Position estimation system

Abstract

To provide a position estimation system capable of estimating a position of a mobile body moving in a site provided with a structure with high accuracy, and excellent in cost.SOLUTION: A position estimation system 1 is a system capable of estimating a position of each operator W moving in a predetermined target region A2 provided with a steel structure 100. The position estimation system 1 includes a first communication device 2 that can be mounted on an operator W, a plurality of slave-side second communication devices 31 and master-side second communication devices 32 provided at fixed positions, respectively, and a server 4. The second communication devices 3 includes first distance information acquisition units that can acquire first distance information indicating a distance between the second communication device 3 and each first communication device 2 according to a radio bidirectional time comparison technology, respectively. The master-side second communication device 32 has a distance information transmission unit 324 that can transmit the first distance information D1 to the server 4. The server 4 includes a position estimation unit 43 that can estimate the position of the operator W on the basis of the plurality of pieces of first distance information D1.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a position estimation system. [Background technology]

[0002] Conventionally, there are technologies in substations that prevent workers from approaching dangerous areas such as live parts of equipment in order to prevent electric shock accidents. Some of these technologies are capable of remotely estimating the location of workers.

[0003] For example, Patent Document 1 discloses a device that uses a position detection sensor to detect the position of a worker at an electric power station and issues an alert when the worker approaches an electric shock hazard area including a live section of a power distribution system. The position detection sensor may be one that can calculate position information using, for example, a GPS or a beacon. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-106010 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when using GPS, radio waves from GPS satellites may be blocked by iron structures and other objects within the power station, which may prevent the location sensor from accurately calculating the location of workers, etc. When using beacons, communication problems caused by iron structures and other objects can be suppressed, but beacon terminals are expensive, so there is room for improvement in terms of cost.

[0006] The present invention has been made in consideration of the above-mentioned problems, and has as its main object to provide a position estimation system that is capable of estimating with high accuracy the position of a moving object moving within a site where a structure is installed, and that is also cost-effective. [Means for solving the problem]

[0007] In order to solve the above problem, a position estimation system of a first invention is a position estimation system capable of estimating the position of one or more moving bodies moving within a specified target area in which buildings are installed, and comprises a plurality of communication devices each having a wireless communication unit capable of wireless communication with each other, and a server having a position estimation unit capable of estimating the position of the moving bodies, wherein the plurality of communication devices include one or more first communication devices that can be equipped to the moving bodies and a plurality of second communication devices installed at fixed positions, the second communication devices have a first distance information acquisition unit that can acquire first distance information indicating the distance between the second communication device and the first communication device using wireless two-way time comparison technology, the wireless communication unit of the second communication devices is capable of transmitting the first distance information to other second communication devices, at least one of the second communication devices has a distance information transmission unit that can transmit the first distance information to the server, and the position estimation unit is capable of estimating the position of the moving body based on the plurality of first distance information.

[0008] A second invention is a position estimation system in which, in the first invention, the communication device has two or more of the first communication devices, the first communication device has a second distance information acquisition unit capable of acquiring second distance information indicating the distance between the first communication device and other first communication devices using wireless two-way time comparison technology, the wireless communication unit of the first communication device is capable of transmitting the second distance information to the second communication device, the distance information transmission unit is capable of transmitting the second distance information to the server, and the position estimation unit is capable of estimating the position of the moving body based on the first distance information and the second distance information.

[0009] A third aspect of the position estimation system is the first or second aspect of the invention, wherein the server has a memory unit capable of storing avoidance target position information indicating the position of a predetermined avoidance target that is an object to be avoided from contacting with the moving body, and a proximity detection unit capable of detecting that the moving body and the predetermined avoidance target have come into close proximity to each other based on the estimation result of the position estimation unit and the avoidance target position information.

[0010] A position estimation system of a fourth invention is any one of the first to third inventions, and is provided with a display unit capable of displaying an image, wherein the memory unit of the server is capable of storing a first map image, which is a map image of the specified target area, as data, and the server has an image processing unit capable of displaying on the display unit a second map image indicating the position of the moving body on the first map image based on the estimation result by the position estimation unit and the first map image.

[0011] A fifth aspect of the present invention is a position estimation system according to any one of the first to fourth aspects of the present invention, wherein the specified target area is located within a substation site, the building is a steel structure, and the moving object is a worker at the substation.

[0012] A position estimation system of a 6th invention is any one of the 2nd to 5th inventions, wherein a part of the two or more first communication devices is provided at a predetermined avoidance target which is an object to be avoided from contacting the moving body, the predetermined avoidance target is movable, and the position estimation unit is capable of estimating a position of the predetermined avoidance target based on the second distance information. Effect of the Invention

[0013] The main object of the present invention is to provide a position estimation system that is capable of estimating with high accuracy the position of a mobile object moving within a site on which structures are installed, and that is also cost-effective. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram showing a system configuration of a position estimation system. [Diagram 2] FIG. 1 is a functional block diagram of a position estimation system. [Diagram 3] 4 is a sequence diagram showing processing in each of the first communication devices and each of the second communication devices. FIG. [Figure 4A] 13 is a flowchart showing a process flow in the server. [Figure 4B] 4 is a flowchart showing a process flow in the alarm device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a schematic diagram showing a system configuration of a position estimation system. Fig. 2 is a functional block diagram of the position estimation system 1.

