JP7795897B2 - Identification marker, method of use thereof, and safety monitoring system - Google Patents

Description

One embodiment of the present invention relates to an identification marker, a method for using the same, and a safety monitoring system. In particular, the invention relates to an identification marker for identifying specific areas at worksites where construction work, such as building construction and civil engineering work, is carried out.

Conventionally, one known technology for recognizing specific positions at a work site involves placing a landmark at the specific target position and detecting the specific position based on the position of the landmark. For example, Patent Document 1 discloses a technology in which identification markers such as two-dimensional codes are placed on the floor of the work site, the identification markers are extracted from images taken of the floor of the work site with a camera placed at an elevated position using image processing, and the specific position is detected based on the extracted identification markers.

Patent Document 2 also discloses a technology in which endpoint markers (road cones) are placed around a no-entry area such as a work site, and the endpoint markers are extracted from images taken of the work site by a camera placed at an elevated position using image processing, and the location of the no-entry area is identified based on the extracted endpoint markers.

Japanese Patent Application Laid-Open No. 2019-078569 Japanese Patent Application Laid-Open No. 2019-016836

When using planar identification markers such as two-dimensional codes as identification markers, as in the above-mentioned conventional technology, the identification marker may not be recognized correctly depending on the camera's angle of view due to the effects of tilt or the reflection of sunlight or lighting. Furthermore, when a planar identification marker is placed on the floor, there is a problem that it may be easily blocked from the camera by work objects placed on it depending on the installation location. Furthermore, when using road cones as identification markers, the accuracy of shape recognition decreases when the road cone is photographed from an angle close to directly above, and it may not be recognized as a road cone.

An object of one embodiment of the present invention is to provide an identification marker that can be stably recognized regardless of the position of the imaging device. Another object of one embodiment of the present invention is to provide a safety monitoring system that uses an identification marker that can be stably recognized regardless of the position of the imaging device.

In one embodiment of the present invention, the identification marker is composed of a spherical member having a bottomed hole with an opening diameter of 50 mm or more. The diameter of the spherical member may be 250 mm or more. The identification marker may further include a threaded portion having a first end fixed to the bottom of the bottomed hole and a second end protruding from the bottomed hole.

The identification marker may further have an attachment portion configured to fit into the bottomed hole. In this case, the spherical member may have a threaded hole at the bottom of the bottomed hole. The attachment portion may include a first threaded portion that screws into the threaded hole, and a second threaded portion that is provided on a second surface opposite to the first surface on which the first threaded portion is provided. The first threaded portion and the second threaded portion may have different nominal diameters.

The spherical member may be colored purple, yellow, or green. The surface of the spherical member may be marked with a plurality of circular or polygonal figures positioned point-symmetrically about the center of the spherical member.

In one embodiment of the present invention, the method of using the identification marker involves fitting the bottomed hole of the above-mentioned identification marker into the tip of the road cone, thereby combining the identification marker with the road cone.

In one embodiment of the present invention, the method of using the identification marker involves attaching the threaded portion of the above-mentioned identification marker to a clamp, thereby using the identification marker in combination with the clamp.

In one embodiment of the present invention, the method of using the identification marker is to attach the second screw portion of the above-described identification marker to a tripod or a clamp, and then use the identification marker in combination with the tripod or the clamp.

In one embodiment of the present invention, the safety monitoring system comprises an imaging device that captures images of a specified space, a monitoring device that analyzes the captured images transmitted from the imaging device, and an identification marker placed within the space. The identification marker is composed of a spherical member with a bottomed hole having an opening diameter of 50 mm or more, and the monitoring device identifies the area to be monitored by extracting the identification marker from the captured images obtained from the imaging device.

The monitoring device may detect whether a person is present in or around the monitored area based on the captured image.

When the monitoring device determines that the person is present in the monitored area, it may transmit an instruction signal to other information processing devices to notify them that a person has entered the monitored area.

