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 technology]

[0002] For example, in a factory, if an operator approaches a machine tool carelessly, the operator may be injured by the machine tool. For this reason, a danger zone may be set near the machine tool, and an alarm may be issued when the operator enters the danger zone.

[0003] For example, Patent Document 1 discloses a safety control system applied to a construction site where there are safe and dangerous areas. The system of Patent Document 1 detects the distance from the boundary between the dangerous and safe areas to the source of the beacon signal based on the reception strength of a beacon signal transmitted from a source installed on a worker, heavy machinery, or the like. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-085185 Summary of the Invention [Problem to be solved by the invention]

[0005] When detecting distance based on the received signal strength of a beacon signal as in Patent Document 1, it becomes difficult to receive a beacon signal with a stable signal strength when moving away from the source of the beacon signal. As a result, it becomes difficult to reliably determine whether the worker is in a safe area or a dangerous area. In order to reliably determine whether the worker is in a safe area or a dangerous area, it is conceivable to arrange many transmission sources at high density so that the area covered by one transmission source becomes narrow. However, in this case, high costs are incurred because many transmission sources are used. Therefore, it is required to determine whether a person or object is in a predetermined area with higher accuracy than before without incurring a significant increase in cost.

[0006] An object of the present disclosure is to provide an alarm system that can determine with higher accuracy than conventional methods whether a person or object is in a predetermined area, and a mobile station and a program for such an alarm system. [Means for solving the problem]

[0007] According to one aspect of the present disclosure, 1. An alarm system including a first fixed station, a second fixed station, and a mobile station, The first and second fixed stations are provided at different positions on a boundary between the first and second areas, The first fixed station comprises: a first transmitting antenna having a first main beam direction from the boundary line toward the first area; a second transmitting antenna having a second main beam direction from the boundary line toward the second area; a first transmitting circuit configured to transmit a first beacon signal via the first transmitting antenna and a second beacon signal via the second transmitting antenna; The second fixed station comprises: a third transmitting antenna having a third main beam direction from the boundary line toward the first area; a fourth transmitting antenna having a fourth main beam direction from the boundary line toward the second area; a second transmitting circuit configured to transmit a third beacon signal via the third transmitting antenna and a fourth beacon signal via the fourth transmitting antenna; The mobile station, A receiving antenna; a receiving circuit that receives the first to fourth beacon signals via the receiving antenna and detects signal levels of the first to fourth beacon signals; a processing circuit that determines whether the mobile station is in the first area or the second area based on the signal levels of the first to fourth beacon signals; 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 processing circuitry includes: determining a first tentative position that provisionally indicates on which side of the boundary line the mobile station is located with respect to the first fixed station based on the signal levels of the first and second beacon signals; determining a second tentative position that provisionally indicates on which side of the boundary line the mobile station is located with respect to the second fixed station based on the signal levels of the third and fourth beacon signals; Based on the first and second interim positions, it is determined whether the mobile station is in the first or second area. Effect of the Invention

[0008] An alarm system according to one aspect of the present disclosure can determine whether a person or object is in a predetermined area with higher accuracy than conventional methods. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing an alarm system according to a first embodiment. [Diagram 2] 2 is a block diagram showing the configuration of a fixed station 1 in FIG. [Diagram 3]FIG. 2 is a block diagram showing a configuration of a mobile station 2 in FIG. [Figure 4] 2 is a block diagram showing a configuration of a server device 4 in FIG. 1. [Diagram 5] FIG. 3 shows an exemplary radiation pattern of the fixed station 1 of FIG. 2. [Figure 6] 4 is a flowchart showing a warning process executed by the processing circuit 24 of FIG. 3. [Figure 7] FIG. 2 is a diagram for explaining the influence of multipath in the alarm system of FIG. [Figure 8] FIG. 13 is a block diagram showing a configuration of a mobile station 2A of the alarm system according to a modified example of the first embodiment. [Figure 9] FIG. 11 is a diagram for explaining the operation of the alarm system according to the second embodiment. [Figure 10] 10 is a flowchart showing warning processing executed by the processing circuit 24 of the mobile station 2 of FIG. [Figure 11] 11 is a flowchart showing a subroutine of step S101 in FIG. 10. [Figure 12] 11 is a flowchart showing a subroutine of step S102 in FIG. 10. [Figure 13] 13 is a table for explaining how a safe area A1 and a dangerous area A2 are determined by a warning system according to a second embodiment. [Figure 14] FIG. 11 is a diagram for explaining the operation of the alarm system according to the third embodiment. [Figure 15] 13 is a flowchart showing warning processing executed by a mobile station 2 in the warning system according to the third embodiment. [Figure 16] 13 is a flowchart showing warning processing executed by a mobile station 2 in the warning system according to the first modified example of the third embodiment. [Figure 17] FIG. 13 is a diagram for explaining the operation of the alarm system according to the second modified example of the third embodiment. [Figure 18] 13 is a flowchart showing warning processing executed by a mobile station 2 in a warning system according to a second modified example of the third embodiment. [Figure 19] FIG. 13 is a diagram for explaining the operation of the alarm system according to the fourth embodiment. [Figure 20] FIG. 13 is a diagram for explaining the operation of the alarm system according to the first modified example of the fourth embodiment. [Figure 21] 20 is a flowchart showing warning processing executed by the processing circuit 24 of the mobile station 2 of FIG. 19. [Figure 22] 22 is a flowchart showing a subroutine of step S201 in FIG. 21. [Figure 23] 22 is a flowchart showing a subroutine of step S202 in FIG. 21. [Figure 24] 13 is a table for explaining the determination of a safe area A1, a dangerous area A2, and a caution area A3 by a warning system according to a first modified example of the fourth embodiment. [Diagram 25] FIG. 13 is a diagram for explaining the operation of the alarm system according to the second modified example of the fourth embodiment. [Figure 26] FIG. 13 is a diagram for explaining the operation of the alarm system according to the fifth embodiment. [Figure 27] FIG. 13 is a block diagram showing the configuration of a fixed station 1A of an alarm system according to a sixth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0011] [First embodiment] [Configuration of the first embodiment] Fig. 1 is a schematic diagram showing an alarm system according to a first embodiment. The alarm system in Fig. 1 includes one or more fixed stations 1, a mobile station 2, an access point device (AP) 3, and a server device 4.