[0016] The position estimation system 1 is a system capable of estimating the position of a worker W who performs work while moving within a site A1 of a substation. In the following, the worker W may be referred to as a "mobile body W." In addition, the following description will be given assuming that there are two workers W, but the number of workers W may be one or three or more.

[0017] As shown in FIG. 1, a building is provided within a site A1 of a substation, and more specifically, a steel structure 100 is provided. The steel structure 100 is an iron structure and includes a plurality of steel columns 101 extending in a substantially vertical direction, a plurality of steel first beams 102 extending in a substantially horizontal direction, and a plurality of second beams 103 extending in a substantially horizontal direction and in a direction substantially perpendicular to each of the first beams 102. Each of the columns 101 is connected to each of the first beams 102 and the second beams 103. At least a portion of the steel structure 100 has a lattice shape in a plan view. The first beams 102 connect the upper ends of the columns 101 to each other. The second beams 103 connect the middle parts of the columns 101 in the vertical direction to each other.

[0018] The pillars 101 include pillars 101A, 101B, 101C, and 101D (hereinafter, collectively referred to as "pillars 101A, 101B, 101C, and 101D"). Each of the pillars 101A, 101B, 101C, and 101D is disposed at each of the four corners of a rectangular area in a plan view.

[0019] The first beam 102 includes a first beam 102A and a first beam 102B. The first beam 102A connects the upper end of the pillar 101A to the upper end of the pillar 101B. The first beam 102B connects the upper end of the pillar 101C to the upper end of the pillar 101D.

[0020] The second beam 103 includes a second beam 103A and a second beam 103B. The second beam 103A connects the vertical middle portion of the pillar 101A to the vertical middle portion of the pillar 101D. The second beam 103B connects the vertical middle portion of the pillar 101B to the vertical middle portion of the pillar 101C.

[0021] Each of the pillars 101A, 101B has a protrusion 105A, 105B at the upper end thereof, which is generally a quadrangular pyramid shape that is convex upward. A lightning protection wire (not shown) can be connected to the protrusions 105A, 105B.

[0022] Each worker W moves below the upper end of the steel structure 100. A crossing gate R1 is provided in the area surrounded by the steel structure 100. The crossing gate R1 is placed on the ground in the area between the pillars 101A and 101D. A cubicle R2 is provided near the steel structure 100. The cubicle R2 is provided on the ground near the pillar 101B. Both the crossing gate R1 and the cubicle R2 are live parts, and are objects that each worker W should avoid coming into contact with. In the following, the crossing gate R1 may be referred to as the "predetermined object to be avoided R1." The cubicle R2 may be referred to as the "predetermined object to be avoided R2." When there is no need to distinguish between them, they may be collectively referred to as the "predetermined object to be avoided R."

[0023] The position estimation system 1 can set a predetermined target area A2 as an area in which the position of a first communication device 2 (worker W) described later can be estimated. The predetermined target area A2 can be set as a three-dimensional area. The position estimation system 1 can estimate the three-dimensional position of the first communication device 2.

[0024] The predetermined target area A2 can be set to include the steel structure 100. The predetermined target area A2 can be set, for example, as a three-dimensional area having a substantially rectangular parallelepiped shape. The predetermined target area A2 can be set to include a rectangular parallelepiped area surrounded by each of the pillar materials 101A, 101B, 101C, and 101D, and each of the predetermined avoidance targets R. Note that the shape of the predetermined target area is not limited to a substantially rectangular parallelepiped shape, and can be set arbitrarily.

[0025] (Configuration of location estimation system) Next, the configuration of the position estimation system 1 will be described.

[0026] As shown in FIGS. 1 and 2, the position estimation system 1 includes a plurality of first communication devices 2, a plurality of second communication devices 3, a server 4, and a notification device 6.

[0027] (First communication device) Each of the first communication devices 2 is a terminal that can be used for communication using Wi-Wire (wireless two-way time comparison technology). Each of the first communication devices 2 can be equipped to each of the moving bodies W. Each of the first communication devices 2 can be attached to, for example, the helmet of each of the workers W. When each of the moving bodies W moves, each of the first communication devices 2 moves together with each of the moving bodies W. The two first communication devices 2 are composed of a first communication device 2A and a first communication device 2B. Each of the first communication devices 2A and 2B has a wireless communication unit 21A and 21B, a second distance information acquisition unit 22A and 22B, and a storage unit 23A and 23B (see FIG. 2). Note that, for convenience, the number of the first communication devices is two in FIG. 2, but the number of the first communication devices is not particularly limited.

[0028] Each of the wireless communication units 21A, 21B is capable of wireless communication with an external device. Each of the first communication devices 2A, 2B is capable of wireless communication with each other through each of the wireless communication units 21A, 21B. Each of the first communication devices 2A, 2B is capable of communication with each of the child side second communication devices 31 and the parent side second communication device 32 through each of the wireless communication units 21A, 21B.

[0029] Each of second distance information acquisition units 22A, 22B can acquire second distance information D2 indicating the distance between first communication device 2A and first communication device 2B based on the result of wireless communication between each of wireless communication units 21A, 21B. Each of second distance information acquisition units 22A, 22B can acquire second distance information D2 via Wi-Wi.

[0030] Each of the wireless communication units 21A, 21B can transmit the second distance information D2 acquired by each of the second distance information acquisition units 22A, 22B to the master side second communication device 32 by wireless communication. Note that it is sufficient that at least one of the first communication devices 2A, 2B can acquire and transmit the second distance information D2.

