Collapse detection system and collapse detection method

Abstract

To make it easy to detect a collapse.SOLUTION: A collapse detection system includes: a plurality of collapse sensors configured to be able to scan a surrounding area by radiating a laser beam in multiple directions and reflect laser beams transmitted from other collapse sensors, and to receive laser beams reflected from one or more other collapse sensors in the surrounding area and determine the direction of each of the collapse sensors in the surrounding area and the distance to each collapse sensor; and a monitoring device that acquires information about the direction and distance of the other collapse sensors identified by each collapse sensor from the plurality of collapse sensors placed at a distance from each other at a location subject to collapse detection, identifies the positional relationship of the plurality of collapse sensors, and detects a collapse based on changes in the positional relationship.SELECTED DRAWING: Figure 1

Description

【Technical Field】 【0001】 The present disclosure relates to a landslide detection system and a landslide detection method. 【Background Art】 【0002】 Conventionally, a landslide detection system for detecting landslides on mountain slopes or the like has been used. For example, Patent Document 1 discloses a system that uses a light reflector installed on a mountain slope to detect landslides. By transmitting and receiving laser light between a laser level provided at the observation site and the light reflector, the distance from the observation site to the light reflector is measured. When a landslide occurs, the position of the light reflector shifts, so the distance from the observation site to the light reflector changes. Based on this change in distance, it is possible to detect the landslide on the slope. 【0003】 Patent Document 2 discloses a system that installs a plurality of mirror reflectors equipped with corner reflectors on a mountain slope to identify the location where a landslide occurs. When laser light is transmitted from a measurement station to a first mirror reflector, the laser light is reflected toward a second mirror reflector. The laser light reflected in sequence by the first, second, third, and a plurality of mirror reflectors is finally received at the measurement station. Each mirror reflector is provided with a corner reflector that reflects the laser light in the incident direction, and the laser light returning from each mirror reflector is also received at the measurement station. For example, when a landslide occurs and the third mirror reflector becomes unavailable, the laser light reflected by the plurality of mirror reflectors in sequence, first and second, will not reach the measurement station, so the occurrence of the landslide can be detected. Also, while laser light returns from the first and second corner reflectors, no laser light returns from the third corner reflector, so it is identified that the location where the landslide occurred is the installation location of the third mirror reflector. 【Prior Art Documents】 【Patent Documents】 【0004】 [Patent Document 1] Japanese Patent Publication No. 2001-133299 [Patent Document 2] Japanese Patent Publication No. 2005-10065 [Overview of the Initiative] [Problems that the invention aims to solve] 【0005】 However, the technology described in Patent Document 1 requires high-precision control of a high-power laser beam to accurately measure the distance to a light reflector several hundred meters away, which results in high costs for system installation and maintenance. Using the technology described in Patent Document 2, even if the observation point is several hundred meters away, it is sufficient to install multiple reflectors between the observation point and the observation point and reflect the laser beam in sequence. Therefore, the performance requirements for the laser beam transmitting and receiving device are lower compared to Patent Document 1, but it is not easy to align the optical axis so that the laser beam can be transmitted and received using dozens of reflectors installed at intervals of about 10 meters, for example. 【0006】 This disclosure has been made in view of the prior art, including the issues described above, and one of its purposes is to provide a collapse detection system and a collapse detection method that are easy to introduce and use. [Means for solving the problem] 【0007】 The collapse detection system according to this disclosure comprises a plurality of collapse sensors configured to scan the surroundings by irradiating laser light in multiple directions and to reflect laser light transmitted from other collapse sensors, and to receive laser light reflected by one or more other collapse sensors in the surroundings to identify the direction of each collapse sensor and the distance to each collapse sensor, and a monitoring device that acquires information relating to the direction and distance of other collapse sensors identified by each collapse sensor from a plurality of the collapse sensors arranged at a distance from each other in the location to be targeted for collapse detection, identifies the positional relationship of the plurality of collapse sensors, and detects a collapse based on the change in the positional relationship. 【0008】 In the above configuration, the collapse sensor may search for other collapse sensors in its vicinity by scanning the laser beam within a predetermined angle range in the vertical direction of a 360-degree radius. 【0009】 In the above configuration, the collapse sensor generates data including identification information for identifying each collapse sensor and the direction and distance of other collapse sensors identified by transmitting and receiving the laser light, and transmits and receives this data with other collapse sensors in the vicinity, thereby delivering the data obtained by each collapse sensor to the monitoring device via one or more collapse sensors. 【0010】 In the above configuration, the collapse sensor may transmit the generated data and the data received from other collapse sensors to yet another collapse sensor. 【0011】 In the above configuration, the collapse sensor may transmit and receive the data by optical wireless communication using the laser light. 【0012】 In the above configuration, the collapse sensor may have a plurality of reflectors that can switch between a transmission state in which the laser light is transmitted and a reflection state in which the laser light is reflected, and the laser light may be transmitted and received in a plurality of different directions by controlling the switching between the transmission state and the reflection state of each reflector with a plurality of reflectors that are arranged at different angles to reflect the laser light incident from a predetermined direction in different directions. 