JP6911802B2 - Snow accretion detection method of laser radar device and snow accretion detection device - Google Patents

Description

The present invention relates to a method for detecting snow accretion of a laser radar device and a snow accretion detection device for detecting snow accretion on a window of the laser radar device.

The laser radar device irradiates the laser light and receives the reflected light reflected by the object at each predetermined scanning angle, and detects the object at each scanning angle and receives the reflected light based on the time until the reflected light is received. We are measuring the distance. Such a laser radar device is provided with a window portion for transmitting laser light.

At this time, when snow adheres to the window portion, that is, when snow accretion occurs on the window portion, the reflection at the window portion increases, while the intensity of the laser beam radiated into the measurement area decreases, or the laser beam or reflected light decreases. Is blocked by snow adhering to the window, which reduces the accuracy of object detection and distance measurement. Therefore, for example, in Patent Document 1, dirt on the window portion is detected by providing a dedicated sensor or the like.

JP-A-2002-6039

However, with the conventional laser radar device, although it is possible to detect that an object is attached to the position of the window as in Patent Document 1 described above, it is not possible to detect whether or not the object is snow accretion. rice field.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a snow accretion detection method and a snow accretion detection device of a laser radar device capable of detecting snow accretion on a window portion of the laser radar device. There is.

As is well known, a laser radar device can measure a distance to an object existing on a scanning surface. Therefore, when there is dirt or an object attached to the window, the irradiated laser beam is reflected by the dirt or the attached object on the window, and as a result of distance measurement by the laser radar device, the distance to the window. Is measured. Therefore, if the distance measuring function of the laser radar device is used, it is possible to detect that an object is attached to the position of the window. However, it is not possible to detect whether or not the object attached to the window is snow accretion only by the distance measuring function of the laser radar device.

It is considered that such snow accretion on the window portion is caused by snowfall. Since snowfall is a meteorological phenomenon, it is considered that the same snowfall condition will occur in a monitoring area monitored by a plurality of laser radar devices and a range in the vicinity thereof, for example, in a range of several tens of meters. Therefore, for multiple laser radar devices provided to monitor the same monitoring area, snow will fall from the same direction, and all of these windows will be in the windward direction. Snow will adhere to the part, that is, the part in the direction of the wind.

For this reason, when snow adheres to the windows of a plurality of laser radar devices for monitoring the same monitoring area, the distance to the window is measured by the plurality of laser radar devices and the distance to the window is measured. It is considered that a phenomenon occurs in which the direction in which the distance is measured becomes the same direction in a plurality of laser radar devices. On the other hand, when the object attached to the window of the plurality of laser radar devices is an object other than snow, the direction in which the distance to the window is measured is necessarily the same in the plurality of laser radar devices. There is no.

In consideration of such a point, the snow accretion detection method of the laser radar device according to claim 1 detects snow accretion on the window portion as follows. First, from the result of distance measurement by the laser radar device, it is possible to acquire the information of the scanning angle in which the distance to the window is measured, but the information of the direction in which the distance to the window is measured is acquired. Can not do it. Therefore, the snow accretion detection method includes a table storage process for storing a conversion table in which each of the scanning angles of the plurality of laser radar devices and the direction are associated with each other. According to this, the scanning angle obtained from the result of distance measurement by each laser radar device can be converted into a direction.

The correspondence between the scanning angle and the direction changes depending on the installation state of the laser radar device. Therefore, the above conversion table is created based on the relationship between the scanning angle and the direction when the laser radar device is actually installed, and at the stage until the device actually operates, such as when the laser radar device is installed. It is preferable to execute the above table storage process and store the conversion table. Further, the snow accretion detection method includes a window ranging determination process for determining whether or not the distance to the window portion has been measured for each of the plurality of laser radar devices. According to this window distance measurement determination process, it is possible to detect the occurrence of the above-mentioned phenomenon that the distance to the window portion is measured, that is, that an object is attached to the position of the window portion.

Then, in the snow accretion detection method, when it is determined by the window distance measurement determination process that the distance to the window is measured by at least two of the plurality of laser radar devices, the scanning in which the distance to the window is measured is measured. It includes a snow accretion determination process for determining that there is snow accretion on the window when the angle is converted into a direction based on the conversion table and it is determined that the degree of coincidence of those directions is higher than a predetermined determination level. According to this snowfall determination process, a phenomenon that is considered to occur when snow adheres to the windows of a plurality of laser radar devices for monitoring the same monitoring area described above, that is, to the windows of a plurality of laser radar devices. When it is detected that the distance to the window is measured and the direction in which the distance to the window is measured is the same in a plurality of laser radar devices, it is determined that there is snow on the window. be able to.

