Work site management system, work site management method, and work site management program

Abstract

By accurately tracking the positions of workers, machinery, and materials, it is possible to prevent accidents involving workers, contact between workers and machinery, and contact between machinery, thereby ensuring safety. Furthermore, proper management of the placement of machinery and materials improves work efficiency. [Solution] The system comprises a plurality of first devices installed at and around the work site and capable of acquiring their own location information, and second devices carried or attached to workers, work machines, and materials performing work at the work site, and includes distance calculation means for calculating the distance between each of the plurality of first devices 1 and the second device 2 based on the bidirectional transmission and reception times of information or signals between each of the plurality of first devices 1 and the second device 2, and location identification means for identifying the location of the second device 2 based on the distance between each of the plurality of first devices 1 and the second device 2 calculated by the distance calculation means, and the location information of each of the first devices 1.

Description

Technical Field

[0001] The present invention relates to a work site management system, a work site management method, and a work site management program for efficiently performing safety management and work management at work sites such as construction sites.

Background Art

[0002] Reducing the risk of accidents while improving work efficiency at work sites such as construction sites is an important management matter at work sites. If work processes are prioritized, unreasonable schedules are set to meet deadlines, overtime work and excessive work become the norm, which accumulates the fatigue of workers and increases the risk of accidents. In addition, when there is a shortage of workers, an excessive burden is placed on the remaining workers, leading to fatigue and a decrease in concentration, thus increasing the risk of accidents during work. Furthermore, in a situation of manpower shortage, safety measures and supervision systems are often insufficient, which also increases the risk of accidents. Therefore, it is necessary to establish a monitoring system to reduce the risk of accidents at work sites. In addition, in order to improve work efficiency, it is necessary to appropriately move and arrange workers, work machines, and materials to perform work. That is, it is necessary to centrally manage the safety management of work sites and the progress of work.

[0003] Based on the above points, conventionally, a method of monitoring the positions of mobile bodies such as employees, workers carrying mobile information terminals, and vehicles equipped with mobile information terminals has been proposed (see Patent Document 1). This is a method in which a mobile information terminal is equipped with a GPS function, the position information of the terminal is periodically transmitted to a wireless slave node, and this GPS positioning information is transmitted to a wireless master node through a wireless communication network and input to a monitoring computer for display on a monitor. Also, in places where it is difficult to obtain GPS positioning information (such as tunnels), positioning is performed by measuring electric field strength.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Japanese Patent Publication No. 2010-16582 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, GPS positioning information has an error margin of several meters, and in some cases, it may not be possible to receive the signal depending on the location of the work site. Furthermore, while positioning by measuring electric field strength is effective in areas where GPS is difficult to use, it is said to be less accurate than GPS, and there are limitations to obtaining an accurate location. Therefore, sufficient positional accuracy is necessary to reliably prevent accidents such as workers falling, workers coming into contact with machinery, and machinery coming into contact with each other. Furthermore, if the positional information of each mobile information terminal is not accurate enough, it becomes impossible to accurately manage the movement of machinery and the transport of materials in real time, resulting in unnecessary movements and instructions, which hinders work efficiency.

[0006] This invention has been made in view of the above circumstances, and its main objective is to provide a work site management system, a work site management method, and a work site management program that can ensure safety by accurately determining the positions of workers, work machinery, and materials, thereby preventing accidents involving workers, contact between workers and work machinery, and contact between work machinery, and that can improve work efficiency by appropriately managing the placement of workers, work machinery, and materials. [Means for solving the problem]

[0007] To achieve the above objectives, the work site management system according to the present invention is a system for managing a work site using a plurality of first devices installed at and around the work site and capable of acquiring their own location information, and second devices carried or attached to workers, work machinery, and materials at the work site, Distance calculation means for calculating the distance between each of the plurality of first devices and the second device based on the bidirectional transmission and reception times of information or signals between each of the plurality of first devices and the second device, A position identification means that identifies the position of the second device based on the distance between each of the first and second devices calculated by the distance calculation means, and the position information of each of the first devices. It is characterized by having [this feature].

[0008] Here, the installation method of the first device is not particularly limited, and it may be installed on the surface of existing fixed objects (utility poles, streetlights, buildings, etc.) or newly installed fixed objects (installation poles, etc.) located in or around the work site, or it may be embedded in these fixed objects. Furthermore, the ability to acquire its own location information includes not only cases where the location information of the first device has been acquired and identified in advance, but also cases where it has been acquired and identified afterward by some means. In addition, the acquired location information of the first device may be stored in a readable manner in its own memory, or it may be compiled into a database and stored in another storage device.

[0009] The position information of the first device is preferably three-dimensional position information, and may be determined using a geocentric Cartesian coordinate system, a geodetic coordinate system, or a coordinate system uniquely set up at the work site.

[0010] Here, it is desirable to intentionally make the height positions on which the first device is installed different, and by managing the height position of the first device, it becomes possible to more accurately determine the three-dimensional position information of the second device.

[0011] Having workers at the work site carry the second device includes cases where the second device is lent to them for them to carry, or where they purchase it in advance and carry it with them. Furthermore, it includes not only cases where the second device is attached to a wristband, glasses, helmet, safety shoes, gloves, work clothes, etc., and worn directly, but also cases where it is attached to other personal belongings carried by workers at the work site (pouches, communication devices, tools, etc.) using clips, belts, magnets, strings, etc., or embedded in them for carrying. Furthermore, the second device may be replaced by a device carried by an employee (such as an electronic wristwatch) or a control device for a work machine, by installing the application of this system on the device.

[0012] Furthermore, when attaching the second device 2 to the work machine, if the second device 2 is used to identify the base position of the work machine, the second device may be attached approximately in the center of the base portion. Alternatively, if the second device 2 is used to identify the movement of the working part of the work machine, the second device may be attached to the end effector. Moreover, if the operating range of the work machine is known, the second device 2 may be installed near the part of the work machine where a person will stand. The second device may be attached to the material either by directly attaching it to the surface of the material or by housing it in a container attached to the material. Furthermore, the second device may be attached to each piece of material, or it may be attached to each bundle that is moved during work, for example, to a band, string, wire, tape, etc., for each pallet or bundle.