The safety monitoring system may further include an alarm device that issues an alarm within the space. In this case, when the monitoring device determines that the person is present in the vicinity of the monitored area, it may send an instruction signal to the alarm device to issue the alarm.

1 is a schematic diagram showing the configuration of a safety monitoring system according to an embodiment of the present invention; 1 is a diagram showing the configuration of an identification marker in one embodiment of the present invention. FIG. 1 is a diagram showing the configuration of an identification marker in one embodiment of the present invention. FIG. FIG. 10 is a schematic diagram showing the configuration of a safety monitoring system according to a modified example of an embodiment of the present invention. 1 is a block diagram showing the configuration of a safety monitoring system according to an embodiment of the present invention. FIG. 4 is a flowchart illustrating the operation of the monitoring device according to the embodiment of the present invention. 10A and 10B are diagrams illustrating the configuration of an identification marker according to another embodiment of the present invention.

Embodiments of the present invention will be described below with reference to the drawings. However, the present invention can be embodied in various forms without departing from the spirit of the present invention, and should not be construed as being limited to the description of the embodiments exemplified below. To clarify the explanation, the drawings may show the width, thickness, size, shape, etc. of each part schematically compared to the actual form, but these are merely examples and do not limit the interpretation of the present invention. In this specification and each drawing, elements with functions similar to those described with reference to previous drawings may be assigned the same reference numerals, and redundant explanations may be omitted.

For the sake of convenience, the present specification may use the terms "top," "upper," or "top," or "bottom," "lower," or "lower," but these merely describe the relative positional relationships between elements or parts. For example, when describing an object, the direction in which gravity acts may be referred to as "down" and the opposite direction as "up," based on the way the object is normally used.

(First embodiment)
[Configuration of safety monitoring system]
1 is a schematic diagram showing the configuration of a safety monitoring system 1000 according to an embodiment of the present invention. The safety monitoring system 1000 of this embodiment includes at least an identification marker 100, an imaging device 200, and a monitoring device 300.

The safety monitoring system 1000 is a system for monitoring specific areas at work sites such as construction sites and civil engineering work sites. The specific area (hereinafter referred to as the "monitored area") is, for example, an unsafe area where safety cannot be ensured, and in this embodiment, it is a no-entry area. In Figure 1, an opening formed in the soil is set as the monitored area 400, and whether or not a person 500 has entered the monitored area 400 is monitored. However, the monitored area 400 is not limited to this example and can be set arbitrarily depending on the purpose of monitoring.

As shown in FIG. 1, multiple identification markers 100 are placed around the monitored area 400. In the safety monitoring system 1000 of this embodiment, an identification marker 100 is placed at each of the four corners of the opening that is the monitored area 400. Here, the identification markers 100 are installed on top of the traffic cones 150, and the traffic cones 150 are placed at each corner of the monitored area 400.

The imaging device 200 functions as a surveillance camera that captures images of the work site from a high vantage point. That is, the imaging device 200 captures bird's-eye images of the work site. It is preferable that the imaging device 200 captures images in video format, but if there are no moving objects such as people, it may switch to still image format, which captures still images intermittently.

Although FIG. 1 illustrates only one imaging device 200, multiple imaging devices 200 may be placed at the work site to be monitored. The imaging device 200 may be placed in a fixed position so that it can take fixed-point images, or it may be placed in a movable position. For example, a crane camera may be used as the imaging device 200, or the imaging device 200 may be mounted on a drone so that it can take aerial images while moving in the sky.

The monitoring device 300 can receive captured images transmitted from the imaging device 200 and perform image analysis on the captured images. An information processing device with image processing functions can be used as the monitoring device 300. In this embodiment, the imaging device 200 and the monitoring device 300 communicate wirelessly with each other, but this is not limited to this example, and the imaging device 200 and the monitoring device 300 may also be connected by wire.

[Configuration of Identification Marker]
Fig. 2 is a diagram showing the configuration of the identification marker 100 according to one embodiment of the present invention. Specifically, Fig. 2(A) is a side view of the identification marker 100, and Fig. 2(B) is a rear view of the identification marker 100. However, for ease of explanation, coloring of the identification marker 100 is omitted in Fig. 2.

