Vehicle detection system

Abstract

To provide a vehicle detection system capable of detecting presence and absence of a vehicle with improved accuracy.SOLUTION: In a vehicle detection system 1, a correction section 42 can calculate correction information based on a moisture content identification value obtained from a detection result of a moisture content detector 3. A determination section 43 designates one of a variation amount detection value and a variation amount reference threshold as a correction target value and the other as a fixed value. When receiving the correction information from the correction section 42, the determination section 43 corrects the correction target value based on the correction information, maintains the fixed value as is, and determines a comparison detection value and a comparison threshold. By comparing the comparison detection value with the comparison threshold, the determination section 43 detects presence and absence of a vehicle in a detection region.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a vehicle detection system having a loop coil.

Background Art

[0002] Patent Document 1 discloses a vehicle detection device that detects a vehicle by sensing a change in the inductance of a loop coil buried in soil.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The inductance of the loop coil changes not only depending on the presence or absence of a vehicle but also depending on a change in the moisture content of the soil in which the loop coil is buried. Therefore, in the conventional vehicle detection device disclosed in Patent Document 1, for example, when adjusting the vehicle detection sensitivity during the dry winter season, the vehicle detection sensitivity increases during the rainy season when the soil is more likely to be wet than in the winter season. As a result, with the conventional vehicle detection device, there is a risk of being erroneously detected as if there is a vehicle even though there is no vehicle. Also, for example, when adjusting the vehicle detection sensitivity during the rainy season, the vehicle detection sensitivity decreases during the winter season. As a result, with the conventional vehicle detection device, there is also a risk that the vehicle will not be detected even though there is a vehicle.

[0005] The present disclosure solves the above problems and aims to provide a vehicle detection system that can more accurately detect the presence or absence of a vehicle.

Means for Solving the Problems

[0006] The vehicle detection system according to the present disclosure includes a loop coil that is embedded in soil on which a road surface is formed and generates a magnetic field in a detection area set above the road surface, a moisture amount detector that is embedded in the soil within a restricted range in which the loop coil is accommodated and detects the moisture amount of the soil, and a vehicle detection device. The vehicle detection device has a change amount detection unit, a correction unit, and a determination unit. The change amount detection unit detects a change amount of the inductance of the loop coil as a change amount detection value. A change amount reference threshold value is stored in the determination unit. The determination unit specifies a comparison detection value from the change amount detection value, specifies a comparison threshold value from the change amount reference threshold value, and compares the comparison detection value with the comparison threshold value to detect the presence or absence of a vehicle in the detection area. The correction unit can calculate correction information based on a moisture amount specific value obtained from the detection result of the moisture amount detector. The determination unit sets one of the change amount detection value and the change amount reference threshold value as a correction target value and the other as a fixed value. When the determination unit receives the correction information from the correction unit, the determination unit corrects the correction target value based on the correction information, maintains the fixed value as it is, and specifies the comparison detection value and the comparison threshold value.

Effect of the Invention

[0007] According to the present disclosure, the presence or absence of a vehicle can be detected more accurately.

Brief Description of the Drawings

[0008]

Figure 1

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[0009] Embodiments for carrying out the subject matter of the present disclosure will be described with reference to the accompanying drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals, and duplicate explanations are appropriately simplified or omitted. Note that the subject matter of the present disclosure is not limited to the following embodiments, and within the scope not departing from the spirit of the present disclosure, deformation of any component of the embodiments or omission of any component of the embodiments is possible.

[0010] Embodiment 1. In Embodiment 1, a vehicle detection system that detects a vehicle when entering a parking lot at the entrance and exit of the parking lot will be described.

[0011] FIG. 1 is a configuration diagram showing a vehicle detection system according to Embodiment 1. FIG. 2 is a block diagram showing the vehicle detection system of FIG. 1. The vehicle detection system 1 includes a loop coil 2, a moisture detector 3, a vehicle detection device 4, an information reader 5, and a gate device 6.

[0012] As shown in FIG. 1, the loop coil 2 is buried in the soil. On the soil, a road surface 8 through which the vehicle 7 passes is formed. The loop coil 2 is disposed below the road surface 8. The loop coil 2 is electrically connected to the vehicle detection device 4.

[0013] Here, FIG. 3 is a schematic configuration diagram showing a state where the vehicle 7 in FIG. 1 has moved out of the detection area 9. FIG. 4 is a graph showing the distribution of the magnetic flux amount in the magnetic field generated in the detection area 9 of FIG. 3 in the direction along the road surface 8. Further, FIG. 5 is a schematic configuration diagram showing a state where the vehicle 7 in FIG. 3 exists within the detection area 9. FIG. 6 is a graph showing the distribution of the magnetic flux amount in the magnetic field generated in the detection area 9 of FIG. 5 in the direction along the road surface 8.