In this way, it is possible to detect that an object is attached to the position of the window portion, and it is possible to determine whether or not the attached object is snow. Therefore, according to the snow accretion detection method, it is possible to detect snow accretion on the window of the laser radar device. If snow accretion on the window can be detected in this way, the following effects can be obtained. That is, in the case of snow accretion, unlike dirt such as mud and sand, it is often possible to deal with it without human removal, such as flying or evaporating due to the wind. Therefore, when actually operating a laser radar device, if it is possible to detect whether or not it has snow accretion, it is possible to determine whether or not to dispatch a person, and the cost of operation and maintenance is reduced. You will be able to do it.

When there is snowfall, it is considered that snow adheres to the window portion of the laser radar device over a range of approximately 180 degrees centered on the direction of the wind. Based on such a premise, the scanning angle (direction) shifted 90 degrees from the end of the scanning angle range (direction range) in which the distance to the window is measured to the center is the direction of the wind direction. It is possible to estimate. Therefore, in the snowfall determination process of the snowfall detection method according to claim 2, the scanning angle in which the distance to the window is not measured in the first range, which is the range of the scanning angle in which the distance to the window is measured. Includes a wind direction estimation process in which it is estimated that the direction corresponding to the scanning angle shifted 90 degrees from the scanning angle of the boundary with the second range, which is the range of, to the first range side is the direction of the wind direction.

According to this wind direction estimation process, the direction of the wind direction can be estimated based on the above-mentioned idea. Then, if the directions of the wind directions estimated as described above for at least two laser radar devices match, it is possible that the directions in which the distance to the window is measured in those laser radar devices are the same. Becomes very high.

Therefore, in this case, in the snow accretion detection process, if the directions of the wind directions estimated by the wind direction estimation process match in at least two laser radar devices, it is determined that the degree of coincidence of the directions is higher than the determination level, and snow accretion occurs on the window. Judge that there is. Therefore, according to the snow accretion detection method, it is possible to further improve the snow accretion detection performance on the window portion of the laser radar device.

The snow accretion detection method according to claim 3 detects snow accretion on the windows of three or more laser radar devices provided for monitoring the same monitoring area. Therefore, in this case, snow accretion on the windows thereof is detected by using the results of distance measurement of three or more laser radar devices. In this way, it is possible to improve the snow accretion detection performance as compared with the one that detects snow accretion on the windows by using the distance measurement results of the two laser radar devices.

That is, when detecting snow accretion using the results of distance measurement of two laser radar devices, if there is an object that obstructs snow such as planting in the vicinity of one laser radar device, one of the lasers may be used depending on the wind direction. Snow may not adhere to the windows of the radar device. Then, even if snow adheres to the window of the other laser radar device due to snow accretion, it is not determined that the distance to the window is measured by the two laser radar devices by the window distance measurement determination process. Cannot be detected.

On the other hand, when snow accretion is detected using the results of distance measurement of three or more laser radar devices as in the above snow accretion detection method, planting is performed in the vicinity of any one of the laser radar devices. However, if there is snowfall, snow will adhere to the windows of the other two or more laser radar devices. Therefore, according to the snow accretion detection method, when there is snowfall, it is determined that the distance to the window portion is measured by at least two laser radar devices by the window distance measurement determination process. Therefore, according to the above snow accretion detection method, snow accretion on the window can be reliably detected even when there is a planting or the like in the vicinity of any one of the three or more laser radar devices. ..

The snow accretion detection device according to claim 4 is based on the technical idea common to each of the above-mentioned snow accretion detection methods, is provided for monitoring the same monitoring area, and is an object for each predetermined scanning angle. A plurality of laser radar devices that measure the distance to, a table acquisition unit that performs the table acquisition process described above, a window distance measurement determination unit that performs the window distance measurement determination process described above, and a snow accretion determination unit that performs the snow accretion determination process described above. It is equipped with a snow determination unit. With such a snow accretion detection device, it is possible to detect snow accretion on the window of the laser radar device in the same manner as in each of the above-described snow accretion detection methods.

The figure which shows typically the structure of the monitoring device to which the snow accretion detection device which concerns on 1st Embodiment is applied. It is a figure which shows typically the arrangement of the two laser radar apparatus which concerns on 1st Embodiment, and is the figure which shows the state at the time of a normal time. The figure which shows typically an example of the reflected light intensity in the case of no snowfall which concerns on 1st Embodiment. The figure which shows typically an example of the reflected light intensity in the case of snowfall which concerns on 1st Embodiment. It is a figure which shows typically the arrangement of the two laser radar devices which concerns on 1st Embodiment, and is the figure which shows the state at the time of snowfall. It is a figure which shows typically the correspondence relationship between the scanning angle and the direction of the laser radar apparatus which concerns on 1st Embodiment, and is the figure which shows the state in a normal state. It is a figure which shows typically the correspondence relationship between the scanning angle and the direction of the laser radar apparatus which concerns on 1st Embodiment, and is the figure which shows the state at the time of snowfall. The figure which shows typically the content of the detection process which concerns on 1st Embodiment The figure which shows typically the structure of the monitoring device to which the snow accretion detection device which concerns on 2nd Embodiment is applied. It is a figure which shows typically the arrangement of the three laser radar apparatus which concerns on 2nd Embodiment, and is the figure which shows the state at the time of a normal time. It is a figure which shows typically the correspondence relationship between the scanning angle and the direction of the laser radar apparatus which concerns on 2nd Embodiment, and is the figure which shows the state in a normal state. The figure which shows typically the content of the detection process which concerns on 2nd Embodiment It is a figure which shows typically the arrangement of three laser radar devices which concerns on 2nd Embodiment, and is the figure which shows the state at the time of snowfall. It is a figure which shows typically the correspondence relationship between the scanning angle and the direction of the laser radar apparatus which concerns on 2nd Embodiment, and is the figure which shows the state at the time of snowfall.