As shown in Figures 2(A) and 2(B), the identification marker 100 of this embodiment has a marker body 110 made of a spherical member. In other words, when viewed from above, the appearance of the identification marker 100 is a sphere no matter what direction it is viewed from. In this embodiment, when the diameter of the marker body 110 is X1, X1 ≥ 250 mm (preferably X1 ≥ 300 mm). However, this is not limited to this example, and the diameter of the marker body 110 may be less than 250 mm.

The marker body 110 is provided with a bottomed hole 120. As shown in FIG. 1, the bottomed hole 120 is used to attach the identification marker 100 to the top of the road cone 150, and is desirably large enough to allow the top of the road cone 150 to be inserted therein. As shown in FIG. 2(B), when the opening diameter (i.e., the diameter of the open end) of the bottomed hole 120 is X2, X2 ≧ 50 mm (preferably X2 ≧ 75 mm), and when the depth of the bottomed hole 120 is X3, X3 ≧ 40 mm (preferably X3 ≧ 50 mm). However, this example is not limiting, and the opening diameter and depth of the bottomed hole 120 may be less than the above numerical ranges as long as they are within a range that allows attachment to the top of the road cone 150.

As shown in FIG. 2(A), a threaded portion 130 is provided in the center of the bottom 121 of the blind hole 120. Specifically, the threaded portion 130 is arranged so that its first end is fixed to the bottom 121 and its second end protrudes from the blind hole 120. If the difference between the depth of the blind hole 120 and the length of the threaded portion 130 is X4, then X4 ≧ 10 mm (preferably, X2 ≧ 20 mm). In other words, the total length of the threaded portion 130 is 50 mm or more (preferably, 70 mm or more). However, this is not a limitation, and the length of the threaded portion 130 may be less than 50 mm.

As described above, the identification marker 100 of this embodiment has high omnidirectional recognizability because the marker body 110 is composed of a spherical member. Therefore, this embodiment can provide an identification marker 100 that can be stably recognized regardless of the position of the imaging device 200. Furthermore, in the safety monitoring system 1000 shown in Figure 1, the monitoring device 300 can stably recognize the identification marker 100 regardless of the relative positional relationship between the identification marker 100 and the imaging device 200. In addition, coloring the marker body 110 can further improve the recognizability of the identification marker 100.

Figure 3 is a diagram showing the configuration of an identification marker 100 in one embodiment of the present invention. Specifically, Figure 3(A) is a side view of an identification marker 100 in which the marker body 10 is colored in two colors, and Figure 3(B) is a side view of an identification marker 100 in which the marker body 10 is colored and also has a pattern.

Figure 3(A) shows an example in which the marker body 110 is divided into two regions and colored. In this embodiment, the colored region 111 on the right side of the marker body 110 is colored purple, and the colored region 112 on the left side of the marker body 110 is colored yellow. However, the number of divided regions is not limited to two, and more regions may be divided and colored in two or more colors. There are no particular restrictions on the colors used for coloring, but it is preferable to use colors that are not often used in work sites, as this increases identification. For example, purple, yellow, or green are suitable. It is also preferable to apply a matte finish to the marker body 110 to prevent reflection from sunlight.

In this embodiment, as shown in Figure 1, each identification marker 100 is positioned so that the purple colored area 111 is located closer to the monitored area 400. This allows the process of identifying the monitored area 400 to be performed more efficiently.

In Figure 3(B), the marker body 110 is divided into two areas and colored as in Figure 3(A), and a polygonal figure 113 is further marked. It is preferable that the figure 113 be colored differently from the colored areas 111 and 112. In this embodiment, an example is shown in which the figure 113 is colored green.