[0012] The alarm system in Fig. 1 is installed in a place including a safety area A1 and a danger area A2, such as a factory or a construction site. The safety area A1 is an area where it is believed that there is no cause of damage to people or objects entering or remaining there. The danger area A2 is an area where there is a possibility of damage to people or objects entering or remaining there, such as near machine tools, steps, or chemicals.

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

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

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

[0016] FIG. 2 is a block diagram showing the configuration of the fixed station 1 in FIG. 1. The fixed station 1 includes 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 dangerous area A2 in which the fixed station 1 is installed. The input device 11 may include a keyboard or a numeric keypad, and may include a communication interface for acquiring information from other devices. The antenna 13 is a directional antenna having a first main beam direction, and the 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 the antenna 13 and transmits a second beacon signal via the antenna 14. As described above, each beacon signal includes identification information of the fixed station 1, identification information of the dangerous area A2 in which the fixed station 1 is installed, 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 one second or less.

[0017] The fixed station 1 further includes a power supply device such as a battery or a commercial power source, but this is omitted for simplicity of illustration.

[0018] FIG. 3 is a block diagram showing the configuration of the mobile station 2 in FIG. 1. The mobile station 2 includes an antenna 21, a transmission / reception circuit 22, an input device 23, a processing circuit 24, and an output device 25. The antenna 21 is an omnidirectional antenna. The transmission / reception circuit 22 receives two beacon signals from the fixed station 1 via the antenna 21 and detects the signal levels of the two beacon signals. The signal levels are, for example, received signal strength indicators (RSSIs). The transmission / reception circuit 22 also requests and acquires information required for the operation of the mobile station 2 (for example, identification information of the dangerous area A2, identification information of the fixed station 1, and identification information of each antenna of the fixed station 1) from the server device 4. The input device 23 receives a user input that triggers a request to the server device 4 for information required for the operation of the mobile station 2. The processing circuit 24 determines whether the mobile station 2 is in the safe area A1 or the dangerous area A2 based on the signal levels of the two beacon signals received from the fixed station 1. Specifically, the processing circuit 24 may determine that the mobile station 2 is in the dangerous area A2 when the signal level of the beacon signal transmitted via the antenna 14 is higher than the signal level of the beacon signal transmitted via the antenna 13. When the mobile station 2 is in the dangerous area A2, the output device 25 outputs an alarm signal indicating that the mobile station 2 is in the dangerous area A2. The output device 25 may include a buzzer or a speaker that outputs the alarm signal by sound, or may include a light-emitting diode that outputs the alarm signal by light. Furthermore, when the mobile station 2 is in the safe area A1, the output device 25 may output a signal indicating that the mobile station 2 is in the safe area A1 by not generating an alarm signal or by generating a sound or light different from the alarm signal.

[0019] The mobile station 2 further includes a power supply device such as a battery, but this is omitted for simplicity of illustration.

[0020] The fixed station 1 and the mobile station 2 may be configured to transmit and receive beacon signals in, for example, a Bluetooth (registered trademark) Low Energy (BLE) format.

[0021] FIG. 4 is a block diagram showing the configuration of the server device 4 in FIG. 1. The server device 4 includes a bus 40, a processor 41, a memory 42, a storage device 43, a communication device 44, an input device 45, and a 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 of the dangerous area A2, identification information of the fixed station 1, and identification information of each antenna of the fixed station 1). The communication device 44 is communicably connected to the mobile station 2 via the access point device 3. The input device 45 receives a user input that controls 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, the memory 42, the storage device 43, the communication device 44, the input device 45, and the display device 46 are connected to each other via the bus 40. The server device 4 operates as an area database that provides the mobile station 2 with information necessary for the operation of the mobile station 2 .

[0022] [Operation of the first embodiment] FIG. 5 is a diagram showing an exemplary radiation pattern of the fixed station 1 of FIG. 2. The fixed station 1 is provided on the boundary line B1 between the safe area A1 and the dangerous area A2. The antennas 13 and 14 of the fixed station 1 have radiation patterns R1 and R2, respectively. In order to explain the directions of the radiation patterns R1 and R2, a reference line tangent to the boundary line B1 at the position of the fixed station 1 is set. In the example of FIG. 5, the straight section of the boundary line B1 on which the fixed station 1 is provided becomes the reference line of the radiation patterns R1 and R2. The radiation pattern R1 has a main beam direction from the boundary line B1 toward the safe area A1 side, and the radiation pattern R2 has a main beam direction from the boundary line B1 toward the dangerous area A2 side. The main beam directions of the radiation patterns R1 and R2 may be perpendicular to the boundary line B1 or may intersect with the boundary line B1 at a predetermined angle (for example, an angle close to 90 degrees). The fixed station 1 is arranged so that the main beam directions of the radiation patterns R1 and R2 are directed toward the safe area A1 and dangerous area A2, respectively.

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

[0024] FIG. 6 is a flow chart showing the alarm processing executed by the processing circuit 24 of FIG.

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

[0026] In step S2, 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, and if YES, proceeds to step S3, and if NO, proceeds to step S5. The processing circuit 24 determines on which side of the boundary line B1 the mobile station 2 is located, based on the signal levels L1 and L2 of the beacon signals N1 and N2.

[0027] In step S3, the processing circuitry 24 determines that the mobile station 2 is in the danger area A2. Then, in step S4, the processing circuitry 24 generates, using the output device 25, an alarm signal indicating that the mobile station 2 is in the danger area A2.

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

[0029] When detecting distance based on the received signal strength of a beacon signal as in Patent Document 1, a weak beacon signal transmitted from a distant source and attenuated cannot be used 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 that even an attenuated weak beacon signal can be used to determine whether the mobile station 2 is in the safe area A1 or the dangerous area A2. A single fixed station 1 can cover a wider area than in the past, and it is not necessary to place many fixed stations 1 at high density. Thus, according to the alarm system of this embodiment, it is possible to determine with higher accuracy than in the past whether a person or object is in a predetermined area without incurring a significant increase in cost.

