Alarm system, mobile station, and program

Abstract

To accurately determine whether or not a person or an object is in a predetermined area.SOLUTION: A processing circuit 24 determines a first provisional position which provisionally shows which side of a boundary line B1 a mobile station 2 is located on with reference to a first fixation station 1 on the basis of signal levels of beacon signals N11 and N12. The processing circuit 24 determines a second provisional position which provisionally shows which side of the boundary line B1 the mobile station 2 is located on with reference to a second fixation station 1 on the basis of signal levels of beacon signals N21 and N22. The processing circuit 24 determines which of a safe area A1 and a dangerous area A2 the mobile station 2 is located in on the basis of the first and second provisional positions.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present disclosure relates to an alarm system, a mobile station, and a program.

Background Art

[0002] For example, in a factory, if an operator inadvertently approaches a machine tool, the operator may be injured by the machine tool. Therefore, a danger area is set near the machine tool, and an alarm may be generated when the operator enters the danger area.

[0003] For example, Patent Document 1 discloses a safety control system applied to a construction site where there are a safety area and a danger area. The system of Patent Document 1 detects the distance from the boundary between the danger area and the safety area to the beacon signal transmission source based on the reception intensity of the beacon signal transmitted from a transmission source provided on an operator, a heavy machine, etc.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When distance is detected based on the received signal strength of a beacon signal, as in Patent Document 1, it becomes difficult to receive the beacon signal with a stable signal strength as one moves away from the beacon signal source. As a result, it becomes impossible to reliably determine whether a worker is in a safe area or a dangerous area. To reliably determine whether a worker is in a safe area or a dangerous area, it is conceivable to arrange a large number of signal sources at high density so that the area covered by a single signal source is narrowed. However, in this case, the cost is high because a large number of signal sources are used. Therefore, there is a need to determine whether a person or object is in a predetermined area with higher accuracy than before, without causing a significant increase in cost.

[0006] The purpose of this disclosure is to provide an alarm system that can determine with greater accuracy than conventional systems whether a person or object is in a predetermined area. Another purpose of this disclosure is to provide a mobile station and program for such an alarm system. [Means for solving the problem]

[0007] According to one aspect of this disclosure, An alarm system including a first fixed station, a second fixed station, and a mobile station, The first and second fixed stations are each located at different positions on the boundary lines between the first and second areas. The aforementioned first fixed station is, A first transmitting antenna having a first main beam direction toward the side of the first area from the boundary line, A second transmitting antenna having a second main beam direction toward the side of the second area from the boundary line, The system includes a first transmitting circuit that transmits a first beacon signal via the first transmitting antenna and a second beacon signal via the second transmitting antenna, The second fixed station mentioned above is, A third transmitting antenna having a third main beam direction toward the side of the first area from the boundary line, A fourth transmitting antenna having a fourth main beam direction toward the side of the second area from the boundary line, The system includes a second transmitting circuit that transmits a third beacon signal via the third transmitting antenna and a fourth beacon signal via the fourth transmitting antenna, The aforementioned mobile station is Receiving antenna and A receiving circuit that receives the first to fourth beacon signals via the receiving antenna and detects the signal levels of the first to fourth beacon signals, A processing circuit that determines whether the mobile station is located in the first or second area based on the signal levels of the first to fourth beacon signals, The system includes an output device that outputs a first alarm signal indicating that the mobile station is in the second area when the mobile station is in the second area, The aforementioned processing circuit is Based on the signal levels of the first and second beacon signals, a first provisional position is determined that provisionally indicates which side of the boundary line the mobile station is located on, with respect to the first fixed station. Based on the signal levels of the third and fourth beacon signals, a second provisional position is determined that provisionally indicates which side of the boundary line the mobile station is located on, with respect to the second fixed station. Based on the first and second provisional locations, it is determined which of the first and second areas the mobile station is located in. [Effects of the Invention]

[0008] An alarm system according to one aspect of this disclosure can determine with greater accuracy than conventional systems whether or not a person or object is in a predetermined area. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing an alarm system according to the first embodiment. [Figure 2] This is a block diagram showing the configuration of fixed station 1 in Figure 1. [Figure 3]It is a block diagram showing the configuration of the mobile station 2 in FIG. 1. [Figure 4] It is a block diagram showing the configuration of the server device 4 in FIG. 1. [Figure 5] It is a diagram showing an exemplary radiation pattern of the fixed station 1 in FIG. 2. [Figure 6] It is a flowchart showing the alarm processing executed by the processing circuit 24 in FIG. 3. [Figure 7] It is a diagram for explaining the influence of multipath in the alarm system in FIG. 1. [Figure 8] It is a block diagram showing the configuration of the mobile station 2A of the alarm system according to a modification of the first embodiment. [Figure 9] It is a diagram for explaining the operation of the alarm system according to the second embodiment. [Figure 10] It is a flowchart showing the alarm processing executed by the processing circuit 24 of the mobile station 2 in FIG. 9. [Figure 11] It is a flowchart showing the subroutine of step S101 in FIG. 10. [Figure 12] It is a flowchart showing the subroutine of step S102 in FIG. 10. [Figure 13] It is a table for explaining the determination of the safe area A1 and the dangerous area A2 by the alarm system according to the second embodiment. [Figure 14] It is a diagram for explaining the operation of the alarm system according to the third embodiment. [Figure 15] It is a flowchart showing the alarm processing executed by the mobile station 2 of the alarm system according to the third embodiment. [Figure 16] It is a flowchart showing the alarm processing executed by the mobile station 2 of the alarm system according to the first modification of the third embodiment. [Figure 17] It is a diagram for explaining the operation of the alarm system according to the second modification of the third embodiment. [Figure 18] It is a flowchart showing the alarm processing executed by the mobile station 2 of the alarm system according to the second modification of the third embodiment. [Figure 19] This is a diagram illustrating the operation of the alarm system according to the fourth embodiment. [Figure 20] This is a diagram illustrating the operation of the alarm system according to the first modification of the fourth embodiment. [Figure 21] Figure 19 is a flowchart showing the alarm processing performed by the processing circuit 24 of the mobile station 2. [Figure 22] Figure 21 is a flowchart of the subroutine for step S201. [Figure 23] Figure 21 is a flowchart showing the subroutine for step S202. [Figure 24] This table illustrates the determination of safe area A1, dangerous area A2, and warning area A3 by the alarm system according to the first modification of the fourth embodiment. [Figure 25] This is a diagram illustrating the operation of an alarm system according to a second modification of the fourth embodiment. [Figure 26] This is a diagram illustrating the operation of the alarm system according to the fifth embodiment. [Figure 27] This is a block diagram showing the configuration of the fixed station 1A of the alarm system according to the sixth embodiment. [Modes for carrying out the invention]

[0010] Hereinafter, an alarm system according to an embodiment of the present invention will be described with reference to the drawings. Throughout the drawings, the same reference numerals indicate the same components.

[0011] [First Embodiment] [Configuration of the first embodiment] Figure 1 is a schematic diagram showing an alarm system according to the first embodiment. The alarm system in Figure 1 comprises one or more fixed stations 1, mobile stations 2, access point devices (APs) 3, and server devices 4.

[0012] The alarm system shown in Figure 1 is installed in locations that include a safe area A1 and a hazardous area A2, such as factories and construction sites. Safe area A1 is an area where there are no known causes of harm to people or property entering or staying. Hazardous area A2 is an area where there is a possibility of harm to people or property entering or staying, such as near machine tools, steps, or chemicals.

[0013] Each fixed station 1 is located at a different position on the boundary line B1 between safe area A1 and dangerous area A2. Each fixed station 1 is equipped with two antennas, each having radiation patterns R1 and R2, as described later. Radiation pattern R1 has a main beam direction from boundary line B1 toward safe area A1, and radiation pattern R2 has a main beam direction from boundary line B1 toward dangerous area A2. Each fixed station 1 transmits a beacon signal via these antennas. Each beacon signal includes identification information for fixed station 1, identification information for dangerous area A2 where fixed station 1 is located, and identification information for the antenna (one of the two antennas) that transmitted the beacon signal.

[0014] Mobile station 2 may be attached to a person's body or clothing (e.g., a helmet), or to an object (e.g., an automated guided vehicle). Mobile station 2 receives a beacon signal from at least one fixed station 1 and determines, based on the beacon signal, whether mobile station 2 is in safe area A1 or dangerous area A2. If mobile station 2 is in dangerous area A2, it generates an alarm signal indicating that mobile station 2 is in dangerous area A2.

[0015] Mobile station 2 is further connected to server device 4 via access point device 3, and obtains information necessary for the operation of mobile station 2 from server device 4. The information necessary for the operation of mobile station 2 includes, for example, identification information for hazardous area A2, identification information for fixed station 1, and identification information for each antenna of fixed station 1.

