JP2006258579A - Light wave type water level measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To acquire accurate water level measurement values even under conditions of low measurement accuracy. <P>SOLUTION: This light wave type water level measuring apparatus 1 is constituted of a laser transmission device 11 for transmitting a pulsed infrared laser beam LB toward a water surface; a laser reception device 13 for receiving reflected light LB acquired by the reflection of the infrared laser beam LB at the water surface; a distance/reflected light quantity measuring part 15 for measuring the transmission time of transmitted and received light between the transmission of the infrared laser beam LB from the laser transmission device 11 and its reflection at the water surface and its reception at the laser reception device 13 and measuring both the distance L between the laser transmission device 11 and the water surface on the basis of the transmission time of transmitted and received light and the quantity of reflected light; a reflected light quantity determination device 33 for determining valid measurement when the quantity of reflected light received at the laser reception device 13 is of a set value or more; and a water level arithmetic unit 31 for computing a water level H<SB>1</SB>on the basis of the distance L computed at the distance/reflected light quantity measuring part 15. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a light wave type water level measuring apparatus, and more particularly to a light wave type water level measuring apparatus that measures the water level of rivers, lakes, ponds, reservoirs, water conduits and the like using an infrared laser.

Conventionally, as a water level measurement device, when measuring the water level of a pond or a river using laser light, the surface of the water to be measured is irradiated with the laser light, and the reflected wave of the laser light reflected by the water surface is received. The distance to the water surface is calculated from the time difference (required propagation time) between the irradiation time of the laser beam and the reception time of the reflected wave corresponding to the laser beam, and the water level is measured (for example, Patent Document 1 and Patent) Reference 2).
JP 2002-107204 A JP-A-9-126860

  By the way, in the conventional water level measuring device, it is difficult to measure the water level with high accuracy depending on the environmental condition when measuring the water level. For example, if the water level changes from moment to moment, large waves occur due to muddy flow or bad weather, or fog is generated and visibility is not good, even if the amount of unstable laser light reception is based on that data The distance to the water surface is measured, and the water level is calculated based on the measured distance. Therefore, there is a problem that even a measurement value under a condition with low measurement accuracy is determined as a correct measurement value as it is.

  The present invention has been made to solve the above-described problems.

The light wave type water level measuring device according to the present invention includes a laser light transmitting device that transmits a pulsed infrared laser toward the water surface, a laser light receiving device that receives reflected light reflected by the water surface, and the infrared light. Measures the transmission / reception transmission time from when the laser is transmitted from the laser transmission device until it is reflected by the water surface and received by the laser light reception device, and from the laser transmission device or laser reception device to the water surface by the transmission / reception transmission time. The distance / reflected light amount measurement unit that calculates the distance and the reflected light amount measurement unit, and the reflected light amount determination that determines that the reflected light amount measured by the distance / reflected light amount measurement unit is equal to or greater than the set value. A water level calculation device that calculates a water level based on the distance calculated by the device and the distance / reflected light amount measurement unit,
It is characterized by comprising.

  The light wave type water level measuring apparatus according to the present invention comprises the light wave type water level measuring apparatus, wherein the reflected light amount judging device has an abnormal value judgment removing function for validating at least one of the obtained raw data. Preferably it is.

  The light wave type water level measurement device according to the present invention is the light wave type water level measurement device, wherein the abnormal value determination and removal function is raw data of distance, raw data of reflected light amount and elapsed time calculated by the distance / reflected light amount measurement unit. It is preferable to remove the abnormal value by determining whether or not it is an abnormal value.

  In the light wave type water level measurement device according to the present invention, in the light wave type water level measurement device, the reflected light amount determination device uses only a reflected light amount equal to or larger than a set value as effective data for smoothing processing, and the effective data is equal to or longer than a predetermined time. If it does not exist, it is preferable to determine that the measurement is impossible.

  The light wave type water level measurement device of the present invention is characterized in that, in the light wave type water level measurement device, a laser marker for confirming a perpendicularity of an infrared laser irradiated substantially perpendicular to the water surface is provided between the laser light transmitting device and the laser light receiving device. It is preferable to provide.

  The light wave type water level measuring device according to the present invention is the light wave type water level measuring device, wherein the laser light transmitting device and the laser light receiving device are arranged obliquely from the water surface, and an infrared laser transmitted from the laser light transmitting device is provided. It is preferable that a float provided with a reflecting plate that reflects toward the laser light receiving device is disposed on the water surface.

  The light wave type water level measurement device according to the present invention is characterized in that, in the light wave type water level measurement device, a reference reflector is provided on the side of the laser light transmission device between the laser light transmission device and the water surface and received by the laser light reception device. It is preferable to include a light amount processing device that performs analogy of the water surface state such as the degree of fog in the space above the water surface and the undulation of the water surface based on the difference in reflected light amount between the reflected light of the reference reflector and the reflected light of the water surface. .