[0013] Therefore, the distance calculation means calculates the distance between each of the multiple first devices and the second device carried or attached to the worker, work machine, or material, and the position identification means makes it possible to identify the position of the second device, i.e., the position of the worker, work machine, or material, based on the distance between each of the multiple first devices and the second device, and the position information of each first device. In order to determine the position of the worker, work machine, and material, The information or signals transmitted from the second device may include identification information that identifies the person carrying or wearing the second device.

[0014] Here, the distance calculation means is, specifically, The difference between the time on the first device's clock when it transmits information or a signal and the time on the second device's clock when it receives the information or signal transmitted from the first device, The difference between the time on the second device's clock when it transmits information or a signal and the time on the first device's clock when it receives the information or signal transmitted from the second device, Based on this, the propagation time of the information or signal between the first device and the second device is calculated, and the distance between the first device and the second device is calculated based on this propagation time. In this configuration, the distance between the first and second devices can be accurately calculated even if time synchronization is not maintained between the first and second devices, by calculating the distance between the first and second devices based on the transmission and reception times of information or signals in both directions between the first and second devices.

[0015] Furthermore, the work site management system includes a time difference calculation means that calculates the time difference between the clock of the first device and the clock of the second device based on the bidirectional transmission and reception times of information or signals between each of the multiple first devices and the second device. Based on the aforementioned time difference, the device time synchronization means synchronizes the time of the second device with the time of the first device which is synchronized to a reference time, It may also be possible to further incorporate this feature.

[0016] Here, the device time synchronization means uses the difference between the time on the first device's clock when it transmits information or a signal from the first device and the time on the second device's clock when it receives the information or signal transmitted from the first device. The difference between the time on the second device's clock when it transmits information or a signal and the time on the first device's clock when it receives the information or signal transmitted from the second device, Based on this, the time difference between the clock of the first device and the clock of the second device may be calculated, and the time of the clock of the second device may be synchronized with the time of the clock of the first device based on this time difference.

[0017] By using such a synchronization method, even when time synchronization using GPS or the Internet cannot be performed, it is possible to synchronize the clock of the second device with the clock of the first device. As a result, it becomes possible to accurately capture the positions of the workers, work machines, and materials in real time, and it becomes possible to centrally manage the safety management and progress status of the work site.

[0018] Particularly, from the viewpoint of ensuring work safety, an area deviation determination means for determining whether or not the second device has deviated from the safety area based on the position information of the second device specified by the position specifying means, a danger area intrusion determination means for determining whether or not the second device has entered the danger area based on the position information of the second device, a fall risk determination means for determining whether or not the risk of falling has increased to a predetermined threshold or more based on the position information of the second device, a proximity determination means for determining whether or not the second device has approached within a predetermined distance of another second device based on the position information of the second device, and when it is determined by the area deviation determination means that the second device has deviated from the safety area, when it is determined by the danger area intrusion determination means that the second device has entered the danger area, when it is determined by the fall risk determination means that the risk of falling has increased to a predetermined threshold or more, or when it is determined by the proximity determination means that the second device has approached within a predetermined distance of another second device, an alarm issuing means for issuing an alarm is preferably further provided. According to such a configuration, based on the position information of the second device specified by the position specifying means, the determination of various determination means can be accurately performed, so that it becomes possible to more surely avoid accidents of workers and work machines.

[0019] an accident estimation means for estimating the presence or absence of an accident in consideration of the temporal change in the position of the second device specified by the position specifying means, When the occurrence of an accident is estimated by the accident estimation means, a notification means notifies the administrator of the estimation result and also notifies the location of the corresponding second device, It may also be provided with additional features. Here, the accident estimation means may, for example, estimate whether an accident has occurred by detecting a sudden change in the position of the second device or the presence or absence of unexpected movement.

[0020] Furthermore, it includes a learning model storage unit that stores a learning model that has been machine-trained to store the correlation between input data, which includes object identification information that identifies an object carrying or wearing the second device and dynamic information of the second device obtained from changes in the position of the second device over time, and output data, which includes whether or not an accident occurred and the cause of the accident. The accident estimation means may use the above-mentioned learning model to estimate whether an accident occurred and the cause of the accident, based on object identification information that identifies an object carrying or wearing the second device, and dynamic information of the second device obtained from changes in the position of the second device over time. This configuration makes it easier to determine the cause of an accident and allows for a quicker response in the event of an accident. [Effects of the Invention]

[0021] As described above, according to the work site management system, work site management method, and work site management program of the present invention, the distance between each of the multiple first devices and the second device is calculated based on the bidirectional transmission and reception times of information or signals between each of the multiple first devices and the second device. From the calculated distance between each of the multiple first devices and the second device, and the position information of each first device, the position of each person carrying or wearing the second device is identified. This makes it possible to accurately grasp the positions of workers, work machinery, and materials, thereby preventing accidents involving workers, contact between workers and work machinery, and contact between work machinery, and ensuring safety. Furthermore, because the accurate positions of workers, work machinery, and materials can be grasped, the placement management of workers, work machinery, and materials can be appropriately carried out, and work efficiency can be improved. [Brief explanation of the drawing]

[0022] [Figure 1] This figure shows an example of a construction site as a work site to which the work site management system according to the present invention is applied. [Figure 2] This is a block diagram showing an example configuration of a work site management system according to the present invention. [Figure 3] This is a block diagram showing an example configuration of the first device. [Figure 4] This is a block diagram showing an example configuration of the second device. [Figure 5] This is a block diagram showing the configuration of the server device. [Figure 6] This is a flowchart showing the distance calculation process. [Figure 7] This is a flowchart showing the location identification process. [Figure 8] This flowchart shows an example of an operation process that monitors the position of the second device to ensure the safety of the workers. [Figure 9] This flowchart shows an example of an operation process that monitors the position of the second device to ensure the safety of the work machine. [Figure 10] This flowchart shows an example of an operation process that monitors the position of the second device and performs safety management of materials. [Figure 11] (a) is a block diagram showing the configuration of a machine learning device, and (b) is a flowchart showing an example of the operation process that uses a learning model to predict whether an accident has occurred and the cause of the accident. [Modes for carrying out the invention]

[0023] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0024] Figure 1 shows an example of a construction site as a work site utilizing the work site management system S according to the present invention. As shown in Figure 2, this work site management system S comprises a first device 1 installed at and around the construction site, a second device 2 carried or attached to workers (such as workers and supervisors) P, work machinery W, and materials M working at the construction site, and a server device 3.

