Vehicle detection system

Abstract

To provide a vehicle detection system which more accurately determines the presence / absence of abnormality relating to means for determining whether or not there is a vehicle in a parking square.SOLUTION: A vehicle detection system comprises: a magnetic sensor for detecting magnetism in a parking square where a vehicle parks; a slave unit which transmits a signal indicating a detection result of the magnetic sensor by a radio wave; a master unit which receives the signal transmitted by the radio wave; and an arithmetic circuit. The arithmetic circuit generates a first determination result obtained by determining whether or not there is a vehicle in the parking square based on a reception signal intensity of the signal received by the master unit, generates a second determination result obtained by determining whether or not there is a vehicle in the parking square based on the detection result of the magnetic sensor and, in a case where the first determination result and the second determination result are not coincident, determines that the second determination result is abnormal.SELECTED DRAWING: Figure 2

Description

Technical Field

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[0001] This disclosure relates to a vehicle detection system.

Background Art

[0002] The state determination device described in Patent Document 1 determines whether a vehicle is parked in a parking space using the measurement result of a geomagnetic sensor and the received signal strength in wireless communication with a communication unit. Patent Document 1 discloses that when the state determination device cannot perform wireless communication with the communication unit, it also determines whether an abnormality has occurred in the communication unit using the measurement result of the geomagnetic sensor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] Vehicle detection system devices relating to other aspects of this disclosure are: A magnetic sensor that detects magnetism within a parking space where a vehicle is parked, A master unit and a slave unit that transmit and receive signals from each other via radio waves, Calculation circuit and, Equipped with, The slave unit transmits to the master unit the received signal strength of the signal received from the master unit and the detection result of the magnetic sensor. The aforementioned arithmetic circuit is Based on the received signal strength, a first determination result is generated that determines whether or not there is a vehicle in the parking space. Based on the detection result of the magnetic sensor, a second determination result is generated that determines whether or not there is a vehicle in the parking space. If the first determination result and the second determination result do not match, the second determination result is determined to be abnormal. [Effects of the Invention]

[0008] According to the vehicle detection system of the present invention, it is possible to more accurately determine whether or not there is an abnormality in the means for determining whether or not there is a vehicle in a parking space. [Brief explanation of the drawing]

[0009] [Figure 1] Block diagram showing a configuration example of a vehicle detection system according to Embodiment 1 [Figure 2] Schematic diagram exemplifying a parking space to which the vehicle detection system of FIG. 1 is applied [Figure 3] Block diagram showing a configuration example of a slave unit [Figure 4] Block diagram showing a configuration example of a master unit [Figure 5] Block diagram showing a configuration example of a management device [Figure 6] Flowchart showing an example of a vehicle detection method executed by the vehicle detection system of FIG. 1 [Figure 7] Schematic graph exemplifying the relationship between radio wave reception level and transition of parking space state [Figure 8] Partial enlarged view of the graph of FIG. 7 [Figure 9] Partial enlarged view of the graph of FIG. 7 [Figure 10] Schematic diagram exemplifying a dipole antenna [Figure 11] Schematic graph exemplifying the relationship between magnetic detection value and transition of parking space state [Figure 12] Partial enlarged view of the graph of FIG. 11 [Figure 13] Partial enlarged view of the graph of FIG. 11 [Figure 14] Schematic diagram for explaining the transition of the state of the parking space unit in Embodiment 2 [[ID=四十三]] [Figure 15] Schematic diagram exemplifying the relationship between the three - space state and the radio wave reception level [Figure 16] Schematic diagram for explaining the determination of the unoccupied parking state based on the radio wave reception level [Figure 17] Schematic diagram for explaining the determination of the occupied parking state based on the radio wave reception level

Mode for Carrying Out the Invention

[0010] Embodiments of this disclosure will be described below with reference to the drawings as appropriate. In each drawing, elements may be exaggerated as appropriate to facilitate understanding of the explanation. This disclosure is not limited to the embodiments described below. Furthermore, this disclosure may be modified as appropriate without departing from the scope of achieving the effects of this disclosure.

[0011] (Background leading to this disclosure) A known object detection system is available that uses the external magnetic field strength measured by magnetic field detection elements in the x, y, and z directions to detect the magnetic field generated by a metallic object.

[0012] However, conventional technology, in order to increase the weighting of the magnetic field strength in the vertical direction, not only dilutes the magnetic field strength in the direction of the adjacent vehicle (width direction) but also dilutes the magnetic field strength in the direction other than the adjacent vehicle (depth direction).

[0013] The direction in which a strong magnetic field is detected varies depending on the vehicle, and by using detection values ​​from three directions, the detection rate for various vehicles can be increased. The inventors have experimentally found that in order to improve the accuracy of magnetic field detection and prevent false detections, it is desirable to suppress the influence of the magnetic field in the width direction caused by adjacent vehicles when vehicles are parked in adjacent spaces.

[0014] 1. Embodiment 1 1-1. Composition Figure 1 is a block diagram showing an example configuration of a vehicle detection system (vehicle detection device) 1 according to Embodiment 1 of this disclosure. Figure 2 is a schematic diagram illustrating a parking space 50 to which the vehicle detection system 1 of Figure 1 is applied.

[0015] As shown in Figure 1, the vehicle detection system 1 comprises a slave unit 10 installed in a parking space 50, a master unit 20 capable of communicating with the slave unit 10, and a management device 30 capable of communicating with the master unit 20. The master unit 20 may be capable of communicating with all of the slave units 10 installed in each of the multiple parking spaces 50 that the master unit 20 is responsible for, and the management device 30 may be capable of communicating with multiple master units 20.

[0016] Figure 2 illustrates mutually orthogonal X, Y, and Z axes for ease of explanation. In the example shown in Figure 2, the Z axis is vertical. The parking space 50 is provided, for example, in a parking lot. In the example shown in Figure 2, the parking space 50 is a rectangle with the X direction as the depth direction (length direction) and the Y direction as the width direction. The vehicle 2 is parked in the parking space 50 by, for example, moving forward or backward toward the parking space 50 so that its width fits within the width of the parking space 50.

[0017] Figure 2 illustrates a parking space 50a and two parking spaces 50b and 50c adjacent to parking space 50a in the Y direction (hereinafter also referred to as "adjacent spaces"). A sub-unit 10 is installed in each of the parking spaces 50a, 50b, and 50c. The sub-unit 10 may be placed on the ground or buried underground. The sub-unit 10 is positioned, for example, in the center of each parking space 50 in a plan view, but it may also be positioned in a location other than the center.

[0018] Figure 3 is a block diagram showing an example configuration of the slave unit 10. The slave unit 10 comprises a magnetic sensor 11, an arithmetic circuit 12, a storage device 13, a communication unit 14, and a battery 15.

[0019] The magnetic sensor 11 is a sensor capable of detecting magnetism in three orthogonal axis directions. The magnetic sensor 11 is installed in the parking space 50, for example, so that the three axis directions coincide with the XYZ directions. This allows the magnetic sensor 11 to detect magnetic components in the XYZ directions. If the three axis directions do not coincide with the XYZ directions, the local coordinates defined by the three axes of the magnetic sensor 11, particularly the XY plane coordinates, may be converted to the XY plane coordinates of the parking space 50 using a rotation matrix by the management device described later.

[0020] The arithmetic circuit 12 performs information processing to realize the functions of the slave device 10. Such information processing is realized, for example, by the arithmetic circuit 12 executing a program stored in the memory device 13. The arithmetic circuit 12 is composed of circuits such as a CPU, MPU, FPGA, etc. The arithmetic circuit 12 may be realized by a single such circuit or by multiple circuits. Furthermore, with respect to the components of the arithmetic circuit 12, functions may be omitted, replaced, and added as appropriate, depending on the embodiment.

[0021] The storage device 13 stores various data, including programs necessary to realize the functions of the slave device 10. The storage device 13 can be implemented as, for example, a semiconductor storage device such as flash memory or a solid-state drive (SSD), a magnetic storage device such as a hard disk drive (HDD), or other recording media, either alone or in combination thereof. The storage device 13 may also include temporary storage devices such as SRAM or DRAM.

[0022] The communication unit 14 is equipped with an antenna and can transmit signals to the master unit 20 by radio waves, and can also receive signals transmitted by radio waves from the master unit 20.

[0023] Battery 15 is a power source that supplies power to each component of the slave unit 10. Battery 15 may be any primary battery, or it may be a secondary battery that can be recharged using a solar cell or the like.

[0024] Figure 4 is a block diagram showing an example configuration of the master unit 20. The master unit 20 comprises an input / output unit 21, an arithmetic circuit 22, a storage device 23, and a communication unit 24.

[0025] The input / output unit 21 is an interface circuit that connects the master unit 20 to an external device, such as a management device 30, in order to output information to the external device and / or to receive information from the external device. The input / output unit 21 may also be a communication circuit that performs data communication in accordance with existing wired communication standards or wireless communication standards.

