JP2000131460A - Snowfall depth meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a snowfall depth meter which is provided with a sensor part forming a strong structure capable of maintaining the performance of an apparatus even in an inferior environment, in which the sensor part can be installed in places other than the vertical line of a measuring point, and which can measure a snowfall depth precisely irrespective of a weather condition or a snowfall state. SOLUTION: This snowfall depth meter is featured in such a way that it is provided with a laser module 6, which measures the phase difference between a laser beam irradiated toward a snowfall surface and a laser beam reflected diffusely by the snowfall surface so as to be received, and which outputs a distance signal up to the snowfall surface; that it is provided with a protective cover 5 which protects the laser module 6, that it is provided with a CPU 21 which controls the laser module 6, which is equipped with a noise removal means used to remove abnormal data on the distance signal to be output from the laser module 6, and which computes a snowfall depth on the basis of the distance signal; and that it is provided with an I/F circuit 4a which transfers a signal between the laser module 6 and the CPU 21 by a communication means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a snow depth gauge that measures the depth of snow by measuring the distance from a sensor installed at a known position to a snow surface, for example, in a heavy snowfall area. is there.

[0002]

2. Description of the Related Art Conventionally, as this type of snow depth gauge, one using an ultrasonic wave is known, for example, as disclosed in Japanese Patent Application Laid-Open No. 5-256944, and its structure is an ultrasonic transceiver installed at a known position. The ultrasonic wave transmitted from the ultrasonic wave is reflected on the snow-covered surface, and the propagation time until the echo wave returns to the ultrasonic transceiver is measured, and the snow-depth is calculated from the propagation time.

In addition, instead of using the ultrasonic waves, LE
There is also a method of measuring the snow depth by using light emitted from D (light emitting element) and measuring the propagation time.

However, in the method of measuring the propagation time of the ultrasonic wave to determine the snow depth, the ultrasonic wave does not reflect off the snow surface depending on the snow condition, and is several centimeters from the snow surface. There is a problem in that the light is reflected from a place where it dives to some extent, causing errors in measurement. This is particularly noticeable when fresh snow is piled up. The reason is that the ultrasonic wave hardly reflects from the soft fresh snow surface,
This is because most of the snow is reflected from the inside of the snow that has been hardened by the weight of the snow piled up by the snow.

[0004] Further, since the propagation speed of an ultrasonic wave changes due to a change in wind, temperature, or humidity, there is a problem that a measurement error occurs due to a change in weather conditions.

[0005] The method of using the light emitted from the LED and measuring the propagation time to determine the snow depth is as follows.
There is a problem that a measurement error occurs due to the influence of rain or fog. This is because most of the light emitted from the LED on the snow surface is blocked or scattered by rain or fog, and the reflected light returning to the light receiver becomes extremely small. Problem.

In order to avoid this problem, there is a method of condensing the light reflected on the snow-covered surface using a large lens, but this not only increases the cost of the lens but also reduces the size and weight of the entire apparatus. This increases the mounting position and increases the mounting cost. Furthermore, it is difficult to measure the light of the LED unless the reflectance of the reflecting surface is large. Therefore, there is no problem when the snow-covered surface is white, but when the snow-covered surface is discolored black due to mud or the like, the reflected light is so small that measurement may not be possible.

In addition, in the conventional snow depth gauge, in addition to the above-described problems, those which require the sensor section to be placed on the vertical line of the depth measurement point regardless of the measurement method are stacked on the sensor section. There is a problem that snow falls to the depth measurement point and disturbs the snow surface at the measurement point. Also,
Since a snow depth gauge is installed outdoors in a heavy snowfall area, it must have a strong structure that can maintain the performance of the device even in a poor environment where the temperature changes drastically and is exposed to wind and rain.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and includes a sensor unit having a strong structure capable of maintaining the performance of the apparatus even in a bad environment. It is an object of the present invention to provide a snow depth gauge that can be installed in a place other than on a vertical line and that can accurately measure the snow depth regardless of weather conditions and snow conditions.

[0009]

In order to achieve the above object, according to the first aspect of the present invention, a laser beam is irradiated from a laser beam irradiating unit to a depth measuring point on a snow surface.
A part of the laser light irregularly reflected at the depth measurement point is received by the laser light receiving means, and the phase difference between the laser light irradiated toward the depth measurement point and the laser light irregularly reflected and received at the depth measurement point is calculated. A laser module that measures and outputs a distance signal from the laser irradiation unit to the snow surface, and a protective cover that protects the laser module,
A CPU (central processing unit) for controlling the laser module and including noise removing means for removing abnormal data generated due to a sudden factor or the like from the distance signal output from the laser module; Processing device), the laser module and the CP
An I / F (interface) circuit for transmitting and receiving signals to and from the U by a communication means, a display for displaying the snow depth, and a power supply circuit for supplying power to each of the modules. is there.