  As will be understood from the means for solving the problems as described above, according to the present invention, since the infrared laser is used for measuring the water level, it is not affected by the temperature or wind, and the snowstorm Highly accurate and stable water level measurement can be performed even under adverse conditions such as. In addition, the reflected light quantity judgment device can confirm that the reflected light quantity when the water level is measured is an effective measurement, so that accurate water level measurements with little measurement error can be obtained even under adverse conditions such as snowstorms. Can do.

  Embodiments of the present invention will be described below with reference to the drawings.

  Referring to FIGS. 1 (A) and 1 (B), the light wave type water level measuring apparatus 1 according to this embodiment includes a measuring unit 3 as a light wave type water level meter, for example, a shore such as a lake shore, a pond, a river, As shown in FIG. 1 (B), the column 7 is erected on the bridge 5 and is directed to the water surface of the river below through the column mounting bracket 9 (for example, substantially perpendicular to the water surface). It is supported. The measurement unit 3 includes a laser beam transmitter 11 that transmits a pulsed infrared semiconductor laser (hereinafter simply referred to as “laser beam LB”) toward the water surface of the river, and the laser beam LB is reflected by the water surface. And a laser receiving device 13 for receiving the reflected light LB. Further, in the measurement unit 3, the laser beam LB transmitted from the laser beam transmitter 11 is reflected on the water surface as shown in FIG. Raw data of the time difference between LB light transmission and light reception is obtained by the distance / reflected light amount measurement unit 15 provided in the measurement unit 3. The raw data of the distance calculated by the distance / reflected light quantity measuring unit 15 and the raw data of the reflected light quantity measured by the distance / reflected light quantity measuring unit 15 based on the raw data of the time difference are converted from time to time by the control device 17 (conversion Input device 19. The input data is stored, calculated and displayed in the memory 21 as a storage device, the calculation unit 23 having various calculation devices, and the display device 25 and is output through the output unit 27.

  More specifically, as shown in the block configuration diagram of FIG. 2, the control device 17 is provided with a CPU 29 as a central processing unit. The CPU 29 is used to input various data such as a keyboard. The device 19 is connected to a display device 25 such as an LCD that outputs various data.

The CPU 29 is connected to a memory 21 for storing a height H ₀ from the measuring unit 3 to the river bed, which is input in advance from the input device 19. A calculation unit 23 including a water level calculation device 31 that calculates the water level H ₁ based on the distance L calculated by the distance / reflection light amount measurement unit 15 is connected.

  More specifically, the principle of water level measurement by the pulse method will be described with reference to FIG. 3. For example, an 870 nm semiconductor laser element provided in the laser transmitter 11 of the measuring unit 3 is a laser with a very short pulse of about 4 nS. The light LB is emitted at about 1 kHz and is transmitted toward the water surface as a measurement target. The reflected light of the laser light LB reflected by the water surface returns to the laser light receiving device 13 efficiently. The reciprocating flight time t to the water surface is measured by the time difference from the rising edge of the clock until the signal enters. If the speed of the laser beam LB is c, the distance L is calculated (measured) by the equation (1).

L = t × c / 2 (1)
For example, in order to obtain a resolution of 1 mm in a distance range of 15 m, a resolution of 6.7 pS is required over a range of 100.5 nS. However, since the required resolution is very small, sufficient time resolution cannot be obtained by time measurement using only the clock. However, in this embodiment, as shown in FIG. 3, by measuring and complementing a 125 MHz high-speed clock and a time difference from the rising edge of the clock until the signal enters using an analog means, Long distance range and high time resolution are compatible.

  Furthermore, since signal processing is digitized, it contributes to miniaturization. Factors that degrade distance accuracy include ambient light, differences in the reflectance of the water surface as a measurement object, temperature changes, etc. Various countermeasure circuits are incorporated for these error factors. The generation of errors is minimized.

  For example, the temperature characteristics of the delay time of an electronic circuit are not stable enough to protect over a wide temperature range in pS units, thus requiring optical self-calibration means. In a general optical distance measuring device, the laser optical path is switched by using an optical shutter. However, such a mechanical movable part causes a failure and the mechanical life of the operating part of the optical shutter is also short. Continuous operation for tens of thousands of hours is difficult and cost increases. However, in this embodiment, self-calibration is performed at high speed by detecting the reflected light of the laser diode provided for self-calibration in the measuring unit 3 as timing. That is, since the responsiveness of the preamplifier and the digital circuit changes from time to time, self-calibration is performed every 100 mS measurement, and the change in the delay time of the electronic circuit unit is cancelled.