[0026] The arithmetic circuit 22 has the same configuration as the arithmetic circuit 12 of the slave unit 10 in Figure 3, and performs information processing to realize the functions of the master unit 20. The storage device 23 has the same configuration as the storage device 13 of the slave unit 10 in Figure 3, and stores various data, including programs necessary to realize the functions of the master unit 20. The communication unit 24 is equipped with an antenna and can transmit signals to the slave unit 10 by radio waves and receive signals transmitted from the slave unit 10 by radio waves. The master unit 20 may be equipped with a commercial power supply to supply power to each component.

[0027] Figure 5 is a block diagram showing an example configuration of the management device 30. The management device 30 comprises an input / output unit 31, an arithmetic circuit 32, a storage device 33, and a communication unit 34.

[0028] The input / output unit 31 is an interface circuit that connects the management device 30 to an external device, such as the master unit 20, in order to output information to the external device and / or to receive information from the external device. The arithmetic circuit 32 has the same configuration as the arithmetic circuit 12 of the slave unit 10 in Figure 3, and performs information processing to realize the functions of the management device 30. The storage device 33 has the same configuration as the storage device 13 of the slave unit 10 in Figure 3, and stores various data, including programs necessary to realize the functions of the management device 30. The communication unit 34 is a communication circuit that performs data communication according to, for example, an existing wired communication standard or wireless communication standard.

[0029] 1-2.Operation 1-2-1. Overview Figure 6 is a flowchart showing an example of a vehicle detection method performed by the vehicle detection system 1 according to this embodiment. The vehicle detection method includes vehicle detection using radio waves (S1-S3), vehicle detection using a magnetic sensor (S4-S6), and a method for combining the vehicle detection results (S7). Figure 6 shows an example where vehicle detection using a magnetic sensor (S4-S6) is performed after vehicle detection using radio waves (S1-S3), but conversely, vehicle detection using a magnetic sensor may be performed before vehicle detection using radio waves, or both may be performed simultaneously. The details of this example of a vehicle detection method will be described below.

[0030] 1-2-2. Vehicle detection using radio waves 1-2-2-1. Central detection method / Slave unit / Central linked detection method When the parking space status becomes occupied and a vehicle is parked on top of the sub-unit 10, the radio wave reception level (received signal strength) of both the sub-unit 10 and the master unit 20 decreases. The sub-unit 10, master unit 20, and / or management device 30 can determine whether or not there is a vehicle in the parking space 50 by detecting the change in the radio wave reception level. The radio wave vehicle detection method will be explained below using Figures 6 to 9.

[0031] The radio wave vehicle detection method includes at least two types: a central detection method in which the radio wave reception level during communication between the master unit 20 or the slave unit 10 is transmitted to a central system such as a management device 30, and the central system executes the vehicle detection method; and a slave unit-central coordinated detection method in which the slave unit 10 also performs part of the vehicle detection method, and the central system performs the remainder. In the vehicle detection method using magnetic sensors described later, both the central detection method and the slave unit-central coordinated detection method can be selected.

[0032] First, the calculation circuits 12, 22, or 32 acquire the radio wave reception level during communication between the master unit 20 or the slave unit 10 (S1). When using the radio wave reception level of the master unit 20, the master unit 20 receives the signal transmitted by radio waves from the slave unit 10, and the calculation circuits 12, 22, or 32 perform vehicle detection based on the strength of the signal received by the master unit 20 from the slave unit 10. When using the radio wave reception level of the slave unit 10, the slave unit 10 transmits and receives signals with the master unit 20 by radio waves, and transmits the strength of the signal received from the master unit 20 and the detection result of the magnetic sensor 11 to the master unit 20 and / or the management device 30 by radio waves. In the following description, the processing will be explained assuming that the calculation circuit 12 of the slave unit 10 performs the processing, but similar processing can also be performed by at least one of the calculation circuit 22 of the master unit 20 and the calculation circuit 32 of the management device 30 instead of the calculation circuit 12.

[0033] The arithmetic circuit 12 uses the radio wave reception level to determine the transition between the "no parking" state and the "parked" state for each parking space (S2, S3). These transitions will be explained below using Figures 7 to 9. Figure 7 is a schematic graph illustrating the relationship between the radio wave reception level and the transition of the parking space state. Figure 7 illustrates the temporal change in the radio wave reception level when the parking space state transitions from "no parking" to "parked" to "no parking" in a time series. Figures 8 and 9 are enlarged sections of the graph in Figure 7.

[0034] [Transition from no parking to parking] Referring to Figure 8, the determination of the transition from a no-parking state to a parking state based on the radio wave reception level will be explained. When the radio wave reception level changes (decreases) significantly below the threshold Tbe1 relative to the no-parking reference value Er1, the calculation circuit 12 determines that the current parking space state has changed from a no-parking state to a parking state. The no-parking reference value Er1 is, for example, the moving average or mode of multiple radio wave reception levels acquired at predetermined intervals at a point in time prior to the present.

[0035] Furthermore, the calculation circuit 12 calculates the reliability of the determination result that the parking space is in a parked state (hereinafter referred to as the "first reliability") based on the radio wave reception level. Here, the reliability represents an indicator of the certainty of the determination result that determines whether or not there is a vehicle in the parking space 50.

[0036] The confidence level includes an indicator of the likelihood of whether or not there has been a change in the parking space status. For example, the confidence level includes an indicator of the likelihood of the judgment that the parking space status changed from "unoccupied" to "occupied," or from "occupied" to "unoccupied" (confidence level for judgment of change). Also, for example, the confidence level includes an indicator of the likelihood of the judgment that the parking space status did not change (confidence level for judgment of no change).

[0037] For example, the calculation circuit 12 sets the first confidence level for the parked state to 1 when the difference between the no-parking reference value Er1 and the radio wave reception level is greater than or equal to a predetermined value De1, and sets the first confidence level for the parked state to 0 when it is less than or equal to the threshold Tbe1. When the difference between the no-parking reference value Er1 and the radio wave reception level is less than the predetermined value De1 and greater than the threshold Tbe1, the calculation circuit 12 increases the first confidence level as the radio wave reception level decreases.

[0038] The calculation circuit 12 may determine that the parking space is unoccupied if the radio wave reception level is very high (for example, if it is above a predetermined value R) (priority determination process for "unoccupied" status).

[0039] [Transition from "parked" state to "unparked" state] Referring to Figure 9, the determination of the transition from a parked state to an unparked state based on the radio wave reception level will be explained. When the radio wave reception level changes (increases) by a threshold Tce1 or more relative to the parked reference value Er2, the calculation circuit 12 determines that the current parking space state has changed from a parked state to an unparked state. The parked reference value Er2 is, for example, the moving average or mode of multiple radio wave reception levels acquired at a predetermined period in time prior to the present.

[0040] Furthermore, the calculation circuit 12 sets the first reliability level for the no-parking state to 1 when the difference between the radio wave reception level and the parking reference value Er2 is greater than or equal to a predetermined value De2, and sets the first reliability level for the no-parking state to 0 when it is less than or equal to the threshold Tce1. When the difference between the radio wave reception level and the parking reference value Er2 is less than the predetermined value De2 and greater than the threshold Tce1, the calculation circuit 12 increases the first reliability level as the radio wave reception level increases.

[0041] 1-2-2-2.0 Point Correction Method The calculation circuits 12, 22 and / or 32 perform zero-point correction of the radio wave reception level, for example, using the mode of the radio wave reception level when the current state of parking space 50a is empty and the states of adjacent spaces 50b and 50c are also empty. Alternatively, the calculation circuits 12, 22 and / or 32 may count up the number of receptions for each predetermined category of the radio wave reception level and correct the category with the most receptions among those where the radio wave reception level is above a predetermined value to zero point.

[0042] 1-2-2-3. Antenna Directivity To stabilize the radio wave reception level during communication between the master unit 20 and the slave units 10, for example, the directivity of each antenna may be set towards the communication partner, or a reflector that reflects radio waves may be installed next to the antenna. In particular, for the slave unit 10, in order to reduce the influence of radio wave reflection by vehicles parked in adjacent spaces, a dipole antenna exhibiting directivity with a lobe in the X direction and a null in the Y direction may be used, as shown by the dashed line in Figure 10. This reduces radiation in the Y direction and reduces the impact on adjacent spaces. If there are many slave units 10 communicating with one master unit 20, multiple antennas may be installed on the master unit 20.

[0043] 1-2-3. Vehicle detection using magnetic sensors 1-2-3-1. Central Detection Method As mentioned above, in vehicle detection using magnetic sensors, either a central detection method or a slave-unit / central linked detection method may be employed. Below, the central detection method will be explained first, followed by the slave-unit / central linked detection method. In this example of the central detection method, the vehicle detection method will be explained as being executed by the calculation circuit 32 of the management device 30, but this embodiment is not limited to this, and the vehicle detection method may be executed by an external calculation circuit of the slave unit 10, such as the calculation circuit of the server device.