【0013】 In the above configuration, the collapse sensor has a reflector capable of changing the reflection direction of the laser light by changing the arrangement of liquid crystal molecules, and the laser light may be transmitted and received in multiple different directions by controlling the arrangement of liquid crystal molecules in the reflector. 【0014】 In the above configuration, the collapse sensor may include a first reflecting section that uses the reflector to reflect the laser light in a plurality of different directions within a predetermined surface, and a second reflecting section that uses another reflector to reflect each of the laser beams reflected by the first reflecting section in a plurality of different directions within the predetermined surface. 【0015】 The collapse detection method according to this disclosure includes the steps of: each of a plurality of collapse sensors, which are arranged at a distance from each other in a location to be targeted for collapse detection, irradiates laser light in multiple directions and scans the surroundings, and identifies the direction of each of the surrounding collapse sensors and the distance to each collapse sensor based on the laser light reflected by one or more other collapse sensors in the surroundings; a monitoring device acquires information from the plurality of collapse sensors regarding the direction and distance of the other collapse sensors identified by each collapse sensor, and identifies the positional relationship of the plurality of collapse sensors; and the monitoring device detects a collapse based on the change in the positional relationship. [Effects of the Invention] 【0016】 The collapse detection system and collapse detection method described herein allow for easy implementation and use of the system. [Brief explanation of the drawing] 【0017】 [Figure 1] Figure 1 is a diagram illustrating the overview of the collapse detection system according to this embodiment. [Figure 2] Figure 2 shows an example of the notification process performed by the collapse detection system. [Figure 3] Figure 3 is a block diagram showing an example configuration of a collapse detection system. [Figure 4] Figure 4 shows an example of the configuration of a collapse sensor. [Figure 5] Figure 5 is a diagram illustrating how the optical communication unit changes the direction of transmission and reception of laser light. [Figure 6] Figure 6 illustrates an example in which multiple optical communication units share the functions of a laser light transmitter and receiver. [Figure 7]FIG. 7 is a diagram for explaining a liquid crystal type reflection member. 【Embodiments for Carrying Out the Invention】 【0018】 Hereinafter, embodiments of the landslide detection system and the landslide detection method according to the present disclosure will be described while referring to the accompanying drawings. FIG. 1 is a diagram for explaining the outline of the landslide detection system 1 according to the present embodiment. The landslide detection system 1 includes a plurality of landslide sensors 100 (100a to 100e) and a monitoring device 200. The landslide sensor 100 has a pile shape composed of a main body portion 101 (101a to 101e) and a support portion 102 (102a to 102e), and is fixed and used on the slope of a mountain that is the detection target of landslides. For example, a plurality of landslide sensors 100 are installed at intervals of about several meters to several tens of meters. The number of landslide sensors 100 used in the landslide detection system 1 is not particularly limited. 【0019】 The landslide sensor 100 transmits and receives electromagnetic waves from the main body portion 101. As shown by the oblique lines in FIG. 1, the landslide sensor 100 can transmit and receive electromagnetic waves in a direction perpendicular to the axial direction of the support portion 102 and in a plurality of directions in which the angle is changed within a predetermined angle range including this direction. Further, as shown by the broken line arrow in FIG. 1, the landslide sensor 100 can change the transmission and reception direction of electromagnetic waves in a 360-degree range around, that is, 360 degrees around the axis of the support portion 102. The type of electromagnetic wave transmitted and received by the landslide sensor 100 is not particularly limited, but hereinafter, the description will continue on the assumption that the landslide sensor 100 transmits and receives laser light. For example, the landslide sensor 100 transmits and receives infrared laser light with a wavelength of 1400 nm or more that is harmless to the human body. 【0020】 The collapse sensor 100a searches for other collapse sensors 100 by transmitting laser light from its main body 101 to scan within a predetermined angular range in the vertical direction (axis direction of the support column 102) over a 360-degree radius (S1). The main body 101 is provided with a reflective member 610 (see Figure 4(a)), and the collapse sensor 100 reflects laser light transmitted from other collapse sensors 100. The collapse sensor 100a, which has transmitted laser light in multiple directions to scan its surroundings, receives the laser light that has been reflected back by the other collapse sensors 100b and 100c. 【0021】 The collapse sensor 100a identifies the locations of the other collapse sensors 100b and 100c by transmitting and receiving laser light with them (S2). Specifically, the collapse sensor 100a identifies the direction in which each of the other collapse sensors 100b and 100c is located, based on the direction in which the laser light was reflected back from the other collapse sensors 100b and 100c, i.e., the direction in which the laser light was transmitted and received between the other collapse sensors 100b and 100c. The collapse sensor 100a also identifies the distance from the collapse sensor 100a to each of the collapse sensors 100b and 100c based on the time required for transmitting and receiving the laser light. 【0022】 The direction of other collapse sensors 100 identified by the collapse sensor 100 includes the direction of other collapse sensors 100 in the horizontal plane and the direction of other collapse sensors 100 in the vertical plane, as viewed from the collapse sensor 100 which is the source of the laser beam. For example, the collapse sensor 100a identifies the location of other collapse sensors 100b such that, as viewed from the collapse sensor 100a, there is a collapse sensor 100b at a direction of 45 degrees northeast with an elevation of 30 degrees, and the straight-line distance from the collapse sensor 100a to the collapse sensor 100b is 11m. However, the direction of other collapse sensors 100 identified by the collapse sensor 100 may be limited to the direction in the horizontal plane only. 