[0030] [Modification of the first embodiment] FIG. 7 is a diagram for explaining the influence of multipath in the alarm system of FIG. 1. The beacon signal propagates in multipath due to reflections from the floor, wall, and ceiling of a building, or other obstacles, and the signal level of the received beacon signal may fluctuate due to interference between the direct wave and the reflected wave of the beacon signal. In the example of FIG. 7, in the area A11, the signal level of the beacon signal N2 is higher than the signal level of the beacon signal N1, and in the area A12, the signal level of the beacon signal N1' is higher than the signal level of the beacon signal N2'. Therefore, the area A11 is a false positive area in which it is erroneously determined that "the mobile station 2 is in the dangerous area A2" even though it is included in the safe area A1. Moreover, the area A12 is a false negative area in which it is erroneously determined that "the mobile station 2' is in the safe area A1" even though it is included in the dangerous area A2.

[0031] Generally, the fluctuation of the signal level due to the multipath is temporary. Therefore, the processing circuit 24 may determine that the mobile station 2 is in the safe area A1 if the number of times that the signal level of the beacon signal N1 exceeds the signal level of the beacon signal N2 during a predetermined time period exceeds a predetermined threshold. The processing circuit 24 may also determine that the mobile station 2' is in the dangerous area A2 if the number of times that the signal level of the beacon signal N2' exceeds the signal level of the beacon signal N1' during a predetermined time period exceeds a predetermined threshold. This reduces the effect of the multipath and makes it possible to more accurately determine whether the mobile station 2 is in the safe area A1 or the dangerous area A2.

[0032] In addition, when the mobile station 2 enters the area A12 from the area A2, since the alarm signal has already been generated when the mobile station 2 is in the area A2, it is not substantially a problem that an alarm signal is not generated in the area A12.

[0033] FIG. 8 is a block diagram showing a configuration of a mobile station 2A of a warning system according to a modification of the first embodiment. The mobile station 2A includes a processing circuit 24A instead of the processing circuit 24 of the mobile station 2 in FIG. 3, and further includes an acceleration sensor 26. The acceleration sensor 26 detects the acceleration of the mobile station 2A. The processing circuit 24A determines whether the mobile station 2A is moving or not based on the acceleration of the mobile station 2A. For example, the processing circuit 24A may determine that the mobile station 2A is moving when the acceleration of the mobile station 2A is non-zero for a predetermined time period. The processing circuit 24A may determine that the mobile station 2A is in a safe area A1 when the mobile station 2A is moving and the signal level of the beacon signal N1 is higher than the signal level of the beacon signal N2. The processing circuit 24A may also determine that the mobile station 2A is in a dangerous area A2 when the mobile station 2A is moving and the signal level of the beacon signal N2 is higher than the signal level of the beacon signal N1. This reduces the effect of multipath and makes it possible to more accurately determine whether the mobile station 2A is in the safe area A1 or the dangerous area A2.

[0034] [Second embodiment] FIG. 9 is a diagram for explaining the operation of the alarm system according to the second embodiment. The fixed stations 1-1 and 1-2 are provided at different positions on a straight section of the boundary line B1 between the safe area A1 and the dangerous area A2. The fixed stations 1-1 and 1-2 are provided at a distance from each other such that the mobile station 2 can receive beacon signals from both the fixed stations 1-1 and 1-2. The fixed stations 1-1 and 1-2 are configured in the same manner as the fixed station 1 in FIG. 2. The antennas 13-1 and 14-1 of the fixed station 1-1 have radiation patterns R1-1 and R2-1, respectively. The antennas 13-2 and 14-2 of the fixed station 1-2 have radiation patterns R1-2 and R2-2, respectively. In order to explain the directions of the radiation patterns R1-1, R2-1, R1-2, and R2-2, reference lines are set that are tangent to the boundary line B1 at the positions of the fixed stations 1-1 and 1-2. In the example of FIG. 5, the straight line section of the boundary line B1 where the fixed stations 1-1 and 1-2 are provided is the reference line of the radiation patterns R1-1, R2-1, R1-2, and R2-2. The radiation pattern R1-1 has a main beam direction from the boundary line B1 toward the safe area A1. The radiation pattern R2-1 has a main beam direction from the boundary line B1 toward the dangerous area A2. The radiation pattern R1-2 has a main beam direction from the boundary line B1 toward the safe area A1. The radiation pattern R2-2 has a main beam direction from the boundary line B1 toward the dangerous area A2. The main beam directions of the radiation patterns R1-1, R2-1, R1-2, and R2-2 may be perpendicular to the boundary line B1, or may intersect with the boundary line B1 at a predetermined angle (for example, an angle close to 90 degrees). The fixed stations 1-1 and 1-2 are arranged so that the main beam directions of the radiation patterns R1-1, R2-1, R1-2, and R2-2 are directed toward the safe area A1 and dangerous area A2, respectively.

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

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

[0037] FIG. 10 is a flow chart showing the warning process executed by the processing circuit 24 of the mobile station 2 of FIG.

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

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

[0040] FIG. 11 is a flowchart showing a subroutine of step S101 in FIG.

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

[0042] In step S112, the processing circuit 24 determines whether or not the signal level L12 is higher than the signal level L11, and if YES, the process proceeds to step S113, and if NO, the process proceeds to step S114.

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

[0044] In step S114, the processing circuit 24 determines that the mobile station 2 is located on the side of the boundary line B1 that does not include the dangerous 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 tentative position indicating on which side of the border B1 the mobile station 2 is located with respect to the fixed station 1-1, based on the signal levels L11, L12 of the beacon signals N11, N12.

[0046] FIG. 12 is a flowchart showing a subroutine of step S102 in FIG.

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

[0048] In step S122, the processing circuit 24 determines whether or not the signal level L22 is higher than the signal level L21, and if YES, the process proceeds to step S123, and if NO, the process proceeds to step S124.

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

[0050] In step S124, the processing circuit 24 determines that the mobile station 2 is located on the side of the boundary line B1 that does not include the dangerous 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 the second tentative position indicating on which side of the border B1 the mobile station 2 is located with respect to the fixed station 1-2, based on the signal levels L21, L22 of the beacon signals N21, N22.

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

[0053] In step S103, the processing circuit 24 determines whether or not the mobile station 2 is in the safety area A1 based on the first and second tentative positions, and if YES, the process proceeds to step S104, and if NO, the process proceeds to step S106.