[0016] Figure 2 is a block diagram showing the configuration of the fixed station 1 in Figure 1. The fixed station 1 comprises an input device 11, a transmission circuit 12, an antenna 13, and an antenna 14. The input device 11 is configured to input identification information of the hazardous area A2 in which the fixed station 1 is located. The input device 11 may include a keyboard or a numeric keypad, or it may include a communication interface for acquiring information from other devices. Antenna 13 is a directional antenna having a first main beam direction, and antenna 14 is a directional antenna having a second main beam direction different from the first main beam direction. The transmission circuit 12 transmits a first beacon signal via antenna 13 and a second beacon signal via antenna 14. As described above, each beacon signal includes identification information of the fixed station 1, identification information of the hazardous area A2 in which the fixed station 1 is located, and identification information of the antenna 13 or 14 that transmitted the beacon signal. The transmission circuit 12 transmits each beacon signal periodically or randomly, for example, at intervals of 1 second or less.

[0017] Fixed station 1 is further equipped with a power supply device such as a battery or commercial power supply, but this is omitted for the sake of simplicity in the illustration.

[0018] Figure 3 is a block diagram showing the configuration of mobile station 2 in Figure 1. Mobile station 2 comprises an antenna 21, a transmit / receive circuit 22, an input device 23, a processing circuit 24, and an output device 25. Antenna 21 is an omnidirectional antenna. The transmit / receive circuit 22 receives two beacon signals from fixed station 1 via antenna 21 and detects the signal levels of the two beacon signals. The signal level is, for example, the Received Signal Strength Indicator (RSSI). The transmit / receive circuit 22 also requests and obtains information necessary for the operation of mobile station 2 (for example, identification information for hazardous area A2, identification information for fixed station 1, and identification information for each antenna of fixed station 1) from server device 4. The input device 23 receives user input that triggers the request for information necessary for the operation of mobile station 2 from server device 4. The processing circuit 24 determines whether mobile station 2 is in safe area A1 or hazardous area A2 based on the signal levels of the two beacon signals received from fixed station 1. Specifically, the processing circuit 24 may determine that the mobile station 2 is in hazardous area A2 if the signal level of the beacon signal transmitted via antenna 14 is higher than the signal level of the beacon signal transmitted via antenna 13. If the mobile station 2 is in hazardous area A2, the output device 25 outputs an alarm signal indicating that the mobile station 2 is in hazardous area A2. The output device 25 may be equipped with a buzzer or speaker that outputs the alarm signal by voice, or it may be equipped with a light-emitting diode that outputs the alarm signal by light. In addition, if the mobile station 2 is in safe area A1, the output device 25 may not generate an alarm signal, or may output a signal indicating that the mobile station 2 is in safe area A1 by generating a different sound or light than the alarm signal.

[0019] Mobile station 2 is further equipped with power supply devices such as batteries, but these are omitted for the sake of simplicity in the illustration.

[0020] The fixed station 1 and the mobile station 2 may be configured, for example, to send and receive beacon signals using the BLE (Bluetooth® Low Energy) method.

[0021] Figure 4 is a block diagram showing the configuration of the server device 4 in Figure 1. The server device 4 comprises a bus 40, a processor 41, memory 42, storage device 43, communication device 44, input device 45, and display device 46. The processor 41 controls the operation of the entire server device 4. The memory 42 temporarily stores programs and data necessary for the operation of the server device 4. The storage device 43 is a non-volatile storage medium that stores programs necessary for the operation of the server device 4. The storage device 43 stores information necessary for the operation of the mobile station 2 (for example, identification information for hazardous area A2, identification information for fixed station 1, and identification information for each antenna of fixed station 1). The communication device 44 is connected to the mobile station 2 via the access point device 3 for communication. The input device 45 receives user input to control the operation of the server device 4. The input device 45 includes, for example, a keyboard and a pointing device. The display device 46 displays information related to the operation of the server device 4. The processor 41, memory 42, storage device 43, communication device 44, input device 45, and display device 46 are connected to each other via the bus 40. Server device 4 operates as an area database that provides mobile station 2 with information necessary for its operation.

[0022] [Operation of the first embodiment] Figure 5 shows an exemplary radiation pattern of the fixed station 1 in Figure 2. The fixed station 1 is located on the boundary line B1 between safe area A1 and hazardous area A2. The antennas 13 and 14 of the fixed station 1 have radiation patterns R1 and R2, respectively. To explain the orientation of radiation patterns R1 and R2, a reference line is set tangent to boundary line B1 at the location of the fixed station 1. In the example of Figure 5, the straight section of boundary line B1 on which the fixed station 1 is located becomes the reference line for radiation patterns R1 and R2. Radiation pattern R1 has a main beam direction from boundary line B1 toward the side of safe area A1, and radiation pattern R2 has a main beam direction from boundary line B1 toward the side of hazardous area A2. The main beam directions of radiation patterns R1 and R2 may be perpendicular to boundary line B1, or they may intersect boundary line B1 at a predetermined angle (for example, an angle close to 90 degrees). Fixed station 1 is positioned such that the main beam directions of radiation patterns R1 and R2 are directed toward the sides of safe area A1 and dangerous area A2, respectively.

[0023] Mobile station 2 receives beacon signal N1 transmitted via antenna 13 and beacon signal N2 transmitted via antenna 14. If mobile station 2 is in safe area A1, the signal level L1 of beacon signal N1 is expected to be higher than the signal level L2 of beacon signal N2. On the other hand, if mobile station 2 is in dangerous area A2 (referred to as "mobile station 2'"), the signal level L2' of beacon signal N2' transmitted via antenna 14 is expected to be higher than the signal level L1' of beacon signal N1' transmitted via antenna 13. Therefore, processing circuit 24 compares the signal levels L1 and L2 of the two beacon signals N1 and N2 received from fixed station 1 and determines whether mobile station 2 is in safe area A1 or dangerous area A2 based on the comparison result.

[0024] Figure 6 is a flowchart showing the alarm processing performed by the processing circuit 24 in Figure 3.

[0025] In step S1, the processing circuit 24 acquires the signal levels L1 and L2 of the two beacon signals N1 and N2.

[0026] In step S2, the processing circuit 24 determines whether the signal level L2 of beacon signal N2 is higher than the signal level L1 of beacon signal N1. If the answer is YES, the process proceeds to step S3; otherwise, it proceeds to step S5. Based on the signal levels L1 and L2 of beacon signals N1 and N2, the processing circuit 24 determines which side of the boundary line B1 the mobile station 2 is located on.

[0027] In step S3, the processing circuit 24 determines that the mobile station 2 is in the hazardous area A2. Then, in step S4, the processing circuit 24 uses the output device 25 to generate an alarm signal indicating that the mobile station 2 is in the hazardous area A2.

[0028] In step S5, the processing circuit 24 determines that the mobile station 2 is in safe area A1. The processing circuit 24 may use the output device 25 to generate a signal indicating that the mobile station 2 is in safe area A1.

[0029] When distance is detected based on the received signal strength of a beacon signal, as in Patent Document 1, it is not possible to use a weak beacon signal that has been transmitted from a distant source and attenuated in order to reliably determine whether a worker is in a safe area or a dangerous area. On the other hand, according to the alarm system of this embodiment, the signal levels of two beacon signals received from the fixed station 1 are compared with each other, so even a weak, attenuated beacon signal can be used to determine whether the mobile station 2 is in safe area A1 or dangerous area A2. A single fixed station 1 can cover a wider area than conventional systems, and it is not necessary to arrange a large number of fixed stations 1 at high density. Thus, according to the alarm system of this embodiment, it is possible to determine with higher accuracy than conventional systems whether a person or object is in a predetermined area without significantly increasing costs.

[0030] [Modified version of the first embodiment] Figure 7 illustrates the effects of multipath in the alarm system shown in Figure 1. Beacon signals propagate via multipath due to reflections from building floors, walls, and ceilings, or other obstacles, and interference between the direct and reflected waves of the beacon signal can cause fluctuations in the received signal level. In the example in Figure 7, in area A11, the signal level of beacon signal N2 is higher than that of beacon signal N1, and in area A12, the signal level of beacon signal N1' is higher than that of beacon signal N2'. Therefore, area A11 is a false positive area where it is incorrectly determined that "mobile station 2 is in dangerous area A2" despite being located in safe area A1. Similarly, area A12 is a false negative area where it is incorrectly determined that "mobile station 2' is in safe area A1" despite being located in dangerous area A2.

[0031] Generally, signal level fluctuations caused by multipath are temporary. Therefore, the processing circuit 24 may determine that mobile station 2 is in safe area A1 if, within a predetermined time period, the number of times the signal level of beacon signal N1 exceeds the signal level of beacon signal N2 exceeds a predetermined threshold. Alternatively, the processing circuit 24 may determine that mobile station 2' is in dangerous area A2 if, within a predetermined time period, the number of times the signal level of beacon signal N2' exceeds the signal level of beacon signal N1' exceeds a predetermined threshold. This reduces the impact of multipath and allows for a more accurate determination of whether mobile station 2 is in safe area A1 or dangerous area A2.

[0032] Furthermore, when mobile station 2 enters area A12 from area A2, an alarm signal has already been generated while mobile station 2 is in area A2, so the absence of an alarm signal in area A12 is not a practical problem.