[0031] Each of the storage units 23A and 23B is configured with a RAM, a ROM, etc., and is capable of storing various types of information.

[0032] (Second communication device) Each second communication device 3 is a terminal that can be used for communication using Wi-Wi. The multiple second communication devices 3 include multiple child side second communication devices 31 and one parent side second communication device 32. For convenience, FIG. 2 shows only one child side second communication device 31 as a representative of the multiple child side second communication devices 31.

[0033] (Child 2nd communication device) Each child side second communication device 31 is provided at a fixed position. The child side second communication device 31 includes a plurality of first child side second communication devices 31A arranged on the lower end side of the steel structure 100, a plurality of second child side second communication devices 31B arranged above the first child side second communication devices 31A, and a plurality of third child side second communication devices 31 arranged in the vertical middle between the first child side second communication device 31A and the second child side second communication device 31B.

[0034] Each of the first child side second communication devices 31A can be fixed, for example, to the lower end side of each of the pillar materials 101A, 101B, 101C, and 101D. Each of the first child side second communication devices 31A can be fixed, for example, to the ground surface. Note that the height position of each of the first child side second communication devices 31A does not need to be the same as the ground surface, and may be slightly separated from the ground surface.

[0035] Each second child side second communication device 31B can be fixed to the upper end side of each pillar material 101A, 101B, 101C, 101D, for example, at the portion where each pillar material 101A, 101B, 101C, 101D and each first beam material 102 intersect.

[0036] Each third child side second communication device 31C can be fixed to the vertical middle part of each pillar material 101A, 101B, 101C, 101D, for example, to the part where each pillar material 101A, 101B, 101C, 101D intersects with each second beam material 103.

[0037] Each slave second communication device 31 includes a wireless communication unit 311 , a first distance information acquisition unit 312 , and a storage unit 313 .

[0038] Each wireless communication unit 311 is capable of wireless communication with an external device. Each child side second communication device 31 is capable of wireless communication with each of the first communication devices 2A and 2B, other child side second communication devices 31, and the parent side second communication device 32 through each wireless communication unit 311.

[0039] Each first distance information acquisition unit 312 can acquire first distance information D1 indicating the distance between the child second communication device 31 and each of the first communication devices 2A, 2B (each of the wireless communication units 21A, 21B) based on a result of wireless communication between the wireless communication unit 321 and each of the first communication devices 2A, 2B. Each first distance information acquisition unit 312 can acquire the first distance information D1 via Wi-Wi.

[0040] Each storage unit 313 is configured with a RAM, a ROM, etc., and is capable of storing various information. Each storage unit 313 is capable of storing the second distance information D2 acquired by each first distance information acquisition unit 312.

[0041] Each wireless communication unit 311 is capable of transmitting the second distance information D2 acquired by each first distance information acquisition unit 312 to the master side second communication device 32 by wireless communication.

[0042] The number of the first child side second communication device 31A, the second child side second communication device 31B, and the third child side second communication device 31C to be installed is not particularly limited. However, by installing more child side second communication devices 31, the measurement accuracy can be improved. Also, since Wi-Wi terminals are generally cheaper than beacon terminals, more child side second communication devices 31 can be installed at a relatively low cost. Therefore, the measurement accuracy can be improved at a relatively low cost.

[0043] (Master side second communication device) The parent side second communication device 32 is provided at a fixed position. The parent side second communication device 32 can be fixed to the upper end side of the pillar material 101A of the steel structure 100, and more specifically, is fixed to the protruding portion 105A. The parent side second communication device 32 has a wireless communication unit 321, a third distance information acquisition unit 322, a storage unit 323, and a distance information transmission unit 324.

[0044] The wireless communication unit 321 is capable of wirelessly communicating with an external device. The master second communication device 32 is capable of wirelessly communicating with each of the first communication devices 2A, 2B and each of the slave second communication devices 31 via the wireless communication unit 321. The wireless communication unit 321 is capable of receiving second distance information D2 transmitted from each of the first communication devices 2A, 2B. The wireless communication unit 321 is capable of receiving each of the first distance information D1 transmitted from each of the slave second communication devices 31.

[0045] The third distance information acquisition unit 322 can acquire third distance information D3 indicating the distance between the master second communication device 32 and each of the first communication devices 2A, 2B (each of the wireless communication units 21A, 21B) based on the result of wireless communication between the wireless communication unit 321 and each of the first communication devices 2A, 2B. The third distance information acquisition unit 322 can acquire the third distance information D3 via Wi-Wi.

[0046] The storage unit 323 is configured with a RAM, a ROM, etc., and is capable of storing various types of information. The storage unit 323 is capable of storing the first distance information D1 and the second distance information D2 received by the wireless communication unit 321. The storage unit 323 is capable of storing the third distance information D3 acquired by the third distance information acquisition unit 322.

[0047] Distance information transmission unit 324 is capable of communicating with server 4. Distance information transmission unit 324 is capable of communicating with server 4, for example, via Wi-Fi (registered trademark). Distance information transmission unit 324 is capable of transmitting each of the first distance information D1, each of the second distance information D2, and each of the third distance information D3 to server 4.