Hereinafter, a plurality of embodiments will be described with reference to the drawings. In each embodiment, substantially the same configuration is designated by the same reference numerals and the description thereof will be omitted.
(First Embodiment)
Hereinafter, the first embodiment will be described with reference to FIGS. 1 to 8.

As shown in FIG. 1, the monitoring device 1 that also functions as a snow accretion detection device is composed of two laser radar devices 2A and 2B and a control device 3 that controls the laser radar devices 2A and 2B. In this embodiment, an example in which the snow accretion detection device is configured by the laser radar devices 2A and 2B and the control device 3 is shown, but each process such as the snow accretion detection process described later is performed on the laser radar devices 2A and 2B side. By doing so, the snow accretion detection device can also be configured by the laser radar devices 2A and 2B.

The laser radar devices 2A and 2B have the same configuration. Hereinafter, when it is not necessary to distinguish between the laser radar devices 2A and 2B, they will be collectively referred to as the laser radar device 2. The laser radar device 2 includes a control unit 20, an irradiation unit 21, a rotating mirror 22, a light receiving unit 23, a storage unit 24, and the like. Each of these configurations is housed inside the housing 25. The housing 25 is provided with a window portion 26 that transmits laser light and reflected light. The control unit 20 of the laser radar device 2 is composed of a microcomputer having a CPU, ROM, RAM, etc. (not shown), and the entire laser radar device 2 is executed by executing a computer program stored in the storage unit 24 or the like. To control.

By rotating the rotary mirror 22, the laser radar device 2 irradiates the laser beam emitted from the irradiation unit 21 toward the target area at a predetermined scanning angle, for example, every 1 °. Then, the laser radar device 2 measures the distance to the object for each scanning angle based on the elapsed time from the irradiation of the laser beam to the reception of the reflected light reflected by the object 4 by the light receiving unit 23. When an object is detected by the laser radar device 2, intrusion detection processing is performed as is well known based on the scanning angle and distance of the detected object. In the intrusion detection process, it is notified that an intruder has been detected, for example, by voice or signal.

In the present embodiment, the range in which the laser radar device 2 can measure the distance is set to the range of 90 ° to −90 °, that is, the range of 180 ° when the front direction of the laser radar device 2 is 0 °. There is. Then, as shown in FIG. 2, the laser radar devices 2A and 2B are arranged so as to face each other. In FIG. 2, the upward direction is represented as north. With such an arrangement, the laser radar devices 2A and 2B each monitor the same monitoring area 100.

The control device 3 includes a control unit 30 and the like. The control device 3 is composed of a so-called personal computer. The control device 3 is provided with measurement data representing the distance measurement results by the laser radar devices 2A and 2B, respectively, via the communication line 5. Although not shown, the control device 3 operates a display unit that displays the monitoring status by the laser radar device 2 and an image captured by the camera, a notification unit that notifies the user of intrusion, and user operations such as a mouse and a keyboard. It has an input unit for input.

In the case of the monitoring device 1 of the present embodiment, the laser radar device 2 side basically performs the process of detecting an object, and the control device 3 side executes a program for determining the presence or absence of an intruder and detecting snow accretion. By doing so, snow accretion detection processing for detecting snow accretion on the window portion 26, notification processing, and the like are performed. The snow accretion detection process includes a table storage process, a window ranging determination process, and a snow accretion determination process, which will be described later. As described above, in the present embodiment, the control unit 30 performs each of the above-described processes, and has functions as a table storage unit, a window distance measurement determination unit, and a snow accretion determination unit.

Next, the operation of the above configuration will be described.
First, as is well known, the laser radar device 2 can measure the distance to an object existing on the scanning surface. At this time, when there is no dirt or adhesion on the window portion 26, for example, as shown in FIG. 3, the reflected light has a small reflected light intensity (reflected light amount) at the position of the window portion 26 and is reflected by the object 4. The light intensity will exceed the threshold. Then, the distance to the object 4 is measured based on the time until the threshold value is exceeded.

On the other hand, when snow 6 has landed on the window 26, for example, as shown in FIG. 4, the laser beam is reflected by the snow 6 to increase the reflected light intensity at the position of the window 26. On the other hand, the intensity of the reflected light on the object 4 becomes low and falls below the threshold value, or the reflected light is not received. Then, in this case, the object cannot be detected.