【0023】 Each collapse sensor 100 can communicate wirelessly with other collapse sensors 100 to send and receive information. The method of communication between the collapse sensors 100 is not particularly limited and may be a method of communication using radio waves or a method of optical communication using laser light. Inside each collapse sensor 100, identification information that can uniquely identify each collapse sensor 100 is stored. Collapse sensor 100a communicates with other collapse sensors 100b and 100c that have reflected laser light to obtain the identification information of each collapse sensor 100b and 100c, whose direction and position have been determined. 【0024】 Similarly, the other collapse sensors 100b to 100e are scanned with laser light within a predetermined angular range vertically in a 360-degree radius around them to determine the direction and distance of each of the surrounding collapse sensors 100, and identification information for each collapse sensor 100 is acquired by wireless communication using radio waves or laser light. 【0025】 Each collapse sensor 100 transmits the location information and identification information of the other collapse sensors 100 obtained in this manner to the other collapse sensors 100 (S3). For example, collapse sensor 100a generates data A, which associates the identification information of collapse sensor 100a, information indicating that collapse sensor 100a is the source of the laser beam, and the identification information, direction, and distance of the other collapse sensors 100b and 100c obtained by transmitting laser beam from collapse sensor 100a. The other collapse sensors 100b to 100e similarly generate data B to E. 【0026】 For example, each collapse sensor 100 transmits data received from another collapse sensor 100 to yet another collapse sensor 100. Collapse sensor 100b transmits data B to collapse sensor 100a, and collapse sensor 100a transmits data B to collapse sensor 100d, and so on, allowing data to be transmitted in a bucket brigade-like manner by multiple collapse sensors 100. 【0027】 Furthermore, for example, each collapse sensor 100 adds its own generated data to the data received from other collapse sensors 100 and transmits it to yet another collapse sensor 100. As shown by the solid arrows in Figure 1, when collapse sensors 100b and 100c transmit data B and data C to collapse sensor 100a, collapse sensor 100a adds data A to the received data B and C and transmits it to collapse sensor 100d. Collapse sensor 100d then transmits the data containing data A, B, C, and D to the next collapse sensor 100. 【0028】 In this way, by sending and receiving data between communicationable collapse sensors 100, data can be transmitted from collapse sensors 100 that cannot directly transmit data to the monitoring device 200 to the monitoring device 200 via other collapse sensors 100. 【0029】 Data is transmitted and received between the collapse sensors 100, and the data from all the collapse sensors 100 is aggregated in the monitoring device 200 (S4). The aggregated data includes identification information of other collapse sensors 100 in the vicinity, as identified by each collapse sensor 100, and information indicating the direction and distance to the other collapse sensors 100. The monitoring device 200 analyzes the aggregated data to determine the positional relationship of each collapse sensor 100. 【0030】 Each collapse sensor 100 repeatedly performs the following processes: transmitting and receiving laser light to identify the direction and distance of other collapse sensors 100, and transmitting data including identification information, direction, and distance to the other collapse sensors 100. For example, each process is repeatedly executed at predetermined intervals, and the data obtained from all collapse sensors 100 is aggregated in the monitoring device 200. 【0031】 Furthermore, after identifying the surrounding collapse sensors 100, the collapse sensors 100 may transmit laser light to scan only within a predetermined range that includes the identified direction, i.e., the direction in which other collapse sensors 100 are located, rather than transmitting laser light to scan the entire 360 ​​degrees around them. 【0032】 Each time the monitoring device 200 receives data from the collapse sensors 100, it identifies the relative positions of each collapse sensor 100. Based on the change in the relative positions of each collapse sensor 100, the monitoring device 200 detects the occurrence of a collapse (S5). Since the collapse sensors 100 are fixed to the slope of the mountain, if the slope shifts, the position of the collapse sensors 100 shifts, and the relative positions of the collapse sensors 100 change. The monitoring device 200 detects a collapse based on this change in relative positions. 【0033】 The positional changes detected by the monitoring device 200 include changes in the direction of other collapse sensors 100 as seen from the collapse sensor 100, and changes in the distance between the collapse sensors 100. It also includes the presence of a collapse sensor 100 that can no longer be detected. For example, if data indicating the direction and distance of collapse sensor 100b can no longer be obtained from collapse sensor 100a, which had previously identified the direction and distance of collapse sensor 100b, the monitoring device 200 will determine that the positional relationship between collapse sensor 100a and collapse sensor 100b has changed. 【0034】 The monitoring device 200 can detect both changes in the relative position of the collapse sensor 100 before a collapse occurs and changes in the relative position of the collapse sensor 100 after a collapse occurs. In other words, the monitoring device 200 can detect both changes in the relative position of the collapse sensor 100 that indicate an impending collapse and changes in the relative position of the collapse sensor 100 that result from the collapse occurring. 【0035】 The monitoring device 200, upon detecting a collapse, performs a predetermined notification process to inform the user of the collapse detection system 1 of the detection result. The content of the notification process is not particularly limited, but for example, the monitoring device 200 may be equipped with a display device and notify the user by displaying information indicating that a collapse has been detected on the display device. The monitoring device 200 may be equipped with a speaker and notify the user by playing a sound through the speaker indicating that a collapse has been detected. The monitoring device 200 may also notify an external device of the detection result, and the external device may notify the user that a collapse has been detected by display or sound. 