Multiple figures 113 are provided on the surface of the marker body 110, which is made of a spherical member, at positions that are point-symmetrical with respect to the center of the marker body 110. For example, multiple figures 113 may be printed at equal intervals on the surface of the marker body 110. By arranging multiple figures 113 on the surface of the marker body 110, it is possible to impart a pattern to the marker body 110. Note that while Figure 3(B) shows an example in which the figure 113 is hexagonal, it may also be another polygon, circular, or elliptical.

The identification marker 100 of this embodiment described above is intended to be used in combination with a road cone 150, as shown in Figure 1. Specifically, the identification marker 100 is attached to the top of the road cone 150 by fitting the bottomed hole 120 into the top of the road cone 150. To achieve this type of use, the identification marker 100 shown in Figure 2 has a bottomed hole 120 in the marker body 110 that is large enough to fit into the road cone 150.

The identification marker 100 of this embodiment can also be used in combination with a clamp using the screw portion 130. Specifically, the identification marker 100 can be fixed to a clamp using the screw portion 130, and the clamp can be connected to a pipe or the like, thereby fixing the identification marker 100 to the pipe or the like.

Figure 4 is a schematic diagram showing the configuration of a safety monitoring system 1000a in a modified example of one embodiment of the present invention. In the example shown in Figure 4, a no-entry area is set as the area to be monitored, and intrusion prevention equipment 450 is placed in front of the monitored area. In this embodiment, the intrusion prevention equipment 450 includes two posts 451, a rope 452 strung across the two posts 451, and a sign 453 attached to the rope 452, but is not limited to this example.

As shown in FIG. 4, an identification marker 100 is fixed to a support 451 via a clamp 160. Here, an example is shown in which the identification marker 100 is colored solely purple, but as shown in FIG. 3(A) or 3(B), it may be colored in two or more colors or may have a pattern. In the example shown in FIG. 4, an identification marker 100 combined with a traffic cone 150 is placed in front of the intrusion prevention equipment 450. As described above, by placing multiple identification markers 100 around the intrusion prevention equipment 450, the area to be monitored can be efficiently identified from the captured image acquired by the imaging device 200.

In the example shown in Figures 2 and 3, the marker body 110 is provided with a threaded portion 130, but this is not limiting and the threaded portion 130 may be omitted. For example, if the road cone 150 to be attached does not have a hole at the top, the bottomed hole 120 cannot be fitted into the top of the road cone 150 if the threaded portion 130 is provided. To accommodate such cases, the marker body 110 may be configured without a threaded portion 130.

Next, we will explain the imaging device 200 and monitoring device 300 that make up the safety monitoring system 1000 of this embodiment.

Figure 5 is a block diagram showing the configuration of a safety monitoring system 1000 according to one embodiment of the present invention. Specifically, Figure 5 illustrates an imaging device 200 and a monitoring device 300 as elements of the safety monitoring system 1000 that are involved in image processing.

The imaging device 200 and monitoring device 300 are connected to a network NW such as the Internet or a communication line. In other words, the safety monitoring system 1000 is a client-server system consisting of the imaging device 200, which functions as a client, and the monitoring device 300, which is an information processing device that functions as a server.

The imaging device 200 is, for example, a camera installed in a position that allows a bird's-eye view of the work site. The imaging device 200 can communicate with the monitoring device 300 by connecting to the network NW. In this embodiment, the imaging device 200 is connected to the network NW via wireless communication, but wired communication may also be used.

The monitoring device 300 is an information processing device that receives captured images transmitted from the imaging device 200 and performs various image analyses on the captured images. The monitoring device 300 monitors whether people are approaching or entering the monitored area 400 based on the image analysis. The information processing related to the monitoring function performed by the monitoring device 300 is realized by executing a program recorded in a storage device included in the monitoring device 300, a recording medium readable by the monitoring device 300, or a database to which the monitoring device 300 can connect via the network NW. In Figure 5, the monitoring device 300 is illustrated as a single information processing device, but it may also be made up of multiple information processing devices.