[0033] Figure 8 is a block diagram showing the configuration of a mobile station 2A of the alarm system according to a modification of the first embodiment. Mobile station 2A includes a processing circuit 24A instead of the processing circuit 24 of mobile station 2 in Figure 3, and further includes an acceleration sensor 26. The acceleration sensor 26 detects the acceleration of mobile station 2A. Based on the acceleration of mobile station 2A, the processing circuit 24A determines whether or not mobile station 2A is moving. For example, if the acceleration of mobile station 2A is non-zero for a predetermined time period, the processing circuit 24A may determine that mobile station 2A is moving. If mobile station 2A is moving and the signal level of beacon signal N1 is higher than the signal level of beacon signal N2, the processing circuit 24A may determine that mobile station 2A is in a safe area A1. Alternatively, if mobile station 2A is moving and the signal level of beacon signal N2 is higher than the signal level of beacon signal N1, the processing circuit 24A may determine that mobile station 2A is in a dangerous area A2. This reduces the effects of multipath interference and allows for a more accurate determination of whether mobile station 2A is in safe area A1 or dangerous area A2.

[0034] [Second Embodiment] Figure 9 is a diagram illustrating the operation of the alarm system according to the second embodiment. Fixed stations 1-1 and 1-2 are each located at different positions on a straight section of the boundary line B1 between safe area A1 and dangerous area A2. Fixed stations 1-1 and 1-2 are spaced apart from each other at a distance sufficient for mobile station 2 to receive beacon signals from both fixed stations 1-1 and 1-2. Fixed stations 1-1 and 1-2 are configured similarly to fixed station 1 in Figure 2. Antennas 13-1 and 14-1 of fixed station 1-1 have radiation patterns R1-1 and R2-1, respectively. Antennas 13-2 and 14-2 of fixed station 1-2 have radiation patterns R1-2 and R2-2, respectively. To explain the orientation of radiation patterns R1-1, R2-1, R1-2, and R2-2, reference lines are set at the positions of fixed stations 1-1 and 1-2, each tangent to the boundary line B1. In the example shown in Figure 5, the straight section of boundary line B1 where fixed stations 1-1 and 1-2 are located serves as the reference line for radiation patterns R1-1, R2-1, R1-2, and R2-2. Radiation pattern R1-1 has a main beam direction that points from boundary line B1 towards the safe area A1. Radiation pattern R2-1 has a main beam direction that points from boundary line B1 towards the hazardous area A2. Radiation pattern R1-2 has a main beam direction that points from boundary line B1 towards the safe area A1. Radiation pattern R2-2 has a main beam direction that points from boundary line B1 towards the hazardous area A2. The main beam directions of radiation patterns R1-1, R2-1, R1-2, and R2-2 may be perpendicular to boundary line B1, or they may intersect boundary line B1 at a predetermined angle (for example, an angle close to 90 degrees). Fixed stations 1-1 and 1-2 are positioned so that the main beam directions of radiation patterns R1-1, R2-1, R1-2, and R2-2 are directed toward the sides of safe area A1 and dangerous area A2, respectively.

[0035] The transmitting circuit 12 of fixed station 1-1 transmits beacon signal N11 via antenna 13-1 and beacon signal N12 via antenna 14-1. The transmitting circuit 12 of fixed station 1-2 transmits beacon signal N21 via antenna 13-2 and beacon signal N22 via antenna 14-2.

[0036] The transmitting and receiving circuit 22 of mobile station 2 receives beacon signal N11 transmitted via antenna 13-1 and beacon signal N12 transmitted via antenna 14-1, and detects the signal levels of beacon signals N11 and N12. The transmitting and receiving circuit 22 of mobile station 2 also receives beacon signal N21 transmitted via antenna 13-2 and beacon signal N22 transmitted via antenna 14-2, and detects the signal levels of beacon signals N21 and N22. The processing circuit 24 of mobile station 2 determines whether mobile station 2 is in safe area A1 or dangerous area A2 based on the signal levels of beacon signals N11 to N22. For this reason, the processing circuit 24 determines a first provisional position that provisionally indicates which side of boundary line B1 mobile station 2 is located on, relative to fixed station 1-1, based on the signal levels of beacon signals N11 and N12. Furthermore, the processing circuit 24 determines a second provisional position based on the signal levels of the beacon signals N21 and N22, which provisionally indicates which side of boundary line B1 the mobile station 2 is located on, with reference to the fixed stations 1 and 2. Then, based on the first and second provisional positions, the processing circuit 24 determines whether the mobile station 2 is in safe area A1 or dangerous area A2.

[0037] Figure 10 is a flowchart showing the alarm processing performed by the processing circuit 24 of the mobile station 2 in Figure 9.

[0038] In step S101, the processing circuit 24 performs a determination process based on the beacon signals N11 and N12, and provisionally determines whether the mobile station 2 is in safe area A1 or dangerous area A2 based on the beacon signals N11 and N12 received from the fixed station 1-1.

[0039] In step S102, the processing circuit 24 performs a determination process based on the beacon signals N21 and N22, and provisionally determines whether the mobile station 2 is in safe area A1 or dangerous area A2 based on the beacon signals N21 and N22 received from the fixed stations 1-2.

[0040] Figure 11 is a flowchart of the subroutine for step S101 in Figure 10.

[0041] In step S111, the processing circuit 24 acquires the signal levels L11 and L12 of the beacon signals N11 and N12 received from the fixed station 1-1.

[0042] In step S112, the processing circuit 24 determines whether the signal level L12 is higher than the signal level L11. If the answer is YES, the circuit proceeds to step S113; otherwise, it proceeds to step S114.

[0043] In step S113, the processing circuit 24 determines that the mobile station 2 is located on the side of boundary line B1 that includes the hazardous area A2. As a result, the processing circuit 24 provisionally determines that the mobile station 2 is in the hazardous area A2.

[0044] In step S114, the processing circuit 24 determines that the mobile station 2 is located on the side of boundary line B1 that does not include the hazardous area A2. As a result, the processing circuit 24 provisionally determines that the mobile station 2 is in the safe area A1.

[0045] In this way, the processing circuit 24 determines a first provisional position indicating which side of the boundary line B1 the mobile station 2 is located on, relative to the fixed station 1-1, based on the signal levels L11 and L12 of the beacon signals N11 and N12.

[0046] Figure 12 is a flowchart of the subroutine for step S102 in Figure 10.

[0047] In step S121, the processing circuit 24 acquires the signal levels L21 and L22 of the beacon signals N21 and N22 received from the fixed stations 1-2.

[0048] In step S122, the processing circuit 24 determines whether the signal level L22 is higher than the signal level L21. If the answer is YES, the circuit proceeds to step S123; otherwise, it proceeds to step S124.

[0049] In step S123, the processing circuit 24 determines that the mobile station 2 is located on the side of boundary line B1 that includes the hazardous area A2. As a result, the processing circuit 24 provisionally determines that the mobile station 2 is in the hazardous area A2.

[0050] In step S124, the processing circuit 24 determines that the mobile station 2 is located on the side of boundary line B1 that does not include the hazardous area A2. As a result, the processing circuit 24 provisionally determines that the mobile station 2 is in the safe area A1.

[0051] In this way, the processing circuit 24 determines a second provisional position indicating which side of the boundary line B1 the mobile station 2 is located on, based on the signal levels L21 and L22 of the beacon signals N21 and N22, with reference to the fixed stations 1 and 2.

[0052] The processing circuit 24 may execute steps S101 and S102 in parallel, as shown in Figure 10, or it may execute steps S101 and S102 sequentially.

[0053] In step S103, the processing circuit 24 determines whether the mobile station 2 is in safe area A1 based on the first and second provisional positions. If the answer is YES, the process proceeds to step S104; otherwise, it proceeds to step S106.

[0054] Figure 13 is a table illustrating the determination of safe area A1 and dangerous area A2 by the alarm system according to the second embodiment. As shown in Figure 13, if both the determination based on beacon signals N11 and N12 and the determination based on beacon signals N21 and N22 indicate that "mobile station 2 is in dangerous area A2", the processing circuit 24 determines that mobile station 2 is in dangerous area A2. On the other hand, if at least one of the determination results indicates that "mobile station 2 is in safe area A1", the processing circuit 24 determines that mobile station 2 is in safe area A1.

[0055] In step S104 of Figure 10, the processing circuit 24 determines that the mobile station 2 is in the hazardous area A2. Then, in step S105, the processing circuit 24 uses the output device 25 to generate an alarm signal indicating that the mobile station 2 is in the hazardous area A2.

[0056] In step S106, the processing circuit 24 determines that the mobile station 2 is in safe area A1. The processing circuit 24 may use the output device 25 to generate a signal indicating that the mobile station 2 is in safe area A1.

[0057] According to the alarm system of this embodiment, by referring to beacon signals N11 to N22 received from two fixed stations 1-1 and 1-2, the effects of multipath can be reduced, and it is possible to more accurately determine whether the mobile station 2 is in safe area A1 or dangerous area A2.