【0036】 Figure 2 shows an example of notification processing performed by the monitoring device 200. Figure 2 shows an example of notification processing using a communication terminal 300 such as a smartphone. The black circles in Figure 2 indicate multiple landslide sensors 100 installed on a mountain slope. The monitoring device 200 communicates with one or more landslide sensors 100 to aggregate data from all landslide sensors 100, identify the positional relationship of each landslide sensor 100, and monitor changes in the positional relationship. When the monitoring device 200 detects a change in the positional relationship, it communicates wirelessly with the communication terminal 300 to display information regarding the detection result on the display unit 400 of the communication terminal 300. 【0037】 For example, the monitoring device 200 creates a mesh model of the mountain slope based on the positional relationship of each collapse sensor 100, as shown by the dashed line in Figure 2. It then categorizes the magnitude of the change in the positional relationship of the collapse sensors 100 into levels for each element of the mesh model, i.e., for each region of the mountain slope, and displays this on the display unit 400. By pre-preparing settings in the storage unit 230 that show the correspondence between the change in the positional relationship of the collapse sensors 100 and each level, the monitoring device 200 displays the collapse information based on these settings on the display unit 400 of the communication terminal 300. 【0038】 For example, as shown in Figure 2, if a larger displacement is detected in region 422 than in region 421, region 422 and region 421 are displayed distinctly on the mountain graphic display 410 on the display unit 400. For example, region 422 and region 421 are displayed in different colors. 【0039】 Furthermore, the display unit 400 displays information 430 indicating areas requiring vigilance. By pre-preparing settings in the memory unit 230 (see Figure 3) that show the correspondence between the amount of change in the positional relationship of the collapse sensor 100 and the criteria for determining whether vigilance is necessary, and settings that show the correspondence between the collapse sensor 100 and the surrounding area of ​​the mountain, the monitoring device 200 displays vigilance information based on these settings on the display unit 400 of the communication terminal 300. Users of the collapse detection system 1 can recognize that signs of a collapse or the occurrence of a collapse have been detected by receiving the information shown in Figure 2 on the screen of a smartphone or the like, and can recognize whether evacuation or other vigilance is necessary and take appropriate action. If the communication terminal 300, such as a smartphone, has a function to acquire its own location information, the vigilance information may be selectively notified to the communication terminals 300 located in areas requiring evacuation or other vigilance based on the location information acquired by the communication terminal 300. For example, the monitoring device 200 can select the communication terminals 300 located in areas requiring vigilance and notify each selected terminal 300 that evacuation or other vigilance is necessary, along with the information shown in Figure 2. 【0040】 [Configuration of the collapse detection system] An example configuration of the collapse detection system 1 will be described. Figure 3 is a block diagram showing an example configuration of the collapse detection system 1. In addition to the collapse sensor 100 and the monitoring device 200, the collapse detection system 1 may also include a communication terminal 300. For example, a terminal such as a smartphone equipped with a display unit, an operation unit, a storage unit, and a communication unit may be used as the communication terminal 300. In the example shown in Figure 3, the collapse sensor 100 and the monitoring device 200 communicate using optical wireless communication, but the communication method is not particularly limited and may also be wireless communication using radio waves. The communication method between the monitoring device 200 and the communication terminal 300 is also not particularly limited and may be wireless communication using radio waves or laser light, or it may be wired communication. 【0041】 The collapse sensor 100 shown in Figure 3 includes an optical communication unit 110, a control unit 120, and a storage unit 130. The storage unit 130 is used to store identification information of the collapse sensor 100, the direction and distance of other collapse sensors 100 identified by transmitting and receiving laser light, identification information of other collapse sensors 100, and data received from other collapse sensors 100. The storage unit 130 is also used to store various data necessary for the operation of the control unit 120. The functions and operation of the collapse sensor 100 described in this embodiment are realized by the control unit 120 controlling each part of the collapse sensor 100 while utilizing the various data stored in the storage unit 130. 【0042】 The optical communication unit 110 includes a transmitting unit 111 that transmits laser light, a receiving unit 112 that receives laser light from other collapse sensors 100, and a changing unit 113 that changes the direction of transmission and reception of laser light, but details will be described later. 【0043】 The control unit 120 includes an optical communication control unit 121 and a data output unit 122. The optical communication control unit 121 controls the operation of the optical communication unit 110. Specifically, the optical communication control unit 121 controls the modification unit 113 of the optical communication unit 110 to change the direction of transmission and reception of laser light by the optical communication unit 110. The optical communication control unit 121 also controls the transmission of laser light from the transmission unit 111 and the reception of laser light by the reception unit 112. As a result, the collapse sensor 100 can change the transmission and reception direction of the laser light transmitted and received by the optical communication unit 110, identify the direction of other collapse sensors 100 and the distance to those other collapse sensors 100, and communicate with other collapse sensors 100 to send and receive data. 【0044】 The data output unit 122 transmits the identification information, direction, and distance of the other collapse sensor 100 obtained by the optical communication unit 110, along with the data received from the other collapse sensor 100, to the other collapse sensor 100. Data transmission is performed using the optical communication unit 110. For example, data transmission and reception via optical communication is performed when a collapse sensor 100a, whose laser beam transmission and reception direction is changed to face the direction of collapse sensor 100b, and a collapse sensor 100b, whose laser beam transmission and reception direction is changed to face the direction of collapse sensor 100a, transmit and receive laser beams. 