Thus, the snow depth gauge can use, as a distance sensor, a laser module that measures a distance by using a phase difference between the irradiation light and the reflected light.
Since the laser beam is hardly affected by temperature, wind, fog, rain, etc., the use of the laser module makes it possible to accurately measure the distance irrespective of a change in weather. Further, the laser module is generally commercially available and is a very compact component. Therefore, it is possible to reduce the size of the sensor unit of the snow depth gauge. Further, by performing noise removal processing on the distance signal output from the laser module, it is possible to remove abnormal data generated due to a sudden factor.

According to a second aspect of the present invention, in the first aspect of the present invention, the protective cover includes an irradiation window through which the laser light passes, and is configured to shut off the outside air and seal the laser module. It is characterized by having been done.

This makes it possible to install the laser module even in a place with a bad environment.

According to a third aspect of the present invention, in the second aspect of the present invention, the protective cover includes a heater circuit for increasing an internal temperature.

This makes it possible to prevent dew condensation inside the protective cover and to keep the internal temperature of the protective cover within a temperature range in which the laser module operates optimally.

According to a fourth aspect of the present invention, in the second aspect of the present invention, the protective cover has a dry N2 inside.
It is characterized by being filled with gas.

This makes it possible to prevent dew condensation inside the protective cover.

According to a fifth aspect of the present invention, in the second aspect of the present invention, the protective cover is filled with dry air.

This makes it possible to prevent dew condensation inside the protective cover.

According to a sixth aspect of the present invention, in the second aspect of the present invention, the protective cover is filled with dry air.

This makes it possible to prevent dew condensation inside the protective cover.

According to a seventh aspect of the present invention, in the second aspect of the present invention, the irradiation window is provided with a fogging prevention film for preventing fogging of the window.

This makes it possible to prevent the irradiation window from fogging.

According to an eighth aspect of the present invention, in the second aspect of the present invention, the protective cover is provided with a cylindrical dust cover attached to the irradiation window.

This makes it possible to prevent snow, ice, dust, dust and the like from adhering to the irradiation window.

According to a ninth aspect of the present invention, in the first aspect of the present invention, the CPU, the display, and the power supply circuit are housed in the same housing as a control unit, and the laser module is protected. It forms a separation structure with the sensor unit closed by the cover, and is configured to be able to be installed at a remote place by transmitting and receiving signals to and from each other via the communication means. is there.

[0026] Thus, the sensor section and the control section can be installed at locations separated from each other.

In a tenth aspect of the present invention, in the ninth aspect of the present invention, the sensor unit is installed at a point shifted by an angle θ with respect to a vertical line of the depth measurement point, and It is characterized in that a laser beam is emitted from a diagonal direction to the depth measurement point.

Thus, the snow accumulated on the sensor unit does not fall to the depth measurement point and does not disturb the snow surface at the measurement point.

According to an eleventh aspect of the present invention, in the ninth aspect of the present invention, the power supply to the sensor unit comprises:
The power supply circuit is configured to be supplied from a power supply circuit inside the control unit.

This makes it possible to make the sensor section compact and simple.

According to a twelfth aspect of the present invention, in the first aspect of the present invention, the I / F circuit includes an RS422
It is characterized by using an I / F circuit conforming to the standard.

This makes it possible to perform long-distance communication using general-purpose components.

According to a thirteenth aspect of the present invention, in the first aspect of the invention, the noise elimination means sets upper and lower limits for a distance signal output from the laser module, and sets the upper and lower limits within this range. Data that does not match is configured to be discarded.

Thus, it is possible to remove abnormal data.

According to a fourteenth aspect of the present invention, in the first aspect of the invention, the noise elimination means stores a distance signal output from the laser module, and stores a distance signal between a previous distance signal and a current distance signal. If the deviation is larger than a predetermined value, the present distance signal is discarded.

Thus, abnormal data can be removed.

According to a fifteenth aspect of the present invention, in the first aspect, the noise elimination means stores the distance signal output from the laser module,
The distance signals are rearranged in the order of their magnitudes, and m data are extracted from the top and bottom of the distance signal at the center of the distance signals.
The average value is detected as a true value of the distance signal.