[0044] The calculation circuit 12 of the slave unit 10 samples the output of the magnetic sensor 11 every 200 msec, calculates the average value over a predetermined period Cc (for example, 2 seconds) as the magnetic detection value, and transmits the calculated magnetic detection value to the management device 30 via the master unit 20. The calculation circuit 32 of the management device 30 collects the magnetic detection values ​​from each slave unit 10 (S4) and performs the following processing based on the collected data.

[0045] First, the calculation circuit 32 calculates the moving average or mode (Xm, Ym, Zm) of Na (for example, 2) magnetic detection values ​​with a predetermined period Cc. If real-time performance is required, the calculation of the current moving average may be omitted (Na=1), and the slave unit transmission data may be used as is.

[0046] Furthermore, the calculation circuit 32 calculates the moving average or mode of Nb magnetic detection values ​​(Nb≧Na) over a predetermined period Cc, using these as reference values ​​(Xr1, Yr1, Zr1) for change detection.

[0047] The calculation circuit 32 uses the above-mentioned detected values ​​(Xm, Ym, Zm) and reference values ​​(Xr1, Yr1, Zr1) to determine the transition between the no-parking state and the parking state for each parking space (S5, S6). These transitions will be explained below using Figures 11 to 13. Figure 11 is a schematic graph illustrating the relationship between the magnetically detected value and the transition of the parking space state. Figure 11 illustrates the temporal change in the magnetically detected value when the parking space state transitions from the no-parking state to the parking state and back to the no-parking state in a time series. The magnetically detected value in Figure 11 is expressed in units of, for example, μT. Figures 12 and 13 are enlarged sections of the graph in Figure 11. Figures 11 to 13 show the magnetically detected value in the Z direction. The concept of state transitions using magnetically detected values ​​in other directions, such as the X direction, is similar, so they are not shown.

[0048] [Transition from no parking to parking] Referring to FIG. 12, the determination of the transition from the non-parking state to the parking state based on the magnetic detection value will be described. In FIG. 12, for the sake of easy understanding of the explanation, the case where the influence on the magnetic detection value when the vehicle approaches the magnetic sensor acts in the positive direction is shown (the same applies to FIG. 13). Hereinafter, in the determination process of whether the vehicle 2 is present in the parking space 50, an example in which the weight Wy of the Y component Ym of the magnetic detection value is set to 0 will be described. However, in the present embodiment, the weight Wy of the Y component Ym of the magnetic detection value only needs to be smaller than the weights Wx of the X component Xm and Wz of the Z component Zm of the magnetic detection value, and is not limited to 0. For example, the arithmetic circuit 32 may set Wx and Wz to 1 and set Wy so as to satisfy 0 < Wy < 1.

[0049] When the current parking space state is the non-parking state, when Xm and Zm change by a threshold value Tbx1 and Tbz1 or more compared with the non-parking reference values Xr1 and Zr1 n cycles ago (for example, n = 5) (for example, when |Xm - Xr1| ≥ Tbx1 and / or |Zm - Zr1| ≥ Tbz1), the arithmetic circuit 32 tentatively determines that the current parking space state is the entry state (hereinafter, also referred to as "entry tentative determination"). Alternatively, when Xm and Zm change such that the sum of the absolute values of the differences from the non-parking reference values Xr1 and Zr1 of Xm and Zm is equal to or greater than the threshold value Tbxz1 (for example, when |Xm - Xr1| + |Zm - Zr1| ≥ Tbxz1), the arithmetic circuit 32 tentatively determines that the current parking space state is the entry state.

[0050] After the entry tentative determination (when there is a change), when the state of the entry tentative determination continues for a predetermined time (does not change for a predetermined time), or when the change per unit time of Xm and Zm becomes equal to or less than the threshold value Te and the sum of the absolute values of the differences between Xm and Zm and the non-parking reference values Xr1 and Zr1 is equal to or greater than the threshold value Tbxz2 (≤ Tbxz1), the arithmetic circuit 32 determines that the current parking space state is the stable state and changes the parking space state to the parking state.

[0051] Furthermore, the calculation circuit 32 calculates the confidence level of the determination result that the parking space is in a parked state (hereinafter referred to as the "second confidence level"). Here, the confidence level represents an indicator of the certainty of the determination result that determines whether or not there is a vehicle in the parking space 50.

[0052] The confidence level includes an indicator of the likelihood of whether or not there has been a change in the parking space status. For example, the confidence level includes an indicator of the likelihood of the judgment that the parking space status changed from "unoccupied" to "occupied," or from "occupied" to "unoccupied" (confidence level for judgment of change). Also, for example, the confidence level includes an indicator of the likelihood of the judgment that the parking space status did not change (confidence level for judgment of no change).

[0053] The confidence level calculated based on the magnetic detection value is determined, for example, based on "the difference between the current detection value and the no-parking standard values ​​Xr1 and Zr1", "the maximum value of the difference between the magnetic detection value and the no-parking standard values ​​Xr1 and Zr1" from the current parking space state from provisional entry judgment (changed) to a stable state, thresholds Tbx1 and Tbz1, and predetermined value Dm1.

[0054] For example, the calculation circuit 32 sets the second confidence level for the parked state to 1 when the difference between the current detected value and the no-parking reference values ​​Xr1 and Zr1 is greater than or equal to a predetermined value Dm1, and sets the second confidence level for the parked state to 0 when it is less than or equal to the thresholds Tbx1 and Tbz1. When the difference between the current detected value and the no-parking reference values ​​Xr1 and Zr1 is less than the predetermined value Dm1 and greater than the thresholds Tbx1 and Tbz1, the calculation circuit 32 decreases the second confidence level as the magnetic detected value decreases. For example, if the current parking space state is tentatively determined to be an entry state (indicating a change), the second confidence level is calculated by (|current detected value - no-parking reference value| - threshold) ÷ (predetermined value - threshold).

[0055] Alternatively, a correspondence table showing a second confidence level corresponding to the difference between the detected value and the threshold may be prepared in advance, and the calculation circuit 32 may calculate the second confidence level based on the current detected value and the correspondence table.

[0056] If no preliminary entry determination has been made (no change), the second confidence level for the no-parking state is set to 1 when the change in the magnetic detection value is 0, and the second confidence level is set to 0 when the difference between the current magnetic detection value and the no-parking standard value is equal to the threshold. For example, the second confidence level is calculated as (threshold - |current detection value - no-parking standard value|) ÷ threshold.

[0057] The calculation circuit 32 may determine that the parking space is in an "unoccupied" state if the difference between the magnetically detected value and the zero point (magnetically detected values ​​X0, Y0, Z0 when no vehicles are present) is very small (for example, if the difference between the magnetically detected value and the zero point is less than or equal to a predetermined value m). ("Unoccupied" priority determination process).

[0058] [Transition from "parked" state to "unparked" state] Referring to Figure 13, the determination of the transition from a parked state to an unparked state based on magnetic detection values ​​will be explained. When the current parking space state is a parked state, when Xm and Zm change in a direction that reduces the difference between them and the unparked reference values ​​Xr1 and Zr1, it can be determined that vehicle 2 has moved out of the parking space. For example, when the difference between them and the parked reference values ​​Xr2 and Zr2 becomes greater than or equal to the threshold Tcx1 and Tcz1, or when Xm and Zm change so that the sum of the absolute values ​​of the differences between Xm and Zm and the parked reference values ​​Xr2 and Zr2 equals the threshold Tcxz1, the calculation circuit 32 tentatively determines that the current parking space state is an advanced state.

[0059] After a provisional determination of advancement (change detected), if the state of the provisional determination of advancement continues for a predetermined time, or if the change in Xm and Zm per unit time becomes less than or equal to the threshold Te, and the sum of the absolute values ​​of the differences between Xm and Zm and the parking reference values ​​Xr2 and Zr2 is greater than or equal to the threshold Tcxz2 (≤ Tcxz1), the calculation circuit 32 determines that the current parking space state is stable and changes the parking space state to an unparked state. The second confidence level is determined based on "the difference between the current detected value and the parking reference values ​​Xr2 and Zr2", "the maximum value of the difference between the magnetically detected value and the parking reference values ​​Xr2 and Zr2" from the provisional determination of advancement (change detected) to the stable state, the thresholds Tcx1 and Tcz1, and the predetermined value Dm2.

[0060] The threshold for detecting the change from a parked state to an unparked state may be set according to the magnitude of the magnetic force of vehicle 2.

[0061] To reduce the power consumption of the slave unit 10 and extend its battery life, the data transmission interval from the slave unit 10 to the management device 30 may be increased (for example, every 20 seconds). In this case, for example, the slave unit 10 compresses the data it transmits to the management device 30.

[0062] Furthermore, in order to reduce the power consumption of the slave unit 10 and extend its battery life, the radio wave transmission and reception time and the activation time of the magnetic sensor 11 may be shortened. In order to shorten the radio wave transmission and reception time, radio waves may be used supplementarily only when there is a change in the magnetic detection value. For example, the magnetic sensor 11 performs magnetic detection at a first time interval, and the detection of the radio wave reception level by the slave unit 10 is performed at a second time interval that is longer than the first time interval, or when there is a change in the magnetic detection value.