Therefore, the abnormality is notified, but when snow accretion occurs on the window portion 26, it is considered that it is possible to deal with it by calling a cleaning staff instead of calling a guard because it has detected an intrusion. That is, if the type of the deposits adhering to the window portion 26 can be determined, a flexible response can be taken.

Therefore, the monitoring device 1 determines whether or not the object detected at the position of the window portion 26 is naturally attached snow accretion by the snow accretion detection method described below. That is, it is considered that the snow accretion on the window portion 26 is caused by the snowfall. Since snowfall is a meteorological phenomenon, it is considered that the same snowfall condition will occur in the monitoring area 100 and its vicinity, for example, in the range of several tens of meters, which are monitored by the laser radar devices 2A and 2B.

Therefore, when it snows, for example, as shown in FIG. 5, snow falls from the same direction Dw on the laser radar devices 2A and 2B provided for monitoring the same monitoring area 100. As a result, snow adheres to the windows 26 of the laser radar devices 2A and 2B in the windward direction, that is, in the wind direction Dw. In FIG. 5, the upward direction is represented as north, and the direction Dw in the wind direction is north-northwest.

Therefore, when snow adheres to the window portions 26 of the laser radar devices 2A and 2B for monitoring the same monitoring area 100, the distance to the window portions 26 is measured by the laser radar devices 2A and 2B. At the same time, it is considered that a phenomenon occurs in which the direction in which the distance to the window portion 26 is measured becomes the same direction in the laser radar devices 2A and 2B. On the other hand, when the object attached to the window 26 of the laser radar devices 2A and 2B is an object other than snow, the direction in which the distance to the window 26 is measured is not necessarily the same in the laser radar devices 2A and 2B. Will never be.

Therefore, if the above-mentioned two phenomena can be detected, it is considered that snow accretion on the window portion 26 can be detected based on the detection results. However, from the result of the distance measurement by the laser radar device 2, it is possible to acquire the information of the scanning angle in which the distance to the window portion 26 is measured, but in the direction in which the distance to the window portion 26 is measured. Information cannot be obtained.

Therefore, the snow accretion detection method of the present embodiment includes a table storage process for storing a conversion table in which the scanning angles of the laser radar devices 2A and 2B are associated with the directions. The correspondence between the scanning angle and the direction of the laser radar device 2 changes according to the installation state. For example, according to the installation state as shown in FIG. 2, the "scanning angle = 0 °" in the laser radar device 2A is in the northeast direction, but the "scanning angle = 0 °" in the laser radar device 2B is in the southwest direction. Become a direction.

Specifically, the correspondence between the scanning angle and the direction of the laser radar device 2 in the installed state as shown in FIG. 2 is as shown in FIG. In FIG. 6, the range in which the laser radar device 2 can measure the distance is represented by hatching of diagonal lines (diagonal lines rising to the right). The conversion table stores the contents as shown in FIG.

The conversion table may be created based on the relationship between the scanning angle and the direction when the laser radar device 2 is actually installed. The table storage process is executed at a stage before the monitoring device 1 actually operates, such as when the laser radar device 2 is installed, whereby the conversion table is stored in the control device 3, that is, It will be registered.

The window distance measurement determination process is a process for determining whether or not the distance to the window portion 26 has been measured for each of the laser radar devices 2A and 2B. According to this window distance measurement determination process, it is possible to detect the occurrence of the phenomenon that the distance to the window portion 26 described above is measured, that is, that an object is attached to the position of the window portion 26.

In the snow accretion determination process, when it is determined by the window distance measurement determination process that the distance to the window portion 26 has been measured by both the laser radar devices 2A and 2B, the scanning angle at which the distance to the window portion 26 is measured is calculated as described above. It is a process of determining that there is snow accretion on the window portion 26 when the directions are converted based on the conversion table and it is determined that the degree of coincidence of those directions is higher than the predetermined determination level.

Specifically, the determination regarding the degree of coincidence of the directions in the snow accretion determination process is performed as follows. That is, when there is snowfall, it is considered that snow adheres to the window portion 26 of the laser radar device 2 over a range of approximately 180 degrees centered on the wind direction Dw, for example, as shown in FIG.

Based on such a premise, the scanning angle (direction) shifted 90 degrees from the edge of the measured scanning angle range (direction range) to the window portion 26 to the center is the direction Dw in the wind direction. It is possible to presume that. In the case of the installation state and the direction Dw of the wind direction as shown in FIG. 5, the end of the scanning angle range in which the distance to the window portion 26 is measured is approximately -22 for both the laser radar devices 2A and 2B. It is .5 °.