[0048] The parent side second communication device 32 does not necessarily have to be disposed at the upper end side of the steel structure 100. However, the parent side second communication device 32 is preferably disposed at a higher end side of the steel structure 100, and is preferably disposed above each of the first beam members 102 and each of the second beam members 103. In this case, it is possible to prevent the radio waves transmitted by the distance information transmission unit 324 from being blocked by the steel structure 100, and therefore it is possible to preferably execute communication between the distance information transmission unit 324 and the server 4.

[0049] The cardinal number of the multiple second communication devices 3 is three or more, and preferably four or more. Furthermore, when the cardinal number of the second communication devices 3 is three, it is preferable that all the second communication devices 3 are not arranged on the same line. This makes it possible for the server 4 to more reliably estimate the position of the first communication device 2 (described in detail later).

[0050] (server) The server 4 includes a communication unit 41, a storage unit 42, a position estimation unit 43, an approach detection unit 44, a display unit 45, and an image processing unit 46. The server 4 can be disposed, for example, in a control tower (not shown) of a power supply station where an administrator remotely monitors the substation.

[0051] The communication unit 41 is capable of network communication with an external device. The communication unit 41 is capable of communicating with the parent side second communication device 32 and the notification device 6, for example, via a mobile network. The communication unit 41 is capable of receiving the first distance information D1, the second distance information D2, and the third distance information D3 transmitted by the parent side second communication device 32. The communication unit 41 is capable of transmitting various types of information to the notification device 6, as will be described in detail later.

[0052] The storage unit 42 is configured with RAM, ROM, etc., and is capable of storing various types of information. The storage unit 42 is capable of storing the first distance information D1, the second distance information D2, and the third distance information D3 received by the communication unit 41. The storage unit 42 is capable of storing in advance information on the position of each predetermined avoidance target R (hereinafter referred to as "avoidance target position information D5") and data on a first map image M1 which is a map image of the site A1 of the substation. Note that the first map image M1 does not need to show the entire area of ​​the site A1 of the substation, but only needs to show at least a predetermined target area A2 of the site A1 of the substation.

[0053] The position estimation unit 43 can estimate the position of each of the first communication devices 2A, 2B based on at least one of the first distance information D1, the second distance information D2, and the third distance information D3. That is, the position estimation unit 43 can acquire mobile object position information D4 indicating the position of each worker W based on at least one of the first distance information D1, the second distance information D2, and the third distance information D3. The storage unit 42 can store each mobile object position information D4.

[0054] The approach detection unit 44 has a calculation unit 441 and an approach determination unit 442. Note that "approach" refers to the distance between a predetermined avoidance target R and each moving object W becoming equal to or less than a reference value S. Note that the reference value S is stored in the storage unit 42 in advance.

[0055] The calculation unit 441 can calculate the distance between the predetermined avoidance target R and each worker W based on the moving object position information D4 and the avoidance target position information D5. The approach determination unit 442 can determine that each worker W has approached the avoidance target R when the distance between the predetermined avoidance target R and each worker W calculated by the approach detection unit 44 is smaller than a reference value S. This allows the approach detection unit 44 to detect that the worker W has approached the avoidance target R.

[0056] Furthermore, the communication unit 41 can transmit information indicating that the approach detection unit 44 has detected that each worker W has approached a predetermined avoidance target R (hereinafter referred to as "approach detection information D6") to the alarm device 6. Furthermore, the storage unit 42 can store each piece of approach detection information D6.

[0057] The display unit 45 is, for example, a liquid crystal monitor, and is capable of displaying various types of information.

[0058] The image processing unit 46 can display a second map image M2 showing the positions of each worker W and each predetermined avoidance target R on the first map image M1 on the display unit 45 based on each moving object position information D4, each avoidance target position information D5, and the first map image M1. The second map image is displayed, for example, as a three-dimensional map with a changeable viewpoint.

[0059] The image processing unit 46 sequentially receives the moving object position information D4 from the position estimation unit 43. When the moving object position information D4 is input, the image processing unit 46 can change the position of the worker W in the second map image M2 based on the moving object position information D4. This makes it possible to show how each worker W moves in the predetermined target area A2. The image processing unit 46 can also display the first map image M1 in which the positions of each worker W and each predetermined avoidance target R are not shown.

[0060] Furthermore, the display unit 45 sequentially receives approach detection information D6 from the approach detection unit 44. When the approach detection information D6 is received, the display unit 45 can display that each worker W has approached each predetermined avoidance target R. For example, the display unit 45 can display a pop-up message indicating that each worker W has approached each predetermined avoidance target R.

[0061] (Alarm device) The notification device 6 is a speaker having a communication function. The notification device 6 includes a communication unit 61 and a sound generating unit 62.

[0062] The communication unit 61 is capable of communicating with an external device via a network. The communication unit 61 is capable of communicating with the server 4. The communication unit 61 is capable of receiving each piece of approach detection information D6 transmitted by the server 4.

[0063] The sound generating unit 62 is capable of emitting a warning sound when the communication unit 61 receives each piece of approach detection information D6.

[0064] (Operation of the location estimation system) Next, the operation of the position estimation system 1 will be described with reference to Fig. 3 and Fig. 4. Fig. 3 is a sequence diagram showing the processing in each of the first communication devices 2A, 2B, each child side second communication device 31, and the parent side second communication device 32. Fig. 4(a) is a flowchart showing the processing flow in the server 4. Fig. 4(b) is a flowchart showing the processing flow in the notification device 6.