In the water level calculation device 31 described above, the water level H _{1 of} the river is calculated based on the distance L calculated by the distance / reflected light amount measurement unit 15 provided in the measurement unit 3. That is, the water level H ₁ is the difference between the height H ₀ from the measuring unit 3 to the river bed input to the memory 21 in advance and the distance L calculated by the distance / reflected light amount measuring unit 15 (H ₁ = H ₀ −L ).

  Referring again to FIG. 2, the CPU 29 performs effective measurement when the amount of reflected light received by the laser light receiving device 13 is equal to or larger than the reference set value S of the effective amount of reflected light previously input from the input device 19. A reflected light amount determination device 33 that compares and determines the presence of the reflected light amount is connected to a setting function unit 35 that holds the reference set value S of the reflected light amount and other set values.

More specifically, since the environmental state at the time of measuring the water level H1 changes _every moment, the amount of reflected light at the time of measuring the water level changes as time passes, as shown in FIG. In addition, as shown in FIG. 5, the average value in the normal histogram of the measured values of a plurality of reflected light amounts is plotted in the water level measurement data at each time in the graph of FIG.

  The reference set value S of the effective reflected light amount is preset as shown in FIG. 4, and the water level is measured with effective measurement accuracy only when the reflected light amount at the time of measuring the water level is equal to or greater than the reference set value S. It is judged that the environmental state is for obtaining a value.

  The reflected light amount determination device 33 preferably has an abnormal value determination removal function. That is, the abnormal value determination / removal function is a function that determines that it is valid if at least one of the obtained raw data is normal. For example, in part A of FIG. 4, the average value of the amount of reflected light at the time of water level measurement is lower than the reference set value S. In this case, even one of the raw data obtained in the histogram of FIG. Any value above is valid. That is, it is not determined that the water level measurement at the time of part A in FIG.

  However, as shown in part B of FIG. 4, when there is no valid data for a predetermined time (reference setting time) or longer, the reflected light amount determination device 33 determines that this is an unmeasurable state. It is desirable that a function for displaying this determination on the display device 25 and outputting that measurement is impossible is provided.

  It should be noted that only the water level measurement data when the amount of reflected light is equal to or greater than the reference set value S is used for smoothing processing as effective data.

  In addition, as the above-described abnormal value determination / removal function, the raw data of the distance L calculated by the distance / reflected light amount measurement unit 15, the raw data of the reflected light amount, and the elapsed time are used to determine whether or not the abnormal value is detected. When it is determined that the value is an abnormal value, the function is to remove the abnormal value. This makes it possible to perform even more accurate water level measurement.

  With the above configuration, since the laser beam LB is used for water level measurement, highly accurate and stable water level measurement can be performed without being affected by the temperature or wind. Furthermore, since the reflected light amount determination device 33 can confirm that the reflected light amount is an effective measurement, an accurate water level measurement value with little measurement error can be obtained even under adverse conditions such as fog or snowstorm. Obtainable.

  The reflected light amount determination device 33 according to the above-described embodiment determines fog as the raw data of the distance L calculated by the distance / reflected light amount measurement unit 15 and the fluctuation state of the raw data of the reflected light amount, and sets the measurement limit. It has a fog processing function to perform fog processing so as to increase.

  Referring again to FIG. 1, as another embodiment, the vertical direction of the laser beam LB irradiated between the laser light transmitting device 11 and the laser light receiving device 13 of the measuring unit 3 substantially perpendicularly to the water surface. A laser marker 37 for checking the degree is provided. The reason is that since the laser beam LB cannot be seen, it cannot be confirmed whether or not the laser beam LB actually transmitted is vertical.

  Referring to FIG. 6, as another embodiment, when the measuring unit 3 including the laser light transmitting device 11 and the laser light receiving device 13 is provided on the shore of a river or a lake, it is arranged obliquely from the water surface. Will be. In this case, the water level measurement is performed by arranging the float 41 including the reflection plate 39 that reflects the laser beam LB transmitted from the laser beam transmitter 11 toward the laser beam receiver 13 at the measurement position on the water surface. Is feasible.

The reflection plate 39 has a surface that is irregular so as to diffusely reflect the light. The laser beam LB transmitted from the laser beam transmitter 11 is irregularly reflected by the irregular surface, and one of the irregularly reflected light beams. One is received by the laser receiving device 13. In this case, when the inclination angle of the laser beam LB with respect to the water surface is θ as shown in FIG. 6, the distance / reflected light amount measurement unit 15 measures the distance L ₀ between the measurement unit 3 and the float 41. Therefore, the vertical distance L ₁ (corresponding to the distance L in FIG. 1) from the measurement unit 3 to the water surface is calculated by the formula L ₁ = L 0 _COS θ, and the water level calculation is performed based on the calculated data of the distance L _1. The water level H ₁ is calculated by the device 31.