This makes it possible to remove abnormal data.

According to a sixteenth aspect of the present invention, in the first aspect of the invention, the laser light is a short wavelength laser light.

Thus, the laser light can be visually observed.

[0041]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration diagram of a snow depth gauge according to the present invention.

In FIG. 1, the laser module 6 irradiates a laser beam toward the snow surface SG, receives a part of the laser beam irregularly reflected on the snow surface, and receives the laser beam irradiated toward the snow surface. It measures the phase difference of the laser light that has been irregularly reflected and received on the snow surface SG, and outputs a distance signal to the snow surface.

The laser module 6 is hermetically closed by the protective cover 5 and is isolated from the outside air. The protective cover 5
Is filled with dry N2 gas. This may use dry air instead of N2 gas. Further, a desiccant 9 is sealed in order to remove moisture that has entered from the outside.

The protective cover 5 is provided with an irradiation window 2 for passing the laser light emitted from the laser module 6. An anti-fog film 1 is attached to the surface of the irradiation window 2.

The heater circuit 3 is provided inside the protective cover 5. For example, when the internal temperature of the protective cover 5 falls below 0 ° C., heating is started, and when it exceeds 5 ° C., heating is stopped. .

The sensor unit 10 of the snow depth gauge according to the present invention is constituted by the above-described devices.

The position signal output from the laser module is transmitted to the CPU via a cable 4c by an I / F circuit 4a and an I / F circuit 4b based on the RS422 standard.
21. The CPU 21 extracts a normal distance signal from the distance signal by a noise removing unit programmed therein, and calculates the snow depth.

Further, the CPU 21 displays the calculated snow depth on the display 22, and furthermore, the external I / F circuit 2.
3 to an external device.

The CPU 21, the display 22, the external I / F circuit 23, and the power supply circuit 24 described above constitute the control unit 20 of the snow depth gauge according to the present invention.

The power supply circuit 24 supplies power to the sensor unit 10 and the control unit 20. With such a configuration, the sensor unit 10 and the control unit 20 having a sealed structure can be installed at locations separated from each other.

Here, the operation of the snow depth gauge described above will be described in detail with reference to FIG.

In FIG. 2, the sensor unit 10 is installed at a point β which is shifted from the depth measuring point SG by an angle θ with respect to a vertical line α, and a laser is obliquely oblique to the depth measuring point SG from this point. It is configured to emit light. By installing the sensor unit 10 at a position shifted from directly above the depth measuring point SG in this manner, it is possible to prevent the snow accumulated on the sensor unit 10 from falling down on the depth measuring point SG and disturbing the snow surface. Can be.

The sensor unit 10 measures the distance L in accordance with a measurement command output from the control unit 20 installed in the observation hut 30, and transmits the distance signal to the control unit 20 via the communication cable 4c.

The control unit 20 detects the snow depth SL based on the distance signal transmitted from the sensor unit 10. This procedure will be described with reference to the flowchart shown in FIG.

In FIG. 3, when the measurer starts level measurement, the control unit 20 outputs a measurement start command to the sensor unit 10. The sensor unit thereby irradiates the laser beam to the depth measurement point SG on the snow surface, measures the distance L, and transmits a distance signal X (i) based on the distance L to the control unit 20. (ST1)

The control unit 20 compares the distance signal X (i) with a preset upper limit value Xmax, and
When (i) is larger than the upper limit value Xmax, the distance signal X (i) is discarded as an abnormal value. Similarly, the control unit 20 compares the distance signal X (i) with a preset lower limit value Xmin, and when the distance signal X (i) is smaller than the lower limit value Xmin, the control unit 20 compares the distance signal X (i). Is discarded as an abnormal value. Here, if the distance signal X (i) is discarded as an abnormal value, the process returns to ST1 to perform re-measurement. If the distance signal X (i) is not discarded as an abnormal value, the process proceeds to ST3. (ST2)

The control unit 20 calculates a deviation between the previous true value Xt and the current distance signal X (i) by a predetermined allowable deviation ΔD.
If the deviation between the previous true value Xt and the current distance signal X (i) is larger than the allowable deviation ΔD, the process returns to ST1 to perform re-measurement, and the previous true value Xt and the current distance signal X (i) are compared.
If the deviation of (i) is equal to or smaller than the allowable deviation ΔD, ST4
Move to. (ST3)