[0014] Above the road surface 8, a detection area 9 is set. The set position of the detection area 9 corresponds to the position of the loop coil 2. A high-frequency current can be passed through the loop coil 2 by the vehicle detection device 4. By passing the high-frequency current through the loop coil 2, the loop coil 2 generates a magnetic field in the detection area 9.

[0015] In the magnetic field in the detection area 9, the distribution of the magnetic flux amount changes continuously according to the position within the detection area 9. As shown in FIGS. 4 and 6, the magnetic flux amount in the detection area 9 has the maximum peak value at the center position of the loop coil 2, and continuously decreases as it moves away from the center position of the loop coil 2.

[0016] The vehicle body of the vehicle 7 is made of metal. Therefore, when the vehicle 7 enters the detection area 9 where the magnetic field is generated, the magnetic flux amount in the detection area 9 decreases due to the eddy current loss in the vehicle body of the vehicle 7. As a result, the peak value of the magnetic flux amount in the detection area 9 is lower in the state of FIG. 5 where the vehicle 7 has entered the detection area 9 than in the state of FIG. 3 where the vehicle 7 has moved out of the detection area 9.

[0017] Therefore, in the state where the vehicle 7 has moved out of the detection area 9, as shown in FIG. 4, the peak value of the magnetic flux amount is larger than the preset magnetic flux amount reference value A. On the other hand, in the state where the vehicle 7 has entered the detection area 9, as shown in FIG. 6, the peak value of the magnetic flux amount is smaller than the magnetic flux amount reference value A.

[0018] The inductance of the loop coil 2 changes due to the change in the amount of magnetic flux in the detection area 9. Therefore, based on the state where the vehicle 7 is outside the detection area 9, the amount of change in the inductance of the loop coil 2 becomes larger when the vehicle 7 is in the detection area 9 and becomes smaller when the vehicle 7 moves out of the detection area 9.

[0019] Also, the amount of change in the inductance of the loop coil 2 also changes depending on the moisture content of the soil. The amount of change in the inductance of the loop coil 2 increases as the moisture content of the soil increases.

[0020] As shown in FIG. 1, the moisture detector 3 is buried in the soil within the restricted range where the loop coil 2 is accommodated. The restricted range is a range where it is assumed that the difference in moisture content is only a slight difference with respect to the moisture content of the soil at the position of the loop coil 2. In the present embodiment, the moisture detector 3 is disposed inside the loop coil 2 below the road surface 8.

[0021] The moisture detector 3 detects the moisture content of the soil at the position of the moisture detector 3. The moisture detector 3 detects the moisture content of the soil at each preset detection cycle.

[0022] The moisture detector 3 is electrically connected to the vehicle detection device 4. When the moisture detector 3 detects the moisture content of the soil, the moisture detector 3 transmits the moisture content detection value, which is the detection result of the moisture detector 3, to the vehicle detection device 4.

[0023] The vehicle detection device 4 includes a change amount detection unit 41, a correction unit 42, and a determination unit 43.

[0024] The change amount detection unit 41 outputs a high-frequency current to the loop coil 2. The change amount detection unit 41 constitutes a resonance circuit together with the loop coil 2. The oscillation frequency of the high-frequency current output by the change amount detection unit 41 to the loop coil 2 is set to the resonance frequency determined by the inductance of the loop coil 2. Accordingly, the oscillation frequency of the high-frequency current output by the change amount detection unit 41 to the loop coil 2 changes due to the change in the inductance of the loop coil 2. The change amount detection unit 41 detects the change amount of the inductance of the loop coil 2 as a change amount detection value by detecting the change amount of the oscillation frequency of the high-frequency current output to the loop coil 2. When the change amount detection unit 41 detects the change amount of the inductance of the loop coil 2, the change amount detection value is transmitted to the determination unit 43.

[0025] The detection result of the moisture content detector 3, that is, the moisture content detection value, is transmitted from the moisture content detector 3 to the correction unit 42. The correction unit 42 obtains a moisture content specific value from the detection result of the moisture content detector 3. In the present embodiment, the average value of the detection results of the moisture content detector 3 over a certain period is calculated by the correction unit 42 as the moisture content specific value. The certain period for calculating the moisture content specific value is a period longer than the detection period of the moisture content detector 3. As the certain period for calculating the moisture content specific value, a period such as one month or two months is used.