[0063] Although the above describes an example of calculating the difference between detected values ​​in the X and Z directions, this disclosure is not limited to this. For example, the calculation circuit 32 may calculate the difference between detected values ​​using detected values ​​in all three axes, or it may calculate the difference between detected values ​​using only one axis.

[0064] 1-2-3-2. Sub-unit / Central Coordination Detection System [Processing of handset 10] The magnetic sensor 11 of the slave unit 10 senses with a period Cs (e.g., 200 msec). The calculation circuit 12 calculates the moving average or mode (Xm, Ym, Zm) over Nc times (e.g., 5 times).

[0065] Furthermore, the calculation circuit 12 calculates the moving average or mode over a predetermined period Cs for Nd times (Nd ≥ Nc) as reference values ​​(Xr1, Yr1, Zr1) for change detection.

[0066] Regarding the determination of the transition between the "unparked" and "parked" states of the parking space status, the calculation circuit 12 of the slave unit 10 performs the same processing as the calculation circuit 32 of the management device 30 in the central detection method described above. However, instead of using an n-period in the calculation circuit 32 in the central detection method, the calculation circuit 12 uses an m-period (for example, m=50).

[0067] In the slave-unit / central linked detection system, when the calculation circuit 12 determines that the current parking space state is stable, it transmits data such as the time the state became stable, the reference value, the current value, and the maximum value of the difference between the current value and the reference value to the management device 30 (central system). This data transmission may be performed in real time, or it may be transmitted from data stored in the storage device 33 instead of in real time. In addition, if real-time performance is required, the reference value and the current detected value may also be transmitted to the management device 30 via the master unit 20 when determining entry / exit from a parking space. If there is no change within one minute, the calculation circuit 12 may transmit the current detected value and the reference value to the management device 30.

[0068] [Processing by the control device 30] When the control device 30 receives data indicating a change in the magnetic detection value, the calculation circuit 32 calculates the reliability of the change determination based on the "difference between the current detection value and the standard value for no parking or parking present" included in the data, the "maximum value of the difference between the magnetic detection value and the standard value for no parking or parking present" from the current parking space state from a provisional determination of entry or exit (change detected) to a stable state, a threshold, and a predetermined value.

[0069] When the calculation circuit 32 receives data indicating that there has been no change in the magnetic detection value, it compares the "difference between the current detection value and the no-parking standard value" contained in the data with a threshold value to determine the reliability of the "no change" judgment.

[0070] 1-2-3-3.0 Point Correction Method The calculation circuits 12, 22 and / or 32 perform a correction, for example, so that the mode of the magnetic detection value is 0 when the current state of parking space 50a is empty and the state of adjacent spaces 50b and 50c is also empty. Alternatively, the calculation circuits 12, 22 and / or 32 may perform a correction so that the mode of the magnetic detection value is 0 when the radio wave reception level is above a predetermined value R.

[0071] 1-2-4. Method for combining vehicle detection results using magnetic sensors and radio waves. As described above, the vehicle detection system 1 can perform either vehicle detection based on the detection results of the magnetic sensor 11 or vehicle detection based on the radio wave reception level, or both, but it can also perform vehicle detection by combining both.

[0072] For example, if the result of vehicle detection based on the radio wave reception level (first determination result) and the result of vehicle detection based on the detection result of the magnetic sensor 11 (second determination result) match, the calculation circuit 32 sets either the first determination result or the second determination result as the final result (third determination result).

[0073] If the first judgment result and the second judgment result do not match, the calculation circuit 32 compares the reliability of each vehicle detection result and adopts the result with the higher reliability. That is, if the first judgment result and the second judgment result do not match, the calculation circuit 32 sets the first judgment result as the third judgment result if the reliability of the first result is greater than the reliability of the second result, and sets the second judgment result as the third judgment result if the reliability of the first result is less than or equal to the reliability of the second result.

[0074] 1-3. Summary of this embodiment 1-3-1. Summary of examples of reducing the weight of the detection results for the magnetic component in the Y direction As described above, the vehicle detection system 1 (vehicle detection device) according to this embodiment includes a calculation circuit (for example, calculation circuit 12, 22, or 32) that determines whether or not there is a vehicle in a parking space 50 based on a first detection result of a first magnetic component parallel to the depth direction (X direction) of the parking space 50, a second detection result of a second magnetic component parallel to the vertical direction (Z direction), a third detection result of a third magnetic component parallel to the width direction (Y direction) of the parking space 50, and weights applied to each detection result. In the process of determining whether or not there is a vehicle in the parking space 50, the calculation circuit makes the weight of the third detection result smaller than the weight of the first detection result and the weight of the second detection result. This configuration makes it possible to improve the accuracy of determining whether or not there is a vehicle in the parking space 50.

[0075] The calculation circuit may set the weight of the third detection result to 0 in the process of determining whether or not there is a vehicle in the parking space 50. By setting the weight of the third detection result, which is affected by vehicles in adjacent spaces, to 0, the accuracy of determining whether or not there is a vehicle in the parking space 50 can be improved.

[0076] The calculation circuit may detect a change in the presence or absence of a vehicle in the parking space 50 when the absolute value of the change in the first detection result, the absolute value of the change in the second detection result, the absolute value of the change in the third detection result, and / or the sum thereof is greater than or equal to a predetermined threshold, and determine whether or not there is a vehicle in the parking space 50 based on the detection result.

[0077] The calculation circuit may make a provisional determination that there has been a change in the presence or absence of a vehicle in the parking space 50 if the difference between the absolute value of the change in the first detection result, the absolute value of the change in the second detection result, the absolute value of the change in the third detection result, and / or the sum thereof, and a predetermined reference value is greater than or equal to a predetermined first threshold. If the result of the provisional determination does not change for a predetermined time, the calculation circuit determines that the state of the parking space 50 is stable and confirms the determination that there has been a change in the presence or absence of a vehicle in the parking space 50. By preventing the determination from being confirmed when the state is not stable, the accuracy of determining whether or not there is a vehicle in the parking space 50 can be improved.

[0078] The calculation circuit may determine that the state of the parking space 50 is stable and confirm that there has been a change in the presence or absence of a vehicle in the parking space 50 if the absolute value of the change in the amount of change of the first detection result, the absolute value of the change in the amount of change of the second detection result, the absolute value of the change in the amount of change of the third detection result, and / or the sum thereof change per unit time is less than or equal to a predetermined value, and the difference from the reference value is greater than or equal to a second threshold that is smaller than the first threshold.

[0079] 1-3-2. Summary of examples of determining whether or not a vehicle is present in a parking space based on confidence level. As described above, the vehicle detection system 1 according to an example of this embodiment includes a magnetic sensor 11 that detects magnetism within a parking space 50 where a vehicle is parked, a first slave unit 10 that transmits a signal indicating the detection result of the magnetic sensor 11 by radio waves, a master unit 20 that receives the signal transmitted from the first slave unit 10, and an arithmetic circuit (for example, arithmetic circuits 12, 22, or 32). The arithmetic circuit generates a first determination result that determines whether or not there is a vehicle in the parking space 50 based on the received signal strength of the signal received by the master unit 20, and determines a first confidence level that represents an indicator of the certainty of the first determination result. The arithmetic circuit generates a second determination result that determines whether or not there is a vehicle in the parking space 50 based on the detection result of the magnetic sensor 11, and determines a second confidence level that represents an indicator of the certainty of the second determination result. The arithmetic circuit determines a third determination result that determines whether or not there is a vehicle in the parking space 50 based on the first determination result, the first confidence level, the second determination result, and the second confidence level. This configuration, which uses confidence levels, can improve the accuracy of determining whether or not there is a vehicle in parking space 50.

[0080] Another example of this embodiment of the vehicle detection system 1 includes a magnetic sensor 11 that detects magnetism within a parking space 50 where a vehicle is parked, a master unit 20 and a first slave unit 10 that transmit and receive signals from each other by radio waves, and a calculation circuit (for example, calculation circuits 12, 22, or 32). The first slave unit 10 transmits the received signal strength of the signal received from the master unit 20 and the detection result of the magnetic sensor 11 to the master unit 20. The calculation circuit generates a first determination result that determines whether or not there is a vehicle in the parking space 50 based on the received signal strength, and determines a first confidence level that represents an indicator of the certainty of the first determination result. The calculation circuit generates a second determination result that determines whether or not there is a vehicle in the parking space 50 based on the detection result of the magnetic sensor 11, and determines a second confidence level that represents an indicator of the certainty of the second determination result. The calculation circuit determines a third determination result regarding whether or not there is a vehicle in the parking space 50, based on the first determination result, the first confidence level, the second determination result, and the second confidence level. This configuration, which uses confidence levels, can improve the accuracy of determining whether or not there is a vehicle in the parking space 50.