In this case, as shown in FIG. 7, for the laser radar device 2A, the first range, which is the range of the scanning angle in which the distance to the window portion 26 is measured, is the range of 90 ° to -22.5 °. Therefore, the range in which normal distance measurement is possible, that is, the range of the scanning angle in which the distance to the window portion 26 is not measured, is the range of -22.5 ° to -90 °. On the other hand, for the laser radar device 2B, the first range is in the range of -22.5 ° to -90 °, and the second range is in the range of 90 ° to -22.5 °. In FIG. 7, the range in which the distance to the window portion 26 is measured is represented by dot hatching.

Therefore, in the snow accretion determination process of the present embodiment, the direction corresponding to the scanning angle shifted by 90 ° from the scanning angle of the boundary with the second range of the first range to the first range side is the direction of the wind direction. Includes wind direction estimation processing to estimate. In this case, for the laser radar device 2A, the boundary is -22.5 °, and the direction corresponding to 67.5 °, which is a scanning angle 90 ° shifted from the scanning angle of the boundary to the first range side, is It will be north-northwest.

Further, in this case, for the laser radar device 2B, the boundary is -22.5 °, which corresponds to a scanning angle of -112.5 ° shifted by 90 ° from the scanning angle of the boundary to the first range side. The direction to do is north-northwest. That is, in this case, the directions of the wind direction estimated by the wind direction estimation process are the same for the laser radar devices 2A and 2B.

In the present embodiment, it is determined whether or not the directions of the wind directions match in 16 directions, but it may be 8 directions or 32 directions. Then, in the snow accretion determination process of the present embodiment, if the directions of the wind direction estimated by the wind direction estimation process match in the two laser radar devices 2A and 2B, it is determined that the degree of coincidence of the above directions is higher than a predetermined level. It is determined that there is snow accretion on the window portion 26.

The monitoring device 1 repeatedly executes the detection process of the contents shown in FIG. 8 by using the result of the distance measurement by the laser radar device 2 and the conversion table. In the present embodiment, the snow accretion detection process for detecting the snow accretion on the window portion 26 is configured from the detection process and the table storage process described above. The snow accretion detection process is realized by causing the control unit 30 of the control device 3 to execute a program for snow accretion detection.

First, in step S101, it is determined whether or not an object is detected at the position of the window portion 26 in both the two laser radar devices 2A and 2B. As described above, step S101 includes the window ranging determination process. Such a determination can be made based on the reflected light intensity corresponding to the position of the window portion 26 as shown in FIGS. 3 and 4. Here, if an object is not detected at the position of at least one of the window portions 26 of the laser radar devices 2A and 2B, the result is "NO" in step S101, and the detection process is completed.

On the other hand, when an object is detected at the positions of the windows 26 of both the two laser radar devices 2A and 2B, the result is "YES" in step S101, and the process proceeds to step S102. In step S102, the scanning angle in which the distance to the window portion 26 is measured is converted into a direction, and it is determined whether or not the degree of coincidence of those directions (direction of window surface measurement) is higher than a predetermined determination level. Such a determination is made based on whether or not the directions of the wind directions estimated by the above-mentioned wind direction estimation process match.

Here, if the degree of coincidence of the directions of the window surface measurement is equal to or less than the determination level, the result becomes “NO” in step S102, and the detection process ends. On the other hand, if the degree of agreement in the direction of the window surface measurement is higher than the determination level, the result is "YES" in step S102, and the process proceeds to step S103. In step S103, it is determined that there is snow on the window portion 26. As described above, steps S102 and S103 include snow accretion determination processing. After the execution of step S103, the detection process ends. If it is determined that there is snow on the window portion 26 in step S103, a notification process for notifying the fact may be executed.

As described above, the following effects can be obtained according to the present embodiment.
As described above, when snow adheres to the window 26 of the laser radar devices 2A and 2B for monitoring the same monitoring area 100, the distance to the window 26 is measured by both the laser radar devices 2A and 2B. It is considered that the direction in which the distance to the window portion 26 is measured becomes the same direction in the laser radar devices 2A and 2B. On the other hand, when the object attached to the window 26 of the laser radar devices 2A and 2B is an object other than snow, the direction in which the distance to the window 26 is measured is not necessarily the same in the laser radar devices 2A and 2B. Will never be.

In consideration of such a point, in the snow accretion detection method of the present embodiment, snow accretion on the window portion 26 is detected as follows. That is, the snow accretion detection method includes a table storage process for storing a conversion table in which each of the scanning angles of the laser radar device 2 and the direction are associated with each other. According to this, the scanning angle obtained from the result of distance measurement by the laser radar device 2 can be converted into a direction. Further, the snow accretion detection method includes a window ranging determination process for determining whether or not the distance to the window portion 26 has been measured for each of the laser radar devices 2A and 2B. According to this window distance measurement determination process, it is possible to detect the occurrence of the phenomenon that the distance to the window portion 26 described above is measured, that is, that an object is attached to the position of the window portion 26.