[0065] (Operations of the first communication device 2, the child side second communication device 31, and the parent side second communication device 32) First, the operations of the first communication device 2, the child second communication device 31 and the parent second communication device 32 will be described.

[0066] 3, in step S11, wireless communication unit 21B of first communication device 2B transmits a wireless signal used for Wi-Wi (hereinafter, sometimes referred to as "Wi-Wi radio waves") to first communication device 2A. In step S12, wireless communication unit 21A of first communication device 2A transmits Wi-Wi radio waves to first communication device 2B. In step S13, second distance information acquisition unit 22B of first communication device 2B calculates second distance information D2 by Wi-Wi.

[0067] Here, a method for calculating distance by Wi-Wire will be described. Each of the first communication devices 2 and the second communication devices 3 has an oscillator (not shown) that oscillates at a predetermined frequency, and a clock (not shown) that can keep time based on the oscillation by the oscillator. Each clock can execute a time synchronization process described later.

[0068] Each first communication device 2 transmits and receives Wi-Wi radio waves to and from the parent second communication device 32. Each first communication device 2 synchronizes the phase of each oscillator of each first communication device 2 with that of the parent second communication device 32 based on the results of transmission and reception of Wi-Wi radio waves with the parent second communication device 32. Next, a time synchronization process is executed to synchronize each clock of each first communication device 2 with the clock of the parent second communication device 32. This makes it possible to synchronize the phase and time of each first communication device 2 with high accuracy based on the phase and time of the parent second communication device 32.

[0069] The time synchronization process will be described in more detail. An example will be described in which the time kept by the clock of the first communication device 2B is synchronized with the time kept by the clock of the master side second communication device 32 (the clock of the master side second communication device 32 is used as a reference). In the following, the time kept by the clock of the first communication device 2B is T2B, and the time kept by the clock of the master side second communication device 32 is T32. The time required for the Wi-Wi radio wave to propagate between the first communication device 2B and the master side second communication device 32 is TD.

[0070] First, the first communication device 2B transmits Wi-Wi radio waves to the parent second communication device 32. At this time, the first communication device 2B stores the time (T2Bs) clocked when the Wi-Wi radio waves are transmitted. Next, the first communication device 2B transmits the Wi-Wi radio waves to the parent second communication device 32. When the parent second communication device 32 receives the Wi-Wi radio waves, it stores the reception time (T32r). If the time difference between the parent second communication device 32 and the first communication device 2B is T2B-T32, then the relationship T2Bs-T32r=(T2B-T32)+TD (hereinafter referred to as "Formula 1") is established.

[0071] Next, the master second communication device 32 transmits the Wi-Wi radio waves including T32r to the first communication device 2B. At this time, the master second communication device 32 clocks the transmission time (T32s) of the Wi-Wi radio waves and includes it in the Wi-Wi radio waves.

[0072] Next, when the first communication device 2B receives the Wi-Wi radio wave transmitted by the parent second communication device 32, it clocks and stores the reception time (T2Br). The first communication device 2B stores T32r and T32s contained in the Wi-Wi radio wave. As a result, T2Bs, T32r, T32s, and T2Br are stored in the first communication device 2B. If the time difference between the first communication device 2B and the parent second communication device 32 is T32-T2B, then the relationship T32s-T2Br=(T32-T2B)+TD (hereinafter referred to as "Formula 2") is established.

[0073] Here, by subtracting both sides of Equation 2 from both sides of Equation 1, T2Bs-T32r-(T32s-T2Br)=(T2B-T32)-(T32-T2B). This allows TD to be removed from the calculation. Furthermore, by rearranging the equation, T32-T2B=1 / 2(T32r-T2Bs+T2Br-T32s). This allows the first communication device 2B to calculate the time difference (T32-T2B) between the first communication device 2B and the parent second communication device 32 based on T2Bs, T32r, T32s, and T2Br. The first communication device 2B can synchronize the clock of the first communication device 2B with the clock of the parent second communication device 32 based on the calculation result.

[0074] The above-mentioned various synchronization processes may be executed periodically, and may be set to be executed, for example, once a day at a predetermined time. Also, each of the first communication devices 2 does not necessarily have to directly communicate with the parent second communication device 32 to execute the above-mentioned synchronization process. For example, only one of the first communication devices 2 (for example, the first communication device 2A) may synchronize the phase and time with the parent second communication device 32, and the other of the first communication devices 2 (for example, the first communication device 2B) may synchronize the phase and time with the first communication device 2A.

[0075] Then, the first communication device 2A transmits Wi-Wi radio waves toward the first communication device 2B. The Wi-Wi radio waves transmitted by the first communication device 2A include information on the time when the first communication device 2A transmitted the Wi-Wi radio waves (hereinafter referred to as the transmission time). The transmission time is the time clocked by the clock of the first communication device 2A. When the first communication device 2B receives the Wi-Wi radio waves transmitted by the first communication device 2A, it acquires the time when the Wi-Wi radio waves were received (hereinafter referred to as the reception time). The reception time is the time clocked by the clock of the first communication device 2B. The second communication device acquires the time required for the Wi-Wi radio waves to propagate between the first communication devices 2 (hereinafter referred to as the propagation time) based on the reception time and the transmission time.