[0081] In the above example or the other example of this embodiment, if the first determination result and the second determination result match, the calculation circuit may set either the first determination result or the second determination result as the third determination result. If the first determination result and the second determination result do not match, the calculation circuit may set the first determination result as the third determination result if the confidence level of the first determination is greater than the confidence level of the second determination, and set the second determination result as the third determination result if the confidence level of the first determination is less than or equal to the confidence level of the second determination. This configuration makes it possible to improve the accuracy of determining whether or not there is a vehicle in the parking space 50.

[0082] In the above example or the other example of this embodiment, the calculation circuit may determine a first confidence level based on the difference between the received signal strength and a first reference value for the received signal strength. The calculation circuit determines a second confidence level based on the difference between the magnetic field strength detected by the magnetic sensor 11 and a second reference value for the magnetic field strength.

[0083] In the above example or the other example of this embodiment, the first reference value and the second reference value may be updated when there is a change in the presence or absence of a vehicle in the parking space 50 and the adjacent space adjacent to the parking space 50, and / or at predetermined intervals. The first reference value may be determined based on the moving average or mode of the received signal strength. The second reference value may be determined based on the moving average or mode of the magnetic field strength detected by the magnetic sensor 11.

[0084] In the other example of this embodiment, the magnetic sensor 11 detects magnetism at a first time interval, and the detection of the signal strength received by the first slave unit 10 may be performed at a second time interval longer than the first time interval, or when there is a change in the detected magnetic value. This configuration reduces the power consumption of the first slave unit 10 and extends the battery life.

[0085] 2. Embodiment 2 Embodiment 1 describes an example in which the moving average or mode of Nb magnetic detection values ​​acquired at a predetermined period is used as the reference value for magnetism, and the moving average or mode of radio wave reception levels acquired at a predetermined period at a point in time prior to the present is used as the reference value for radio wave reception levels.

[0086] The magnetic level within parking space 50a, the strength of the radio waves transmitted from the sub-unit 10 within parking space 50a, and the strength of the radio waves received by the sub-unit 10 within parking space 50a are affected not only by whether or not a vehicle is parked in parking space 50a, but also by whether or not there are vehicles around parking space 50a. In particular, they are affected by the presence or absence of vehicles in each of the parking spaces 50a, 50b, and 50c (see Figure 2).

[0087] Therefore, in Embodiment 2, three adjacent parking spaces are observed as a single unit, and a reference value, threshold value, and / or predetermined value for vehicle detection are determined based on the state of the parking space unit.

[0088] Figure 14 is a schematic diagram illustrating the transition of the state of the parking space unit 51 in Embodiment 2 (hereinafter referred to as the "3-space state"). In this embodiment, an example is described in which three adjacent parking spaces 50a, 50b, and 50c from among the multiple parking spaces managed by the master unit 20 are treated as the parking space unit 51. However, three other adjacent parking spaces may also be treated as the parking space unit.

[0089] In Figure 14, the presence of vehicles in parking spaces 50a, 50b, and 50c is indicated by a circle ("○"). As shown in Figure 14, the three-space state can result in the following eight conditions. First state: V0 Second state: V1L Third state: V1R Fourth state: V2 Fifth state: O0 State 6: O1L State 7: O1R State 8: O2

[0090] Here, the prefix V for states 1 to 4 indicates that parking space 50a is vacant, and the prefix O for states 5 to 8 indicates that parking space 50a is occupied. The suffix "0" for states 1 and 5 indicates that there are no vehicles in either the adjacent spaces 50b or 50c. The suffix "1L" for states 2 and 6 indicates that there is a vehicle in the adjacent space 50b to the left. The suffix "1R" for states 3 and 7 indicates that there is a vehicle in the adjacent space 50c to the right. The suffix "2" for states 4 and 8 indicates that there are vehicles in both the adjacent spaces 50b and 50c.

[0091] If, at a given time, the presence or absence of a vehicle in only one of the parking spaces 50a, 50b, and 50c changes, that is, if the presence or absence of a vehicle in two or more of the parking spaces 50a, 50b, and 50c does not change simultaneously, then the state of the three spaces can transition between the two states connected by the solid and dashed lines in Figure 14. Note that the presence or absence of a vehicle in two or more of the parking spaces 50a, 50b, and 50c may change simultaneously.

[0092] Of these transitions, the transitions where the presence or absence of a vehicle in parking space 50a changes are those between V0-O0, V1L-O1L, V1R-O1R, and V2-O2, which are connected by solid lines.

[0093] In this embodiment, by observing the three parking spaces as a single unit and considering the timing of changes in the state of the three spaces, it is possible to more appropriately determine the reference value, threshold, and / or predetermined value for vehicle detection. This makes it possible to determine with greater accuracy whether or not there is a vehicle in the parking space.

[0094] 2-1. Vehicle detection using radio waves As shown in Figure 15, the radio wave reception level during communication between the master unit 20 or the slave unit 10 of the parking space 50a may differ depending on which of the 3-space states is in the 1st to 8th state. Therefore, in this embodiment, reference values ​​corresponding to each state are set in advance. The set reference values ​​are stored, for example, in the storage devices 13, 23, or 33.

[0095] Such reference values ​​are measured in advance, for example, in situations corresponding to the 1st to 8th states. Alternatively, during the learning period, the calculation circuits 12, 22 and / or 32 count up the number of receptions for each predetermined category of radio wave reception level, and set the center value of the radio wave reception level in the category with the most receptions among the categories where the radio wave reception level is equal to or greater than the 1st set value as the reference value for the no-parking state, and set the center value of the radio wave reception level in the category with the most receptions among the categories where the radio wave reception level is less than the 2nd set value as the reference value for the parking state. The 2nd set value may be equal to the 1st set value, or it may be less than the 1st set value.

[0096] The calculation circuits 12, 22, and / or 32 update the reference value when, for example, at least one of the parking conditions of parking spaces 50a, 50b, and 50c changes. The calculation circuits 12, 22, and / or 32 may also update the reference value when such a preliminary determination is made for at least one of the parking spaces 50a, 50b, and 50c. Alternatively, or in conjunction with these, the calculation circuits 12, 22, and / or 32 may determine whether or not to change the reference value at predetermined intervals and change the reference value as necessary.

[0097] As described above, of the transitions between the three grid states, the presence or absence of a vehicle in parking grid 50a changes in the four cases shown by solid lines in Figure 14. In each of these four transition cases, the change in radio wave reception level (difference) is different. The calculation circuits 12, 22 and / or 32 set this difference to a predetermined value (for example, a predetermined value corresponding to De1 and De2 in Embodiment 1), and set half of this difference as the threshold.

[0098] If, at the time of the entry / exit determination (change detected) in parking space 50a, or immediately before, there is a change in the parking state of adjacent spaces 50b and 50c, the current parking space state may be considered as unchanged, or a change may be detected while the confidence level of the change detection is lowered. Alternatively, if, at the time of the determination of a change detected in parking space 50a, or within a predetermined time before or after, there is a change in the parking state of adjacent spaces 50b and 50c, the changes in the radio wave reception levels of parking space 50a and adjacent spaces 50b and 50c are compared. For example, if the difference in the change in the radio wave reception level of parking space 50a is smaller than the difference in the change in the radio wave reception levels of adjacent spaces 50b and 50c, the current parking space state may be considered as unchanged with high confidence, or a change may be detected while the confidence level of the change detection is lowered. On the other hand, if the difference in the radio wave reception level of parking space 50a is larger than the difference in the radio wave reception levels of adjacent spaces 50b and 50c, the confidence level of the change detection for the current parking space state may be increased.

[0099] 2-2. Vehicle detection using magnetic sensors The magnetic detection value by the magnetic sensor 11 of the sub-unit 10 of parking space 50a is more significantly affected by the type of vehicle than the radio wave reception level. Therefore, for example, in the first state V0 where parking space 50a and adjacent spaces 50b and 50c are both empty, a fixed reference value is set and stored in the storage device 13, 23, or 33. The reference value in other states may change depending on the type of vehicle in the parking space unit 51.

[0100] The calculation circuits 12, 22, and / or 32 update the reference value when, for example, at least one of the parking conditions of parking spaces 50a, 50b, and 50c changes. The calculation circuits 12, 22, and / or 32 may also update the reference value when such a preliminary determination is made for at least one of the parking spaces 50a, 50b, and 50c. Alternatively, or in conjunction with these, the calculation circuits 12, 22, and / or 32 may determine whether or not to change the reference value at predetermined intervals and change the reference value as necessary.

[0101] In the four cases shown by solid lines in Figure 14, the calculation circuits 12, 22, and / or 32 set a predetermined fixed value for the magnetic detection value when the state of the parking space 50a transitions from an unparked state to a parked state. When the state of the parking space 50a transitions from a parked state to an unparked state, the threshold value is the change (difference) in the magnetic detection value detected at the time of the change from unparked to parked state. The threshold value is set to half of this difference.