Then, in the snow accretion detection method, when it is determined that the distance to the window portion 26 has been measured by both the laser radar devices 2A and 2B by the window distance measurement determination process, the scanning in which the distance to the window portion 26 is measured is measured. It includes a snow accretion determination process for determining that there is snow accretion on the window portion 26 when the angles are converted into directions based on the conversion table and it is determined that the degree of coincidence of those directions is higher than the determination level. According to this snow landing determination process, a phenomenon considered to occur when snow adheres to the window portion 26 of the laser radar devices 2A and 2B for monitoring the same monitoring area 100 described above, that is, the laser radar devices 2A and 2B. When the distance to the window portion 26 is measured and the measured direction of the distance to the window portion 26 is detected in the laser radar devices 2A and 2B, the window portion is detected. It can be determined that there is snow on 26.

In this way, it is possible to detect that an object is attached to the position of the window portion 26, and it is possible to determine whether or not the attached object is snow. Therefore, according to the snow accretion detection method, it is possible to detect snow accretion on the window portion 26 of the laser radar device 2. If snow accretion on the window portion 26 can be detected, the following effects can be obtained. That is, in the case of snow accretion, unlike dirt such as mud and sand, it is often possible to deal with it without human removal, such as flying or evaporating due to the wind. Therefore, when actually operating the laser radar device 2, if it is possible to detect whether or not it is snow accretion, it is possible to determine whether or not to dispatch a person, and the operation and maintenance costs are reduced. You will be able to lower it.

When there is snowfall, it is considered that snow adheres to the window portion 26 of the laser radar device 2 over a range of approximately 180 ° centering on the direction of the wind. Based on such a premise, it is possible to estimate that the scanning angle in which the distance to the window 26 is shifted 90 ° from the edge of the measured scanning angle range to the center is the direction of the wind. be.

Therefore, the snowfall determination process of the present embodiment is the range of the scanning angle in which the distance to the window 26 is not measured, out of the first range in which the distance to the window 26 is measured. It includes a wind direction estimation process of estimating that the direction corresponding to the scanning angle shifted by 90 ° from the scanning angle of the boundary with the two ranges to the first range side is the direction of the wind direction.

According to this wind direction estimation process, the direction of the wind direction can be estimated based on the above-mentioned idea. Then, when the directions of the wind directions estimated as described above for the two laser radar devices 2A and 2B match, the directions in which the distance to the window portion 26 is measured in the laser radar devices 2A and 2B are the same. It is very likely that it has become.

Therefore, in this case, in the snow accretion detection process, if the directions of the wind directions estimated by the wind direction estimation process match in the two laser radar devices 2A and 2B, it is determined that the degree of coincidence of the directions is higher than the determination level, and the window portion 26 Judge that there is snow accretion. Therefore, according to the present embodiment, it is possible to further improve the detection performance of snow accretion on the window portion 26 of the laser radar device 2.

Further, monitoring as a snow accretion detection device including laser radar devices 2A and 2B, and a table storage unit, a window ranging determination unit, and a snow accretion determination unit realized by the control unit 30 of the control device 3 in the embodiment. The device 1 can also obtain the same effect as the snow accretion detection method described above.

(Second Embodiment)
Hereinafter, the second embodiment will be described with reference to FIGS. 9 to 14.
As shown in FIG. 9, the monitoring device 41 of the present embodiment also functions as a snow accretion detection device like the monitoring device 1 of the first embodiment. The monitoring device 41 is different from the monitoring device 1 in that the laser radar device 2C is added and the control device 42 is provided in place of the control device 3. The control device 42 includes a control unit 43 and the like, and has substantially the same configuration as the control device 3.

The laser radar device 2C has the same configuration as the laser radar devices 2A and 2B. Hereinafter, when it is not necessary to distinguish between the laser radar devices 2A, 2B, and 2C, they will be collectively referred to as the laser radar device 2. In this case, the laser radar device 2 is arranged as shown in FIG. In FIG. 10, the upward direction is represented as north.

That is, the laser radar devices 2A and 2B are arranged so as to face each other. However, in this case, the centers of the laser radar devices 2A and 2B do not match. Further, in this case, the laser radar device 2C is arranged so that its front direction faces west. With such an arrangement, the three laser radar devices 2A, 2B, and 2C each monitor the same monitoring area. In this case, an object such as planting P exists in the vicinity of the laser radar device 2B in the north-northwest direction.

For example, according to the installation state as shown in FIG. 10, the "scanning angle = 0 °" in the laser radar device 2A is in the northeast direction, and the "scanning angle = 0 °" in the laser radar device 2B is in the southwest direction. The "scanning angle = 0 °" in the radar device 2C is in the west direction. Specifically, the correspondence between the scanning angle and the direction of the laser radar device 2 in the installed state as shown in FIG. 10 is as shown in FIG. The conversion table stored by the table storage process of the present embodiment stores the contents as shown in FIG.

Next, the operation of the above configuration will be described.
The monitoring device 41 repeatedly executes the detection process as shown in FIG. 12 by using the result of the distance measurement by the laser radar device 2 and the conversion table. In the present embodiment, the snow accretion detection process for detecting the snow accretion on the window portion 26 is configured from the detection process and the table storage process described above. The snow accretion detection process is realized by causing the control unit 43 of the control device 42 to execute a program for snow accretion detection.