[0076] The propagation speed of the Wi-Wi radio waves is stored in advance in the storage unit 23 of each first communication device 2. The first communication device 2B acquires the second distance information D2 based on the propagation speed and propagation time of the Wi-Wi radio waves. At this time, the respective clock units of each first communication device 2 acquire the transmission time and the reception time in a state where they are synchronized with each other with high accuracy. Therefore, the first communication device 2B can acquire the second distance information D2 with high accuracy.

[0077] Note that the process of acquiring the first distance information D1 in each child second communication device 31 (steps S15, S16, S17) and the process of acquiring the third distance information D3 in the parent second communication device 32 (steps S19, S21, S22) can be executed in a similar manner. The phase and time in each first communication device 2 and each second communication device 3 can be synchronized, for example, based on the phase and time of the parent second communication device 32.

[0078] In step S14, wireless communication unit 21B of first communication device 2B transmits second distance information D2 to master side second communication device 32. Although not shown, first communication device 2A can acquire second distance information D2 between first communication devices 2A, 2B using second distance information acquisition unit 22A and transmit the second distance information D2 to master side second communication device 32 using wireless communication unit 21A. Storage unit 323 of master side second communication device 32 stores the second distance information D2 transmitted from first communication device 2B.

[0079] In step S15, the wireless communication unit 311 of the child second communication device 31 transmits Wi-Wi radio waves to the first communication device 2B. In step S16, the wireless communication unit 21B of the first communication device 2B transmits Wi-Wi radio waves to the child second communication device 31. In step S17, the first distance information acquisition unit 312 of the child second communication device 31 calculates first distance information D1 between the child second communication device 31 and the first communication device 2B by Wi-Wi. Although not shown, the child second communication device 31 transmits and receives Wi-Wi radio waves to and from the first communication device 2A, and acquires the first distance information D1 between the child second communication device 31 and the first communication device 2A.

[0080] In step S18, the wireless communication unit 311 of each child second communication device 31 transmits the second distance information D2 to the parent second communication device 32. The memory unit 323 of the parent second communication device 32 stores the first distance information D1 transmitted from each child second communication device 31.

[0081] In step S19, the wireless communication unit 321 of the master second communication device 32 transmits Wi-Wi radio waves to the first communication device 2B. In step S21, the wireless communication unit 21B of the first communication device 2B transmits Wi-Wi radio waves to the master second communication device 32. In step S22, the first distance information acquisition unit 312 of the master second communication device 32 calculates third distance information D3 between the first communication device 2B and the master second communication device 32 by Wi-Wi.

[0082] Although not shown, the master second communication device 32 transmits and receives Wi-Wire radio waves to and from the first communication device 2A, and acquires third distance information D3 between the first communication device 2A and the master second communication device 32. The storage unit 323 of the master second communication device 32 stores the third distance information D3.

[0083] In step S23, the distance information transmitter 324 of the master second communication device 32 transmits to the server 4 the first distance information D1, the second distance information D2, and the third distance information D3.

[0084] (Server 4 operation) Next, there will be described an operation of the server 4. The flowchart in Fig. 4(a) is repeatedly executed by the server 4 at a predetermined cycle.

[0085] 4(a), in step S31, the position estimation unit 43 determines whether the communication unit 41 has received any of the first distance information D1, the second distance information D2, and the third distance information D3. If any of the first distance information D1, the second distance information D2, and the third distance information D3 has been received, the result is YES and the process proceeds to step S32. If none of the first distance information D1, the second distance information D2, and the third distance information D3 has been received, the result is NO and the process ends.

[0086] In step S32, the position estimation unit 43 acquires each moving object position information D4 based on at least one of the first distance information D1, the second distance information D2, and the third distance information D3. The storage unit 42 stores the first distance information D1, the second distance information D2, and the third distance information D3 transmitted from the master side second communication device 32, and each moving object position information D4 calculated by the position estimation unit 43. Next, the process proceeds to step S33.

[0087] In step S33, the image processing unit 46 displays the second map image M2 showing each worker W and each predetermined avoidance target R on the display unit 45 based on each moving object position information D4, the avoidance target position information D5, and the first map image M1. The position of each worker W displayed on the display unit 45 is changed every time the moving object position information D4 is input to the image processing unit 46. That is, the position of each worker W displayed on the display unit 45 is changed every time the server 4 receives the first distance information D1, the second distance information D2, or the third distance information D3. This allows the manager to grasp the position of each worker W, and therefore to warn each worker W as necessary.

[0088] In step S34, the approach detection unit 44 (calculation unit 441) calculates the distance between each worker W and each predetermined avoidance target R based on each moving object position information D4 acquired by the position estimation unit 43 and each avoidance target position information D5 stored in the memory unit 42. The memory unit 42 stores the distance between each worker W and each predetermined avoidance target R. Next, the process proceeds to step S35.

[0089] In step S35, the approach detection unit 44 (approach determination unit 442) determines whether the distance between each worker W and each predetermined avoidance target R is equal to or less than the reference value S. If the distance between any worker W and each predetermined avoidance target R is equal to or less than the reference value S, the approach determination unit 442 determines YES and proceeds to step S36. If the distance between each worker W and each predetermined avoidance target R is greater than the reference value S, the approach determination unit 442 determines NO and ends this process.

[0090] In step S36, the communication unit 41 of the server 4 transmits the approach detection information D6 to the alarm device 6. Next, the process proceeds to step S37.