[0102] Reference values ​​for magnetic detection values ​​are stored, for example, in memory devices 13, 23, or 33. Such reference values ​​are measured in advance in situations corresponding to the 1st to 8th states, for example. Alternatively, when the radio wave reception level during the learning period is higher than a predetermined set value, the calculation circuits 12, 22, and / or 32 count up the number of receptions for each predetermined category of magnetic detection values ​​and set the center value of the most frequent category as the reference value for the no-parking state. Thereafter, if there is a change in the presence or absence of a vehicle in parking space 50a or adjacent spaces 50b, 50c, the calculation circuits 12, 22, and / or 32 update the most frequent value or moving average of the magnetic sensor detection values ​​for parking space 50a over a predetermined period as the reference value for the corresponding transition state.

[0103] 2-3. Adjustment of reliability based on the state of adjacent squares The presence of vehicles in adjacent spaces 50b and 50c may affect the first and second reliability levels in parking space 50a. Therefore, the calculation circuits 22 and / or 32 may adjust the first and / or second reliability levels according to the state of the adjacent spaces.

[0104] For example, a slave unit 10 (second slave unit) in an adjacent cell 50b or 50c transmits a signal to the master unit 20 via radio waves indicating the detection result of a magnetic sensor in the adjacent cell 50b or 50c. The master unit 20 receives the signal transmitted from the second slave unit, and the calculation circuits 22 and / or 32 correct the first reliability and / or second reliability based on the received signal strength (radio wave reception level) of the signal received by the master unit 20.

[0105] Alternatively, the second slave unit may transmit to the master unit 20 the received signal strength (radio wave reception level) of the signal received from the master unit 20, and the detection result of the magnetic sensor in the adjacent square 50b or 50c. The calculation circuits 22 and / or 32 correct the first reliability and / or second reliability based on the received signal strength of the signal from the second slave unit that the master unit 20 has received.

[0106] Furthermore, if the determination of the parking state based on the magnetic detection value indicates a change, and the difference in the change in the radio wave reception level of parking space 50a is smaller than the difference in the change in the radio wave reception level of the adjacent space 50b or 50c, the calculation circuits 22 and / or 32 either determine that there is no change in the current parking space state with high confidence, or they determine that there is a change but lower the confidence of the change determination. On the other hand, if the difference in the radio wave reception level of parking space 50a is larger than the difference in the radio wave reception level of the adjacent space 50b or 50c, the calculation circuits 22 and / or 32 increase the confidence of the change determination.

[0107] Furthermore, if the difference in the timing of changes in magnetic detection values ​​between parking space 50a and adjacent space 50b or 50c is less than or equal to a predetermined time, the calculation circuits 22 and / or 32 may correct the first and second reliability of parking space 50a based on a comparison between the difference in magnetic detection values ​​in parking space 50a and the difference in magnetic detection values ​​in adjacent space 50b or 50c.

[0108] 2-3. Summary of this embodiment As described above, the vehicle detection system 1 according to an example of this embodiment includes a magnetic sensor 11, a first slave unit 10, a master unit 20, a calculation circuit (for example, calculation circuit 22 or 32), an adjacent space magnetic sensor that detects magnetism in adjacent spaces 50b or 50c adjacent to parking space 50a, and a second slave unit 10 that transmits a signal indicating the detection result of the adjacent space magnetic sensor to the master unit 20 by radio waves. The master unit 20 receives the signal transmitted from the second slave unit 10, and the calculation circuit corrects the first reliability and / or second reliability based on the received signal strength of the signal received by the master unit 20. This configuration improves the accuracy of determining whether or not there is a vehicle in the parking space 50.

[0109] Another example of this embodiment of the vehicle detection system 1 includes a magnetic sensor 11, a first slave unit 10, a master unit 20, a calculation circuit (for example, calculation circuit 22 or 32), an adjacent space magnetic sensor that detects magnetism in adjacent spaces 50b or 50c adjacent to parking space 50a, and a second slave unit 10 that transmits and receives signals between itself and the master unit 20 via radio waves. The second slave unit 10 transmits to the master unit 20 the received signal strength of the signal received from the master unit 20 and the detection result of the adjacent space magnetic sensor. The calculation circuit corrects the first confidence level and / or second confidence level based on the received signal strength of the signal received by the master unit 20 from the second slave unit. This configuration improves the accuracy of determining whether or not there is a vehicle in the parking space 50.

[0110] 3. Embodiment 3 3-1. Overview The detection accuracy of a method for detecting vehicles based on radio wave reception levels is thought to be affected by multiple reflections of radio waves, which are thought to be caused by the passage of other vehicles. On the other hand, it is conceivable that the effects of short-term multiple reflections of radio waves caused by the passage of vehicles can be eliminated by continuously monitoring and smoothing the radio wave reception levels for a relatively long period of time. Therefore, the inventors considered using a method for detecting vehicles based on radio wave reception levels as a means of detecting abnormalities such as failures of magnetic sensors and for maintenance purposes, and came up with the vehicle detection system according to Embodiment 3.

[0111] In this embodiment, the vehicle detection system determines that the second determination result is abnormal if the vehicle detection result based on the radio wave reception level (first determination result) and the vehicle detection result based on the detection result of the magnetic sensor 11 (second determination result) do not match. If the second determination result is abnormal, it is possible that there is a malfunction or other abnormality in the magnetic sensor 11. Thus, the vehicle detection system according to this embodiment can detect the detection result from the magnetic sensor 11 or an abnormality in the magnetic sensor 11.

[0112] For example, the vehicle detection system according to this embodiment continuously monitors the radio wave reception level during wireless communication between the master unit 20 and the slave unit 10 for a relatively long predetermined period of time (e.g., 1 minute). When the parking space status is "parked," the magnetic sensor 11 built into the slave unit 10 is obscured by the vehicle body, and the radio waves are shielded by the vehicle body. The inventors have experimentally found that due to such radio wave shielding, the radio wave reception level in the "parked" state decreases by more than 10 dB compared to the "unparked" state, even within the communicationable frequency band. If there is no decrease in the radio wave reception level due to radio wave shielding by the vehicle body and a sufficiently high radio wave reception level continues, it can be estimated that there is a high probability that the parking space status is "unparked."

[0113] If the vehicle detection result based on the radio wave reception level (first determination result) indicates a high probability of no parking, the presence or absence of a malfunction in the magnetic sensor 11 can be detected by comparing the first determination result with the determination result of whether or not a vehicle is parked by the magnetic sensor 11 (second determination result).

[0114] The input / output unit 21 or 31 may output the detection result from the magnetic sensor 11 or the result of the determination of whether or not there is an abnormality in the magnetic sensor 11 to a light-emitting device such as a display, speaker, or LED. This allows the user to know the result of the determination of whether or not there is an abnormality.

[0115] The following describes specific methods for detecting detection results from the magnetic sensor 11 or detecting abnormalities in the magnetic sensor 11.

[0116] 3-2.Method 1 Communication is performed between the master unit 20 and the slave unit 10 at predetermined intervals (e.g., 8 seconds), and the radio wave reception level at that time is acquired by either the master unit 20 or the slave unit 10. The calculation circuits 12, 22 and / or 32 determine that the parking space status is "no parking" if a sufficiently high radio wave reception level continues. For example, as shown in Figure 16, if the moving average value (or mode) of the data acquired over a predetermined period (1 minute) is greater than or equal to a first neighboring value (first threshold) that is smaller than the no-parking standard value Er1, the parking space status is determined to be "no parking".

[0117] On the other hand, as shown in Figure 17, the calculation circuits 12, 22 and / or 32 determine that a parking space is in a parked state if the radio wave reception level remains low and falls below a second neighboring value (second threshold) that is greater than the parking reference value Er2. The calculation circuits 12, 22 and / or 32 compare the result of vehicle detection based on the radio wave reception level (first determination result) with the determination result of whether a parking space is present or not by the magnetic sensor 11 (second determination result), and if there is a mismatch, they determine that there is an abnormality in the detection result by the magnetic sensor 11 or in the magnetic sensor 11.

[0118] If the calculation circuits 12, 22 and / or 32 determine that the result of vehicle detection based on the radio wave reception level (first determination result) and the determination result of whether or not a vehicle is parked by the magnetic sensor 11 (second determination result) do not match, they may modify the second determination result to match the first determination result. Alternatively, if the reliability of the first determination result (first confidence level) is above a predetermined threshold, they may modify the second determination result to match the first determination result.

[0119] The arithmetic circuits 12, 22, and / or 32 may store the results of multiple judgments on whether the first judgment result and the second judgment result match in the memory device 13, 23, or 33. The arithmetic circuits 12, 22, and / or 32 may determine that the second judgment result is abnormal if the number of times the first judgment result and the second judgment result do not match and the reliability of the first result is greater than the reliability of the second result exceeds a predetermined value. That is, in the case of a mismatch, the arithmetic circuits 12, 22, and / or 32 increment the rejection counter for the result with the lower reliability that was not adopted. If the rejection counter reaches a predetermined number of times within a predetermined period, the arithmetic circuits 12, 22, and / or 32 determine that there is an abnormality in the detection result by the magnetic sensor 11 or in the magnetic sensor 11. If the number is less than the predetermined number, the rejection counter is reset.