[0025] The first device 1 may be installed on the surface of fixed objects in and around a construction site, such as utility poles, streetlights, buildings, dedicated installation poles, radio towers, observation decks, sheds, rest areas, scaffolding, signboards, etc., or it may be embedded in such fixed objects.

[0026] These first devices 1 acquire their own 3D position information by some means. The three-dimensional position information of the first device 1 may be acquired in advance and stored readably inside the first device 1, or it may be acquired retrospectively by some means after the system has been started. Furthermore, the three-dimensional position information of the first device 1 may be compiled into a database and stored in the storage unit (storage unit 33, described later) of the server device 3. Here, the 3D position information may be expressed, for example, by latitude, longitude, and ellipsoidal height in the WGS8 coordinate system, or it may be expressed by a unique 3D coordinate system set up at the construction site.

[0027] The first device 1 and the second device 2 can communicate directly with each other. Furthermore, the first device 1 can be connected to the server device 3 via the communication network 4, and the second device 2 can also be connected to the server device 3 via the communication network 4. Each of the first device 1 and the second device 2 has an internal clock, which can be synchronized to a reference time using a method described later.

[0028] Furthermore, the first device 1 can also function as the first device 1 for multiple second devices 2, and when multiple second devices 2 exist, each of these second devices 2 may be configured to function as the first device for multiple other second devices. In other words, if the precise location of a second device can be determined, the distance between that second device and other second devices can be calculated and used to determine the location of the other second devices. In this embodiment, we will describe a case where only the first device is used to locate the second device.

[0029] (Regarding the first device) As shown in Figure 3, the first device 1 comprises a control unit 11, an RF chip 12, and an oscillator 13, each connected by a bus. It also includes a RAM 14 and a storage unit 15, each connected to the control unit 11 by a bus.

[0030] The control unit 11 consists of a CPU and ROM, and executes programs stored in ROM to control the first device 1. The RF chip 12 is equipped with at least a clock 16, but may also be equipped with a phase detector. The RF chip 12 also has the function of processing the transmission and reception of wireless signals, and the data received by the RF chip 12 is subject to calculation processing by the control unit 11. The RAM 14 is the work area of ​​the control unit 11, and the storage unit 15 is a storage area for saving programs, data, etc.

[0031] The oscillator 13 oscillates at a predetermined frequency and outputs a signal to provide the operating timing for each part of the device. A crystal oscillator or an atomic oscillator can be used as the oscillator 13. The clock 16 keeps time using the output signal of the oscillator 13 as the source oscillation and outputs the time. The time kept by the clock 16 is controlled by the control unit 11 to be transmitted to the second device 2 via the RF chip 12. If a phase detector is also provided, it detects the phase of the carrier wave that constitutes the information received from the second device 2, and also detects the phase of the signal transmitted by the oscillator 13 of the first device 1.

[0032] The RF chip 12 is capable of sending and receiving data with other computer devices. Data received by the RF chip 12 is stored in the RAM 14 or storage unit 15 and is subject to calculation processing by the control unit 11. When the 3D position information of the first device 1 is received via the RF chip 12, it is stored in the RAM 14 or storage unit 15 and controlled by the control unit 11 to be transmitted to the second device 2 via the RF chip 12.

[0033] In this work site management system S, the installation location of the first device 1 is not particularly limited, but since it is used to identify the current locations of workers P, work machines W, and materials M at a construction site, it is preferable to install it in a location that has a clear line of sight from as many workers P, work machines W, and materials M as possible. For example, when using existing infrastructure such as utility poles, streetlights, sheds, houses, or dedicated mounting poles, it is best to place them at the top of these structures. Also, when constructing scaffolding, it is best to place them at the highest level of the scaffolding.

[0034] In order to obtain three-dimensional positional information of the second device 2, the first device 1 does not need to be installed on the same plane; rather, it is preferable that adjacent first devices 1 be installed at different heights. For example, even when the first device 1 is attached to a nearby fixed object, it is preferable to make the mounting height of the first device different for each fixed object. Furthermore, it is desirable that the first device 1 be installed comprehensively at the construction site and its surroundings.

[0035] Furthermore, the location information of the installation site of the first device 1 may be stored in its own storage unit 15, associated with identification information that can identify the first device 1, or stored in the storage unit 33 of the server device 3, or it may be made available via the communication network 4 from another management server that manages location information.

[0036] (Regarding the second device) Next, the second device 2 will be described. This second device 2 is to be carried by workers P engaged in work at the construction site, and is also attached to construction machinery (working equipment) W and materials M used at or around the construction site. "Workers" refers to people who are directly engaged in work at a construction site. This includes on-site workers (workers, craftsmen such as carpenters, rebar workers, plumbers, electricians, plasterers, etc.), heavy equipment operators, site supervisors, site management engineers, surveyors, architects and designers, and other professionals (painters, waterproofers, demolition workers, etc.). Construction machinery includes bulldozers, excavators (backhoes, rafters), cranes (tower cranes, mobile cranes), road rollers, wheel loaders, forklifts, and mixer trucks (concrete mixers), and the appropriate machinery is selected according to the scale and type of construction. Materials include reinforcing bars, lumber, bricks and blocks, insulation materials, and piping materials, and are stored in a dedicated space set up in a corner of the construction site, or in temporary warehouses or containers.

[0037] The second device, when carried by a worker, may be fixed to clothing, a hat, safety vest, gloves, safety glasses, a watch, or other items worn directly on the body, or it may be embedded in such items. Furthermore, the second device 2 may be attached to or embedded in items carried by worker P, such as a pouch, tool holder, measuring instrument, communication device, or lighting fixture. Alternatively, the application of this system may be installed on an electronic device carried by worker P (such as a mobile phone or electronic watch), and this electronic device may be used as a substitute.