[0054] Fig. 13 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. As shown in Fig. 13, when the determination based on the beacon signals N11, N12 and the determination based on the beacon signals N21, N22 both indicate that "the mobile station 2 is in the dangerous area A2", the processing circuit 24 determines that the mobile station 2 is in the dangerous area A2. On the other hand, when at least one of the determination results indicates that "the mobile station 2 is in the safe area A1", the processing circuit 24 determines that the mobile station 2 is in the safe area A1.

[0055] 10, the processing circuit 24 determines that the mobile station 2 is in the dangerous 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 dangerous area A2.

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

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

[0058] The processing circuit 24 may determine on which side of the boundary line B1 the mobile station 2 is located, based on the number of times that the signal level satisfies a predetermined condition during a predetermined time period. The processing circuit 24 may determine a first tentative position to indicate that the mobile station 2 is located on the side including the dangerous area A2 with respect to the boundary line B1, if the number of times that the signal level L12 exceeds the signal level L11 during a predetermined time period exceeds a predetermined threshold. The processing circuit 24 may also determine a second tentative position to indicate that the mobile station 2 is located on the side including the dangerous area A2 with respect to the boundary line B1, if the number of times that the signal level L22 exceeds the signal level L21 during this time period exceeds a threshold. The processing circuit 24 then determines whether the mobile station 2 is located in the safe area A1 or the dangerous area A2, based on the first and second tentative positions. This makes it possible to further reduce the effect of multipath and more accurately determine whether the mobile station 2 is located in the safe area A1 or the dangerous area A2.

[0059] In the case of a mobile station 2A having an acceleration sensor 26 as shown in FIG. 8, it may be determined whether the mobile station 2A is moving based on the acceleration of the mobile station 2A, and on which side of the boundary line B1 the mobile station 2A is located based on whether the mobile station 2A is moving. When 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 tentative position to indicate that the mobile station 2A is located on the side including the dangerous area A2 with respect to the boundary line B1. When 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 tentative position to indicate that the mobile station 2A is located on the side including the dangerous area A2 with respect to the boundary line B1. Thereafter, the processing circuit 24A determines whether the mobile station 2A is located in the safe area A1 or the dangerous area A2 based on the first and second tentative positions. This makes it possible to further reduce the effects of multipath and more accurately determine whether the mobile station 2A is in the safe area A1 or the dangerous area A2.

[0060] [Third embodiment] FIG. 14 is a diagram for explaining the operation of the warning system according to the third embodiment. In this embodiment, an alert area A3 is set in a part of a safety area A1 close to a danger area A2. The alert area A3 is an area where there is a high possibility that the mobile station 2 will enter the danger area A2 as the mobile station 2 moves in the future. The alert area A3 is an area outside the danger area A2, and is an area whose distance from a reference line (i.e., boundary line B1) passing through the base station 1 is equal to or less than a threshold value Th1. In this embodiment, it is determined whether the mobile station 2 is in the safety area A1, the danger area A2, or the alert area A3.

[0061] FIG. 15 is a flowchart showing warning processing executed by the mobile station 2 of the warning system according to the third embodiment.

[0062] In step S11, the processing circuit 24 obtains 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, and if YES, proceeds to step S18, and if NO, proceeds to step S13.

[0064] In step S13, the processing circuit 24 calculates the distance d from the boundary line B1 to the mobile station 2 based on the signal levels of the beacon signals N1 and N2. The distance d is calculated mainly based on the signal level of the beacon signal N1. The smaller the signal level, the larger the distance d. However, if the beacon signals N1 and N2 are comparable, the mobile station 2 is considered to be near the 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 a threshold value Th1, and if YES, the process proceeds to step S15, and if NO, the process proceeds to step S16.

[0066] In step S15, the processing circuitry 24 determines that the mobile station 2 is in the safety area A1 (i.e., a portion of the safety area A1 that is not the alert area A3). The processing circuitry 24 may use the output device 25 to generate a signal indicating that the mobile station 2 is in the safety 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 circuitry 24 determines that the mobile station 2 is in the dangerous area A2. Then, in step S19, the processing circuitry 24 generates, using the output device 25, an alarm signal indicating that the mobile station 2 is in the dangerous area A2.

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

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

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

[0072] After acquiring the signal levels L1 and L2 of the two beacon signals N1 and N2 in step S11 of FIG. 16, in step S21, the processing circuit 24 calculates a feature amount based on the signal levels of the beacon signals N1 and N2.

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

[0074] In step S23, the processing circuit 24 determines whether the mobile station 2 is in the danger area A2 using the first machine learning model. If 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 determines whether the mobile station 2 is in the warning area A3 using the second machine learning model. If 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 danger 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 danger area A2' is set outside the danger area A2. The additional danger area A2' is an area outside the danger 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 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 and objects can be further improved by setting an additional dangerous area A2'.

[0082] [Fourth embodiment] FIG. 19 is a diagram for explaining the operation of the alarm system according to the fourth embodiment. The fixed stations 1-1 and 1-2 are provided on the boundary line B1 between the safe area A1 and the dangerous area A2, respectively, near the corner of the dangerous area A2 and sandwiching the corner. In order to explain the directions 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 position of the fixed station 1-1 and a reference line B1-2 tangent to the boundary line B1 at the position of the fixed station 1-2 are set. The radiation pattern R1-1 has a main beam direction from the boundary line B1 toward the safe area A1. The radiation pattern R2-1 has a main beam direction from the boundary line B1 toward the dangerous area A2. The radiation pattern R1-2 has a main beam direction from the boundary line B1 toward the safe area A1. The radiation pattern R2-2 has a main beam direction from the boundary line B1 toward the dangerous area A2. The main beam directions of the radiation patterns R1-1 and R2-1 may be perpendicular to the reference line B1-1 or may intersect with the reference line B1-1 at a predetermined angle (for example, an angle close to 90 degrees). The main beam directions of the radiation patterns R1-2 and R2-2 may be perpendicular to the reference line B1-2 or may intersect with the reference line B1-2 at a predetermined angle (for example, an angle close to 90 degrees). The radiation patterns R1-2 and R2-2 have main beam directions different from the main beam directions of the radiation patterns R1-1 and R2-1. The fixed stations 1-1 and 1-2 are arranged so that the main beam directions of the radiation patterns R1-1, R2-1, R1-2, and R2-2 are directed toward the safe area A1 and the dangerous area A2, respectively.