【0045】 The monitoring device 200 includes a communication unit 210, a control unit 220, and a storage unit 230. The monitoring device 200 may further include an operation unit and a display unit. The communication unit 210 performs communication with the collapse sensor 100 and with the communication terminal 300. The storage unit 230 is used to store data received from the collapse sensor 100. The storage unit 230 is also used to store various data necessary for the operation of the control unit 220. The functions and operation of the collapse detection system 1 described in this embodiment are realized by the control unit 220 controlling each unit while utilizing the various data stored in the storage unit 230. 【0046】 The control unit 220 includes a data analysis unit 221, a collapse detection unit 222, and a notification unit 223. The data analysis unit 221 analyzes the data received from each collapse sensor 100 to determine the relative positions of the collapse sensors 100. 【0047】 The collapse detection unit 222 detects a collapse based on the analysis results obtained by the data analysis unit 221. The determination conditions for detecting a collapse are prepared in advance in the storage unit 230. The collapse detection unit 222 determines that a collapse has occurred when the positional relationship of the collapse sensors 100 identified by the data analysis unit 221 changes by more than a predetermined threshold. For example, a collapse is determined to have occurred when the distance between the collapse sensors 100 changes by more than a threshold, when the direction between the collapse sensors 100 changes by more than a threshold, or when there are collapse sensors 100 whose direction and distance can no longer be determined. 【0048】 When the collapse detection unit 222 detects a collapse, the notification unit 223 notifies the communication terminal 300 via the communication unit 210. The communication terminal 300 notifies the user of the collapse by displaying, for example, the screen shown in Figure 2. The communication terminal 300 may also emit an alarm sound. 【0049】 [Example of a collapse sensor configuration] Figure 4 shows an example of the configuration of the collapse sensor 100. Figure 4(a) shows a side view of the main body 101 of the collapse sensor 100, and Figure 4(b) shows a top view of the main body 101. The collapse sensor 100 has a stake-like shape in which a cylindrical main body 101 is attached to the upper end of a support column 102 which has an axial shape. For example, the support column 102 and the main body 101 are configured to be detachable, and the support column 102 is driven into the slope of a mountain and fixed, and then the main body 101 is fixed to the upper end of the support column 102 for use. 【0050】 The waterproof main body 101 houses multiple optical communication units 110 (110a to 110f) and a control board 600. The control board 600 includes a control unit 120, a memory unit 130, and a battery, and the collapse sensor 100 can be operated by power supplied from the battery. 【0051】 The reflective member 610 receives laser light transmitted from other collapse sensors 100 and reflects the laser light in the direction from which it was transmitted. As shown in Figure 4(b), the reflective member 610 is provided on the entire side surface of the cylindrical main body 101 near the upper end of the side surface, around the cylindrical axis, so that it can receive and reflect laser light from other collapse sensors 100 installed in the vicinity. The type of reflective member 610 is not particularly limited, but for example, a sheet member made by arranging microprisms having a retroreflective structure may be used as the reflective member 610. Alternatively, for example, multiple corner reflectors having a retroreflective function may be provided along the outer peripheral side surface of the main body 101 and used as the reflective member 610. Note that the reflective member 10 is not limited to being provided around the collapse sensor 100 in a 360-degree radius, but may be provided to reflect laser light transmitted from other collapse sensors 100 within a certain angular range of the 360-degree radius. For example, when multiple landslide sensors 100 are installed and used in a band-shaped area set on a mountain slope, a reflective member 610 should be provided so as to reflect the laser light within the range that covers this band-shaped area. If the direction in which the laser light is reflected can be limited, a concave mirror or the like may be used as the reflective member 610. 【0052】 The optical communication unit 110 identifies the direction of other collapse sensors 100 and the distance to those other collapse sensors 100 by transmitting and receiving laser light. The optical communication unit 110 also transmits and receives data with other collapse sensors 100 via optical communication that transmits and receives laser light. As shown in Figure 4(b), by providing multiple communication units 110a to 110f inside the main body 101, the collapse sensor 100 can change the direction of transmission and reception of laser light around the main body 101 in a 360-degree radius around the support column 102. Furthermore, the collapse sensor 100a can change the angle at which it transmits and receives laser light in the axial direction of the support column 102 in a 360-degree radius. 【0053】 Figure 5 is a diagram illustrating how the optical communication unit 110 changes the direction of transmission and reception of laser light. Figures 5(a) to 5(c) show coordinate axes to illustrate the relationships between each component. The Z-axis shown in Figure 5 indicates the axial direction of the support column 102. Depending on the angle at which the support column 102 is driven into the slope of the mountain, the axial direction (Z-axis) may not coincide with the vertical direction, but for the sake of simplicity, the following explanation will assume that the Z-axis is the vertical direction and the X-axis and Y-axis are the horizontal directions. 【0054】 As shown in Figure 5(b), the laser beam 801 emitted from the transmitting unit 111 in the Z-axis direction passes through the half mirror 700 and travels upward. The laser beam 804 received from the other collapse sensor 100 is reflected by the half mirror 700 and received by the receiving unit 112. Alternatively, an optical circulator may be used instead of the half mirror 700 to transmit the laser beam 801 and receive the laser beam 804. 【0055】 The changing unit 113 for changing the transmission direction of the laser beam 801 includes a vertical reflector 710 (710a to 710e) and a horizontal reflector 720 (720a to 720e). The vertical reflector 710 is configured to be switchable between a transmission state that transmits the laser beam 801 and a reflection state that reflects the laser beam 801. For example, the switching between the transmission state and the reflection state is electrically controlled by whether or not a voltage is applied to the vertical reflector 710. 