  In order to stabilize the position of the float 41, for example, as shown by a two-dot chain line in FIG. 6, a wave breaker 43 is provided around the float 41, or the float 41 and the reflector 39 are It is desirable to devise various measures such as increasing the size of itself.

  Referring to FIG. 1 again, as another embodiment, it is desirable that the reference reflecting plate 45 be installed on the laser light transmitting device 11 side between the laser light transmitting device 11 and the water surface. Thereby, a part of the laser beam LB transmitted from the laser beam transmitter 11 is reflected by the reference reflector 45 and the remaining laser beam LB is reflected by the water surface. Therefore, both the reflected light LB of the reference reflector 45 and the reflected light LB of the water surface are received by the laser light receiving device 13. For example, when the field of view is not good, there is a difference between the reflected light amount of the reference reflector 45 and the reflected light amount of the water surface. Since the difference in the amount of reflected light changes depending on the degree of field of view, it is possible to infer the water surface condition such as the degree of fog in the space above the water surface and the ripples on the water surface by the difference in the amount of reflected light. Thereby, in this embodiment, a water level measurement and a water surface state measurement can be performed simultaneously.

  In this case, as shown in FIG. 2, the CPU 29 of the control device 17 estimates the water surface state based on the difference in the amount of reflected light between the reflected light LB of the reference reflector 45 and the reflected light LB of the water surface. A light amount processing device 47 is connected to this.

(A) is a front view of the light wave type water level measuring device of an embodiment of this invention, and (B) is a partial side view of (A). It is a block block diagram of a control apparatus. It is a schematic explanatory drawing which shows the water level measurement principle by a pulse system. It is a time-varying reflected light amount diagram showing the reflected light amount at the time of each water level measurement over time. It is a normal histogram figure of the measured value of several reflected light quantity. It is a schematic explanatory drawing of the light wave type water level measuring device of other embodiments of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light wave type water level measuring device 3 Measuring part 11 Laser light transmitting device 13 Laser light receiving device 15 Distance / reflected light amount measuring unit 17 Control device 19 Input device 21 Memory 23 Calculation unit 25 Display device 29 CPU
31 Water level calculation device 33 Reflected light amount judging device 35 Setting function unit 37 Laser marker 39 Reflecting plate 41 Float 43 Wave breaker tube 45 Reference reflecting plate 47 Light amount processing device

Claims (7)

A laser beam transmitter that transmits a pulsed infrared laser toward the water surface, a laser beam receiver that receives reflected light reflected by the water surface of the infrared laser, and the infrared laser beam transmitted from the laser beam transmitter. Measures the light transmission / reception transmission time from when the light is reflected on the water surface until it is received by the laser light receiving device, calculates the distance from the laser light transmission device or the laser light receiving device to the water surface, and measures the amount of reflected light. A distance / reflected light amount measurement unit, a reflected light amount determination device for determining that the reflected light amount measured by the distance / reflected light amount measurement unit is greater than or equal to a set value, and the distance / reflected light amount measurement unit A water level arithmetic unit that calculates the water level based on the distance calculated in
A light wave type water level measuring device comprising:   2. The light wave type water level measuring device according to claim 1, wherein the reflected light amount judging device has an abnormal value judgment removing function for validating at least one normal data among the obtained raw data.   The abnormal value determination / removal function uses the raw data of the distance calculated by the distance / reflected light amount measurement unit, the raw data of the reflected light amount, and the elapsed time to determine whether or not there is an abnormal value and removes the abnormal value. The light wave type water level measuring device according to claim 2, wherein:   The reflected light amount determination device uses only reflected light amount equal to or larger than a set value as effective data for smoothing processing, and determines that the measurement is impossible when the effective data does not exist for a predetermined time or more. The light wave type water level measuring device according to 1, 2 or 3.   The laser marker for confirming the perpendicularity of the infrared laser irradiated substantially perpendicular to the water surface is provided between the laser light transmitting device and the laser light receiving device. The light wave type water level measuring device described in 1.   The laser light transmitter and the laser light receiver are disposed obliquely from the water surface, and a float including a reflector that reflects the infrared laser transmitted from the laser light transmitter toward the laser light receiver is disposed on the water surface. It arrange | positions, The light wave type water level measuring apparatus as described in any one of Claims 1-5 characterized by the above-mentioned. A reference reflector is installed on the laser transmitter side between the laser transmitter and the water surface, and the reflected light amount difference between the reflected light of the reference reflector received by the laser receiver and the reflected light of the water surface is reduced. The light wave type according to any one of claims 1 to 6, further comprising a light amount processing device for performing analogy of a water surface state such as a degree of fog in the space above the water surface and a wave surface of the water surface. Water level measuring device.

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