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

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

[0085] 20 is a diagram for explaining the operation of a warning system according to a first modified example of the fourth embodiment. In this modified example, as in the third embodiment, a warning area A3 is set in a part of a safety area A1 adjacent to a danger area A2.

[0086] FIG. 21 is a flowchart showing the warning process executed by the processing circuit 24 of the mobile station 2 of FIG.

[0087] In step S201, the processing circuit 24 executes a judgment process based on the beacon signals N11 and N12, and provisionally determines whether the mobile station 2 is in the safe area A1, the dangerous area A2, or the 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 executes a judgment process based on the beacon signals N21, N22, and provisionally determines whether the mobile station 2 is in the safe area A1, the dangerous area A2, or the alert area A3 based on the beacon signals N21, N22 received from the fixed station 1-2.

[0089] FIG. 22 is a flowchart showing a subroutine of step S201 in FIG.

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

[0091] In step S212, the processing circuit 24 determines whether or not the signal level L12 is higher than the signal level L11, and if YES, the process proceeds to step S217, and if NO, the process 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 value Th1, and if YES, the process proceeds to step S215, and if NO, the process 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 dangerous 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 dangerous area A2 and that the mobile station 2 is close to the reference line B1-1. As a result, the processing circuit 24 provisionally determines that the mobile station 2 is in the security area A3.

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

[0097] FIG. 23 is a flowchart showing the subroutine of step S202 in FIG.

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

[0099] In step S222, the processing circuit 24 determines whether or not the signal level L22 is higher than the signal level L21, and if YES, the process proceeds to step S227, and if NO, the process 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 value Th1, and if YES, the process proceeds to step S225, and if NO, the process 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 dangerous 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 dangerous area A2 and that the mobile station 2 is close to the reference line B1-2. As a result, the processing circuit 24 provisionally determines that the mobile station 2 is in the security area A3.

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

[0105] The processing circuit 24 may execute steps S201 and S202 in parallel as shown in FIG. 21, or 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 relative to the reference lines B1-1, B1-2, and proceeds to step S208 if the result is YES, and proceeds to step S204 if the result is NO. In step S204, the processing circuit 24 determines whether the mobile station 2 is in the security area A3 based on the position of the mobile station 2 relative to the reference lines B1-1, B1-2 and the distance d1 or d2, and proceeds to step S206 if the result is YES, and proceeds to step S205 if the result is NO.

[0107] Fig. 24 is a table for explaining the determination of the safe area A1, the danger area A2, and the alert area A3 by the alarm system according to the first modified example of the fourth embodiment. When both the determination based on the beacon signals N11, N12 and the determination based on the beacon signals N21, N22 indicate that "the mobile station 2 is in the danger area A2", the processing circuit 24 determines that the mobile station 2 is in the danger area A2. On the other hand, when at least one of the determination results indicates that "the mobile station 2 is in the safety area A1", the processing circuit 24 determines that the mobile station 2 is in the safety area A1. When neither of these is the case, the processing circuit 24 determines that the mobile station 2 is in the alert area A3.

[0108] 21, the processing circuit 24 determines that the mobile station 2 is in the safety area A1 (i.e., an area of ​​the safety area A1 that is not the 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 the safety 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 circuitry 24 determines that the mobile station 2 is in the danger area A2. In step S209, the processing circuitry 24 generates, using the output device 25, an alarm signal indicating that the mobile station 2 is in the danger area A2.

[0111] According to this modification, by setting an alert area A3 and determining whether the mobile station 2 is in the safe area A1, the dangerous area A2, or the alert area A3, it is possible to manage the movement of people or objects in more detail.

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

[0113] FIG. 25 is a diagram for explaining the operation of the alarm system according to the second modification of the fourth embodiment. In this modification, an additional dangerous area A2' is set outside the dangerous area A2, similar to the case of FIG. 17. In this case, the process of FIG. 22 further includes a step of determining whether or not the distance d1 is shorter than the threshold value Th2, similar to step S31 of FIG. 18. Moreover, the process of FIG. 23 further includes a step of determining whether or not the distance d2 is shorter than the threshold value Th2, similar to step S31 of FIG. 18. The processing circuit 24 can determine whether or not the mobile station 2 is in the additional dangerous area A2' based on the position of the mobile station 2 relative to the 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 dangerous area A2'.

[0114] [Fifth embodiment] 26 is a diagram for explaining the operation of the alarm system according to the fifth embodiment. The alarm system in Fig. 26 includes a plurality of base stations 1-1 to 1-3 and a mobile station 2. The base stations 1-1 to 1-3 are configured similarly to the base station 1 in Fig. 2.

[0115] The multiple fixed stations 1-1 to 1-3 are provided at different positions on the boundary line B1. The dangerous area A2 may have, for example, a convex polygon shape having 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 tangent to the boundary line B1 at the position of the fixed station 1-1, a reference line B1-2 tangent to the boundary line B1 at the position of the fixed station 1-2, and a reference line B1-3 tangent to the boundary line B1 at the position of the fixed station 1-3 are set.

[0116] The transmission / reception circuit 22 of the 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 the mobile station 2 determines a first tentative position that provisionally indicates on which side of the boundary line the mobile station 2 is located with respect 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 tentative position that provisionally indicates on which side of the boundary line the mobile station 2 is located with respect to the fixed station based on the signal levels of the two beacon signals received from the other one of the fixed stations 1-1 to 1-3. Next, the processing circuit 24 determines whether the mobile station 2 is in the safe area A1 or the dangerous area A2 based on the first and second tentative positions. The processing circuitry 24 may determine whether the mobile station 2 is in the safe area A1 or the dangerous area A2 based on the tentative positions of any two of the base stations 1-1 to 1-3. Alternatively, the processing circuitry 24 may obtain the tentative positions of all of the base stations 1-1 to 1-3 and determine whether the mobile station 2 is in the safe area A1 or the dangerous area A2 based on two of these tentative 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 a safe area A1 or a dangerous area A2, even if the boundary line B1 has a complex shape including corners, etc.