[0120] According to this method, even if an incorrect second determination result is generated, such as the influence of adjacent vehicles on magnetism, indicating that a parking space is occupied when it is actually empty, and this state persists, the second determination result can be reset.

[0121] 3-3.Method 2 In each state shown in the state transition diagram of Figure 14, the radio wave reception levels of the radio waves transmitted or received by the slave unit 10 in the parking space 50a are different from each other, so the calculation circuits 12, 22 and / or 32 detect the change in these levels and detect the state transition.

[0122] Although Figure 14 illustrates eight states, the number of states is not limited to eight. For example, the number of states could be two: a state with a parked car and a state without a parked car in parking space 50a. Alternatively, these two states could be combined with the states with and without a parked car in adjacent spaces 50b and / or 50c, resulting in four or six states.

[0123] The reference values ​​for radio wave reception levels in each state may be set in advance. Such reference values ​​are measured in advance in situations corresponding to the 1st to 8th states, for example. As vehicles enter and exit the parking mass unit 51 (see Figure 14), the radio wave reception levels of the master unit 20 or slave unit 10 change, and the calculation circuits 12, 22 and / or 32 continuously monitor these changes for a predetermined time. The calculation circuits 12, 22 and / or 32 calculate the moving average value (or mode) of the detected radio wave reception level and compare it with the reference value to determine which state has been transitioned to. For example, the calculation circuits 12, 22 and / or 32 calculate the deviation of the moving average value (or mode) of the detected radio wave reception level from the reference value for each state. The calculation circuits 12, 22 and / or 32 determine that a transition has occurred to a particular state when the deviation from the reference value of the state before the transition is greater than or equal to a predetermined value, and the deviation from the reference value of one of the transitionable states is within a predetermined value.

[0124] Alternatively, the model may be trained to learn the mode (or moving average) of the radio wave reception level for each state, based on the state transitions determined from the detection results of the magnetic sensor 11. By inputting the mode (or moving average) of the radio wave reception level into the trained model thus generated, the determination result of which state the system has transitioned to is output.

[0125] If the calculation circuits 12, 22 and / or 32 determine that the result of vehicle detection based on the radio wave reception level (first determination result) and the determination result of whether or not a vehicle is parked by the magnetic sensor 11 (second determination result) do not match, they may modify the second determination result to match the first determination result. Alternatively, if the reliability of the first determination result (first reliability) is above a predetermined threshold, they may modify the second determination result to match the first determination result. The reliability of the determination result based on the radio wave reception level is determined by the magnitude of the above-mentioned deviation, and the reliability is increased when the deviation is small.

[0126] 3-4. Summary of this embodiment As described above, the vehicle detection system according to an example of this embodiment includes a magnetic sensor 11 that detects magnetism within a parking space 50 where a vehicle is parked, a slave unit 10 that transmits a signal indicating the detection result of the magnetic sensor 11 by radio waves, a master unit 20 that receives the signal transmitted by radio waves, and a calculation circuit (for example, calculation circuits 12, 22 and / or 32). The calculation circuit generates a first determination result that determines whether or not there is a vehicle in the parking space 50 based on the received signal strength of the signal received by the master unit 20, and generates a second determination result that determines whether or not there is a vehicle in the parking space 50 based on the detection result of the magnetic sensor 11. If the first determination result and the second determination result do not match, the second determination result is determined to be abnormal. With this configuration, it is possible to more accurately determine whether or not there is an abnormality with respect to the magnetic sensor 11.

[0127] Another example of this embodiment of a vehicle detection system includes a magnetic sensor 11 that detects magnetism within a parking space 50 where a vehicle is parked, a master unit 20 and a slave unit 10 that transmit and receive signals from each other by radio waves, and a calculation circuit (for example, calculation circuits 12, 22 and / or 32). The slave unit 10 transmits the received signal strength of the signal received from the master unit 20 and the detection result of the magnetic sensor 11 to the master unit 20. The calculation circuit generates a first determination result based on the received signal strength, determining whether or not there is a vehicle in the parking space 50, and generates a second determination result based on the detection result of the magnetic sensor 11, determining whether or not there is a vehicle in the parking space 50. If the first determination result and the second determination result do not match, the calculation circuit determines that the second determination result is abnormal. This configuration allows for a more accurate determination of whether or not there is an abnormality with respect to the magnetic sensor 11.

[0128] In the above example or the other example of this embodiment, the calculation circuit may determine a first confidence level, which represents an indicator of the likelihood of the first determination result, based on the received signal strength of the signal received by the master unit 20, and determine a second confidence level, which represents an indicator of the likelihood of the second determination result, based on the detection result of the magnetic sensor 11. If the first determination result and the second determination result do not match, the circuit may determine whether or not there is an abnormality in the second determination result based on a comparison of the first confidence level and the second confidence level. This configuration using confidence levels makes it possible to more accurately determine whether or not there is an abnormality related to the magnetic sensor 11.

[0129] In the above example or the other example of this embodiment, the arithmetic circuit may accumulate the results of multiple determinations regarding whether the first determination result and the second determination result match, and if the number of times the first determination result and the second determination result do not match and the confidence level of the first is greater than the confidence level of the second reaches a predetermined value or more, it may determine that the second determination result is abnormal.

[0130] In the above example or the other example of this embodiment, the calculation circuit may, in the process of generating a first determination result, monitor the received signal strength at regular intervals and generate a first determination result that determines whether or not there is a vehicle in the parking space 50 based on a comparison between the moving average or mode of the received signal strength over a predetermined period and a predetermined reference value.

[0131] In the above example or the other example of this embodiment, the calculation circuit, in the process of generating the first determination result, determines the moving average value or mode of the received signal intensity over a predetermined period. (1) If the value exceeds a first threshold (first neighboring value) which is smaller than the first reference value that indicates the criteria for determining whether there is no vehicle in parking space 50, it is determined that there is no vehicle in parking space 50. (2) If the value falls below a second threshold (second neighboring value) which is greater than a second reference value that indicates the criteria for determining whether there is a vehicle in parking space 50, it may be determined that there is a vehicle in parking space 50.

[0132] In the above example or the other example of this embodiment, if the arithmetic circuit determines that the first determination result and the second determination result do not match, it may modify the second determination result to match the first determination result.

[0133] In the above example or the other example of this embodiment, the vehicle detection system may further include an output unit (for example, an input / output unit 21 or 31) that outputs the result of the determination of whether or not there is an abnormality in the first determination result or the second determination result. With this configuration, the user can find out the result of the determination of whether or not there is an abnormality.

[0134] 4. Variations Although embodiments of the present disclosure have been described in detail above, the above description is merely illustrative in all respects of the present disclosure. Various improvements and modifications can be made without departing from the scope of the present disclosure. For example, the following modifications are possible. In the following, the same reference numerals are used for components similar to those in the above embodiments, and explanations of the same points as in the above embodiments will be omitted as appropriate. The following modifications can be combined as appropriate.

[0135] 4-1. First Modified Example In Embodiment 1, an example where the magnetic sensor 11 is included in the slave unit 10 has been described. However, the magnetic sensor 11 may be installed in the parking space 50 as a separate body from the slave unit 10.

[0136] 4-2. Second Modified Example In Embodiment 1, as a method for detecting a vehicle by radio waves, an example of monitoring the radio wave reception level during communication between the master unit 20 and the slave unit 10 has been described. However, the present disclosure is not limited to this. For example, a method of monitoring the radio wave reception level during communication between slave units 10, or a method of monitoring the reflection level of the transmitted radio wave during communication may be adopted. Further, when two or more slave units are embedded in one parking space, such as when the parking space is a large space for large vehicles, the communication between the master unit 20 and one slave unit may be intercepted by another slave unit, and the change in its radio wave reception level may be used for determining the presence or absence of parking. Also, a method of monitoring the reflected wave of the transmitted wave by the master unit 20 and / or the slave unit 10 may be adopted if the vehicle detection system further includes a radio wave transmitter, or a method of monitoring the radio wave reception level from a radio wave transmitter used for another purpose may be adopted.

[0137] 4-3. Third Modified Example In Embodiment 1, in the determination process of whether there is a vehicle 2 in the parking space 50, an example where the weight Wy of the Y component Ym of the magnetic detection value is set to 0, and an example where Wy is set to satisfy 0 < Wy < 1 have been described. However, the present disclosure is not limited to this, and Wy may be set to 1.