[0038] Furthermore, when the second device is attached to a work machine, if the base position of the work machine is to be determined, the second device may be attached approximately in the center of the base portion. Alternatively, if the operating range of the work machine is known, the second device 2 may be installed at or near the point where a person stands on the work machine. Also, if the second device is used to monitor the movement of the working parts of the work machine and to avoid contact with those moving parts, it may be attached to the end effector of each work machine. The second device may be attached to the material either by directly attaching it to the surface of the material or by housing it in a container attached to the material. Furthermore, the second device may be attached individually to each piece of material, or it may be attached to each group of materials that will be moved during work, for example, each pallet or bundle, using bands, strings, wire, tape, etc.

[0039] As shown in Figure 4, the second device 2 comprises a control unit 21, an RF chip 22, and an oscillator 23, each connected by a bus. It also includes a RAM 24 and a storage unit 25, each connected to the control unit 21 by a bus.

[0040] The RF chip 22 includes at least a clock 26, but may also include a phase detector if necessary.

[0041] The control unit 21 is configured with a CPU and ROM, and executes programs stored in the storage unit 25 to control the second device 2. The RAM 24 is the work area of ​​the control unit 21, and the storage unit 25 is a storage area for saving programs and data. The control unit 21 performs calculation processing based on programs and data read from the RAM 24 and the storage unit 25, as well as data input from an input unit (not shown).

[0042] The RF chip 22 is capable of sending and receiving data with other computer devices. The data received by the RF chip 22 is loaded into the RAM 24 and subjected to calculation processing by the control unit 21.

[0043] The oscillator 23 oscillates at a predetermined frequency and outputs a signal to provide the operating timing for each part of the device. A crystal oscillator or an atomic oscillator can be used as the oscillator 23. The clock 26 keeps time using the output signal of the oscillator 23 as the source oscillation and outputs the time. The time kept by the clock is controlled by the control unit 21 to be transmitted to the first device 1 via the RF chip 22. If a phase detector is also present, it detects the phase of the carrier wave that constitutes the information received from the first device 1, and also detects the phase of the signal oscillated by the oscillator 23 of the second device 2.

[0044] (Regarding server equipment) Next, the server device 3 of the present invention will be described. The server device 3 can acquire location information from the second device 2.

[0045] The acquired location information is stored in server device 3 as location information for worker P, work machine W, and materials M (second device 2). The location information for worker P, work machine W, and materials M (second device 2) is transmitted from second device 2 to server device 3, for example, along with identification information that can identify second device 2 and the time when the location information was identified. Server device 3 may also enable communication between first device 1 and second device 2 via smart meters installed in houses, electrical equipment, etc., in the vicinity of the construction site.

[0046] Figure 5 is a block diagram showing the configuration of a server device 3 according to an embodiment of the present invention. The server device 3 comprises at least a control unit 31, a RAM 32, a storage unit 33, and a communication interface 34, each connected by an internal bus. It also includes a database 35 for storing information received from the first device 1 and the second device 2. The location information of the first device 1 may also be stored in this database 35 after being compiled into the database.

[0047] The control unit 31 consists of a CPU, ROM, etc., and executes programs stored in the storage unit 33 to control the server device 3. The control unit 31 also has an internal timer for measuring time. The RAM 32 is the work area of ​​the control unit 31. The storage unit 33 is a storage area for saving programs and data. The control unit 31 reads programs and data from the storage unit 33 and RAM 32, and, based on information received from the first device 1 or the second device 2, executes various control processes in the control unit according to the program.

[0048] (Distance calculation process) Using the above configuration, the process for calculating the distance between the first device 1 and the second device 2 will now be described.

[0049] This distance calculation process calculates the distance between each of the first devices 1 and the second device 2, based on the propagation time Tp of the information or signal between each of the first devices 1 and the second device 2, provided that the first devices 1 and the second device 2 are within a distance range that allows them to mutually send and receive information or signals.

[0050] The distance calculation process is performed at predetermined time intervals (for example, every second) or whenever a predetermined condition is met, and the process is carried out in steps S1 to S16 as shown in Figure 6. For convenience, here we will explain the case of calculating the distance between one first device 1 and one second device 2.

[0051] First, information or a signal is transmitted from the first device 1 to the second device 2 (step S1). The information or signal transmitted from the first device 1 to the second device 2 is not particularly limited.

[0052] In the first device 1, the time (T11) when information or a signal is transmitted in step S1 is recorded (step S2), and this recorded time is stored in the memory or storage unit 15 within the control unit 11 (step S3).

[0053] Subsequently, the second device 2 receives the information or signal from the first device 1 (step S4). The second device 2 records the time (T21) when the information or signal was received in step S4 (step S5). The recorded time (including the measured phase, if one is measured) is then stored in the memory or storage unit 25 of the control unit 21 (step S6).

[0054] Next, the second device 2 transmits information or a signal to the first device 1 (step S7). The information or signal transmitted from the second device 2 to the first device 1 is not particularly limited. The second device 2 records the time (T22) when the information or signal was transmitted in step S7 (step S8). Then, the recorded time is stored in the memory or storage unit 25 of the control unit 21 (step S9).

[0055] The first device 1 receives the information or signal transmitted in step S7 (step S10). The first device 1 records the time (T12) when it received the information or signal in step S10 (step S11). The recorded time (including the measured phase if the phase is measured) is then stored in the memory or storage unit 15 of the control unit 11 (step S12).

[0056] Subsequently, the first device 1 transmits to the second device 2 via its RF chip 12 the information stored in step S3 regarding the time (T11) when the signal was transmitted in step S1, and the information stored in step S12 regarding the time (T12) when the signal was received in step S10 (step S13). At this time, the position information of the first device 1 is also transmitted to the second device 2.

[0057] Then, in step S1, the second device 2 receives information regarding the time (T11) when the first device 1 transmitted information or a signal, and information regarding the time (T12) when the first device received information or a signal in step S10 (step S14).

[0058] Next, the distance between the first device 1 and the second device 2 is calculated using the second device 2 (step S15). This distance is calculated in the following manner.