[0118] [Sixth embodiment] FIG. 27 is a block diagram showing the configuration of a fixed station 1A of an alarm system according to a sixth embodiment. The fixed station 1A includes an input device 11, a transmission circuit 12A, an antenna 13A, and an antenna 14A. Each of the antennas 13A and 14A includes a plurality of antenna elements. Each of the antennas 13A and 14A is configured to transmit signals that are distinguishable from each other from each antenna element. The transmission circuit 12A controls the antennas 13A and 14A to transmit beacon signals via the antennas 13A and 14A, respectively. The transmission / reception circuit 22 of the mobile station 2 selects only the beacon signal having the highest signal level among the received beacon signals. This reduces the effect of multipath and makes it possible to more accurately determine whether the mobile station 2 is in the safe area A1 or the dangerous area A2.

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

[0120] The alarm processing and / or other processing of the mobile station 2 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 via the access point device 3, for example.

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

[0122] The alarm signal may be output from an output device 25 provided inside the mobile station 2, and additionally or alternatively, may be output from a server device 4 or other device connected via the access point device 3.

[0123] The warning system may be used to identify more areas than is limited to identifying a safe area A1 and a dangerous area A2, or to identifying a safe area A1, a dangerous area A2, and an alert area A3. For example, the warning system may be configured to identify multiple alert levels based on distance from a boundary line.

[0124] The alarm system is not limited to detecting that the mobile station is in a dangerous area, but may also be used to detect that the mobile station is in a safe area or other predetermined area. The alarm system may also be used to restrict access to a predetermined area. In this case, identification information (occupation ID) indicating the occupation of a user who can enter each area is set, and the occupation ID of the user who holds the mobile station 2 is also set in the mobile station 2. The area database of the server device 4 registers the occupation ID in association with each area. When the user starts using the mobile station 2 or when the area setting is changed, the user operates the input device 23 of the mobile station 2 to obtain a part of the area database and the user's own occupation ID from the server device 4. The fixed station 1 is installed in the area to be detected. The identification information (area ID) of the area is manually set in the fixed station 1. When the mobile station 2 detects that it is approaching the area, it compares the area ID included in the beacon signal with the area database downloaded from the server device 4. If the user's occupation ID is not set to "enterable", the mobile station 2 outputs an alarm signal. If the user's occupation ID is set to "entry permitted", the mobile station 2 does not output an alarm signal. When the mobile station 2 detects entry into an area, it compares the area ID included in the beacon signal with the area database downloaded from the server device 4. If the user's occupation ID is not set to "entry permitted", the mobile station 2 outputs an alarm signal indicating that the user has entered the area, and also notifies the server device 4 that the user has entered the area. If the user's occupation ID is set to "entry permitted", the mobile station 2 notifies the server device 4 that the user has entered the area. This makes it possible to manage the user's entry into an area.

[0125] [Summary of the embodiment] According to a first aspect of the present disclosure, 1. An alarm system including a first fixed station, a second fixed station, and a mobile station, The first and second fixed stations are provided at different positions on a boundary between the first and second areas, The first fixed station comprises: a first transmitting antenna having a first main beam direction from the boundary line toward the first area; a second transmitting antenna having a second main beam direction from the boundary line toward the second area; a first transmitting circuit configured to transmit a first beacon signal via the first transmitting antenna and a second beacon signal via the second transmitting antenna; The second fixed station comprises: a third transmitting antenna having a third main beam direction from the boundary line toward the first area; a fourth transmitting antenna having a fourth main beam direction from the boundary line toward the second area; a second transmitting circuit configured to transmit a third beacon signal via the third transmitting antenna and a fourth beacon signal via the fourth transmitting antenna; The mobile station, A receiving antenna; a receiving circuit that receives the first to fourth beacon signals via the receiving antenna and detects signal levels of the first to fourth beacon signals; a processing circuit that determines whether the mobile station is in the first area or the second area based on the signal levels of the first to fourth beacon signals; 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 processing circuitry includes: determining a first tentative position that provisionally indicates on which side of the boundary line the mobile station is located with respect to the first fixed station based on the signal levels of the first and second beacon signals; determining a second tentative position that provisionally indicates on which side of the boundary line the mobile station is located with respect to the second fixed station based on the signal levels of the third and fourth beacon signals; Based on the first and second interim positions, it is determined whether the mobile station is in the first or second area.

[0126] According to a second aspect of the present disclosure, in the first aspect, The processing circuitry includes: determining on which side of a first reference line that is tangent to the boundary line at the location of the first fixed station the mobile station is located based on the signal levels of the first and second beacon signals, thereby determining the first tentative location; The second interim position is determined by determining on which side of a second reference line that is tangent to the boundary line at the location of the second fixed station the mobile station is located based on the signal levels of the third and fourth beacon signals.

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

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

[0129] According to a fifth aspect of the present disclosure, in one of the first to fourth aspects, The processing circuitry includes: determining the first tentative location to indicate that the mobile station is located on a side of the border that includes the second area when the signal level of the second beacon signal is higher than the signal level of the first beacon signal; When the signal level of the fourth beacon signal is higher than the signal level of the third beacon signal, the second tentative position is determined to indicate that the mobile station is located on the side of the border that includes the second area.

[0130] According to a sixth aspect of the present disclosure, in one of the first to fourth aspects, The processing circuitry includes: determining the first tentative location to indicate that the mobile station is located on a side of the border that includes the second area when the number of times that the signal level of the second beacon signal exceeds the signal level of the first beacon signal during a predetermined time period exceeds a first threshold; If the number of times that the signal level of the fourth beacon signal exceeds the signal level of the third beacon signal during the time period exceeds the first threshold, the second tentative 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 a seventh aspect of the present disclosure, in one of the first to fourth aspects, the mobile station further includes an acceleration sensor that detects an acceleration of the mobile station; The processing circuitry includes: determining whether the mobile station is moving based on an acceleration of the mobile station; determining the first tentative location to indicate that the mobile station is located on a side of the border that includes the second area when the mobile station is moving and a signal level of the second beacon signal is higher than a signal level of the first beacon signal; When the mobile station is moving and the signal level of the fourth beacon signal is higher than the signal level of the third beacon signal, the second tentative 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 an eighth aspect of the present disclosure, in one of the second to fourth aspects, The processing circuitry includes: calculating a first distance from the first reference line to the mobile station based on signal levels of the first and second beacon signals; calculating a second distance from the second reference line to the mobile station based on signal levels of the third and fourth beacon signals; determining whether the mobile station is in a third area included in the first area and adjacent to the second area with a distance shorter than a second threshold based on the first and second tentative positions and the first or second distance; When the mobile station is in the third area, the output device outputs a second warning signal indicating that the mobile station is in the third area.