【0056】 By setting the vertical reflector 710a to a reflective state, the laser beam 801 is reflected by the vertical reflector 710a. By setting the vertical reflector 710a to a transparent state and the vertical reflector 710b to a reflective state, the laser beam 801 is reflected by the vertical reflector 710b. By setting the vertical reflectors 710a and 710b to transparent states and the vertical reflector 710c to a reflective state, the laser beam 801 is reflected by the vertical reflector 710c. By setting the vertical reflectors 710a to 710c to transparent states and the vertical reflector 710d to a reflective state, the laser beam 801 is reflected by the vertical reflector 710d. By setting the vertical reflectors 710a to 710d to transparent states and the vertical reflector 710e to a reflective state, the laser beam 801 is reflected by the vertical reflector 710e. 【0057】 As shown in Figure 5(b), the five vertical reflectors 710a to 710e are arranged in a line vertically (Z-axis direction) at different angles so that they reflect the laser beam 801 incident from the same direction at different angles. This allows the collapse sensor 100 to change the reflection direction within the vertical plane within the angle Av formed by the reflection direction of the bottom vertical reflector 710a and the reflection direction of the top vertical reflector 710e. 【0058】 By controlling each of the vertical reflectors 710a to 710e to either a transmission or reflection state, the laser beam 802 (802a to 802e) reflected at the reflection angles of each of the vertical reflectors 710a to 710e is transmitted to the horizontal reflector 720, as shown in Figure 5(b). The laser beam 802 transmitted from the vertical reflector 710 is incident on the horizontal reflector 720 and reflected, as shown in Figure 5(c). 【0059】 By setting the horizontal reflector 720a to a reflective state, the laser beam 802 is reflected by the horizontal reflector 720a. By setting the horizontal reflector 720a to a transparent state and the horizontal reflector 720b to a reflective state, the laser beam 802 is reflected by the horizontal reflector 720b. By setting the horizontal reflectors 720a and 720b to transparent states and the horizontal reflector 720c to a reflective state, the laser beam 802 is reflected by the horizontal reflector 720c. By setting the horizontal reflectors 720a to 720c to transparent states and the horizontal reflector 720d to a reflective state, the laser beam 802 is reflected by the horizontal reflector 720d. By setting the horizontal reflectors 720a to 720d to transparent states and the horizontal reflector 720e to a reflective state, the laser beam 802 is reflected by the horizontal reflector 720e. 【0060】 As shown in Figure 5(c), five horizontal reflectors 720a to 720e are arranged in a line horizontally (Y-axis direction) at different angles so that they reflect the laser beam 802 incident from the same direction at different angles. This allows the collapse sensor 100 to change the reflection direction in the horizontal plane within the angle Ah formed by the reflection directions of the two outer horizontal reflectors 720a and 720e. 【0061】 The laser beams 802a to 802e, reflected by the five vertical reflectors 710a to 710e, are then reflected in five different directions by the horizontal reflectors 720a to 720e. As shown in Figure 5(c), the laser beams 803 (803a to 803e) reflected at the reflection angles of each horizontal reflector 720a to 720e are transmitted towards the other collapse sensors 100. 【0062】 While maintaining the transmission or reflection state of each vertical reflector 710a to 710e and the transmission or reflection state of each horizontal reflector 720a to 720e, the laser beam 804 reflected by the reflective member 610 of the other collapse sensor 100 returns to the half mirror 700 by following the reverse path from when it was transmitted, is reflected by the half mirror 700, and is received by the receiving unit 112. 【0063】 Figure 5(a) schematically illustrates how the direction of transmission and reception of laser light is changed for clarity. Therefore, the transmission and reception direction by the horizontal reflector 720a and the transmission direction by the horizontal reflector 720e appear to be shifted vertically (Z-axis direction). However, in reality, laser light is transmitted and received in multiple directions from approximately the same vertical position, with the horizontal angle changed. Note that if the axis direction of the support column 102 of the collapse sensor 100 is shifted from the vertical direction, the direction shown as vertical in Figure 5 will be the axis direction of the support column 102 of the collapse sensor 100, and the direction shown as horizontal will be perpendicular to the axis direction of the support column 102. 【0064】 Figure 5 does not limit the number of horizontal reflectors 720. Furthermore, while Figure 5 shows an example where a set of horizontal reflectors 720a to 720e are used to change the reflection direction within the horizontal plane, multiple sets may also be used. 【0065】 For example, when using horizontal reflectors 720 in a two-stage configuration, each pair of horizontal reflectors 720 placed in the first stage reflects laser light in multiple different directions within the horizontal plane. A pair of horizontal reflectors 720 in the second stage are placed corresponding to each reflection direction of the horizontal reflectors 720 in the first stage. Then, each horizontal reflector 720 placed in the second stage reflects laser light in multiple directions within the horizontal plane that are different from the reflection directions of the first stage. 【0066】 Specifically, for example, with a predetermined direction in the horizontal plane defined as 0 degrees, the first stage horizontal reflector 720 is arranged to reflect the laser beam in six different directions: 0 degrees, 10 degrees, 20 degrees, 30 degrees, 40 degrees, and 50 degrees. Furthermore, the second stage horizontal reflector 720 is arranged to reflect each laser beam reflected by the first stage at angles of 0-9 degrees, 10-19 degrees, 20-29 degrees, 30-39 degrees, 40-49 degrees, and 50-59 degrees, respectively. As a result, the optical communication unit 110 can transmit and receive laser beam while changing the reflection angle in 1-degree increments from 0 to 59 degrees using the first and second stage horizontal reflectors 720. By arranging six of these optical communication units 110 at 60-degree intervals around the axis of the support column 102, as shown in Figure 4(b), the collapse sensor 100 can transmit and receive laser beam in 360-degree directions in the horizontal plane at 1-degree intervals. Furthermore, the number of stages and the number of horizontal reflectors 720 used in each stage are not particularly limited. 