[0059] Information regarding the time of the first device's clock (T11) is transmitted to the second device 2 via radio waves. The difference between this time and the time of the second device 2's clock (T21) when the second device 2 receives this information is recorded as ΔTa on the second device 2 side. In other words, if we define the time of the first device's clock when it transmits information or a signal from the first device 1 to the second device 2 as T11, and the time of the second device's clock when it receives the information or signal transmitted from the first device 1 and sets time as T21, and the difference between them as ΔTa, then this ΔTa (the difference in transmission and reception times when information or a signal is transmitted from the first device 1 to the second device 2) is the difference between the time of the first device 1's clock and the second device 2's clock (time difference: T20-T10) plus the propagation time (propagation delay) Tp, resulting in the relationship shown in Equation 1. This time difference (T20-T10) would be zero if the clocks of the first device 1 and the second device 2 were synchronized, but here we assume that a time difference (T20-T10) exists (they are not synchronized). [Formula 1] ΔTa=T21-T11=(T20-T10)+Tp

[0060] To determine this propagation time Tp, the second device 2 also sends information about the time of this clock (T22) to the first device 1, and the difference between this time and the time of the first device 1's clock (T12) when the first device 1 receives it is recorded as ΔTb on the first device side. That is, if we define the time of the second device's clock when the second device 2 transmits information or a signal to the first device 1 as T22, and the time of the first device 1's clock when it receives the information or signal transmitted from the second device 2 as T12, and the difference between them as ΔTb, then this ΔTb (the difference in transmission and reception times when the second device 2 transmits information or a signal to the first device 1) is the difference between the time of the first device 1's clock and the second device 2's clock (time difference: T10-T20) plus the propagation time (propagation delay) Tp, resulting in the relationship shown in Equation 2. Here, the time difference (T10-T20) would be zero if the clocks of the first device 1 and the second device 2 were synchronized, but here we assume that a time difference (T10-T20) exists (they are not synchronized). [Formula 2] ΔTb=T12−T22=(T10−T20)+Tp

[0061] The time differences between the two clocks, (T20-T10) and (T10-T20), are added when transmitting from the first device to the second device, and the same amount of time difference is subtracted when transmitting from the second device to the first device. Therefore, to find the propagation time Tp, we add equations 1 and 2, which cancels out the terms for the time differences (T20-T10) and (T10-T20), resulting in the relationship in equation 3. [Formula 3] Tp=(ΔTa+ΔTb) / 2 =((T21-T11)+(T12-T22)) / 2

[0062] Therefore, the propagation time Tp can be calculated based only on the time read by the clock of the first device 1 and the time read by the clock of the second device 2.

[0063] Incidentally, the time difference (T10-T20) between the clock of the first device 1 and the clock of the second device 2 is given by the relationship in Equation 4, obtained by [Equation 1] - [Equation 2]. [Formula 4] (T10-T20)=(ΔTa−ΔTb) / 2

[0064] Subsequently, the distance between the first device 1 and the second device 2 is calculated by multiplying the propagation time calculated using Equation 3 by the propagation speed of the information or signal (e.g., high speed) (step S15).

[0065] Then, the distance between the first device 1 and the second device 2 calculated in step S15 is stored in the memory or storage unit 25 of the control unit 21 and transmitted to the server device 3 (step S16). By executing step S16, the distance calculation process is completed.

[0066] Therefore, since equation (3) for calculating the propagation time Tp does not include a term for the time difference (time difference: T20-T10) between the clocks of the first device 1 and the second device 2, the propagation time for information or signals to propagate between the first device 1 and the second device 2 can be calculated regardless of whether there is a time difference between the clocks of the first device 1 and the second device 2 (independent of the time difference (time difference: T10-T20) between the clocks of the first device 1 and the second device 2).

[0067] [Location identification process] Next, the process for determining the location of the second device 2 will be explained. This location determination process determines the location of the second device 2 based on the distances calculated in the distance calculation process between each of the multiple first devices 1 and the second device 2. Since the second device 2 is carried or attached to the worker P, the work machine W, and the materials M, it can be said that this process determines the locations of the worker P, the work machine W, and the materials M.

[0068] This positioning process should preferably be performed immediately after the distance calculation process is completed. Furthermore, in order to determine the position of the second device 2, it is assumed that the distance calculation device has calculated the distance to each of the multiple first devices 1 for each of the second devices 2.

[0069] In other words, when obtaining three-dimensional positional information of a worker P, a work machine W, and materials M (to obtain x, y, and z coordinates), the position of the second device 2 can be determined by using a well-known multi-point surveying calculation method, based on the distance between one second device 2 and at least four first devices 1, and the positional information of each of the four first devices 1 used to calculate this distance. Therefore, this system can determine the three-dimensional position of the second device 2 if four or more distance data points are available between the first device 1 and the second device 2. Thus, even if the second device 2 (worker P, work machine W, materials M) moves, it is advisable to appropriately distribute the first device 1 so that the second device 2 can send and receive information or signals with at least four first devices 1. In particular, in locations where positional accuracy is required, it is necessary to pre-adjust the number and three-dimensional position of the first device 1 to achieve the required accuracy.

[0070] Figure 7 shows a flowchart of the location identification process according to an embodiment of the present invention. This location identification process can be performed on either the first device 1, the second device 2, or the server device 3. When the location identification process is performed on the first device 1 or the server device 3, the distance between each of the multiple first devices 1 and the second device 2, as well as the location information of the first device 1, can be associated with the identification information of the second device 2, transmitted to the first device 1 or the server device 3, and used. Here, an example of performing the location identification process on the server device will be described.

[0071] First, the position determination process requires that distance information for at least four different first devices 1 and second devices 2 be obtained at the same time or close together. Here, "close together" means that the time at which the distances between the four first devices 1 and second devices 2 used to determine the position of second device 2 are calculated is within a range that does not hinder the capture of the movement of the second device. If the distances are not calculated at the same time or close together (for example, if the time at which the propagation time of information or signals between each of the multiple first devices 1 and second device 2 is measured is the same time or close together), it becomes difficult to accurately determine the position of second device 2 (especially if the worker P or work machine W) is moving.

[0072] Therefore, first, it is determined whether four or more data points of the distance between the first device 1 and the second device 2 have been acquired within a predetermined time range (step S21).