[0026] The correction unit 42 has a storage unit (not shown). The correction unit 42 stores the detection result for each detection period of the moisture content detector 3 in the storage unit of the correction unit 42 together with the date and time. Therefore, in the storage unit of the correction unit 42 after a certain period has elapsed, a plurality of moisture content detection values for the certain period are stored together with the date and time. The average value of the detection results of the moisture content detector 3 is calculated by averaging a plurality of moisture content detection values for the certain period stored in the storage unit of the correction unit 421.

[0027] The correction unit 42 stores a moisture content reference range. In the present embodiment, the moisture content reference range is determined with the moisture content specific value obtained from the detection result of the moisture content detector 3 during the dry winter season as the reference value. The upper limit value of the moisture content reference range is set to a value larger than the reference value, and the lower limit value of the moisture content reference range is set to a value smaller than the reference value.

[0028] The correction unit 42 is capable of calculating correction information based on the moisture content specific value obtained from the detection result of the moisture content detector 3. The correction information is information for adjusting the sensitivity for detecting the presence or absence of the vehicle 7 in the detection area 9.

[0029] The correction unit 42 determines whether it is necessary to calculate the correction information by comparing the moisture content specific value with the moisture content reference range. That is, the correction unit 421 makes a non-correction determination that it is not necessary to calculate the correction information when the moisture content specific value is within the moisture content reference range, and makes a correction determination that it is necessary to calculate the correction information when the moisture content specific value is outside the moisture content reference range.

[0030] When the correction unit 42 makes a non-correction determination, it does not calculate the correction information. On the other hand, when the correction unit 42 makes a correction determination, it calculates the correction information. When the correction unit 42 calculates the correction information, it transmits the correction information to the determination unit 43.

[0031] A change amount reference threshold value is stored in the determination unit 43. The change amount reference threshold value is a threshold value corresponding to the moisture content reference range stored in the correction unit 42. That is, the change amount reference threshold value is a threshold value used when the moisture content specific value obtained from the detection result of the moisture content detector 3 is within the moisture content reference range.

[0032] The determination unit 43 specifies a comparison detection value from the change amount detection value received from the change amount detection unit 41. Further, the determination unit 43 specifies a comparison threshold value from the change amount reference threshold value stored in the determination unit 43.

[0033] When the determination unit 43 has not received the correction information from the correction unit 42, it maintains the change amount detection value as it is and specifies it as the comparison detection value, and maintains the change amount reference threshold value as it is and specifies it as the comparison threshold value.

[0034] In the determination unit 43, one of the change amount detection value and the change amount reference threshold value is set as the value to be corrected, and the other is set as the fixed value. When the determination unit 43 has received the correction information from the correction unit 42, it corrects the value to be corrected based on the correction information and maintains the fixed value as it is, thereby specifying the comparison detection value from the change amount detection value and specifying the comparison threshold value from the change amount reference threshold value.

[0035] In the present embodiment, in the determination unit 43, the change amount reference threshold value is set as the value to be corrected, and the change amount detection value is set as the fixed value. Accordingly, in the present embodiment, when the determination unit 43 has received the correction information from the correction unit 42, it corrects the change amount reference threshold value based on the correction information and specifies it as the comparison threshold value, and maintains the change amount detection value as it is and specifies it as the comparison detection value.

[0036] When the moisture content of the soil changes, the change amount detection value changes in response to the change in the moisture content of the soil, while the change amount reference threshold value does not change. Therefore, the relationship between the change amount detection value and the change amount reference threshold value changes as the moisture content specific value changes. In the present embodiment, since the change amount reference threshold value is corrected based on the moisture content specific value and specified as the comparison threshold value, the relationship between the comparison detection value and the comparison threshold value is less likely to change even when the moisture content specific value changes. In the determination unit 43, the relationship between the change amount detection value and the change amount reference threshold value is replaced with the relationship between the comparison detection value and the comparison threshold value.

[0037] The determination unit 43 detects the presence or absence of the vehicle 7 in the detection area 9 by comparing the detection value for comparison with the threshold value for comparison. In the present embodiment, the determination unit 43 determines that there is a vehicle 7 in the detection area 9 when the detection value for comparison is greater than the threshold value for comparison, and determines that there is no vehicle 7 in the detection area 9 when the detection value for comparison is less than or equal to the threshold value for comparison. The determination unit 43 transmits a vehicle detection signal to the information reading device 5 by determining that there is a vehicle 7 in the detection area 9.