[Configuration of imaging device]
5, the imaging device 200 of this embodiment includes a control unit 210, an imaging unit 220, and a communication unit 230. However, the imaging device 200 is not limited to this example and may include other elements.

The control unit 210 includes a processor (arithmetic processing device) such as a CPU (Central Processing Unit) and a storage device such as RAM. The control unit 210 controls the imaging unit 220 and the communication unit 230. In this embodiment, the imaging unit 220 is controlled continuously or intermittently to acquire captured images. The control unit 210 can also control the imaging unit 220 based on control information transmitted from the monitoring device 300.

The imaging unit 220 captures images with an angle of view that includes the entire work site (or part of it) and generates a captured image of the work site captured from a high vantage point. The imaging unit 220 can be, for example, a camera that includes a solid-state imaging element such as a CCD (Charge-Coupled Device) image sensor or a CMOS (Complementary MOS) image sensor. The imaging unit 220 may capture images continuously in video format, or intermittently in still image format. The imaging unit 220 may also be equipped with a depth sensor. By equipping the imaging unit 220 with a depth sensor, distance information from the imaging device 200 to the subject can be obtained.

The communication unit 230 is a wireless communication module that connects to the network NW under the control of the control unit 210 and transmits captured images to the monitoring device 300 connected to the network NW. The communication unit 230 may also have the function of receiving control information transmitted from the monitoring device 300. Note that although a wireless communication module is exemplified as the communication unit 230 in this embodiment, it may also be a wired communication module.

[Configuration of monitoring device]
The monitoring device 300 of this embodiment includes a control unit 310, a storage unit 320, a notification unit 330, and a communication unit 340. However, the monitoring device 300 is not limited to this example, and may include other elements, or the notification unit 330 may be omitted.

The control unit 310 includes a processing circuit (control device) such as a CPU and a storage device such as RAM. The control unit 310 executes programs stored in the storage unit 320 using the CPU, causing the monitoring device 300 to realize various functions related to monitoring processing. Signals output from each element of the monitoring device 300 are used by the various functions realized by the monitoring device 300. The specific functions of the control unit 310 will be described below.

The storage unit 320 is a recording device (recording medium) that can permanently retain and rewrite information, such as a non-volatile memory or a hard disk drive. The storage unit 320 stores programs and information such as parameters required to execute those programs. For example, a program related to the aforementioned monitoring function (monitoring program) is stored in the storage unit 320. The storage unit 320 also has a database unit (DB unit) 321 that stores various information (e.g., captured images) received from other devices (e.g., the imaging device 200) via the network NW.

The alarm unit 330 has the function of executing instructions to issue warnings or cautions in accordance with instructions from the control unit 310. Specifically, when the monitoring function described below determines that a person 500 (e.g., a worker) has approached the monitored area 400, the alarm unit 330 can send an instruction signal to an alarm device (not shown) located at the work site to issue an alarm to the person 500. In this case, the alarm may be an audible warning sound, or a voice message such as "Please be careful as it is dangerous."

Furthermore, when the monitoring function determines that person 500 is present in the monitored area 400, the alarm unit 330 can send an instruction signal to an information processing device (not shown) managed by the site manager to notify that fact. The information processing device managed by the site manager may be, for example, a laptop computer, tablet device, smartphone, or other mobile device. This allows the site manager to take appropriate action against person 500 entering the monitored area. Note that while an example has been shown here in which the alarm unit 330 notifies the site manager of person 500's entry, instead of or in addition to this, an instruction signal to issue an alarm to the aforementioned alarm device may also be sent.

The communication unit 340 is a wireless communication module that connects to the network NW under the control of the control unit 310 to receive captured images from the imaging device 200 connected to the network NW and transmit instruction signals to other devices, such as the imaging device 200, an alarm device, or another information processing device (for example, an information processing device managed by a site manager). The communication unit 340 may also have the function of receiving control information and instruction signals transmitted from other information processing devices. Note that, although a wireless communication module has been exemplified as the communication unit 340 in this embodiment, a wired communication module may also be used.