The control section 20 repeats the above-mentioned operations from ST1 to ST3, for example, 30 times, and obtains 30 distance signals X
(1) to X (30) are accumulated. (ST4)

The control unit 20 controls the 30 distance signals X
(1) to X (30) are rearranged in descending order. (ST
5)

The control unit 20 discards, for example, data from the maximum value data to the tenth largest value in the data sequence rearranged in ST5, and similarly discards the data from the minimum value data to the tenth largest value. Discard the data up to. The average value of the remaining 10 data is obtained, and this is set as the true distance signal value Xt. (ST6)

The control unit 20 uses the installation height h of the sensor unit 10 which is a known value and the true value of the distance signal Xt,
The snow depth SL is obtained by the following equation. (ST7) SL = h−Xt × cos θ (1)

The control unit 20 determines the snow depth S obtained in ST6.
L is displayed on the display 22. In addition, external I /
The F circuit 23 outputs a snow depth signal to an external device. (ST8)

The control section 20 continues the above-described operations from ST1 to ST8 until a measurement end notification is made by the operator (ST9).

The foregoing description merely illustrates certain preferred embodiments for purposes of explanation and illustration of the invention. Therefore, the present invention is not limited to the above-described embodiment, and includes many more modifications without departing from the spirit thereof.
This includes deformation.

[0065]

As is apparent from the above description,
According to the present invention, the following effects can be obtained. According to the first, second, and thirteenth to fifteenth aspects of the invention, in the snow depth meter, the laser light is irradiated from the laser light irradiation means toward the depth measuring point on the snow surface, and one of the laser lights irregularly reflected at the depth measuring point is measured. Part is received by the laser light receiving means, the phase difference between the laser light irradiated toward the depth measurement point and the laser light irregularly reflected and received at the depth measurement point is measured, and A laser module that outputs a distance signal up to, a radiation cover through which the laser light passes, a protective cover configured to shut off outside air and hermetically seal the laser module, and control the laser module and the laser. The distance signal output from the module is provided with noise removing means for removing abnormal data generated due to a sudden factor or the like from the distance signal. A CPU for calculating the snow depth, by having the I / F circuit for performing the communication means transmits and receives signals to and from the laser module and the CPU, the conventional ultrasound and LED
Compared to a snow depth gauge that measures the snow depth using the light of the sun, the laser light is used for the measurement, so the snow depth is measured with little effect from weather changes such as temperature, wind, fog, rain, etc. Became possible. In addition, since the laser module having a compact structure was used, the laser module could be shielded from the outside air and protected by a small and strong protective cover having a closed structure. Therefore, it is possible to install the sensor unit even in an inferior place, and to provide a sensor unit with a low installation cost. Furthermore, by providing a noise elimination means for selecting a distance signal output from the laser module and extracting normal distance data as a true value of the distance signal, it is generated when an animal crosses the depth measurement point or the like. It is now possible to completely remove abnormal data.

According to a third aspect of the present invention, in the second aspect of the present invention, the protective cover is capable of preventing dew condensation occurring inside, and the inside of the protective cover is provided with the laser module. It is possible to maintain an environment that operates optimally.

According to a seventh aspect of the present invention, in the second aspect of the present invention, the irradiation window is caused by a sudden change in air temperature or the like due to the application of an anti-fogging film for preventing fogging of the window. Clouding of the irradiation window can be prevented.

According to an eighth aspect of the present invention, in the second aspect of the present invention, the snow depth gauge can be easily diverted as it is as a powder level meter.

According to the ninth aspect of the present invention, in the first aspect of the present invention, it is possible to install the sensor section and the control section at locations separated from each other.

According to a tenth aspect of the present invention, in the ninth aspect of the present invention, the sensor unit is installed at a point shifted by an angle θ with respect to a vertical line of the depth measurement point, and Since the laser beam is emitted from the oblique direction to the depth measurement point, it is possible to prevent the depth measurement point from being disturbed due to, for example, falling snow on the sensor unit.

According to the eleventh aspect of the present invention, in the ninth aspect of the present invention, the power supply to the sensor unit comprises:
By being configured to be supplied from the power supply circuit inside the control unit, the sensor unit can have a simple structure.

According to a twelfth aspect of the present invention, in the first aspect of the present invention, the I / F circuit includes an RS422
By using an I / F circuit conforming to the standard, it is possible to perform long-distance communication using general-purpose components.