[0058] The processing circuit 24 may determine which side of boundary line B1 the mobile station 2 is located on based on the number of times the signal level satisfies a predetermined condition during a predetermined time period. The processing circuit 24 may determine a first provisional position to indicate that the mobile station 2 is located on the side of boundary line B1 that includes hazardous area A2 if the number of times the signal level L12 exceeds the signal level L11 exceeds a predetermined threshold during the predetermined time period. The processing circuit 24 may also determine a second provisional position to indicate that the mobile station 2 is located on the side of boundary line B1 that includes hazardous area A2 if the number of times the signal level L22 exceeds the signal level L21 exceeds a threshold during the same time period. Subsequently, the processing circuit 24 determines whether the mobile station 2 is in safe area A1 or hazardous area A2 based on the first and second provisional positions. This further reduces the effects of multipath and allows for a more accurate determination of whether the mobile station 2 is in safe area A1 or hazardous area A2.

[0059] As shown in Figure 8, in the case of a mobile station 2A equipped with an acceleration sensor 26, the processing circuit 24A may determine whether or not the mobile station 2A is moving based on the acceleration of the mobile station 2A, and based on whether or not the mobile station 2A is moving, it may determine which side of the boundary line B1 the mobile station 2A is located on. If the mobile station 2A is moving and the signal level L12 is higher than the signal level L11, the processing circuit 24A may determine a first provisional position to indicate that the mobile station 2A is located on the side of the boundary line B1 that includes the hazardous area A2. If the mobile station 2A is moving and the signal level L22 is higher than the signal level L21, the processing circuit 24A may determine a second provisional position to indicate that the mobile station 2A is located on the side of the boundary line B1 that includes the hazardous area A2. Subsequently, based on the first and second provisional positions, the processing circuit 24A determines whether the mobile station 2A is in the safe area A1 or the hazardous area A2. This further reduces the effects of multipath and allows for a more accurate determination of whether mobile station 2A is in safe area A1 or hazardous area A2.

[0060] [Third Embodiment] Figure 14 is a diagram illustrating the operation of the alarm system according to the third embodiment. In this embodiment, a warning area A3 is set up in a part of the safe area A1, adjacent to the dangerous area A2. The warning area A3 is an area where there is a high probability that the mobile station 2 will enter the dangerous area A2 due to its future movement. The warning area A3 is an area outside the dangerous area A2 where the distance from the reference line (i.e., boundary line B1) passing through the fixed station 1 is less than or equal to the threshold Th1. In this embodiment, it is determined whether the mobile station 2 is in the safe area A1, the dangerous area A2, or the warning area A3.

[0061] Figure 15 is a flowchart showing the alarm processing performed by the mobile station 2 of the alarm system according to the third embodiment.

[0062] In step S11, the processing circuit 24 acquires the signal levels L1 and L2 of the two beacon signals N1 and N2.

[0063] In step S12, the processing circuit 24 determines whether the signal level L2 of the beacon signal N2 is higher than the signal level L1 of the beacon signal N1. If the answer is YES, the circuit proceeds to step S18; otherwise, it proceeds to step S13.

[0064] In step S13, the processing circuit 24 calculates the distance d from boundary line B1 to mobile station 2 based on the signal levels of beacon signals N1 and N2. The distance d is mainly calculated based on the signal level of beacon signal N1. The smaller the signal level, the larger the distance d. However, if beacon signals N1 and N2 are of similar magnitude, mobile station 2 is considered to be near boundary line B1, and therefore the distance d is small.

[0065] In step S14, the processing circuit 24 determines whether the distance d is longer than the threshold Th1. If the answer is YES, the process proceeds to step S15; otherwise, the process proceeds to step S16.

[0066] In step S15, the processing circuit 24 determines that the mobile station 2 is in safe area A1 (i.e., the area of ​​safe area A1 that is not in alert area A3). The processing circuit 24 may use the output device 25 to generate a signal indicating that the mobile station 2 is in safe area A1.

[0067] In step S16, the processing circuit 24 determines that the mobile station 2 is in the surveillance area A3. Then, in step S17, the processing circuit 24 uses the output device 25 to generate an alarm signal indicating that the mobile station 2 is in the surveillance area A3.

[0068] In step S18, the processing circuit 24 determines that the mobile station 2 is in the hazardous area A2. Then, in step S19, the processing circuit 24 uses the output device 25 to generate an alarm signal indicating that the mobile station 2 is in the hazardous area A2.

[0069] According to this embodiment, by setting a warning area A3 and determining whether the mobile station 2 is in safe area A1, dangerous area A2, or warning area A3, the movement of people or objects can be managed in more detail.

[0070] Figure 16 is a flowchart showing the alarm processing performed by the mobile station 2 of the alarm system according to the first modification of the third embodiment. The processing in Figure 16 includes steps S21 to S25 instead of steps S12 to S14 in Figure 15. In the processing in Figure 16, a machine learning model is used to determine whether the mobile station 2 is in safe area A1, dangerous area A2, or alert area A3.

[0071] To generate a machine learning model, one or more features are calculated based on the signal levels of beacon signals N1 and N2. The features may include the signal levels themselves, or they may include the sum, difference, product, ratio, maximum value, average value, etc., of the two signal levels. Alternatively, the features may include multiple samples of signal levels acquired over a predetermined time period, and they may include the sum, difference, product, ratio, maximum value, average value, etc., of those samples. Based on the features, a first machine learning model is generated that is trained to determine whether mobile station 2 is in safe area A1 or dangerous area A2. Also, based on the features, a second machine learning model is generated that is trained to determine whether mobile station 2 is in alert area A3 of safe area A1 or the remaining area (i.e., the area where the distance from boundary line B1 is greater than the threshold Th1). The processing circuit 24 stores the first and second machine learning models internally.

[0072] In step S11 of Figure 16, the signal levels L1 and L2 of the two beacon signals N1 and N2 are obtained. Then, in step S21, the processing circuit 24 calculates feature quantities based on the signal levels of the beacon signals N1 and N2.

[0073] In step S22, the processing circuit 24 inputs the features into the first machine learning model.

[0074] In step S23, the processing circuit 24 uses the first machine learning model to determine whether the mobile station 2 is in the dangerous area A2. If the result is YES, it proceeds to step S18; if NO, it proceeds to step S23.

[0075] In step S24, the processing circuit 24 inputs the feature amount into the second machine learning model.

[0076] In step S25, the processing circuit 24 uses the second machine learning model to determine whether the mobile station 2 is in the warning area A3. If the result is YES, it proceeds to step S16; if NO, it proceeds to step S15.

[0077] Other steps in FIG. 16 are the same as the corresponding steps in FIG. 15.

[0078] According to this modification example, by using the machine learning model, it is possible to flexibly follow various conditions such as fluctuations in the radio wave propagation environment.

[0079] FIG. 17 is a diagram for explaining the operation of the warning system according to the second modification example of the third embodiment. Even outside the dangerous area A2, in the vicinity of the boundary line B1, people or objects entering or staying there may be damaged. Therefore, in this modification example, an additional dangerous area A2' is set outside the dangerous area A2. The additional dangerous area A2' is an area outside the dangerous area A2 and where the distance from the boundary line B1 is less than or equal to the threshold value Th2. Here, Th2 < Th1 is satisfied.

[0080] FIG. 18 is a flowchart showing the warning process executed by the mobile station 2 of the warning system according to the second modification example of the third embodiment. The process in FIG. 18 further includes step S31 after step S13 in FIG. 15. In step S31, the processing circuit 24 determines whether the distance d is shorter than the threshold value Th2. If the result is YES, it proceeds to step S18; if NO, it proceeds to step S14. Other steps in FIG. 18 are the same as the corresponding steps in FIG. 15.

[0081] According to this modification, the safety of people or objects can be further improved by establishing an additional hazard area A2'.

[0082] [Fourth Embodiment] Figure 19 is a diagram illustrating the operation of the alarm system according to the fourth embodiment. Fixed stations 1-1 and 1-2 are located near the corner of the hazardous area A2, and on the boundary line B1 between the safe area A1 and the hazardous area A2, respectively, with the corner in between. To explain the orientation of the radiation patterns R1-1, R2-1, R1-2, and R2-2, a reference line B1-1 tangent to the boundary line B1 at the location of fixed station 1-1 and a reference line B1-2 tangent to the boundary line B1 at the location of fixed station 1-2 are set. Radiation pattern R1-1 has a main beam direction from the boundary line B1 toward the safe area A1 side. Radiation pattern R2-1 has a main beam direction from the boundary line B1 toward the hazardous area A2 side. Radiation pattern R1-2 has a main beam direction from the boundary line B1 toward the safe area A1 side. Radiation pattern R2-2 has a main beam direction from the boundary line B1 toward the hazardous area A2 side. The main beam directions of radiation patterns R1-1 and R2-1 may be perpendicular to the reference line B1-1, or they may intersect the reference line B1-1 at a predetermined angle (for example, an angle close to 90 degrees). Similarly, the main beam directions of radiation patterns R1-2 and R2-2 may be perpendicular to the reference line B1-2, or they may intersect the reference line B1-2 at a predetermined angle (for example, an angle close to 90 degrees). Radiation patterns R1-2 and R2-2 have main beam directions different from those of radiation patterns R1-1 and R2-1. Fixed stations 1-1 and 1-2 are arranged such that the main beam directions of radiation patterns R1-1, R2-1, R1-2, and R2-2 are directed toward the sides of safety area A1 and hazardous area A2, respectively.