The monitoring device 300 described above performs image analysis processing under the control of the control unit 310. The control unit 310 includes the following functional blocks: an area identification unit 311, a person detection unit 312, and a determination unit 313. Each block is realized by the control unit 310 executing a monitoring program read from the memory unit 320.

The area identification unit 311 extracts the identification marker 100 (see Figure 1) from the captured image acquired from the imaging device 200, and identifies the position of the monitored area 400 (here, the opening) based on the position of the identification marker 100. The position of the identification marker 100 can be identified by performing image analysis processing on the captured image in accordance with a known algorithm (e.g., pattern matching technology, coordinate detection technology, etc.).

The person detection unit 312 detects a person 500 (see Figure 1) from the captured image acquired from the imaging device 200. The position of the person 500 can be identified by performing image analysis processing on the captured image in accordance with a known algorithm (e.g., pattern matching technology, frame difference detection technology, etc.).

The determination unit 313 compares the position of the monitored area 400 identified by the area identification unit 311 with the position of the person 500 detected by the person detection unit 312, and determines the relative positional relationship between the monitored area 400 and the person 500. Specifically, the determination unit 313 determines the position of the monitored area 400, i.e., whether or not the person 500 is present within a rectangular area connecting the positions of each identification marker 100 with a line, or whether or not the person 500 is present in the periphery of that rectangular area.

When the determination unit 313 determines that a person 500 is present in the monitored area 400, it instructs the notification unit 330 to generate an instruction signal to notify the site manager that a person has entered the monitored area 400. Furthermore, when the determination unit 313 determines that a person 500 is present in the periphery of the monitored area 400, it instructs the notification unit 330 to generate an instruction signal to issue an alarm.

[Monitoring process flow]
The safety monitoring system 1000 of this embodiment monitors unsafe areas such as no-entry areas at a work site and executes a monitoring process to ensure the safety of people. The flow of the monitoring process will be described below.

Figure 6 is a flowchart showing the operation of the monitoring device 300 in one embodiment of the present invention. In this embodiment, the control unit 310 of the monitoring device 300 executes the processing of each step shown in Figure 6. That is, the control unit 310 reads and executes the monitoring program stored in the storage unit 320, thereby realizing each process shown in Figure 6.

The control unit 310 executes the monitoring program to sequentially acquire captured images from the imaging device 200 and perform an analysis process on the acquired captured images. When the analysis process is performed, the area identification unit 311 determines whether the captured image contains an identification marker 100 (step S101).

If the determination result in step S101 is YES, the area identification unit 311 identifies the monitored area 400 by extracting the identification marker 100 from the captured image (step S102). Specifically, the area identification unit 311 calculates the position coordinates of the extracted identification marker 100, and identifies the area identified by the calculated position coordinates as the monitored area 400.

The identification marker 100 can be extracted based on a known algorithm, such as pattern matching. The position coordinates of the identification marker 100 can be calculated by correcting the two-dimensional coordinates obtained from the captured image according to the angle of view of the imaging device 200, in accordance with a known algorithm (such as the marker detection algorithm used in ARTToolKit).

If the determination result in step S101 is NO, the control unit 310 returns control to step S101 again.

Once the monitored area 400 has been identified, the person detection unit 312 then determines whether or not a person 500 is included in the captured image (step S103). Specifically, the person detection unit 312 detects the presence or absence of a person by performing pattern matching on the captured image and detecting frame differences between multiple captured images.

If the determination result in step S103 is YES, the person detection unit 312 calculates the position coordinates of the person 500 from the captured image and identifies the position of the person 500 (step S104). The position coordinates of the person 500 can be calculated by correcting the two-dimensional coordinates obtained from the captured image according to the angle of view of the imaging device 200, according to a known algorithm.

If the determination result in step S103 is NO, the control unit 310 returns control to step S101.