According to a sixteenth aspect of the present invention, in the first aspect of the present invention, the laser light can be visually observed by using a short wavelength laser light. Therefore, not only can the position of the depth measurement point be easily adjusted, but also anyone near the snow depth gauge can easily recognize that the snow depth measurement is being performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of a snow depth gauge according to the present invention.

FIG. 2 is a diagram illustrating the operation of the present invention.

FIG. 3 is an operation explanatory diagram of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fogging prevention film 2 Irradiation window 3 Heater circuit 4a, 4b I / F circuit 4c Cable 5 Protective cover 6 Laser module 8 N2 gas 9 Desiccant 10 Sensor part 20 Control part 21 CPU 22 Display 23 External I / F circuit 24 Power supply

Continuation of the front page (72) Inventor Nokazu Hashimoto 500 Soya, Hadano-shi, Kanagawa F-term (reference) 2F014 FA01 GA01 GA04 2F065 AA06 AA25 BB01 CC00 DD16 FF13 GG04 HH04 HH12 PP01 PP22 QQ23 QQ25 QQ34 QQ41 QQ42 SS03 SS11 2F112 AD10 BA07 CA12 DA21 DA25 DA40 FA03 FA33 FA41 FA45 FA50 5J084 AA06 AB16 AD01 BA02 BA03 BA32 CA03 CA31 DA01 EA01

Claims (16)

[Claims] 1. A laser beam is irradiated from a laser beam irradiating unit toward a depth measuring point on a snow surface, and a part of the laser beam irregularly reflected at the depth measuring point is received by a laser beam receiving unit. A laser module that measures a phase difference between a laser beam irradiated toward the laser beam and a laser beam irregularly reflected at the depth measurement point and outputs a distance signal to the depth measurement point; and protection for protecting the laser module. A CPU that controls the laser module and includes a noise removing unit that removes abnormal data generated due to a sudden factor or the like from a distance signal output from the laser module and calculates a snow depth from the distance signal; An I / F circuit for transmitting and receiving signals between the laser module and the CPU by communication means; and a table for displaying the snow depth. And vessels, snow depth gauge, characterized in that a power supply circuit for supplying power to the respective modules. 2. The snow depth gauge according to claim 1, wherein the protective cover includes an irradiation window through which the laser beam passes, and is configured to shut off the outside air and seal the laser module. . 3. The snow depth gauge according to claim 2, wherein said protective cover includes a heater circuit for raising an internal temperature. 4. The snow depth gauge according to claim 2, wherein said protective cover is filled with dry N2 gas. 5. The snow depth gauge according to claim 2, wherein said protective cover is filled with dry air. 6. The snow depth meter according to claim 2, wherein a desiccant is enclosed in the protective cover. 7. The snow depth gauge according to claim 2, wherein the irradiation window is provided with an anti-fogging film for preventing fogging of the window. 8. The snow depth gauge according to claim 2, wherein said protection cover is provided with a cylindrical dust cover on said irradiation window. 9. The communication means, wherein the CPU, the display, and the power supply circuit are housed in the same housing as a control unit, and form a separation structure from a sensor unit in which the laser module is sealed by the protective cover. The snow depth gauge according to claim 1, characterized in that it is configured to be able to be installed at a distant place by transmitting and receiving signals to and from each other. 10. The sensor unit is installed at a point shifted by an angle θ with respect to a vertical line of the depth measurement point, and irradiates the depth measurement point with a laser beam obliquely from this point. 10. A structure according to claim 9, wherein
Snow depth gauge described in. 11. The snow depth gauge according to claim 9, wherein the power supply to the sensor unit is configured to be supplied from a power supply circuit inside the control unit. 12. The snow depth gauge according to claim 1, wherein said I / F circuit is configured using an I / F circuit conforming to the RS422 standard. 13. The apparatus according to claim 13, wherein said noise removing means sets upper and lower limits for the distance signal output from said laser module, and discards data that does not match said range. The snow depth gauge according to claim 1. 14. The noise removing means stores a distance signal output from the laser module, and if a deviation between a previous distance signal and a current distance signal is larger than a predetermined value, the current distance signal is discarded. The snow depth gauge according to claim 1, wherein the snow depth gauge is configured as follows. 15. The noise elimination means stores a distance signal output from the laser module, rearranges the past n distance signals in the order of their magnitudes, and increases and decreases the distance signal at the center thereof. 2. The snow depth gauge according to claim 1, wherein m data are extracted from the data, and an average value thereof is detected as a true value of the distance signal. 16. The snow depth meter according to claim 1, wherein a short wavelength laser beam is used as said laser beam.