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

[0134] According to a tenth aspect of the present disclosure, in one of the second to fourth aspects, The processing circuitry includes: calculating a first characteristic amount based on signal levels of the first and second beacon signals; determining, based on the first feature amount, whether or not the mobile station is located on a side including the second area with respect to the first reference line, thereby determining the first tentative location using a first machine learning model; calculating a second characteristic amount based on signal levels of the third and fourth beacon signals; The second tentative position is determined by using the first machine learning model based on the second feature to determine whether the mobile station is located on a side of the second reference line that includes the second area.

[0135] According to an eleventh aspect of the present disclosure, in the tenth aspect, The processing circuitry includes: when the mobile station is on a side of the first reference line that does not include the second area, determining, based on the first feature, whether a first distance from the first reference line to the mobile station is shorter than a second threshold using a second machine learning model; when the mobile station is on a side of the second reference line that does not include the second area, determining, based on the second feature, whether a second distance from the second reference line to the mobile station is shorter than the second threshold value using the second machine learning model; determining whether the mobile station is in a third area included in the first area and adjacent to the second area with a distance shorter than the second threshold value based on the first and second tentative positions and the first or second distance; When the mobile station is in the third area, the output device outputs a second warning signal indicating that the mobile station is in the third area.

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

[0137] According to a thirteenth aspect of the present disclosure, in one of the first to twelfth aspects, the warning system further includes a third fixed station provided at a position on the boundary line different from the first and second fixed stations; The third fixed station comprises: a fifth transmitting antenna having a fifth main beam direction from the boundary line toward the first area; a sixth transmitting antenna having a sixth main beam direction from the boundary line toward the second area; a third transmitting circuit configured to transmit 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 signal levels of the fifth and sixth beacon signals; The processing circuitry includes: determining a third tentative position that provisionally indicates on which side of the boundary line the mobile station is located with respect to the first fixed station based on the signal levels of the fifth and sixth beacon signals; Based on two of the first to third tentative positions, it is determined whether the mobile station is in the first or second area.

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

[0139] According to a fifteenth aspect of the present disclosure, A program comprising 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 program comprising: The first and second fixed stations are provided at different positions on a boundary between the first and second areas, The first fixed station comprises: a first transmitting antenna having a first main beam direction from the boundary line toward the first area; a second transmitting antenna having a second main beam direction from the boundary line toward the second area; a first transmitting circuit configured to transmit a first beacon signal via the first transmitting antenna and a second beacon signal via the second transmitting antenna; The second fixed station comprises: a third transmitting antenna having a third main beam direction from the boundary line toward the first area; a fourth transmitting antenna having a fourth main beam direction from the boundary line toward the second area; a second transmitting circuit configured to transmit a third beacon signal via the third transmitting antenna and a fourth beacon signal via the fourth transmitting antenna; The mobile station, A receiving antenna; a receiving circuit that receives the first to fourth beacon signals via the receiving antenna and detects signal levels of the first to fourth beacon signals; the processing circuit; an output device; The instructions cause the processing circuit to: determining a first tentative position that provisionally indicates on which side of the boundary line the mobile station is located with respect to the first fixed station based on signal levels of the first and second beacon signals; determining a second tentative position that provisionally indicates on which side of the boundary line the mobile station is located with respect to the second fixed station based on the signal levels of the third and fourth beacon signals; determining whether the mobile station is in the first or second area based on the first and second interim positions; When the mobile station is in the second area, a first alarm signal indicating that the mobile station is in the second area is output from the output device. [Industrial Applicability]

[0140] An alarm system according to one aspect of the present disclosure is applicable to locations including safe areas and dangerous 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 equipment 11 Input Devices 12,12A Transmitting circuit 13,13A Antenna 14,14A Antenna 21 Antenna 22 Transmitting and receiving circuit 23 Input Devices 24,24A Processing circuit 25 Output Device 26 Acceleration Sensor 40 Bus 41 Processors 42 Memory 43 Storage device 44 Communication Equipment 45 Input Devices 46 Display device A1 Safety Area A2 Danger Area A3 Security Area A11 False positive area A12 False negative area B1 border R1 Radiation pattern of antenna 13 R2 Radiation pattern of antenna 14

Claims

1. 1. An alarm system including a first fixed station, a second fixed station, and a mobile station, The first and second fixed stations are provided at different positions on a boundary between the first and second areas, The first fixed station comprises: a first transmitting antenna having a first main beam direction from the boundary line toward the first area; a second transmitting antenna having a second main beam direction from the boundary line toward the second area; a first transmitting circuit configured to transmit a first beacon signal via the first transmitting antenna and a second beacon signal via the second transmitting antenna; The second fixed station comprises: a third transmitting antenna having a third main beam direction from the boundary line toward the first area; a fourth transmitting antenna having a fourth main beam direction from the boundary line toward the second area; a second transmitting circuit configured to transmit a third beacon signal via the third transmitting antenna and a fourth beacon signal via the fourth transmitting antenna; The mobile station, A receiving antenna; a receiving circuit that receives the first to fourth beacon signals via the receiving antenna and detects signal levels of the first to fourth beacon signals; a processing circuit for determining whether the mobile station is in the first area or the second area based on the signal levels of the first to fourth beacon signals; 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 processing circuitry includes: determining a first tentative position that provisionally indicates on which side of the boundary line the mobile station is located with respect to the first fixed station based on the signal levels of the first and second beacon signals; determining a second tentative position that provisionally indicates on which side of the boundary line the mobile station is located with respect to the second fixed station based on the signal levels of the third and fourth beacon signals; determining whether the mobile station is in the first or second area based on the first and second interim positions; Alarm system.