[0083] The processing circuit 24 of the mobile station 2 determines whether the mobile station 2 is in safe area A1 or dangerous area A2 by performing alarm processing as described with reference to Figures 10 to 12. However, the processing circuit 24 determines a first provisional position that provisionally indicates which side of reference line B1-1 the mobile station 2 is located on, based on the signal levels of beacon signals N11 and N12. The processing circuit 24 also determines a second provisional position that provisionally indicates which side of reference line B1-2 the mobile station 2 is located on, based on the signal levels of beacon signals N21 and N22. The processing circuit 24 determines whether the mobile station 2 is in safe area A1 or dangerous area A2, based on the first and second provisional positions, as described with reference to Figure 13.

[0084] According to the alarm system of this embodiment, by referring to beacon signals N11 to N22 received from two fixed stations 1-1 and 1-2, it is possible to more accurately determine whether the mobile station 2 is in safe area A1 or dangerous area A2, even if the boundary line B1 has a complex shape including corners.

[0085] Figure 20 is a diagram illustrating the operation of the alarm system according to the first modification of the fourth embodiment. In this modification, similar to the third embodiment, a warning area A3 is set up in a part of the safe area A1, adjacent to the dangerous area A2.

[0086] Figure 21 is a flowchart showing the alarm processing performed by the processing circuit 24 of the mobile station 2 in Figure 19.

[0087] In step S201, the processing circuit 24 performs a determination process based on the beacon signals N11 and N12, and provisionally determines whether the mobile station 2 is in safe area A1, dangerous area A2, or alert area A3 based on the beacon signals N11 and N12 received from the fixed station 1-1.

[0088] In step S202, the processing circuit 24 performs a determination process based on the beacon signals N21 and N22, and provisionally determines whether the mobile station 2 is in safe area A1, dangerous area A2, or alert area A3 based on the beacon signals N21 and N22 received from the fixed stations 1-2.

[0089] Figure 22 is a flowchart showing the subroutine for step S201 in Figure 21.

[0090] In step S211, the processing circuit 24 acquires the signal levels L11 and L12 of the beacon signals N11 and N12 received from the fixed station 1-1.

[0091] In step S212, the processing circuit 24 determines whether the signal level L12 is higher than the signal level L11. If the answer is YES, the circuit proceeds to step S217; otherwise, it proceeds to step S213.

[0092] In step S213, the processing circuit 24 calculates the distance d1 from the reference line B1-1 to the mobile station 2 based on the signal levels L11 and L12.

[0093] In step S214, the processing circuit 24 determines whether the distance d1 is longer than the threshold Th1. If the answer is YES, the process proceeds to step S215; otherwise, it proceeds to step S216.

[0094] In step S215, the processing circuit 24 determines that the mobile station 2 is located on the side of the reference line B1-1 that does not include the hazardous area A2, and that the mobile station 2 is far from the reference line B1-1. As a result, the processing circuit 24 provisionally determines that the mobile station 2 is in the safe area A1 (i.e., the area of ​​the safe area A1 that is not the alert area A3).

[0095] In step S216, the processing circuit 24 determines that the mobile station 2 is located on the side of the reference line B1-1 that does not include the danger area A2, and that the mobile station 2 is close to the reference line B1-1. Based on this, the processing circuit 24 provisionally determines that the mobile station 2 is in the warning area A3.

[0096] In step S217, the processing circuit 24 determines that the mobile station 2 is located on the side of the reference line B1-1 that includes the hazardous area A2. As a result, the processing circuit 24 provisionally determines that the mobile station 2 is in the hazardous area A2.

[0097] Figure 23 is a flowchart showing the subroutine for step S202 in Figure 21.

[0098] In step S221, the processing circuit 24 acquires the signal levels L21 and L22 of the beacon signals N21 and N22 received from the fixed station 1-2.

[0099] In step S222, the processing circuit 24 determines whether the signal level L22 is higher than the signal level L21. If the answer is YES, the process proceeds to step S227; otherwise, it proceeds to step S223.

[0100] In step S223, the processing circuit 24 calculates the distance d2 from the reference line B1-2 to the mobile station 2 based on the signal levels L21 and L22.

[0101] In step S224, the processing circuit 24 determines whether the distance d2 is longer than the threshold Th1. If the answer is YES, the process proceeds to step S225; otherwise, it proceeds to step S226.

[0102] In step S225, the processing circuit 24 determines that the mobile station 2 is located on the side of the reference line B1-2 that does not include the hazardous area A2, and that the mobile station 2 is far from the reference line B1-2. As a result, the processing circuit 24 provisionally determines that the mobile station 2 is in the safe area A1 (i.e., the area of ​​the safe area A1 that is not the alert area A3).

[0103] In step S226, the processing circuit 24 determines that the mobile station 2 is located on the side of the reference line B1-2 that does not include the danger area A2, and that the mobile station 2 is close to the reference line B1-2. Based on this, the processing circuit 24 provisionally determines that the mobile station 2 is in the warning area A3.

[0104] In step S227, the processing circuit 24 determines that the mobile station 2 is located on the side of the reference line B1-2 that includes the hazardous area A2. As a result, the processing circuit 24 provisionally determines that the mobile station 2 is in the hazardous area A2.

[0105] The processing circuit 24 may execute steps S201 and S202 in parallel, as shown in Figure 21, or it may execute steps S201 and S202 sequentially.

[0106] In step S203, the processing circuit 24 determines whether the mobile station 2 is in the danger area A2 based on the position of the mobile station 2 with respect to the reference lines B1-1 and B1-2. If the answer is YES, the process proceeds to step S208; otherwise, it proceeds to step S204. In step S204, the processing circuit 24 determines whether the mobile station 2 is in the warning area A3 based on the position of the mobile station 2 with respect to the reference lines B1-1 and B1-2 and the distance d1 or d2. If the answer is YES, the process proceeds to step S206; otherwise, it proceeds to step S205.

[0107] Figure 24 is a table illustrating the determination of safe area A1, dangerous area A2, and alert area A3 by the alarm system according to the first modification of the fourth embodiment. If both the determination based on beacon signals N11 and N12 and the determination based on beacon signals N21 and N22 indicate that "mobile station 2 is in dangerous area A2", the processing circuit 24 determines that mobile station 2 is in dangerous area A2. On the other hand, if at least one of the determination results indicates that "mobile station 2 is in safe area A1", the processing circuit 24 determines that mobile station 2 is in safe area A1. If neither of these is the case, the processing circuit 24 determines that mobile station 2 is in alert area A3.

[0108] In step S205 of Figure 21, the processing circuit 24 determines that the mobile station 2 is in safe area A1 (i.e., the area of ​​safe area A1 that is not in alert area A3). The processing circuit 24 may use the output device 25 to generate a signal indicating that the mobile station 2 is in safe area A1.

[0109] In step S206, the processing circuit 24 determines that the mobile station 2 is in the surveillance area A3. Then, in step S207, the processing circuit 24 uses the output device 25 to generate an alarm signal indicating that the mobile station 2 is in the surveillance area A3.

[0110] In step S208, the processing circuit 24 determines that the mobile station 2 is in hazardous area A2. In step S209, the processing circuit 24 uses the output device 25 to generate an alarm signal indicating that the mobile station 2 is in hazardous area A2.

[0111] According to this modified version, by setting a warning area A3 and determining whether mobile station 2 is in safe area A1, dangerous area A2, or warning area A3, the movement of people or objects can be controlled in more detail.

[0112] In the alarm system of Figure 20, the processing circuit 24 of the mobile station 2 may use a machine learning model to determine whether the mobile station 2 is in safe area A1, dangerous area A2, or warning area A3, similar to the processing in Figure 16. In this case, the processing in Figure 22 includes steps S21 to S25 of Figure 16 instead of steps S212 to S214. The processing circuit 24 calculates a first feature quantity based on the signal levels of beacon signals N11 and N12. Based on the first feature quantity, the processing circuit 24 determines a first provisional position by using a first machine learning model to determine whether the mobile station 2 is located on the side of the reference line B1-1 that includes dangerous area A2. If the mobile station 2 is on the side of the reference line B1-1 that does not include dangerous area A2, the processing circuit 24 uses a second machine learning model based on the first feature quantity to determine whether the first distance d1 from the reference line B1-1 to the mobile station 2 is shorter than a threshold Th1. Furthermore, the processing in Figure 23 includes steps S21 to S25 in Figure 16 instead of steps S222 to S224. The processing circuit 24 calculates a second feature quantity based on the signal levels of beacon signals N21 and N22. Based on the second feature quantity, the processing circuit 24 determines a second provisional position by using a first machine learning model to determine whether the mobile station 2 is located on the side of the reference line B1-2 that includes the hazardous area A2. If the mobile station 2 is on the side of the reference line B1-2 that does not include the hazardous area A2, the processing circuit 24 determines, based on the second feature quantity and using a second machine learning model, whether the second distance d2 from the reference line B1-2 to the mobile station 2 is shorter than the threshold Th1. Based on the position of the mobile station 2 relative to the reference lines B1-1 and B1-2 and the distance d1 or d2, the processing circuit 24 determines whether the mobile station 2 is in the safe area A1, the hazardous area A2, or the warning area A3. By using machine learning models, it is possible to flexibly adapt to various conditions, such as fluctuations in the radio wave propagation environment.