First, in step S201, it is determined whether or not an object is detected at the position of the window portion 26 in at least two of the three laser radar devices 2A, 2B, and 3C. As described above, step S201 includes the window ranging determination process. Such a determination can be made in the same manner as in step S101 of the first embodiment. Here, if no object is detected at the position of the window portion 26 in at least two of the laser radar devices 2A, 2B, and 2C, the result is "NO" in step S201, and the detection process is completed.

On the other hand, when an object is detected at the position of the window portion 26 in at least two of the laser radar devices 2A, 2B, and 2C, the result is "YES" in step S201, and the process proceeds to step S202. In step S202, the scanning angle in which the distance to the window portion 26 is measured is converted into a direction, and it is determined whether or not the degree of coincidence of those directions (direction of window surface measurement) is higher than a predetermined determination level. Such a determination can be made in the same manner as in step S102 of the first embodiment.

Here, if the degree of coincidence of the directions of the window surface measurement is equal to or less than the determination level, the result becomes “NO” in step S202, and the detection process ends. On the other hand, if the degree of agreement in the direction of the window surface measurement is higher than the determination level, the result is "YES" in step S202, and the process proceeds to step S203. In step S203, it is determined that there is snow on the window portion 26. As described above, steps S202 and S203 include snow accretion determination processing. After the execution of step S203, the detection process ends. If it is determined that there is snow on the window portion 26 in step S203, a notification process for notifying the fact may be executed.

As described above, in the snow accretion detection method of the present embodiment, snow accretion on the windows 26 of the three laser radar devices 2A, 2B, and 2C provided for monitoring the same monitoring area is detected. It has become. Therefore, in this case, snow accretion on the window portion 26 is detected by using the results of distance measurement of the three laser radar devices 2A, 2B, and 2C. In this way, it is possible to improve the snow accretion detection performance as compared with the one that detects the snow accretion on the window portion 26 by using the distance measurement results of the two laser radar devices. The reason is as follows.

That is, when detecting snow accretion using the results of distance measurement of two laser radar devices, if there is an object that obstructs snow such as planting in the vicinity of one laser radar device, one of the lasers may be used depending on the wind direction. Snow may not adhere to the windows of the radar device. Specifically, in the installation state as shown in FIG. 10, when snow accretion is detected using the results of distance measurement of the laser radar devices 2A and 2B, the planting P is located in the vicinity of one of the laser radar devices 2B. exist.

Here, as shown in FIG. 13, when the wind direction is north-northwest and there is snowfall, the snowfall 6 causes snow 6 to adhere to the window portion 26 of the laser radar device 2A. However, since the snow 6 blown by the wind from the north-northwest direction is hindered by the planting P, the snow 6 does not adhere to the window portion 26 of the laser radar device 2B. Then, even if snow 6 adheres to the window portion 26 of the laser radar device 2A due to snowfall, it is not determined that the distance to the window portion 26 has been measured by the two laser radar devices 2A and 2B by the window distance measurement determination process. Therefore, the snow accretion cannot be detected.

On the other hand, when snow accretion is detected using the results of distance measurement of the three laser radar devices 2A, 2B and 2C as in the snow accretion detection method of the present embodiment, the laser radar devices 2A, 2B and 2C Even if planting P or the like is present in the vicinity of any one of them, if there is snowfall, snow will adhere to the windows of the other two laser radar devices. Specifically, as shown in FIG. 13, if the wind direction is north-northwest and there is snowfall, the snow is hindered by the planting P, so that the snow 6 does not adhere to the window 26 of the laser radar device 2B. Snow 6 adheres to the window portions 26 of the laser radar devices 2A and 2C.

Therefore, in the snow accretion detection method of the present embodiment, when there is snow accretion, it is determined that the distance to the window portion 26 has been measured by at least two laser radar devices 2A and 2C by the window distance measurement determination process. Snow can be detected. Therefore, according to the snow accretion detection method of the present embodiment, snow accretion on the window portion 26 is present even when the planting P or the like is present in the vicinity of any one of the three laser radar devices 2A, 2B, and 2C. Can be reliably detected.

The snow accretion determination process of the present embodiment also includes the same wind direction estimation process as the snow accretion determination process of the first embodiment. In this case, as shown in FIG. 14, for the laser radar device 2A, the first range (dot hatched portion in FIG. 14), which is the range of the scanning angle in which the distance to the window portion 26 is measured, is from 90 °. The second range (hatched portion of the diagonal line in FIG. 14), which is the range of -22.5 ° and is the range where normal distance measurement is possible, that is, the range of the scanning angle where the distance to the window portion 26 is not measured, is -22. It ranges from .5 ° to -90 °. Further, for the laser radar device 2C, the first range is in the range of 22.5 ° to −90 °, and the second range is in the range of 90 ° to 22.5 °.