2. The processing circuitry includes: determining on which side of a first reference line that is tangent to the boundary line at the location of the first fixed station the mobile station is located based on the signal levels of the first and second beacon signals, thereby determining the first interim location; determining on which side of a second reference line that is tangent to the boundary line at the location of the second fixed station the mobile station is located based on the signal levels of the third and fourth beacon signals, thereby determining the second tentative location; 2. The alarm system of claim 1.

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

4. The first and second reference lines intersect with each other at a predetermined angle.

3. The alarm system of claim 2.

5. The processing circuitry includes: determining the first tentative location to indicate that the mobile station is located on a side of the border that includes the second area when a signal level of the second beacon signal is higher than a signal level of the first beacon signal; determining the second tentative location to indicate that the mobile station is located on a side of the border that includes the second area when the signal level of the fourth beacon signal is higher than the signal level of the third beacon signal; An alarm system according to one of claims 1 to 4.

6. The processing circuitry includes: determining the first interim location to indicate that the mobile station is located on a side of the border that includes the second area when the number of times that the signal level of the second beacon signal exceeds the signal level of the first beacon signal during a predetermined time period exceeds a first threshold; determining the second tentative location to indicate that the mobile station is located on a side of the border that includes the second area when the number of times that the signal level of the fourth beacon signal exceeds the signal level of the third beacon signal during the time period exceeds the first threshold value; An alarm system according to one of claims 1 to 4.

7. the mobile station further includes an acceleration sensor that detects an acceleration of the mobile station; The processing circuitry includes: determining whether the mobile station is moving based on an acceleration of the mobile station; When the mobile station is moving and the signal level of the second beacon signal is higher than the signal level of the first beacon signal, determining the first tentative position to indicate that the mobile station is located on a side of the border that includes the second area; determining the second tentative location to indicate that the mobile station is located on a side of the border that includes the second area when the mobile station is moving and the signal level of the fourth beacon signal is higher than the signal level of the third beacon signal; An alarm system according to one of claims 1 to 4.

8. The processing circuitry includes: calculating a first distance from the first reference line to the mobile station based on signal levels of the first and second beacon signals; calculating a second distance from the second reference line to the mobile station based on signal levels of the third and fourth beacon signals; determining whether the mobile station is in a third area included in the first area and adjacent to the second area with a distance shorter than a second threshold value based on the first and second tentative positions and the first or second distance; the output device outputs, when the mobile station is in the third area, a second alarm signal indicating that the mobile station is in the third area. An alarm system according to one of claims 2 to 4.

9. The processing circuit determines whether the mobile station is in a fourth area included in the first area and adjacent to the second area at a distance less than a third threshold value that is less than the second threshold value, based on the first and second interim positions and the first or second distance; the output device outputs the first alarm signal when the mobile station is in the fourth area.

9. The alarm system of claim 8.

10. The processing circuitry includes: calculating a first characteristic amount based on signal levels of the first and second beacon signals; determining, using a first machine learning model based on the first feature amount, whether or not the mobile station is located on a side including the second area with respect to the first reference line, thereby determining the first tentative location; calculating a second characteristic amount based on the signal levels of the third and fourth beacon signals; determining, using the first machine learning model based on the second feature amount, whether or not the mobile station is located on a side including the second area with respect to the second reference line, thereby determining the second tentative position; An alarm system according to one of claims 2 to 4.

11. The processing circuitry includes: when the mobile station is on a side of the first reference line that does not include the second area, determining, based on the first feature amount, whether a first distance from the first reference line to the mobile station is shorter than a second threshold value using a second machine learning model; when the mobile station is on a side of the second reference line that does not include the second area, determining, based on the second feature amount, using the second machine learning model, whether a second distance from the second reference line to the mobile station is shorter than the second threshold; determining whether the mobile station is in a third area included in the first area and adjacent to the second area with a distance shorter than the second threshold value based on the first and second tentative positions and the first or second distance; the output device outputs, when the mobile station is in the third area, a second alarm signal indicating that the mobile station is in the third area.

11. The alarm system of claim 10.

12. Each of the first to fourth transmitting antennas includes a plurality of antenna elements.

2. The alarm system of claim 1.

13. the warning system further includes a third fixed station provided at a position on the boundary line different from the first and second fixed stations; The third fixed station comprises: a fifth transmitting antenna having a fifth main beam direction from the boundary line toward the first area; a sixth transmitting antenna having a sixth main beam direction from the boundary line toward the second area; a third transmitting circuit configured to transmit 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 signal levels of the fifth and sixth beacon signals; The processing circuitry includes: determining a third tentative position that provisionally indicates on which side of the boundary line the mobile station is located with respect to the first fixed station based on the signal levels of the fifth and sixth beacon signals; determining whether the mobile station is in the first area or the second area based on two of the first to third interim positions; 2. The alarm system of claim 1.

14. A mobile station for the alarm system of claim 1.

15. A program comprising 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 program comprising: The first and second fixed stations are provided at different positions on a boundary between the first and second areas, The first fixed station comprises: a first transmitting antenna having a first main beam direction from the boundary line toward the first area; a second transmitting antenna having a second main beam direction from the boundary line toward the second area; a first transmitting circuit configured to transmit a first beacon signal via the first transmitting antenna and a second beacon signal via the second transmitting antenna; The second fixed station comprises: a third transmitting antenna having a third main beam direction from the boundary line toward the first area; a fourth transmitting antenna having a fourth main beam direction from the boundary line toward the second area; a second transmitting circuit configured to transmit a third beacon signal via the third transmitting antenna and a fourth beacon signal via the fourth transmitting antenna; The mobile station, A receiving antenna; a receiving circuit that receives the first to fourth beacon signals via the receiving antenna and detects signal levels of the first to fourth beacon signals; the processing circuit; an output device; The instructions cause the processing circuit to: determining a first tentative position that provisionally indicates on which side of the boundary line the mobile station is located with respect to the first fixed station based on signal levels of the first and second beacon signals; determining a second tentative position that provisionally indicates on which side of the boundary line the mobile station is located with respect to the second fixed station based on the signal levels of the third and fourth beacon signals; determining whether the mobile station is in the first or second area based on the first and second interim positions; and when the mobile station is in the second area, causing the output device to output a first alarm signal indicating that the mobile station is in the second area. program.

Images