Once the person 500 has been identified, the determination unit 313 then determines whether the person 500 is located inside the monitored area (step S105). Specifically, the determination unit 313 compares the position coordinates of the monitored area 400 identified in step S102 with the position coordinates of the person 500 identified in step S104, and determines whether the person 500 is located inside or outside the monitored area 400.

If the determination result in step S105 is YES, the alarm unit 330 generates an instruction signal to notify that a person 500 has entered the monitored area 400, and transmits it to the information processing device managed by the site manager (step S106). Upon receiving the instruction signal from the alarm unit 330, the site manager's information processing device can display on a display screen that a person has entered the monitored area 400, or can emit an alarm to that effect. This allows the site manager to quickly take action against the person 500 in the monitored area 400.

On the other hand, if the determination result in step S105 is NO, the alarm unit 330 generates an instruction signal to notify that a person 500 is present in the vicinity of the monitored area 400, and transmits the signal to an alarm device or the like located at the work site (step S107). Upon receiving the instruction signal from the alarm unit 330, the alarm device or the like issues an alarm (warning sound or warning voice) to the person 500 present in the vicinity of the monitored area 400. This allows the person 500 present in the vicinity of the monitored area 400 to be appropriately alerted.

As described above, according to this embodiment, in a safety monitoring system 1000 that monitors a predetermined space such as a work site, by using an identification marker 100 composed of a spherical member, it is possible to stably recognize the identification marker 100 regardless of the position of the imaging device 200. This makes it possible to realize a safety monitoring system that can stably recognize the identification marker 100 regardless of the relative positional relationship between the identification marker 100 and the imaging device 200.

Second Embodiment
In this embodiment, an identification marker 100a having a different structure from that of the first embodiment will be described. Specifically, the identification marker 100a of this embodiment has an attachment part 140 that is attached to a marker body 110a. In this embodiment, the same elements as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

Figure 7 is a diagram showing the configuration of an identification marker 100a in another embodiment of the present invention. Specifically, Figure 7 is an exploded side view of the identification marker 100a. As shown in Figure 7, the identification marker 100a has an attachment portion 140. The attachment portion 140 includes a first threaded portion 141 and a second threaded portion 142.

The first screw portion 141 is provided on the first surface 140a facing the marker body 110a. The first screw portion 141 screws into the screw hole 116 provided in the center of the bottom 121a of the bottomed hole 120a. In other words, the nominal diameter of the first screw portion 141 and the nominal diameter of the screw hole 116 match. The length of the first screw portion 141 and the length (depth) of the screw hole 116 also match.

The second screw portion 142 is provided on the second surface 140b opposite the first surface 140a facing the marker body 110a. In this embodiment, the nominal diameter of the second screw portion 142 is smaller than the nominal diameter of the first screw portion 141. However, this is not limited to this example, and the nominal diameter of the second screw portion 142 may be larger than the nominal diameter of the first screw portion 141, or may be the same as the nominal diameter of the first screw portion 141.

In this embodiment, the nominal diameter of the second screw portion 142 can be changed as appropriate depending on the object to which the identification marker 100a is to be fixed. For example, when attaching the identification marker 100a to a tripod or a small clamp, the nominal diameter of the second screw portion 142 can be set to match the nominal diameter of the screw hole in that object. In this case, multiple types of attachment portions 140 having second screw portions 142 with different nominal diameters can be prepared, and the attachment portion 140 can be replaced depending on the object to which the identification marker 100a is to be fixed.

Furthermore, as shown in FIG. 7, the attachment part 140 has the same outer shape as the inner wall of the bottomed hole 120a so that it can close the bottomed hole 120a. In other words, when the attachment part 140 is attached to the marker body 110a, the identification marker 100a becomes substantially spherical. However, this is not limited to this example, and the shape of the attachment part 140 can be any shape as long as it fits inside the bottomed hole 120a.

When the attachment part 140 is not attached, the identification marker 100a of this embodiment has no part protruding inside the bottomed hole 120a. Therefore, when it is assumed that the identification marker 100a will be used in combination with a road cone 150, as in the first embodiment, the identification marker 100a can be attached to the top of the road cone 150 regardless of whether or not there is a hole in the top of the road cone 150.