Therefore, the direction of the wind direction estimated by the wind direction estimation process is 90 ° shifted from -22.5 °, which is the boundary between the first range and the second range, to the first range side for the laser radar device 2A. The direction corresponding to the angle of 67.5 °, that is, north-northwest. Further, the direction of the wind direction estimated by the wind direction estimation process is −67.5 °, which is a scanning angle of the laser radar device 2C shifted by 90 ° from the above boundary of 22.5 ° to the first range side. The corresponding direction, that is, north-northwest.

As described above, also in the configuration of the present embodiment, the directions of the wind direction estimated by the wind direction estimation process are the same for the laser radar devices 2A and 2C in which the window portion 26 has been snowed due to the snowfall. Therefore, the snow accretion detection method of the present embodiment can also realize the same wind direction estimation accuracy as the snow accretion detection method of the first embodiment, and thus the snow accretion detection performance.

Further, as a snow accretion detection device including laser radar devices 2A, 2B, 2C, and in the embodiment, a table storage unit, a window ranging determination unit, and a snow accretion determination unit realized by the control unit 43 of the control device 42. The same effect as the above-mentioned snow accretion detection method can be obtained by the monitoring device 41 of the above.

(Other embodiments)
It should be noted that the present invention is not limited to each of the above-described embodiments and described in the drawings, and can be arbitrarily modified, combined, or extended without departing from the gist thereof.
The numerical values and the like shown in each of the above embodiments are examples, and are not limited thereto.

In each of the above embodiments, the control unit 30 of the control device 3 constitutes a table storage unit, a window ranging determination unit, a snow accretion determination unit, and the like, but the control unit 20 of the laser radar device 2 is used for snow accretion detection. Table storage processing, window distance measurement determination processing, snow accretion determination processing, and the like may be performed by executing the above program. That is, the control unit 20 of the laser radar device 2 may configure a table storage unit, a window ranging determination unit, a snow accretion determination unit, and the like.

The present invention is provided not only for detecting snow accretion on the window of two or three laser radar devices provided for monitoring the same monitoring area, but also for monitoring the same monitoring area. It can also be applied to detect snow accretion on the windows of four or more laser radar devices.

The arrangement of the plurality of laser radar devices may not be limited to the arrangement as described in each of the above embodiments. According to the snow accretion detection method of the present invention, it is possible to detect snow accretion on the windows of a plurality of laser radar devices regardless of their arrangement.

1, 41 ... Monitoring device, 2A, 2B, 2C ... Laser radar device, 3, 42 ... Control device, 26 ... Window unit, 30, 43 ... Control unit.

Claims (4)

A snow accretion detection method for detecting snow accretion on windows of a plurality of laser radar devices provided for monitoring the same monitoring area and measuring the distance to an object at each predetermined scanning angle.
A table storage process for storing a conversion table in which each of the scanning angles of the plurality of laser radar devices and a direction are associated with each other,
Window distance measurement determination processing for determining whether or not the distance to the window portion has been measured for each of the plurality of laser radar devices, and
When it is determined by the window distance measurement determination process that the distance to the window is measured by at least two of the plurality of laser radar devices, the scanning angle at which the distance to the window is measured is converted. When the directions are converted based on the table and it is determined that the degree of coincidence of those directions is higher than the predetermined determination level, the snow accretion determination process for determining that there is snow on the window portion, and the snow accretion determination process.
Snow accretion detection method for laser radar equipment including. The snow accretion determination process
From the scanning angle of the boundary with the second range which is the range of the scanning angle where the distance to the window is not measured in the first range which is the range of the scanning angle where the distance to the window is measured. Includes a wind direction estimation process that estimates that the direction corresponding to the scanning angle shifted 90 degrees to the first range side is the direction of the wind direction.
A claim that when the directions of the wind direction estimated by the wind direction estimation process match in at least two of the laser radar devices, it is determined that the degree of coincidence of the directions is higher than the determination level, and it is determined that there is snow accretion on the window portion. The method for detecting snow accretion of the laser radar device according to 1. The method for detecting snow accretion of a laser radar device according to claim 1 or 2, wherein snow accretion on the windows of three or more laser radar devices provided for monitoring the same monitoring area is detected. A plurality of laser radar devices provided for monitoring the same monitoring area and measuring the distance to an object at each predetermined scanning angle.
A table storage unit that stores a conversion table in which each of the scanning angles and directions of the plurality of laser radar devices is associated with each other.
A window ranging determination unit that determines whether or not the distance to the window unit has been measured for each of the plurality of laser radar devices, and a window ranging determination unit.
When it is determined by the window ranging determination unit that the distance to the window is measured by at least two of the plurality of laser radar devices, the scanning angle at which the distance to the window is measured is converted. A snow accretion determination unit that determines that there is snow accretion on the window portion when the directions are converted based on the table and it is determined that the degree of coincidence of the converted directions is higher than a predetermined determination level.
A snow accretion detection device equipped with.

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