[0113] Figure 25 is a diagram illustrating the operation of the alarm system according to a second modification of the fourth embodiment. In this modification, an additional hazard area A2' is set outside the hazard area A2, similar to the case in Figure 17. In this case, the process in Figure 22 further includes a step of determining whether the distance d1 is shorter than the threshold Th2, similar to step S31 in Figure 18. The process in Figure 23 further includes a step of determining whether the distance d2 is shorter than the threshold Th2, similar to step S31 in Figure 18. The processing circuit 24 can determine whether the mobile station 2 is in the additional hazard area A2' based on the position of the mobile station 2 with respect to reference lines B1-1, B1-2 and the distance d1 or d2. According to this modification, the safety of people or objects can be further improved by setting the additional hazard area A2'.

[0114] [Fifth Embodiment] Figure 26 is a diagram illustrating the operation of the alarm system according to the fifth embodiment. The alarm system in Figure 26 includes a plurality of fixed stations 1-1 to 1-3 and a mobile station 2. Fixed stations 1-1 to 1-3 are configured similarly to fixed station 1 in Figure 2.

[0115] Multiple fixed stations 1-1 to 1-3 are each provided at different positions on boundary line B1. The hazardous area A2 may have, for example, a convex polygonal shape with multiple sides connected to each other at a predetermined angle. In this case, at least one fixed station is provided on each side of the polygon. In this case, a reference line B1-1 is set that is tangent to boundary line B1 at the position of fixed station 1-1, a reference line B1-2 is set that is tangent to boundary line B1 at the position of fixed station 1-2, and a reference line B1-3 is set that is tangent to boundary line B1 at the position of fixed station 1-3.

[0116] The transmitting and receiving circuit 22 of mobile station 2 receives two beacon signals from each of the fixed stations 1-1 to 1-3 and detects the signal level of each beacon signal. The processing circuit 24 of mobile station 2 determines a first provisional position that provisionally indicates which side of the boundary line mobile station 2 is located on, relative to the fixed station, based on the signal levels of the two beacon signals received from one of the fixed stations 1-1 to 1-3. The processing circuit 24 also determines a second provisional position that provisionally indicates which side of the boundary line mobile station 2 is located on, relative to the fixed station, based on the signal levels of the two beacon signals received from the other fixed station 1-1 to 1-3. Then, based on the first and second provisional positions, the processing circuit 24 determines whether mobile station 2 is in safe area A1 or dangerous area A2. The processing circuit 24 may determine whether the mobile station 2 is in safe area A1 or dangerous area A2 based on the provisional positions of any two fixed stations 1-1 to 1-3. Alternatively, the processing circuit 24 may obtain the provisional positions of all fixed stations 1-1 to 1-3 and determine whether the mobile station 2 is in safe area A1 or dangerous area A2 based on two of these provisional positions.

[0117] According to this embodiment, by receiving beacon signals from multiple fixed stations 1-1 to 1-3, it is possible to more accurately determine whether the mobile station 2 is in safe area A1 or dangerous area A2, even if the boundary line B1 has a complex shape including corners.

[0118] [Sixth Embodiment] Figure 27 is a block diagram showing the configuration of the fixed station 1A of the alarm system according to the sixth embodiment. The fixed station 1A comprises an input device 11, a transmitting circuit 12A, an antenna 13A, and an antenna 14A. Each of the antennas 13A and 14A includes multiple antenna elements. Each of the antennas 13A and 14A is configured to transmit a signal that is identifiable from each other from each antenna element. The transmitting circuit 12A controls the antennas 13A and 14A and transmits beacon signals via the antennas 13A and 14A, respectively. The transmitting and receiving circuit 22 of the mobile station 2 selects only the beacon signal with the highest signal level from among the received beacon signals. This reduces the effects of multipath and allows for a more accurate determination of whether the mobile station 2 is in a safe area A1 or a dangerous area A2.

[0119] [Other embodiments] Each of the embodiments and modifications described may be combined with one another. For example, the third embodiment is also applicable when fixed stations 1-1 and 1-2 are on the same straight section and each transmitting antenna has the same main beam direction, as in the second embodiment. In addition, in the third and fourth embodiments, whether the mobile station is in safe area A1 or dangerous area A2 (or safe area A1, dangerous area A2, and alert area A3) may be determined based on the number of times the signal level satisfies a predetermined condition during a predetermined time period. In addition, in the third and fourth embodiments, whether the mobile station is moving may be determined based on the acceleration of the mobile station, and whether the mobile station is in safe area A1 or dangerous area A2 (or safe area A1, dangerous area A2, and alert area A3) may be determined based on whether the mobile station is moving.

[0120] The alarm processing and / or other processing of the mobile station 2, as described with reference to Figures 6, 15, 16, and 18, may be provided as a program executed by a general-purpose processor. The mobile station 2 may download the program from the server device 4, for example, via the access point device 3.

[0121] The main beam directions of the two antennas 13 and 14 installed at the fixed station 1 are not limited to directions perpendicular to the boundary line B1, but may be set to other angles.

[0122] The alarm signal may be output from an output device 25 located inside the mobile station 2, or, as an additional or alternative, from a server device 4 or other device connected via the access point device 3.

[0123] The alarm system may be used to identify more areas, not limited to identifying safe area A1 and dangerous area A2, or safe area A1, dangerous area A2, and alert area A3. For example, the alarm system may be configured to identify multiple alert levels based on distance from a boundary line.

[0124] The alarm system may be used not only to detect when a mobile station is in a dangerous area, but also to detect when a mobile station is in a safe area or another predetermined area. The alarm system may also be used to restrict access to a predetermined area. In this case, each area is assigned identification information (job ID) indicating the occupation of users who are allowed to enter, and mobile station 2 is also assigned the job ID of the user who holds mobile station 2. The area database of server device 4 registers the job ID in association with each area. When a user starts using mobile station 2, or when the area setting is changed, they obtain a portion of the area database and their own job ID from server device 4 by operating the input device 23 of mobile station 2. Fixed station 1 is installed in the area to be detected. The identification information (area ID) of the area is manually set on fixed station 1. When mobile station 2 detects that it is approaching an area, it compares the area ID included in the beacon signal with the area database downloaded from server device 4. If the user's job ID is not set to "allowed to enter," mobile station 2 outputs an alarm signal. If the user's occupation ID is set to "accessible," mobile station 2 does not output an alarm signal. When mobile station 2 detects that the user has entered the area, it compares the area ID included in the beacon signal with the area database downloaded from server device 4. If the user's occupation ID is not set to "accessible," mobile station 2 outputs an alarm signal indicating that the user has entered the area and also notifies server device 4 that the user has entered the area. If the user's occupation ID is set to "accessible," mobile station 2 notifies server device 4 that the user has entered the area. This allows for the management of user access to the area.

[0125] [Summary of Embodiments] According to the first aspect of this disclosure, An alarm system including a first fixed station, a second fixed station, and a mobile station, The first and second fixed stations are each located at different positions on the boundary lines between the first and second areas. The aforementioned first fixed station is, A first transmitting antenna having a first main beam direction toward the side of the first area from the boundary line, A second transmitting antenna having a second main beam direction toward the side of the second area from the boundary line, The system includes a first transmitting circuit that transmits a first beacon signal via the first transmitting antenna and a second beacon signal via the second transmitting antenna, The second fixed station mentioned above is, A third transmitting antenna having a third main beam direction toward the side of the first area from the boundary line, A fourth transmitting antenna having a fourth main beam direction toward the side of the second area from the boundary line, The system includes a second transmitting circuit that transmits a third beacon signal via the third transmitting antenna and a fourth beacon signal via the fourth transmitting antenna, The aforementioned mobile station is Receiving antenna and A receiving circuit that receives the first to fourth beacon signals via the receiving antenna and detects the signal levels of the first to fourth beacon signals, A processing circuit that determines whether the mobile station is located in the first or second area based on the signal levels of the first to fourth beacon signals, The system includes an output device that outputs a first alarm signal indicating that the mobile station is in the second area when the mobile station is in the second area, The aforementioned processing circuit is Based on the signal levels of the first and second beacon signals, a first provisional position is determined that provisionally indicates which side of the boundary line the mobile station is located on, with respect to the first fixed station. Based on the signal levels of the third and fourth beacon signals, a second provisional position is determined that provisionally indicates which side of the boundary line the mobile station is located on, with respect to the second fixed station. Based on the first and second provisional locations, it is determined which of the first and second areas the mobile station is located in.

[0126] According to a second aspect of this disclosure, in the first aspect, The aforementioned processing circuit is Based on the signal levels of the first and second beacon signals, the first provisional position is determined by determining which side of the first reference line tangent to the boundary line the mobile station is located on at the location of the first fixed station. The second provisional position is determined by determining, based on the signal levels of the third and fourth beacon signals, which side of the second reference line tangent to the boundary line at the location of the second fixed station the mobile station is located on.