【0067】 The number of vertical reflectors 710 is not limited, and, similar to the horizontal reflectors 720 consisting of multiple stages described above, multiple vertical reflectors 710 may be used as a set, with multiple sets being used in a multi-stage configuration. 【0068】 Figure 5 shows an example in which a single optical communication unit 110 includes a transmitting unit 111 and a receiving unit 112. However, multiple optical communication units 110 may utilize a single transmitting unit 111. For example, as shown in Figure 6(a), a laser beam 801 transmitted by a single transmitting unit 111 may be split into multiple laser beams 811 (811a, 811b) by an optical splitter 115, reflected by a mirror 116, and transmitted to the half-mirrors 700 of each of the multiple optical communication units 110. 【0069】 Similarly, on the receiving side, multiple optical communication units 110 may utilize a single receiving unit 112. For example, as shown in Figure 6(b), multiple laser beams 814 (814a, 814b) reflected by the half-mirrors 700 of each of the multiple optical communication units 110 may be transmitted to a single receiving unit 112 using an optical coupler 118. When laser beams are transmitted and received simultaneously by multiple optical communication units 110, as shown in Figure 6(b), optical shutters 117 (117a, 117b) corresponding to each optical communication unit 110 may be provided, and the optical communication control unit 121 may control the optical shutters 117 so that only one optical communication unit 110 receives the laser beam. 【0070】 Figure 5 shows an example of changing the reflection direction using multiple members that can switch between transmitting and reflecting laser light, but it is also possible to use a single member. For example, as shown in Figure 7(a), a liquid crystal reflective member 900 is used, which contains a large number of liquid crystal molecules 910 whose arrangement changes depending on the applied voltage, between a transparent plate-shaped member 901 on which a large number of transparent electrodes 911 are arranged and a transparent plate-shaped member 902 on which a large number of transparent electrodes 912 are arranged. As shown in Figure 7(a), when laser light 801 is incident on this liquid crystal reflective member 900 from one end, the laser light 801 is transmitted to the other end. 【0071】 As shown in Figure 7(b), when a voltage is applied between the transparent electrode 911a of the transparent plate-like member 901 and the transparent electrode 912a of the transparent plate-like member 902, the arrangement of liquid crystal molecules 910 changes in the region connecting these transparent electrodes 911a and 912a, as shown by the dashed line in Figure 7(b), causing the laser light to be reflected. As shown in Figure 7(c), by changing the transparent electrodes to which the voltage is applied to transparent electrodes 911b and 912b, the reflection direction of the laser light 801 can be changed to a direction different from the reflection direction shown in Figure 10(b). 【0072】 By replacing the vertical reflector 710 shown in Figure 5 with the liquid crystal reflector 900 shown in Figure 7, it becomes possible to control the reflection direction of the laser light in a vertical plane in multiple different directions by changing the transparent electrodes 911 and 912 of the liquid crystal reflector 900 to which voltage is applied. Similarly, the horizontal reflector 720 can also be replaced with the liquid crystal reflector 900 to control the reflection direction of the laser light in a horizontal plane in multiple different directions. Either the vertical reflector 710 or the horizontal reflector 720 may be replaced with the liquid crystal reflector 900, or both may be replaced with the liquid crystal reflector 900. Control of the liquid crystal reflector 900 can be achieved by storing a pre-prepared setting based on the relationship between the transparent electrodes 911 and 912 to which voltage is applied and the reflection angle of the laser light in the memory unit 130 of the collapse sensor 100, and then the optical communication control unit 121 can perform electrical control of the liquid crystal reflector 900 based on this setting. 【0073】 The laser light transmission and reception method described in this embodiment is illustrative, and other methods of transmitting and receiving laser light are also acceptable as long as the direction of transmission and reception of the laser light can be controlled as described above. For example, optical elements such as wide-angle lenses, fisheye lenses, and mirrors may be placed in the path of the laser light in the collapse sensor 100 to change the direction of transmission and reception of the laser light. For example, if a fisheye lens is provided on the top of the collapse sensor 100 and the distance measurement wave is transmitted and received from the collapse sensor 100 via the fisheye lens, the irradiation range of the laser light can be expanded while keeping the size of the collapse sensor 100 the same. In this case, in the example shown in Figure 5, the number, placement, and direction of the modification units 113, the configuration of the modification units 113, etc., should be changed so that the distance measurement wave can be transmitted and received in a desired range via the fisheye lens. 【0074】 In this embodiment, an example is shown in which the reflection direction of laser light is changed using a component that can be switched between transmission and reflection by electrical control. However, the reflection direction of laser light may also be changed mechanically. For example, an actuator is provided to rotate the component that transmits and receives laser light around the X axis as shown in Figure 5. If this actuator is rotated around the Z axis by another actuator, the transmission and reception direction of the laser light can be changed 360 degrees horizontally, and the transmission and reception direction of the laser light can also be changed vertically in each direction. In addition, the transmission and reception direction of laser light may also be changed using one or more MEMS (Micro Electro Mechanical Systems) type mirrors. 【0075】 In this embodiment, an example is shown in which other collapse sensors 100 are searched for by scanning a 360-degree area around the collapse sensor 100 with laser light. However, the scanning range of the collapse sensor 100 may be less than 360 degrees. For example, if it is sufficient to search only for other collapse sensors 100 located below the collapse sensor 100 on a mountain slope, a collapse sensor 100 may be used in which the scanning range of the laser light is narrowed to a range of less than 360 degrees that includes the search range. 