[0091] In step S37, the display unit 45 displays a pop-up message indicating that the worker W has approached the predetermined avoidance target R. This allows the substation manager to know that the worker W has approached the predetermined avoidance target R, and therefore, can order the worker W to evacuate. After that, this process ends.

[0092] (Operation of the notification device 6) Next, a description will be given of the operation of the notification device 6. The flowchart in Fig. 4(b) is repeatedly executed by the notification device 6 at a predetermined cycle.

[0093] 4(b), in step S51, the sound output unit 62 determines whether or not the communication unit 61 has received approach detection information D6. If the communication unit 61 has received approach detection information D6, the process returns to YES and proceeds to step S52. If the communication unit 61 has not received approach detection information D6, the process returns to NO and ends this process.

[0094] In step S52, the sound generator 62 issues a warning sound. This makes it possible to warn the worker W who approaches any of the predetermined avoidance targets R. Thereafter, this process ends.

[0095] The position estimation system 1 according to the present embodiment described above provides the following advantages.

[0096] When estimating the position of a mobile object moving within an area where buildings are located, if one tries to estimate the position of the mobile object using measurement technology that uses GPS, there is a risk that the GPS radio waves will be blocked by the buildings, making it impossible to accurately estimate the position of the mobile object.

[0097] However, according to the above embodiment, the position estimation system 1 includes a first communication device 2 equipped to a worker W, and a plurality of second communication devices 3 fixedly installed. The position estimation system 1 acquires first distance information D1 indicating the distance between each of the first communication devices 2 and each of the second communication devices 3 (i.e., the distance between the worker W and each of the second communication devices 3) by Wi-Wi-Fi, and is capable of acquiring mobile object position information D4 of each of the first communication devices 2 based on the first distance information D1. This allows the position of the worker W to be estimated with high accuracy. Therefore, it is possible to estimate the position of each worker W with higher accuracy than when the mobile object position information D4 is acquired by a measurement technique using GPS.

[0098] Moreover, Wi-Wire terminals are generally cheaper than beacon terminals, so they are also advantageous in terms of cost.

[0099] According to the above embodiment, for example, even if there are multiple moving objects, each of the moving objects can be equipped with a first communication device 2. Each first communication device 2 can acquire the second distance information D2 by Wi-Wi, and transmit the second distance information D2 to the server 4 via the master second communication device 32. The server 4 (position estimation unit 43) can estimate the position of each worker W based on the first distance information D1 and the second distance information D2. This makes it possible to estimate the position of each worker W with greater accuracy.

[0100] According to the above embodiment, the server 4 (storage unit 42) stores the avoidance target position information D5. The server 4 (approach detection unit 44) is capable of detecting the approach of each worker W to each predetermined avoidance target R based on the avoidance target position information D5 and the mobile object position information D4. This makes it possible to prevent the worker W from coming into contact with each predetermined avoidance target R.

[0101] According to the above embodiment, the server 4 (storage unit 42) stores a first map image M1. The server 4 (image processing unit 46) is capable of displaying on the display unit 45 a second map image M2 showing the positions of each worker W and each predetermined avoidance target R on the first map image M1 based on the moving object position information D4, the avoidance target position information D5, and the first map image M1. This allows the position of each worker W to be visually grasped, making it easier to grasp the position of each worker W. In addition, it makes it easier to grasp the positional relationship between each worker W and each predetermined avoidance target R.

[0102] In a substation, multiple devices such as power transmission lines and transformers are arranged, and live and non-live parts are mixed in a complex manner. For this reason, it is important for the substation manager and the workers themselves to be able to grasp the positions of the workers with high accuracy. However, if there are steel structures such as iron structures on the premises of the substation, the GPS radio waves are blocked by the steel structures, and the GPS cannot measure the positions of the workers with high accuracy. However, according to the above embodiment, it is possible to estimate the positions of each worker W with high accuracy and low cost even within the premises A1 of the substation.

[0103] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and can be modified as appropriate.

[0104] In the above embodiment, the site where the position estimation system 1 estimates the position of each worker W is the substation site A1, but this is not limited to this. For example, the site where the position estimation system estimates the position of a moving object may be the site of a construction site or a site where a warehouse is installed.

[0105] In the above embodiment, the building is a steel structure of a substation, but the present invention is not limited to this. For example, the building may be a factory, a warehouse, or a building under construction.

[0106] In the above embodiment, the predetermined object to be avoided is a barrier or a cubicle, but the present invention is not limited to this. The predetermined object to be avoided may be a movable object.

[0107] For example, assuming that a worker works in a construction site where a cleaning robot is active, the cleaning robot may be considered as a predetermined target to be avoided. In this case, the predetermined target to be avoided (cleaning robot) may be equipped with a first communication device. The position estimation unit may acquire the avoidance target position information based on at least one of the first distance information, the second distance information, and the third distance information related to the first communication device equipped on the cleaning robot. This makes it possible to grasp the position of the predetermined target to be avoided (cleaning robot), thereby suppressing contact between the worker and the cleaning robot.

[0108] Furthermore, the predetermined avoidance target may be a target having a part that is movable. For example, assuming a case where a logistics robot equipped with a movable arm unit is working in a logistics warehouse, it is conceivable that the tip of the arm unit of the logistics robot is the predetermined avoidance target. In this case, the tip of the arm unit can be equipped with a first communication device. Even in such a case, it is possible to grasp the position of the arm unit and prevent contact between the worker and the arm unit.