[0127] According to a third aspect of this disclosure, in a second aspect, The first and second reference lines are common straight lines passing through the positions of the first and second fixed stations.

[0128] According to a fourth aspect of this disclosure, in a second aspect, The first and second reference lines intersect each other at a predetermined angle.

[0129] According to the fifth aspect of this disclosure, in one aspect of the first to fourth aspects, The aforementioned processing circuit is If the signal level of the second beacon signal is higher than the signal level of the first beacon signal, the first provisional position is determined to indicate that the mobile station is located on the side of the boundary line that includes the second area. If the signal level of the fourth beacon signal is higher than the signal level of the third beacon signal, the second provisional position is determined to indicate that the mobile station is located on the side of the boundary line that includes the second area.

[0130] According to the sixth aspect of this disclosure, in one aspect of the first to fourth aspects, The aforementioned processing circuit is If, during a predetermined time period, the number of times the signal level of the second beacon signal exceeds the signal level of the first beacon signal exceeds a first threshold, the first provisional position is determined to indicate that the mobile station is located on the side of the boundary line that includes the second area. If, during the aforementioned time period, the number of times the signal level of the fourth beacon signal exceeds the signal level of the third beacon signal exceeds the first threshold, the second provisional position is determined to indicate that the mobile station is located on the side of the boundary line that includes the second area.

[0131] According to the seventh aspect of this disclosure, in one aspect of the first to fourth aspects, The mobile station further comprises an acceleration sensor for detecting the acceleration of the mobile station, The aforementioned processing circuit is Based on the acceleration of the mobile station, it is determined whether or not the mobile station is moving. If the mobile station is in motion and the signal level of the second beacon signal is higher than the signal level of the first beacon signal, the first provisional position is determined to indicate that the mobile station is located on the side of the boundary line that includes the second area. If the mobile station is in motion and the signal level of the fourth beacon signal is higher than the signal level of the third beacon signal, the second provisional position is determined to indicate that the mobile station is located on the side of the boundary line that includes the second area.

[0132] According to the eighth aspect of this disclosure, in one of the second to fourth aspects, The aforementioned processing circuit is Based on the signal levels of the first and second beacon signals, a first distance from the first reference line to the mobile station is calculated. Based on the signal levels of the third and fourth beacon signals, the second distance from the second reference line to the mobile station is calculated. Based on the first and second provisional positions and the first or second distance, it is determined whether the mobile station is in a third area included in the first area and is adjacent to the second area by a distance shorter than the second threshold. The output device outputs a second alarm signal indicating that the mobile station is in the third area when the mobile station is in the third area.

[0133] According to the ninth aspect of this disclosure, in the eighth aspect, The processing circuit determines, based on the first and second provisional positions and the first or second distance, whether the mobile station is in a fourth area included in the first area, and is adjacent to the second area by a distance shorter than the second threshold and shorter than the third threshold. The output device outputs the first alarm signal when the mobile station is in the fourth area.

[0134] According to the tenth aspect of this disclosure, in one of the second to fourth aspects, The aforementioned processing circuit is Based on the signal levels of the first and second beacon signals, a first feature quantity is calculated. Based on the first feature, the first provisional position is determined by using a first machine learning model to determine whether the mobile station is located on the side of the first reference line that includes the second area, A second feature quantity is calculated based on the signal levels of the third and fourth beacon signals. Based on the second feature, the second provisional position is determined by using the first machine learning model to determine whether the mobile station is located on the side of the second reference line that includes the second area.

[0135] According to the eleventh aspect of this disclosure, in the tenth aspect, The aforementioned processing circuit is If the mobile station is located on the side of the first baseline that does not include the second area, then, based on the first feature, a second machine learning model is used to determine whether the first distance from the first baseline to the mobile station is shorter than a second threshold. If the mobile station is located on the side of the second reference line that does not include the second area, then, based on the second feature, the second machine learning model is used to determine whether the second distance from the second reference line to the mobile station is shorter than the second threshold. Based on the first and second provisional positions and the first or second distance, it is determined whether the mobile station is in a third area included in the first area and is adjacent to the second area by a distance shorter than the second threshold. The output device outputs a second alarm signal indicating that the mobile station is in the third area when the mobile station is in the third area.

[0136] According to the twelfth aspect of this disclosure, in one aspect of the first to eleventh aspects, Each of the first to fourth transmitting antennas includes multiple antenna elements.

[0137] According to the 13th aspect of this disclosure, in one aspect of the 1st to 12th aspects, The alarm system further includes a third fixed station located on the boundary line at a different location from the first and second fixed stations, The third fixed station is, A fifth transmitting antenna having a fifth main beam direction toward the side of the first area from the boundary line, A sixth transmitting antenna having a sixth main beam direction toward the side of the second area from the boundary line, The system includes a third transmitting circuit that transmits a fifth beacon signal via the fifth transmitting antenna and a sixth beacon signal via the sixth transmitting antenna, The receiving circuit receives the fifth and sixth beacon signals via the receiving antenna and detects the signal levels of the fifth and sixth beacon signals. The aforementioned processing circuit is Based on the signal levels of the fifth and sixth beacon signals, Third A third provisional position is determined that provisionally indicates which side of the boundary line the mobile station is located on, based on the fixed station. The first to third provisional positions mentioned above of Based on two of these, it is determined whether the mobile station is located in the first or second area.

[0138] According to a fourteenth aspect of this disclosure, a mobile station for an alarm system according to one of the first to thirteenth aspects is provided.

[0139] According to the 15th aspect of this disclosure, A program including instructions executed by a processing circuit implemented in a mobile station of an alarm system including a first fixed station, a second fixed station, and a mobile station, The first and second fixed stations are each located at different positions on the boundary lines between the first and second areas. The aforementioned first fixed station is, A first transmitting antenna having a first main beam direction toward the side of the first area from the boundary line, A second transmitting antenna having a second main beam direction toward the side of the second area from the boundary line, The system includes a first transmitting circuit that transmits a first beacon signal via the first transmitting antenna and a second beacon signal via the second transmitting antenna, The second fixed station mentioned above is, A third transmitting antenna having a third main beam direction toward the side of the first area from the boundary line, A fourth transmitting antenna having a fourth main beam direction toward the side of the second area from the boundary line, The system includes a second transmitting circuit that transmits a third beacon signal via the third transmitting antenna and a fourth beacon signal via the fourth transmitting antenna, The aforementioned mobile station is Receiving antenna and A receiving circuit that receives the first to fourth beacon signals via the receiving antenna and detects the signal levels of the first to fourth beacon signals, The processing circuit and, Equipped with an output device, The instruction is given to the processing circuit, Based on the signal levels of the first and second beacon signals, a first provisional position is determined that provisionally indicates which side of the boundary line the mobile station is located on with respect to the first fixed station; Based on the signal levels of the third and fourth beacon signals, a second provisional position is determined that provisionally indicates which side of the boundary line the mobile station is located on, with respect to the second fixed station; Based on the first and second provisional locations, determine which of the first and second areas the mobile station is located in, If the mobile station is in the second area, the output device outputs a first alarm signal indicating that the mobile station is in the second area. [Industrial applicability]

[0140] An alarm system according to one aspect of this disclosure is applicable to locations that include safe areas and hazardous areas, such as factories and construction sites. [Explanation of Symbols]

[0141] 1,1-1~1-3,1A fixed station 2,2A mobile station 3. Access Point Device (AP) 4 Server devices 11 Input devices 12,12A Transmitter Circuit 13,13A antenna 14,14A antenna 21 Antennas 22 Transmit / Receive Circuit 23 Input device 24,24A Processing Circuit 25 Output device 26 Accelerometer 40 buses 41 processors 42 memory 43 Storage device 44 Communication equipment 45 Input device 46 Display device A1 Safety Area A2 Dangerous Area A3 Restricted Area A11 False Positive Area A12 False Negative Area B1 border Radiation pattern of antenna 13 (R1) Radiation pattern of antenna 14 (R2)

Claims

1. An alarm system including a first fixed station, a second fixed station, and a mobile station, The first and second fixed stations are each provided at different locations on the boundary lines between the first and second areas. The first fixed station is, A first transmitting antenna having a first main beam direction toward the side of the first area from the boundary line, A second transmitting antenna having a second main beam direction toward the side of the second area from the boundary line, The system includes a first transmitting circuit that transmits a first beacon signal via the first transmitting antenna and a second beacon signal via the second transmitting antenna, The second fixed station mentioned above is, A third transmitting antenna having a third main beam direction toward the side of the first area from the boundary line, A fourth transmitting antenna having a fourth main beam direction toward the side of the second area from the boundary line, The system includes a second transmitting circuit that transmits a third beacon signal via the third transmitting antenna and a fourth beacon signal via the fourth transmitting antenna, The aforementioned mobile station is Receiving antenna and A receiving circuit that receives the first to fourth beacon signals via the receiving antenna and detects the signal levels of the first to fourth beacon signals, A processing circuit that determines whether the mobile station is located in the first or second area based on the signal levels of the first to fourth beacon signals, The system includes an output device that outputs a first alarm signal indicating that the mobile station is in the second area when the mobile station is in the second area, The aforementioned processing circuit is Based on the signal levels of the first and second beacon signals, a first provisional position is determined that provisionally indicates which side of the boundary line the mobile station is located on, with respect to the first fixed station. Based on the signal levels of the third and fourth beacon signals, a second provisional position is determined that provisionally indicates which side of the boundary line the mobile station is located on, with respect to the second fixed station. If both the first and second provisional locations indicate that the mobile station is located on the side of the boundary line that includes the second area, then it is determined that the mobile station is in the second area. Alarm system.

