wave detection (ship side wave) and hull attitude detection. However, for example, when the hull itself is used as the other electrode of the electrode pair, only one electrode may be set as such.

  In general, the resistivity of water varies depending on the environment, such as the impurity concentration of water and the water temperature. For this reason, in the configuration of FIG. 2, the resistance R between the electrodes 11 and 12 may change not only due to H but also due to fluctuations in the resistivity of water, and the balance of the bridge circuit also changes accordingly. For this purpose, it is preferable to insert a compensation resistor (compensation element) that compensates for such a variation in conditions into the bridge circuit of FIG.

FIG. 8 is a diagram illustrating a circuit configuration in the first example using a compensation resistor and a specific configuration of the compensation resistor. In this circuit configuration, the fixed resistor 33 (resistance value R ₃ ) in FIG. 2 is replaced with a compensation resistor 51 (resistance value R _C1 ). As the compensation resistor 51, compensation electrodes 511 and 512 having the same configuration as the electrodes 11 and 12 provided in the seawater 200 are used. However, unlike the electrodes 11 and 12, the compensation electrodes 511 and 512 are installed in the lower part of the hull 100 so that the whole is always submerged. According to this configuration, when the resistivity of the seawater 200 changes, R _C1 and R change similarly. For this reason, it is possible to reduce the deviation of the equilibrium state (R ₁ R = R ₂ R _C1 ) in the bridge circuit when the change in resistivity occurs. The widths, lengths, and intervals of the compensation electrodes 511 and 512 can be set as appropriate so that the deviation in the equilibrium state is reduced.

FIG. 9 is a diagram illustrating a circuit configuration in a second example using a compensation resistor and a specific configuration of the compensation resistor. In this circuit configuration, the fixed resistors 31 to 33 are the same as in FIG. 2, and a compensation resistor 52 (resistance value R _C2 ) is provided in parallel with R, and a compensation resistor 53 (resistance value R _C3 ) is provided in series. The compensation resistors 52 and 53 are configured using compensation electrodes 521 and 522 and compensation electrodes 531 and 532, respectively, similarly to the compensation resistor 51 described above. The compensation electrodes 521 and 522 and the compensation electrodes 531 and 532 are always submerged. When the resistivity of the seawater 200 changes, R _C2 and R _C3 also change in the same manner as R. Therefore, by appropriately setting these values, the deviation in the equilibrium state of the bridge circuit is reduced as described above. It is possible. In particular, in the case of this configuration, the compensation electrodes 521 and 522 (R _C2 ) and the compensation electrodes 531 and 532 (R _C3 ) can be adjusted independently, so that the compensation for the deviation of the equilibrium state can be performed particularly precisely. Is possible.

Note that the compensation resistors 51, 52, and 53 may be appropriately combined. In the example of FIG. 8, the compensation resistor 51 (R _C1 ) is provided instead of the fixed resistor 33 (R ₃ ), but the compensation resistor 51 can be provided instead of the fixed resistor 32 (R ₂ ). That is, the compensation resistor can be used by being appropriately inserted into the bridge circuit.

  FIG. 10 is a diagram showing a configuration of the third example in which the configuration of the electrode and the compensation electrode is simplified. In this configuration, the electrodes and compensation electrodes used in the configuration of FIG. 8 are simplified to the minimum. Here, the fixed resistors 31 and 32 are not changed, the common electrode 61 connected to the node D is used, the electrode 62 is connected to the node B, and the compensation electrode 71 is connected to the node A. The common electrode 61 and the electrode 62 are partially submerged, and the electrode 62 functions in the same manner as the electrode 11 and the like. On the other hand, the common electrode 61 extends to a position deeper than the electrode 62, and a short compensation electrode 71 that is always submerged is present at a depth equivalent to the deepest portion. In this configuration, the space between the common electrode 61 and the electrode 62 corresponds to between the electrodes 11 and 12 in the configuration of FIG. 8, and the space between the common electrode 61 and the compensation electrode 71 corresponds to between the compensation electrodes 511 and 512 in the configuration of FIG. . For this reason, the number of electrodes and compensation electrodes to be used is reduced, and functions similar to those in FIG. 8 are realized.

  FIG. 11 also shows a fourth example in which the configuration of FIG. 8 is modified. 11A is a configuration diagram viewed from the side, FIG. 11B is a cross-sectional view in the DD direction, and FIG. 10C is a cross-sectional view in the EE direction. The connection and circuit configuration are the same as in FIG. In this configuration, the electrodes 11 and 12 are formed on the side wall of the hull 100 as in FIG. 8 (FIG. 1 and the like). On the other hand, the compensation electrodes 511 and 512 are provided in a compensation electrode case 80 provided in the hull 100. The inside of the compensation electrode case 80 is connected to the seawater 200 and is always filled with the seawater 200. For this reason, the influence of the temperature change of the seawater 200 etc. can be compensated similarly to FIG. At this time, the compensation electrodes 511 and 512 can be always submerged regardless of the attitude of the hull 100, and thus stable operation is possible. Particularly in this case, the compensation electrodes 511 and 512 do not need to be thin.