According to this embodiment, similar to the first embodiment, in a safety monitoring system 1000 that monitors a predetermined space such as a work site, by using an identification marker 100a composed of a spherical member, it is possible to stably recognize the identification marker 100a regardless of the position of the imaging device 200. Furthermore, even if the object to which the identification marker 100a is fixed is changed, it can be appropriately fixed to various objects by appropriately replacing the attachment part 140.

The embodiments of the present invention and their variations can be combined as appropriate, provided they are not mutually inconsistent. Those embodiments or variations thereof that have been implemented by a person skilled in the art, with appropriate additions, deletions, or design changes to components, or with additions, omissions, or changes to conditions based on the above-described embodiments or their variations, are also included within the scope of the present invention, as long as they incorporate the essence of the present invention.

Furthermore, even if there are other effects and advantages different from those brought about by the above-described embodiments or their modified forms, if these are clear from the description in this specification or can be easily predicted by a person skilled in the art, they are naturally understood to be brought about by the present invention.

100, 100a... Identification marker, 110, 110a... Marker body, 111, 112... Colored area, 113... Graphic, 116... Screw hole, 120, 120a... Bottomed hole, 121, 121a... Bottom, 130... Screw portion, 140... Attachment portion, 140a... First surface, 140b... Second surface, 141... First screw portion, 142... Second screw portion, 150... Road cone, 160... Clamp, 200... Imaging device, 210...control unit, 220...imaging unit, 230...communication unit, 300...monitoring device, 310...control unit, 311...area identification unit, 312...person detection unit, 313...determination unit, 320...storage unit, 321...database unit (DB unit), 330...alarm unit, 340...communication unit, 400...monitoring target area, 451...support, 452...rope, 453...sign, 500...person, 1000, 1000a...safety monitoring system

Claims (10)

An identification marker that can be recognized by an imaging device placed at a high position in the work site,
a hole into which a support member disposed at the work site can be inserted to support the identification marker at a predetermined height;
The identification marker is configured as a spherical member. The identification marker of claim 1, further comprising a threaded portion having a first end fixed to the hole and a second end protruding from the hole. The attachment portion is configured to be able to fit into the hole,
The spherical member has a screw hole in the hole,
An identification marker as described in claim 1 or 2, wherein the attachment portion includes a first screw portion that screws into the screw hole and a second screw portion that is provided on a second surface opposite to the first surface on which the first screw portion is provided. The identification marker described in claim 3, wherein the first threaded portion and the second threaded portion have different nominal diameters. The identification marker according to claim 1 , wherein a visually detectable color or graphic is marked on the surface of the spherical member. An identification marker according to any one of claims 1 to 5, wherein the surface of the spherical member is marked with a plurality of circular or polygonal figures arranged in point-symmetric positions relative to the center of the spherical member. A method of using an identification marker according to any one of claims 1 to 6, in which the hole in the identification marker is fitted onto the tip of a road cone, thereby combining the identification marker with the road cone. A method of using an identification marker according to claim 2, in which the threaded portion of the identification marker is attached to a clamp, thereby using the identification marker in combination with the clamp. an imaging device that images a predetermined space;
a monitoring device that analyzes the captured image transmitted from the imaging device;
an identification marker disposed within the space;
the identification marker is composed of a spherical member supported at a predetermined height by a support member,
A safety monitoring system in which the monitoring device identifies the area to be monitored by extracting the identification marker from the image acquired from the imaging device, and detects whether or not a person is present in or around the area to be monitored based on the image. further comprising an alarm device that issues an alarm within the space;
The safety monitoring system of claim 9, wherein when the monitoring device determines that the person is present in the vicinity of the monitored area, it transmits an instruction signal to the alarm device to issue the alarm, and when it determines that the person is present in the monitored area, it transmits an instruction signal to another information processing device to notify that a person has entered the monitored area.