[0073] If four or more distance data points between the first device 1 and the second device 2 are not acquired within a predetermined time range, accurate three-dimensional positional information cannot be obtained using this positioning method. Therefore, the system waits until four or more distance data points are obtained within the predetermined time range. In contrast, if four or more distance data points between the first device 1 and the second device 2 can be acquired within a predetermined time range, three-dimensional position information can be obtained with high accuracy using this position determination method that utilizes wireless bidirectional time comparison. Then, the current position of the second device 2 is determined using the multi-point surveying calculation method described above (step S22), and display processing is performed such as displaying the current position of the second device 2 (worker P, work machine W, materials M) on a display screen (not shown) of the server device 3 (step 23). At the same time, it is preferable to store the position information of the second device 2 along with the time it was calculated in the storage unit 33 of the server device 3 for use in subsequent processing.

[0074] Therefore, if there are four or more first devices 1 that can transmit and receive data from the second device 2 carried or attached to the worker P, work machine W, and material M within a predetermined time range, the three-dimensional position of the second device 2 is determined by a position identification process based on the distance between each first device 1 and the second device 2 calculated by the distance calculation process, and the position information of each first device 1 used in this distance calculation. As a result, the position of the second device 2 can be continuously tracked as the four first devices 1 that can calculate distances are sequentially switched as the worker P, work machine W, and material M move. Thus, if there are four or more first devices 1 capable of calculating distance, it becomes possible to determine the three-dimensional position of the second device 2. By adjusting the objects to which the first devices are attached and their mounting heights to ensure they are appropriately scattered, it becomes possible to capture the position of the displaced second devices (worker P, work machine W, materials M) in real time.

[0075] Furthermore, in order to distinguish the location information of worker P, work machine W, and material M, the signal transmitted from the second device 2 during the distance calculation process may be accompanied by device-specific identification information, as well as information that identifies whether it is a person, machine, or material. The display device may then display people, machines, and materials with different marks or by color coding.

[0076] By performing the above process for all workers P, work machines W, and materials M that are carrying or wearing the second device 2, accurate three-dimensional positional information for each worker P, work machine W, and material M can be obtained. Based on this positional information, it becomes possible to accurately determine the position of each worker P, work machine W, and material M without error.

[0077] Conventional distance measurement systems calculate propagation time based on the difference between the transmission time of a transmitter (corresponding to the first device) and the reception time of a receiver (corresponding to the second device), and then calculate distance based on this time. However, in this method, unless the transmitter and receiver are time-synchronized, if there is a time difference between the two devices, the calculated propagation time will differ from the actual propagation time. In other words, if the receiver is different, the calculated propagation time may differ. In contrast, this system calculates the propagation time based on the transmission and reception times in both directions between the first device 1 and the second device 2, and then calculates the distance between the first device 1 and the second device 2. Therefore, even if there is a time difference between the first device 1 and the second device 2, there is no inconvenience in that the calculated propagation time will differ.

[0078] Furthermore, if the second device carried by worker P, the second device attached to the work machine W, and the second device attached to material M are not time-synchronized, the location information of worker P, work machine W, and material M recorded on the server at a certain time will become inaccurate (a discrepancy will occur between the location known on the server at a certain time and the actual location of worker P, work machine W, and material M at that time). In particular, when trying to prevent worker P from falling or worker P from colliding with work machine W, the data recorded with the same timestamp will differ from the actual location of worker P, work machine W, and material M, making it impossible to issue appropriate alarms or instructions. For this reason, in order to collect accurate location information known with the same timestamp, all first devices 1 and second devices 2 must be time-synchronized with the server device 3.

[0079] Therefore, the time of the second device 2 can be synchronized with the time of the first device based on the time difference in equation (4). By synchronizing multiple first devices with the server device 3 to a reference time at a predetermined timing, it becomes possible to synchronize all second devices 2 with the first device 1 and the server device 3. This makes it possible to accurately collect the simultaneous locations of all workers P, work machines W, and materials M at the construction site, enabling accurate monitoring. In other words, it becomes possible to accurately identify situations such as when workers are in positions with a high risk of falling, when they are within the range of motion of work machinery and there is a risk of contact, or when work machinery is in danger of contacting each other, enabling appropriate responses (warnings and instructions) to be taken. Furthermore, the second device 2 attached to the work machinery W and materials M allows for accurate management of materials (such as the current location and quantity of materials M) and work machinery (such as the location, number, and operating status of work machinery W), making it possible to improve work efficiency by properly managing their placement.

[0080] (Examples of using this system) Using the above-described work site management system S, monitoring and control as shown in Figures 8 to 10 is possible to ensure work safety by monitoring workers P, work machinery W, and materials M at the construction site. This monitoring and control may be performed by the server device 3 or by other control devices. Here, we show an example where the monitoring and control of the worker P, the work machine W, and the materials M are monitored separately. However, these may also be controlled together simultaneously or in a predetermined sequence.

[0081] First, regarding the monitoring and control of the worker, as shown in Figure 8, the position of the second device 2, that is, the position of worker P, is first calculated using the method described above, and the position of worker P is monitored in real time (step S40). Subsequently, based on the position of the second device 2 (the position of the worker P), it is determined whether or not the worker has deviated from the safety zone (step S41). In the case of work at height, for example, it is determined whether or not the distance between the worker and the first device installed at height exceeds a threshold that ensures safety, thus increasing the risk of falling (step S42). Furthermore, since workers often work in close proximity to the work machine, it is determined whether or not the risk of worker P approaching the work machine W within a predetermined distance (the working range of the work machine) and colliding with it has increased (step S43).

[0082] Based on the above assessment of dangerous conditions, if it is determined that worker P has deviated from the safe area, if the risk of falling has increased, or if the risk of collision with the work machine has increased as it approaches within a predetermined distance, an alarm signal is sent to the relevant second device to alert the person carrying the second device that danger is imminent (step S44). At the same time, an alarm is sent to the manager (including supervisors) (step S45), and the ID of the relevant second device is further transmitted to the manager along with the location information of the second device (worker at high risk of accident) (step S46).