[0138] 4-4. Fourth Modified Example In Embodiment 1, an example was described in which the calculation circuit 32 determines the moving average or mode of Nb magnetic detection values ​​(Nb≧Na) over a predetermined period Cc as reference values ​​(Xr1, Yr1, Zr1) for change detection. However, the disclosure is not limited thereto. For example, the reference values ​​may be predetermined for each parking space state (parked state and unparked state) of the parking space 50. Alternatively, for example, the reference values ​​may be predetermined for each of the eight states (see Figure 14) of the parking space unit 51. The reference values ​​may be updated when determining the parking space state of the parking space 50a, for example, when switching between the parked state and the unparked state. Furthermore, the reference values ​​may be updated when the state of the parking space unit 51 changes.

[0139] 4-5. Fifth variation Embodiment 3 described a vehicle detection system that detects the detection result (second determination result) of the magnetic sensor 11 or an abnormality of the magnetic sensor 11, but the disclosure is not limited thereto. For example, if the number of times the first determination result and the second determination result do not match and the reliability of the second result is greater than the reliability of the first result exceeds a predetermined value, the calculation circuit may determine that the first determination result is abnormal instead of the second determination result.

[0140] (Note) Examples of aspects of this disclosure are given below.

[0141] <Aspect 1> A magnetic sensor that detects magnetism within a parking space where a vehicle is parked, A sub-unit that transmits a signal indicating the detection result of the magnetic sensor via radio waves, A master unit that receives the signal transmitted by the aforementioned radio waves, Calculation circuit and, Equipped with, The aforementioned arithmetic circuit is Based on the received signal strength of the signal received by the master unit, a first determination result is generated that determines whether or not there is a vehicle in the parking space. Based on the detection result of the magnetic sensor, a second determination result is generated that determines whether or not there is a vehicle in the parking space. If the first determination result and the second determination result do not match, the second determination result is determined to be abnormal. Vehicle detection system.

[0142] <Aspect 2> A magnetic sensor that detects magnetism within a parking space where a vehicle is parked, A master unit and a slave unit that transmit and receive signals from each other via radio waves, Calculation circuit and, Equipped with, The slave unit transmits to the master unit the received signal strength of the signal received from the master unit and the detection result of the magnetic sensor. The aforementioned arithmetic circuit is Based on the received signal strength, a first determination result is generated that determines whether or not there is a vehicle in the parking space. Based on the detection result of the magnetic sensor, a second determination result is generated that determines whether or not there is a vehicle in the parking space. If the first determination result and the second determination result do not match, the second determination result is determined to be abnormal. Vehicle detection system.

[0143] <Aspect 3> The aforementioned arithmetic circuit is Based on the received signal strength of the signal received by the master unit, a first confidence level representing an indicator of the likelihood of the first determination result is determined. Based on the detection results of the magnetic sensor, a second confidence level is determined, which represents an indicator of the likelihood of the second determination result. If the first determination result and the second determination result do not match, the presence or absence of an abnormality in the second determination result is determined based on a comparison of the confidence level of the first and the confidence level of the second. A vehicle detection system according to embodiment 1 or 2.

[0144] <Aspect 4> The aforementioned arithmetic circuit is The results of multiple determinations regarding whether the first determination result and the second determination result match are accumulated. If the first judgment result and the second judgment result do not match, and the number of times the confidence level of the first result is greater than the confidence level of the second result exceeds a predetermined value, then the second judgment result is determined to be abnormal. The vehicle detection system described in Embodiment 3.

[0145] <Aspect 5> The calculation circuit, if the number of times the first determination result and the second determination result do not match, and the reliability of the second result is greater than the reliability of the first result exceeds a predetermined value, determines that the first determination result is abnormal instead of the second determination result. The vehicle detection system described in Embodiment 4.

[0146] <Aspect 6> The calculation circuit, in the process of generating the first determination result, monitors the received signal strength at regular intervals and generates the first determination result, which determines whether or not there is a vehicle in the parking space, based on a comparison of the moving average or mode of the received signal strength over a predetermined period with a predetermined reference value. A vehicle detection system according to any one of embodiments 1 to 5.

[0147] <Aspect 7> In the process of generating the first determination result, the calculation circuit determines that the moving average or mode of the received signal intensity over a predetermined period is If the first threshold value, which is smaller than the first reference value that indicates the criteria for determining whether there is a vehicle in the parking space, is exceeded, it is determined that there is no vehicle in the parking space. If the value falls below a second threshold that is greater than a second standard value indicating the criteria for determining whether a vehicle is in the parking space, it is determined that a vehicle is in the parking space. A vehicle detection system according to any one of embodiments 1 to 6.

[0148] <Aspect 8> If the calculation circuit determines that the first determination result and the second determination result do not match, it modifies the second determination result to match the first determination result. A vehicle detection system according to any one of embodiments 1 to 7.

[0149] <Pattern 9> The vehicle detection system according to any one of embodiments 1 to 8, further comprising an output unit that outputs the result of a determination regarding whether or not there is an abnormality in the first determination result or the second determination result. [Industrial applicability]

[0150] The present invention can be applied, for example, to a vehicle detection system that determines whether or not there is a vehicle in a parking space. [Explanation of symbols]

[0151] 1. Vehicle detection system (vehicle detection device) 2 vehicles 10 Handset 11 Magnetic Sensor 12 Arithmetic circuit 13 Storage device 14 Communications Department 15 Batteries 20 Master unit 21 Input / output section 22 Arithmetic circuit 23 Storage device 24 Communications Department 30 Management device 31 Input / output section 32 Arithmetic circuit 33 Storage device 34 Communications Department 50 parking spaces 50a Parking space 50b Parking space (adjacent space) 50c Parking space (adjacent space) 51 Parking Manhole Unit

Claims

1. A magnetic sensor that detects magnetism within a parking space where a vehicle is parked, A sub-unit that transmits a signal indicating the detection result of the magnetic sensor via radio waves, A master unit that receives the signal transmitted by the aforementioned radio waves, Calculation circuit and, Equipped with, The aforementioned arithmetic circuit is Based on the received signal strength of the signal received by the master unit, a first determination result is generated that determines whether or not there is a vehicle in the parking space, and a first confidence level is determined that represents an indicator of the certainty of the first determination result. Based on the detection result of the magnetic sensor, a second determination result is generated that determines whether or not there is a vehicle in the parking space, and a second confidence level is determined that represents an indicator of the certainty of the second determination result. If the first determination result and the second determination result do not match, the presence or absence of an abnormality in the second determination result is determined based on a comparison of the confidence level of the first and the confidence level of the second. Vehicle detection system.

2. A magnetic sensor that detects magnetism within a parking space where a vehicle is parked, A master unit and a slave unit that transmit and receive signals from each other via radio waves, Calculation circuit and, Equipped with, The slave unit transmits to the master unit the received signal strength of the signal received from the master unit and the detection result of the magnetic sensor. The aforementioned arithmetic circuit is Based on the received signal strength, a first determination result is generated that determines whether or not there is a vehicle in the parking space, and a first confidence level is determined that represents an indicator of the certainty of the first determination result. Based on the detection result of the magnetic sensor, a second determination result is generated that determines whether or not there is a vehicle in the parking space, and a second confidence level is determined that represents an indicator of the certainty of the second determination result. If the first determination result and the second determination result do not match, the presence or absence of an abnormality in the second determination result is determined based on a comparison of the confidence level of the first and the confidence level of the second. Vehicle detection system.

3. The aforementioned arithmetic circuit is The results of multiple determinations regarding whether the first determination result and the second determination result match are accumulated. If the first judgment result and the second judgment result do not match, and the number of times the confidence level of the first result is greater than the confidence level of the second result exceeds a predetermined value, then the second judgment result is determined to be abnormal. The vehicle detection system according to claim 1 or 2.

4. The calculation circuit determines that the first determination result is abnormal if the number of times the first determination result and the second determination result do not match and the reliability of the second result is greater than the reliability of the first result exceeds a predetermined value, instead of determining the second determination result. The vehicle detection system according to claim 3.

5. The calculation circuit, in the process of generating the first determination result, monitors the received signal strength at regular intervals and generates the first determination result, which determines whether or not there is a vehicle in the parking space, based on a comparison of the moving average or mode of the received signal strength over a predetermined period with a predetermined reference value. The vehicle detection system according to claim 1 or 2.

6. In the process of generating the first determination result, the calculation circuit determines that the moving average or mode of the received signal intensity over a predetermined period is If the value exceeds a first threshold that is smaller than a first standard value indicating the criteria for determining whether there is a vehicle in the parking space, it is determined that there is no vehicle in the parking space. If the value falls below a second threshold that is greater than a second standard value indicating the criteria for determining whether a vehicle is in the parking space, it is determined that a vehicle is in the parking space. The vehicle detection system according to claim 1 or 2.

7. If the calculation circuit determines that the first determination result and the second determination result do not match, it modifies the second determination result to match the first determination result. The vehicle detection system according to claim 1 or 2.

8. The vehicle detection system according to claim 1 or 2, further comprising an output unit that outputs the result of a determination regarding whether or not there is an abnormality in the first determination result or the second determination result.

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