[0109] In the above embodiment, the moving object is a worker, but is not limited to this. For example, the moving object may be a vehicle, a robot, an animal such as livestock, or an air vehicle such as a drone.

[0110] In the above embodiment, the position estimation system 1 is capable of estimating the three-dimensional position of the worker W, but may be capable of estimating only the horizontal position of the worker W. However, the configuration of the above embodiment is preferable in that it is possible to more preferably grasp the positional relationship between the moving body and a predetermined object to be avoided. For example, if an electric wire is hanging down from above the worker W and the electric wire is a predetermined object to be avoided, the first communication device 2 is fixed to the head of the worker W and the height position of the first communication device 2 can be estimated, thereby making it possible to preferably avoid contact between the worker W and the electric wire.

[0111] In the above embodiment, the image processing unit 46 is configured to display the second map image M2 in which the position of each worker W and each predetermined avoidance target R are shown on the first map image M1. However, it is not essential to display the positions of the predetermined avoidance targets R on the second map image M2.

[0112] In the above embodiment, the second distance information D2 between the first communication devices 2A, 2B can be acquired, and the second distance information D2 can be used by the server 4 to acquire the moving object position information D4. However, the second distance information D2 is not essential for the server 4 to acquire the moving object position information D4. Therefore, even when there is only one moving object, it is possible to acquire the moving object position information D4. However, when there are multiple moving objects, the configuration of the above embodiment is preferable because it is possible to acquire the moving object position information D4 with higher accuracy.

[0113] In the above embodiment, the position estimation system 1 includes the alarm device 6, but the alarm device 6 is not an essential component. For example, a substation manager may be able to grasp the danger of the worker W on the display unit 45 of the server 4 and alert the worker W himself / herself. Furthermore, the use of the position estimation system 1 is not limited to the safety management of the workers, and may be, for example, an investigation of the behavior patterns of the workers.

[0114] In the above embodiment, the display unit 45 is provided in the control tower of the power supply station where the administrator remotely monitors the substation as a part of the server 4, but is not limited to this. The display unit does not need to be a part of the server, and does not need to be provided in the control tower of the power supply station. For example, the display unit may be a display unit of a tablet terminal carried by each worker W. [Explanation of symbols]

[0115] 1. Location Estimation System 2. First communication device (communication device) 3. Second communication device (communication device) 4 Server 22A, 22B 2nd distance information acquisition section 42 Storage section 43 Position estimation part 44 Approach detection unit 45 Display section 46 Image Processing Section 100 Steel structures (buildings) 312 1st distance information acquisition unit 322 Third distance information acquisition unit 324 Distance information transmission unit A1 Substation site A2 Prescribed subject area M1 1st map image M2 2nd map image R1 Circuit Breaker (prescribed avoidance target) R2 Cubicle (prescribed avoidance target) W Worker (mobile)

Claims

1. A position estimation system capable of estimating the position of one or more moving objects moving within a predetermined target area in which a structure is provided, comprising: A plurality of communication devices each having a wireless communication unit capable of wirelessly communicating with each other; A server including a position estimation unit capable of estimating a position of the moving object and a storage unit; Equipped with the plurality of communication devices include one or more first communication devices that can be installed in the moving object, and a plurality of second communication devices that are provided at fixed positions; the second communication device has a first distance information acquisition unit capable of acquiring first distance information indicating a distance between the second communication device and the first communication device by a wireless two-way time comparison technique; the wireless communication unit of the second communication device is capable of transmitting the first distance information to another of the second communication devices; At least one of the second communication devices has a distance information transmission unit capable of transmitting the first distance information to the server, A position estimation system, wherein the position estimation unit is capable of estimating a position of the moving object based on a plurality of the first distance information.

2. The communication device includes two or more of the first communication devices, the first communication device has a second distance information acquisition unit capable of acquiring second distance information indicating a distance between the first communication device and another first communication device by a wireless two-way time comparison technique; the wireless communication unit of the first communication device is capable of transmitting the second distance information to the second communication device; the distance information transmission unit is capable of transmitting the second distance information to the server; The position estimation system according to claim 1 , wherein the position estimation unit is capable of estimating the position of the moving object based on the first distance information and the second distance information.

3. the storage unit of the server is capable of storing avoidance target position information indicating a position of a predetermined avoidance target which is a target for which contact with the moving object should be avoided; 3. The position estimation system according to claim 1, wherein the server includes a proximity detection unit capable of detecting that the moving body and a predetermined target for avoidance have come into proximity to each other based on the estimation result of the position estimation unit and the target for avoidance position information.

4. A display unit capable of displaying an image is provided, the storage unit of the server is capable of storing a first map image, which is a map image of the predetermined target area, as data; 2. The position estimation system according to claim 1, wherein the server has an image processing unit capable of displaying, on the display unit, a second map image indicating the position of the moving object on the first map image based on an estimation result by the position estimation unit and the first map image.

5. The predetermined target area is provided within the premises of a substation, The building is a steel structure, The position estimation system according to claim 1 , wherein the moving object is a worker at the substation.

6. a part of the two or more first communication devices is provided at a predetermined avoidance target that is a target for which contact with the moving object should be avoided; The predetermined avoidance target is movable, The position estimation system according to claim 2 , wherein the position estimation unit is capable of estimating the position of the predetermined avoidance target based on the second distance information.

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