【0076】 As described above, according to the collapse detection system and collapse detection method of this embodiment, the collapse sensor can irradiate a laser beam to scan its surroundings, search for other collapse sensors that reflect the laser beam, and determine the direction and distance of these collapse sensors. Therefore, even when using a large number of collapse sensors, there is no need to perform optical axis alignment work between each collapse sensor. Furthermore, by having the collapse sensor transmit data including the direction and distance of other collapse sensors and identification information to other collapse sensors, the data from each collapse sensor is aggregated to the monitoring device via one or more collapse sensors. Therefore, the monitoring device can acquire data from all collapse sensors, including data from collapse sensors located in distant places that cannot communicate directly. The monitoring device can determine the positional relationship of each collapse sensor from the information contained in the data and detect a collapse by monitoring changes in the positional relationship using data transmitted periodically from each collapse sensor. Since there is no need to send and receive laser beams to and from distant collapse sensors, and there is no need to perform optical axis alignment between collapse sensors, the collapse detection system can be easily introduced and used. [Industrial applicability] 【0077】 As described above, the collapse detection system and collapse detection method described herein are useful for facilitating the introduction and use of the collapse detection system. [Explanation of Symbols] 【0078】 1. Collapse detection system 100 (100a~100e) Collapse Sensor 101 (101a~101e) Main body 102(102a~102e) Post part 110(110a~110f) Optical communication department 111 Transmitter 112 Receiving Unit 113 Changes 115 Optical Splitter 116 Mirror 117 Light Shutter 118 Optical coupler 120, 220 Control Unit 130, 230 storage section 200 Monitoring equipment 210 Communications Department 300 communication terminals 400 Display 610 Reflective material 700 Half Mirror 710(710a~710e) Vertical reflector 720(720a~720e) Horizontal reflector 900 Liquid crystal reflective material 901, 902 Transparent plate-like member 911(911a, 911b), 912(912a, 912b) Transparent electrode

Claims

[Claim 1] Multiple collapse sensors are configured to scan the surroundings by irradiating laser light in multiple directions and to reflect laser light transmitted from other collapse sensors, and to receive laser light reflected by one or more other collapse sensors in the surroundings to determine the direction of each collapse sensor and the distance to each collapse sensor in the surroundings. A monitoring device that detects a collapse based on changes in the positional relationship between multiple collapse sensors, which are placed at a distance from each other in the area to be targeted for collapse detection, by acquiring information related to the direction and distance of other collapse sensors identified by each collapse sensor, and determining the positional relationship between the multiple collapse sensors. A collapse detection system characterized by having the following features. [Claim 2] The collapse detection system according to claim 1, characterized in that the collapse sensor searches for other collapse sensors in the surrounding area by scanning the laser beam within a predetermined angle range in the vertical direction of a 360-degree radius. [Claim 3] The collapse detection system according to claim 1, characterized in that the collapse sensor generates data including identification information for identifying each collapse sensor and the direction and distance of other collapse sensors identified by transmitting and receiving the laser light, and transmits and receives this data with other collapse sensors in the vicinity so that the data obtained by each collapse sensor is delivered to the monitoring device via one or more collapse sensors. [Claim 4] The collapse detection system according to claim 3, characterized in that the collapse sensor transmits the generated data and the data received from other collapse sensors to yet another collapse sensor. [Claim 5] The collapse detection system according to claim 3 or 4, characterized in that the collapse sensor transmits and receives data by optical wireless communication using the laser light. [Claim 6] The aforementioned collapse sensor is The system has multiple reflectors that can switch between a transmission state in which the laser light is transmitted and a reflection state in which the laser light is reflected. Multiple reflectors, arranged at different angles to reflect the laser light incident from a predetermined direction in different directions, control the switching between the transmission state and the reflection state of each reflector, thereby transmitting and receiving the laser light in multiple different directions. The collapse detection system according to feature 1. [Claim 7] The aforementioned collapse sensor is The device has a reflector capable of changing the reflection direction of the laser light by changing the arrangement of liquid crystal molecules, By controlling the arrangement of liquid crystal molecules in the reflector, the laser light is transmitted and received in multiple different directions. The collapse detection system according to feature 1. [Claim 8] The aforementioned collapse sensor is A first reflecting unit that uses the reflector to reflect the laser light in multiple different directions within a predetermined surface, A second reflecting section further reflects each laser beam reflected by the first reflecting section in multiple different directions within the predetermined surface using another reflecting plate. including The collapse detection system according to claim 6 or 7, characterized by the features described above. [Claim 9] The process involves each of several collapse sensors, positioned at a distance from each other in the area to be detected for collapse, emitting laser light in multiple directions to scan the surroundings, and determining the direction of each surrounding collapse sensor and the distance to each collapse sensor based on the laser light reflected by one or more other collapse sensors in the surroundings. The monitoring device acquires information from a plurality of the collapse sensors regarding the direction and distance of other collapse sensors identified by each collapse sensor, and determines the positional relationship of the plurality of collapse sensors. The monitoring device performs the steps of detecting a collapse based on the change in the positional relationship. A collapse detection method characterized by including the following.

Images