  As described above, similarly to the electrode pair, the configuration of the compensation electrode in the hull 100 is arbitrary as long as the influence of the temperature of the seawater 200 and the like can be detected by the compensation electrode. Two compensation electrodes are used in the same manner as the measurement electrode, but only one of them is always submerged, and the other is a common electrode used in common with the measurement electrode. Can do. As described above, a hull having a conductive surface can be used as the common electrode. Thereby, the number of used electrodes and compensation electrodes can also be reduced.

  The configuration of this ship side wave measurement system is simple and can be made lightweight, and the presence of this ship side wave measurement system does not affect the function or operation of the ship. For this reason, it is obvious that the hull 100 described above may be a hull in which humans actually board or a model hull. When used for a model hull, it can be used for various experiments related to the function of the ship.

(Example)
Below, the result of actually installing the ship side wave measurement system described above on a model ship and performing the measurement will be described.

First, it was confirmed that H can actually be calculated by the configuration of FIG. For this reason, the electrodes 11 and 12 were formed by apply | coating a silver paste to an insulating acrylic board by 2 cm width and 1 cm space | interval. Here, a silver paste having a resistivity of 1 to 10 × 10 ⁻⁵ Ω · cm was used. In this case, FIG. 12 shows the result of actually measuring the H dependence of the voltage between the CDs in FIG. It can be seen that the linearity is good and it is sufficiently possible to measure H by measuring the voltage across CD.

Next, the ship side wave measurement system is attached to a Wigley model with a ship length L _PP = 4.0 m, a width B = 0.4 m, a depth D = 0.375 m, and a draft d = 0.25 m. Ship side waves were measured. The electrode pairs were arranged at unequal intervals as shown in FIG. The measurement results of this example are shown in FIG. 13 together with the results obtained by analyzing the image from the side and the calculation results by the Rankine source method. From this result, it was confirmed that the result of the example is consistent with the result of the image analysis and the calculation result and is effective. In particular, in the embodiment, the waveform is correctly recognized even in a place where it is difficult to photograph the ship side wave. In addition, it is also confirmed that the wavelength of the waveform is shorter on the bow side (FP) and the stern side (AP) than the center part, and it can also be confirmed that the arrangement configuration of the electrode pair shown in FIG. 3 is effective. .

  Next, the time change of the wave height H when the hull was moved was measured. FIG. 14A shows the time change of the speed of the hull in this case, and FIGS. 14B and 14C show the time change of H at different positions. The horizontal axes (time) in FIGS. 14A, 14B, and 14C are displayed correspondingly. From this result, the change of the wave height H corresponding to the measured speed change was measured, and it was confirmed that highly accurate measurement without noise and drift was realized.

In addition, a model of a bulker ship type (cargo ship) (captain L _PP = 3.0 m, width B = 0.446 m, depth D = 0.2655 m, draft d = 0.1687 m, square coefficient Cb = 0.8398, The above-mentioned ship side wave measurement system was attached to the amount of discharged water V = 0.1895 m ³ ), and the heave (hull up and down) and pitch (same vertical inclination) of the hull were measured. At this time, the hull is fixed so that no roll is generated. The measurements were taken with the hull stationary and the waves on the water surface. FIG. 15 is a diagram showing the measurement results. FIG. 15A shows the result of measuring a change in water surface height due to the generated waves at one point with an electrostatic water level gauge. FIG. 15B is a heave (unit: mm) measured by the ship side wave measurement system 10 described above, and FIG. 15C is a pitch (unit deg). It was confirmed that both the heave and the pitch were measured in correspondence with the wave waveform (FIG. 15A). Although not measured here, it is clear that the roll (lateral inclination) can be similarly measured by providing electrode pairs on both the left and right sides.

  In this way, it was confirmed that waves and the attitude of the hull can be detected with high accuracy in the examples.

  In the ship side wave measurement system described above, the change in resistance between electrodes was measured using a bridge circuit, but other detection methods should be used as long as the change in resistance between electrodes due to fluctuations in the water level can be detected. You can also.

  Further, as described above, the hull may be in the above actual ship or in a model. In particular, when a model is used, the same measurement may be performed by floating the hull on another liquid instead of water. In this case, when the resistivity of the liquid is extremely high, instead of measuring the resistance between the electrodes, the capacitance between the electrodes can be measured. In this case, the configuration of the electrode pair can be measured in the same manner as described above, and the height of the liquid level can be measured in the same manner by measuring the capacitance between the electrodes with the measuring unit. In this case as well, a configuration is effective in which, for example, a Schering bridge circuit is used instead of the Wheatstone bridge circuit, and a voltage resulting from a deviation from the equilibrium condition of the circuit due to a change in capacitance is measured. Even in this case, similarly to the above-described compensation resistor, it is possible to configure a compensation element (compensation capacitor) using the capacitance between compensation electrodes that are always immersed in the liquid. This compensation capacitance can be inserted into the bridge circuit as appropriate to compensate for the change in capacitance in the electrode pair due to the change in liquid characteristics.