2. The aforementioned processing circuit is Based on the signal levels of the first and second beacon signals, the first provisional position is determined by determining which side of the first reference line tangent to the boundary line the mobile station is located on at the location of the first fixed station. The second provisional position is determined by determining, based on the signal levels of the third and fourth beacon signals, which side of the second reference line tangent to the boundary line at the location of the second fixed station the mobile station is located on. The alarm system according to claim 1.

3. The first and second reference lines are common straight lines passing through the positions of the first and second fixed stations. The alarm system according to claim 2.

4. The first and second reference lines intersect each other at a predetermined angle. The alarm system according to claim 2.

5. The aforementioned processing circuit is If the signal level of the second beacon signal is higher than the signal level of the first beacon signal, the first provisional position is determined to indicate that the mobile station is located on the side of the boundary line that includes the second area. If the signal level of the fourth beacon signal is higher than the signal level of the third beacon signal, the second provisional position is determined to indicate that the mobile station is located on the side of the boundary line that includes the second area. An alarm system according to one of claims 1 to 4.

6. The aforementioned processing circuit is If, during a predetermined time period, the number of times the signal level of the second beacon signal exceeds the signal level of the first beacon signal exceeds a first threshold, the first provisional position is determined to indicate that the mobile station is located on the side of the boundary line that includes the second area. If, during the aforementioned time period, the number of times the signal level of the fourth beacon signal exceeds the signal level of the third beacon signal exceeds the first threshold, the second provisional position is determined to indicate that the mobile station is located on the side of the boundary line that includes the second area. An alarm system according to one of claims 1 to 4.

7. The mobile station further comprises an acceleration sensor for detecting the acceleration of the mobile station, The aforementioned processing circuit is Based on the acceleration of the mobile station, it is determined whether or not the mobile station is moving. If the mobile station is in motion and the signal level of the second beacon signal is higher than the signal level of the first beacon signal, the first provisional position is determined to indicate that the mobile station is located on the side of the boundary line that includes the second area. If the mobile station is in motion and the signal level of the fourth beacon signal is higher than the signal level of the third beacon signal, the second provisional position is determined to indicate that the mobile station is located on the side of the boundary line that includes the second area. An alarm system according to one of claims 1 to 4.

8. The aforementioned processing circuit is Based on the signal levels of the first and second beacon signals, a first distance from the first reference line to the mobile station is calculated. Based on the signal levels of the third and fourth beacon signals, the second distance from the second reference line to the mobile station is calculated. Based on the first and second provisional positions and the first or second distance, it is determined whether the mobile station is in a third area included in the first area and is adjacent to the second area by a distance shorter than the second threshold. The output device outputs a second alarm signal indicating that the mobile station is in the third area when the mobile station is in the third area. The alarm system according to one of claims 2 to 4.

9. The processing circuit determines, based on the first and second provisional positions and the first or second distance, whether the mobile station is in a fourth area included in the first area, and is adjacent to the second area by a distance shorter than the second threshold and shorter than the third threshold. The output device outputs the first alarm signal when the mobile station is in the fourth area. The alarm system according to claim 8.

10. The aforementioned processing circuit is Based on the signal levels of the first and second beacon signals, a first feature quantity is calculated. Based on the first feature quantities, the first provisional position is determined by using a first machine learning model to determine whether the mobile station is located on the side of the first reference line that includes the second area, Based on the signal levels of the third and fourth beacon signals, a second feature quantity is calculated. Based on the second feature, the second provisional position is determined by using the first machine learning model to determine whether the mobile station is located on the side of the second reference line that includes the second area. The alarm system according to one of claims 2 to 4.

11. The aforementioned processing circuit is If the mobile station is located on the side of the first reference line that does not include the second area, then, based on the first feature, a second machine learning model is used to determine whether the first distance from the first reference line to the mobile station is shorter than a second threshold. If the mobile station is located on the side of the second reference line that does not include the second area, then, based on the second feature quantity, the second machine learning model is used to determine whether the second distance from the second reference line to the mobile station is shorter than the second threshold. Based on the first and second provisional positions and the first or second distance, it is determined whether the mobile station is in a third area included in the first area and is adjacent to the second area by a distance shorter than the second threshold. The output device outputs a second alarm signal indicating that the mobile station is in the third area when the mobile station is in the third area. The alarm system according to claim 10.

12. Each of the first to fourth transmitting antennas includes a plurality of antenna elements. The alarm system according to claim 1.

13. An alarm system including a first fixed station, a second fixed station, a third fixed station, and a mobile station, The first to third fixed stations are each located at different positions on the boundary lines between the first and second areas. The first fixed station is, A first transmitting antenna having a first main beam direction toward the side of the first area from the boundary line, A second transmitting antenna having a second main beam direction toward the side of the second area from the boundary line, The system includes a first transmitting circuit that transmits a first beacon signal via the first transmitting antenna and a second beacon signal via the second transmitting antenna, The second fixed station mentioned above is, A third transmitting antenna having a third main beam direction toward the side of the first area from the boundary line, A fourth transmitting antenna having a fourth main beam direction toward the side of the second area from the boundary line, The system includes a second transmitting circuit that transmits a third beacon signal via the third transmitting antenna and a fourth beacon signal via the fourth transmitting antenna, The third fixed station is, A fifth transmitting antenna having a fifth main beam direction toward the side of the first area from the boundary line, A sixth transmitting antenna having a sixth main beam direction toward the side of the second area from the boundary line, The system includes a third transmitting circuit that transmits a fifth beacon signal via the fifth transmitting antenna and a sixth beacon signal via the sixth transmitting antenna, The aforementioned mobile station is Receiving antenna and A receiving circuit that receives the first to sixth beacon signals via the receiving antenna and detects the signal levels of the first to sixth beacon signals, A processing circuit that determines whether the mobile station is located in the first or second area based on the signal levels of the first to sixth beacon signals, The system includes an output device that outputs a first alarm signal indicating that the mobile station is in the second area when the mobile station is in the second area, The aforementioned processing circuit is Based on the signal levels of the first and second beacon signals, a first provisional position is determined that provisionally indicates which side of the boundary line the mobile station is located on, with respect to the first fixed station. Based on the signal levels of the third and fourth beacon signals, a second provisional position is determined that provisionally indicates which side of the boundary line the mobile station is located on, with respect to the second fixed station. Based on the signal levels of the fifth and sixth beacon signals, a third provisional position is determined that provisionally indicates which side of the boundary line the mobile station is located on, with respect to the third fixed station. If two of the first to third provisional locations indicate that the mobile station is located on the side of the boundary line that includes the second area, then it is determined that the mobile station is in the second area. Alarm system.

14. A mobile station for the alarm system according to claim 1.

15. A program including instructions executed by a processing circuit implemented in a mobile station of an alarm system including a first fixed station, a second fixed station, and a mobile station, The first and second fixed stations are each provided at different locations on the boundary lines between the first and second areas. The first fixed station is, A first transmitting antenna having a first main beam direction toward the side of the first area from the boundary line, A second transmitting antenna having a second main beam direction toward the side of the second area from the boundary line, The system includes a first transmitting circuit that transmits a first beacon signal via the first transmitting antenna and a second beacon signal via the second transmitting antenna, The second fixed station mentioned above is, A third transmitting antenna having a third main beam direction toward the side of the first area from the boundary line, A fourth transmitting antenna having a fourth main beam direction toward the side of the second area from the boundary line, The system includes a second transmitting circuit that transmits a third beacon signal via the third transmitting antenna and a fourth beacon signal via the fourth transmitting antenna, The aforementioned mobile station is Receiving antenna and A receiving circuit that receives the first to fourth beacon signals via the receiving antenna and detects the signal levels of the first to fourth beacon signals, The processing circuit and, Equipped with an output device, The instruction is given to the processing circuit, Based on the signal levels of the first and second beacon signals, a first provisional position is determined that provisionally indicates which side of the boundary line the mobile station is located on, with respect to the first fixed station; Based on the signal levels of the third and fourth beacon signals, a second provisional position is determined that provisionally indicates which side of the boundary line the mobile station is located on, with respect to the second fixed station; If both the first and second provisional locations indicate that the mobile station is located on the side of the boundary line that includes the second area, then it is determined that the mobile station is in the second area. If the mobile station is in the second area, the output device will output a first alarm signal indicating that the mobile station is in the second area. program.

Images