[0083] Furthermore, it is determined whether the position of worker P has suddenly changed (step S47). If it is determined that the worker's position has suddenly changed, there is a possibility of an accident such as the worker falling, being thrown by a work machine, or falling from a height. In this case, the manager is notified of the possibility of an accident and the location information of the person carrying the second device in question (step S48). This allows administrators to rush to the location based on the transmitted location information, quickly rescue worker P, investigate the cause of the sudden change in worker P's location, and take appropriate action.

[0084] Next, the monitoring and control of the work machine W will be explained. As shown in Figure 9, first, the position of the second device 2 attached to the work machine W, that is, the position of the work machine W, is calculated using the method described above, and the position of the work machine W is monitored in real time (step S50). Subsequently, based on the position of the second device 2 (position of the work machine W), it is determined whether or not the work machine has been moved to an unsafe area (step S51). Also, since the work machine W often works in close proximity to workers and other work machines, it is determined whether or not there is a high risk of the work machine W approaching workers and other work machines within a predetermined distance and colliding with them (step S52).

[0085] If, based on the above assessment of dangerous conditions, it is determined that the work machine W has moved to an unsafe area, or if the risk of the work machine approaching a worker or other work machine within a predetermined distance and colliding with them increases, an alarm signal is issued to the relevant second device to alert the person carrying the second device that danger is imminent (step S53). At the same time, an alarm is issued to the administrator (step S54), and the ID of the relevant second device is further transmitted to the administrator along with the location information of the second device (the work machine W with a high risk of accident) (step S55).

[0086] Furthermore, it is determined whether or not an unexpected movement occurred in the work machine W for any reason (step S56). For example, if the work machine falls over and stops, or if two work machines collide and their positions are suddenly shifted, this is a movement that deviates from the normal movement of the work machine, and therefore an accident may have occurred. In this case, the administrator is notified of the possibility of an accident and the location information of the second device in question (the location information of the work machine to which the second device is attached) (step S57). This allows administrators to rush to the location based on the transmitted location information, promptly carry out rescue operations, investigate the cause of the unexpected movement of the work machinery, and take appropriate action.

[0087] Next, the monitoring and control of the materials will be explained. As shown in Figure 10, first, the position of the second device 2 attached to the material M, that is, the position of the material M, is calculated using the method described above, and the position of the material M (second device 2) is monitored in real time (step S60). Subsequently, based on the position of the second device 2 (the position of material M), it is determined whether or not material M has been moved to an unsafe area (step S61). If this determination determines that material M has moved to an unsafe area, an alarm is issued to the administrator (step S62), and the ID of the second device in question is transmitted to the administrator along with the location information of the second device (material M) (step S63).

[0088] Furthermore, it is determined whether or not material M has made any unexpected movement for any reason (step S64). For example, if the wire securing material M breaks while material M is being moved suspended from a crane and the material falls, or if material being transported collides with a work machine W and scatters, the position of the second device 2 attached to material M changes abruptly, which is an unexpected movement of material M and may indicate that an accident has occurred. In this case, the administrator is notified of the possibility of an accident and the location information of the second device in question (location information of the material to which the second device is attached) (step S65). This allows administrators to quickly go to the location based on the transmitted location information, investigate the cause of the unexpected movement of material M, and take appropriate action.

[0089] Furthermore, it is determined whether the material M on which the second device 2 is installed is located in a place necessary for carrying out the work (step S66). If materials are not placed in the required location, it is possible that the materials have been mistakenly moved to another location or that the delivery of the materials is delayed. Therefore, instructions are given to move the materials to the required location, and the delivery date and time are notified by referring to the materials management database, which does not show the date and time (step S67).

[0090] Therefore, with the above system, the precise location information of workers P, work machinery W, and materials M at a construction site can be captured in real time, and their safety can be constantly monitored. In the event of an accident, it is possible to instantly identify the accident, notify the manager, and have them take appropriate action. Furthermore, by confirming the current positions of workers P, machinery W, and materials M, it becomes possible to monitor the progress of the work. By properly managing the placement of workers P, machinery W, and materials M, unnecessary movements and shifts can be eliminated, thereby improving work efficiency.

[0091] In the example described above, the presence or absence of an accident was determined by detecting sudden changes in the position of the second device and unexpected movements. However, the presence or absence of an accident and its cause could also be inferred using a learning model based on dynamic information obtained from the temporal changes in the positions of the worker P, the work machine W, and the materials M. In other words, as shown in Figure 11(a), a machine learning device 5 may be provided, which is connected to a communication network 4 and includes an input data acquisition unit 51 that acquires data sets as input data, including object identification information that identifies an object (worker P, work machine W, material M) carrying or wearing the second device, and dynamic information obtained from the temporal change in the position of the second device 2 (amount of change per unit time (velocity, acceleration) and movement trajectory (time series of past position data)); a label acquisition unit 52 that acquires data sets as labels, including whether or not an accident occurred (binary information) and categorical labels of the cause of the accident (0: collision, 1: fall, 2: slip, 3: drop, 4: environmental factors, etc.); and a learning model storage unit 53 that constructs a learning model 55 by performing supervised learning using the input data and label set as training data, and stores the learning model. By using such a learning model 55, as shown in Figure 11(b), it is possible to acquire object identification information that identifies the object on which the second device 2 is carried or attached, and information on how the object moves (dynamic information obtained from the temporal change in the position of the second device 2, for example, the amount of change per unit time (velocity, acceleration) and the movement trajectory (time series of past position data), etc.) (step S70), and from this acquired information, to infer whether or not an accident occurred and the cause of the accident (step S71), and to send the inference result to the administrator (step S72), thereby enabling early investigation of the cause of the accident and the development of countermeasures.

[0092] Furthermore, the aforementioned work site management system S can also be provided in the form of a program (work site management program) that causes a computer to execute each step of the work site management method described above. Furthermore, while the above example showed a construction site as the work site, it can also be applied to other construction sites, manufacturing sites, forestry sites, agricultural sites, fishing sites, infrastructure development sites, etc. [Explanation of Symbols]

[0093] 1 1st device 2 Second device 3 Server equipment S Work Site Management System 5 Machine Learning Devices 51 Input data acquisition unit 53 Learning Model Memory Unit 55 Learning Models

Claims

1. A work site management system that manages a work site using a plurality of first devices installed at and around the work site and capable of acquiring their own location information, and second devices carried or attached to workers, work machinery, and materials at the work site, Distance calculation means for calculating the distance between each of the plurality of first devices and the second device based on the bidirectional transmission and reception times of information or signals between each of the plurality of first devices and the second device, A position determination means that determines the position of the second device based on the distance between each of the first and second devices calculated by the distance calculation means, and the position information of each of the first devices. A work site management system characterized by having the following features.