  Thus, in the ship side wave measurement system, it is possible to select and measure either a change in electric resistance or a change in capacitance according to the characteristics of the liquid. In any case, by using the electrode pair having the above-described configuration, it is possible to measure the height of the liquid surface by using the characteristic change between the two electrodes. In either case, the hull itself can be used as one of the two electrodes.

  Further, as described in the above-described embodiment, the wave waveform on the water surface can be accurately measured by the ship side wave measurement system. The calculation circuit and the personal computer connected to it use the time change of this waveform, or the movement information of the hull separately measured on this, and the presence of waves on the water and its traveling direction Etc. can be recognized.

  At this time, even when the waves are multidirectional waves, the analysis can be performed and the traveling waves constituting the multidirectional waves can be analyzed. Moreover, in a ship etc., the draft height of a ship etc. can also be known by measuring the height of a water surface.

  As described above, the ship side wave measurement system can measure the height of the water surface around a structure such as a ship on the water. As this structure, any floating body floating on the liquid can be used in addition to the ship. Obviously, it can be used to measure the height of a liquid surface around a structure that exists on the surface of any liquid, and can be used to measure the spatial and temporal distribution of that height. Obviously we can do it.

11, 12 electrodes (electrode pairs)
15, 18, 62 Electrode 16 Conductive paint layer 17 Insulating paint layer 19, 61 Common electrode 20 Measuring unit 30 Detection control circuit 31-33 Fixed resistance 35 Amplifying circuit 40 Calculation circuit 51-53 Compensation resistance 71, 511, 512, 521, 522, 531, 532 Compensation electrode 80 Compensation electrode case
100, 110, 140 Hull 120, 151-155 Electrode pair 171 Insulating coating layer opening 181 Electrode opening 200 Seawater 201 Sea surface 202 Water line

Claims (16)

A liquid level measurement system that measures the height of the liquid level relative to a structure that exists on the liquid level so that a part of the liquid level lies below the liquid level,
An electrode pair consisting of two electrodes, at least one of which is an electrode formed in a thin film shape so that a part of the electrode is submerged in the liquid below the liquid surface;
A liquid level measurement system comprising: a measurement unit that detects a height of the liquid level at a location where the electrode pair is formed from an electrical characteristic between the two electrodes.   The liquid level measurement system according to claim 1, wherein the structure having a conductive surface is used as the other electrode of the two electrodes.   3. The liquid level measurement system according to claim 1, wherein the one electrode is made of a conductive paint applied to a side surface of the structure.   The said measurement part detects the height of the said liquid level from the shift | offset | difference of the equilibrium conditions resulting from the change of the electrical property between the said 2 electrodes in a bridge circuit, The Claim 1 to Claim 3 characterized by the above-mentioned. The liquid level measurement system according to any one of the above. In the bridge circuit,
The liquid level measurement system according to claim 4, wherein a compensation element including a compensation electrode that is always submerged in the liquid is inserted.   The said measurement part detects the height of the liquid level between the said two electrodes by measuring the electrical resistance between the said two electrodes, The any one of Claim 1-5 characterized by the above-mentioned. The liquid level measurement system according to Item 1.   The liquid level measurement system according to claim 4, wherein the measurement unit applies an AC voltage between the two electrodes.   The liquid level measurement system according to claim 1, wherein the structure is a ship hull.   9. The liquid level measurement system according to claim 8, wherein a plurality of measurement points at which the height of the liquid level is measured using the electrodes are arranged at a plurality of positions in the horizontal direction on the side surface of the hull. .   The liquid level measurement system according to claim 9, wherein the measurement points are arranged substantially symmetrically on both right and left sides of the hull.   11. The liquid level according to claim 10, wherein the measurement points are arranged on a bow part of the hull, left and right sides of the stern part, and left and right sides of the middle of the bow part and the stern part, respectively. Measuring system.   The liquid level measurement system according to any one of claims 9 to 11, wherein an interval between the adjacent measurement points is shorter at a bow portion and / or a stern portion than at a center portion of the hull. .   9. The one electrode is configured to extend in the depth direction of the liquid at least at the height of the water line in the ballast state of the hull and at the height of the water line when the hull is fully loaded. The liquid level measurement system according to any one of claims 1 to 12.   The liquid level measurement system according to any one of claims 1 to 13, wherein the detection result of the liquid level is processed to recognize a wave.   The liquid level measurement system according to claim 14, wherein a directional wave constituting a multidirectional wave is recognized by analyzing a time change of the wave.   A ship equipped with the liquid level measurement system according to any one of claims 1 to 15.

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