2. A time difference calculation means calculates the time difference between the clock of the first device and the clock of the second device based on the bidirectional transmission and reception times of information or signals between each of the plurality of first devices and the second device. Based on the aforementioned time difference, the device time synchronization means synchronizes the time of the second device with the time of the first device which is synchronized with the reference time, The work site management system according to claim 1, further comprising:

3. The distance calculation means is The difference between the time on the first device's clock when it transmits information or a signal and the time on the second device's clock when it receives the information or signal transmitted from the first device, The difference between the time on the second device's clock when it transmits information or a signal and the time on the first device's clock when it receives the information or signal transmitted from the second device, The work site management system according to claim 1, characterized in that it calculates the propagation time of the information or signal between the first device and the second device based on this propagation time, and calculates the distance between the first device and the second device based on this propagation time.

4. The aforementioned device time synchronization means is The difference between the time on the first device's clock when it transmits information or a signal and the time on the second device's clock when it receives the information or signal transmitted from the first device, The difference between the time on the second device's clock when it transmits information or a signal and the time on the first device's clock when it receives the information or signal transmitted from the second device, The work site management system according to claim 2, characterized in that, based on this, the time difference between the clock of the first device 1 and the clock of the second device 2 is calculated, and the time of the clock of the second device is synchronized with the time of the clock of the first device based on this time difference.

5. A zone deviation determination means that determines whether or not the device has deviated from the safety zone based on the position information of the second device identified by the position identification means, A means for determining whether or not the device has entered a dangerous area, based on the location information of the second device, A fall risk determination means that determines whether the risk of falling has increased to above a predetermined threshold based on the position information of the second device, The system includes proximity determination means that determines whether or not the second device has approached another second device within a predetermined distance based on the position information of the second device, If the area departure determination means determines that the device has deviated from the safe area, if the danger area intrusion determination means determines that the device has entered the danger area, if the fall risk determination means determines that the risk of falling has risen to a predetermined threshold or higher, or if the proximity determination means determines that the device has approached another second device within a predetermined distance, the alarm issuing means issues an alarm. The work site management system according to claim 1, further comprising the following:

6. An accident estimation means that estimates whether or not an accident has occurred by taking into account the change in the position of the second device identified by the position identification means over time, When the occurrence of an accident is estimated by the accident estimation means, a notification means notifies the administrator of the estimation result and also notifies the location of the corresponding second device, The work site management system according to claim 1, further comprising the following:

7. The system includes a learning model storage unit that stores a learning model that has been machine-learned to determine the correlation between input data, which includes object identification information that identifies an object carrying or wearing the second device and dynamic information of the second device obtained from changes in the position of the second device over time, and output data, which includes whether or not an accident occurred and the cause of the accident. The accident estimation means is, The work site management system according to claim 6, wherein the learning model is used to infer whether an accident occurred and the cause of the accident from object identification information that identifies an object on which the second device is carried or attached, and dynamic information of the second device obtained from changes in the position of the second device over time.

8. A work site management method for managing a work site, comprising: a plurality of first devices installed at and around the work site and capable of acquiring their own location information; and second devices carried or attached to workers, work machinery, and materials at the work site, wherein the work site is managed using these devices. A distance calculation step in which the distance between each of the plurality of first devices and the second device is calculated based on the bidirectional transmission and reception times of information or signals between each of the plurality of first devices and the second device, A position determination step in which the position of the second device is determined based on the distance between each of the first and second devices calculated in the distance calculation step, and the position information of each of the first devices, A work site management method characterized by having the following features.

9. A time difference calculation step, which calculates the time difference between the clock of the first device and the clock of the second device based on the bidirectional transmission and reception times of information or signals between each of the plurality of first devices and the second device, A device time synchronization step is performed to synchronize the time of the second device with the time of the first device which is synchronized to a reference time, based on the aforementioned time difference. The work site management method according to claim 8, further comprising:

10. A zone departure determination step, which determines whether or not the device has deviated from the safety zone based on the location information of the second device identified in the position identification step, A hazardous area intrusion determination step, which determines whether or not the device has entered a hazardous area based on the location information of the second device, A fall risk determination step, which determines whether the risk of falling has increased to above a predetermined threshold based on the position information of the second device, The system includes a proximity determination step that determines whether or not the second device has approached another second device within a predetermined distance based on the location information of the second device, If the area departure determination step determines that the device has deviated from the safe area, if the danger area intrusion determination step determines that the device has entered the danger area, if the fall risk determination step determines that the risk of falling has risen to a predetermined threshold or higher, or if the proximity determination step determines that the device has approached another second device within a predetermined distance, an alarm is issued in the event that an alarm is issued. The work site management method according to claim 8, further comprising the following:

11. An accident estimation step that estimates whether or not an accident has occurred by taking into account the change in the position of the second device identified in the position identification step over time, If the occurrence of an accident is estimated by the accident estimation step, a notification step is made to notify the administrator of the estimation result and the location of the relevant second device, The work site management method according to claim 8, further comprising the following:

12. The system includes a learning model storage step that stores a learning model that has been machine-trained to store the correlation between input data, which includes object identification information that identifies an object carrying or wearing the second device and dynamic information of the second device obtained from changes in the position of the second device over time, and output data, which includes whether or not an accident occurred and the cause of the accident. The aforementioned accident estimation step is, The work site management method according to claim 11, wherein the presence or absence of an accident and the cause of an accident are estimated using the learning model based on object identification information that identifies an object on which the second device is carried or attached, and dynamic information of the second device obtained from changes in the position of the second device over time.

13. A work site management program for causing a computer to perform each step of the work site management method according to any one of claims 8 to 12.

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