[0038] As the correction information, a correction value determined according to the degree to which the specific moisture content value deviates from the reference moisture content range is used. In the present embodiment, when the specific moisture content value is greater than the upper limit value of the reference moisture content range, a correction value determined according to the difference between the specific moisture content value and the upper limit value of the reference moisture content range is used as the correction information. Also, in the present embodiment, when the specific moisture content value is less than the lower limit value of the reference moisture content range, a correction value determined according to the difference between the lower limit value of the reference moisture content range and the specific moisture content value is used as the correction information. In the present embodiment, the correction value becomes a positive value when the specific moisture content value is greater than the upper limit value of the reference moisture content range, and becomes a negative value when the specific moisture content value is less than the lower limit value of the reference moisture content range.

[0039] In the present embodiment, the determination unit 43 increases the threshold value for comparison by the amount of the correction value compared to the change amount reference threshold when the correction value is a positive value, and decreases the threshold value for comparison by the amount of the correction value compared to the change amount reference threshold when the correction value is a negative value. Therefore, in the present embodiment, the correction unit 42 calculates, as the correction information, information for increasing the threshold value for comparison to be greater than the change amount reference threshold when the specific moisture content value is greater than the upper limit value of the reference moisture content range, and for decreasing the threshold value for comparison to be less than the change amount reference threshold when the specific moisture content value is less than the lower limit value of the reference moisture content range.

[0040] As shown in Fig. 1, the information reading device 5 is installed together with the vehicle detection device 4. In this embodiment, the information reading device 5 is separate from the vehicle detection device 4. The information reading device 5 is electrically connected to the vehicle detection device 4. The information reading device 5 receives a vehicle detection signal from the determination unit 43 and reads the identification information transmitted from a wireless communication unit (not shown) mounted on the vehicle 7. The wireless communication unit may be carried by a person getting into the vehicle 7.

[0041] The wireless communication unit has a function of storing the identification information of the vehicle 7 or the identification information of a person getting into the vehicle 7 and transmitting the stored identification information. Examples of the wireless communication unit include an RF (Radio Frequency) tag for RFID (Radio Frequency IDentification) and a non-contact IC (Integrated Circuit) card.

[0042] The information reading device 5 has a function of receiving the identification information transmitted from a wireless communication unit such as an RF tag or a non-contact IC card and reading the identification information. The information reading device 5 determines whether to permit the entry of the vehicle 7 into the parking lot based on the identification information read from the wireless communication unit. That is, the information reading device 5 makes a permission determination to permit the entry of the vehicle 7 when the identification information matches the registered information registered in advance, and makes a non-permission determination not to permit the entry of the vehicle 7 when the identification information does not match the registered information. In addition, even when the information reading device 5 fails to read the identification information, it corresponds to the case where the identification information does not match the registered information, and a non-permission determination is made in the information reading device 5.

[0043] When the information reading device 5 makes a permission determination, it transmits a permission signal to the determination unit 43 of the vehicle detection device 4. On the other hand, when the information reading device 5 makes a non-permission determination, it does not transmit a permission signal and maintains a state where the signal transmission is stopped.

[0044] After the determination unit 43 transmits the vehicle detection signal to the information reading device 5, it receives the permission signal from the information reading device 5 and then transmits the gate opening signal to the gate device 6. After the determination unit 43 transmits the gate opening signal to the gate device 6, if it determines that there is no vehicle 7 in the detection area 9, it transmits the gate closing signal to the gate device 6.

[0045] As shown in FIG. 1, the gate device 6 is installed at a position closer to the parking lot than the detection area 9 in the direction along the road surface 8. The gate device 6 includes a gate device main body 61 and a gate bar 62. The gate device main body 61 is installed on the side of the road surface 8. The gate bar 62 is provided on the gate device main body 61.

[0046] The gate bar 62 is movable between a gate closed position that crosses above the road surface 8 to block the passage of the vehicle 7 and a gate open position that retracts from the gate closed position to allow the passage of the vehicle 7. The gate device main body 61 moves the gate bar 62 from the gate closed position to the gate open position when it receives the gate opening signal from the determination unit 43 of the vehicle detection device 4. Also, the gate device main body 61 moves the gate bar 62 from the gate open position to the gate closed position when it receives the gate closing signal from the determination unit 43 of the vehicle detection device 4.

[0047] Next, the processing operation of the correction unit 42 in the vehicle detection system 1 will be described. FIG. 7 is a flowchart showing the processing operation of the correction unit 42 in FIG. 2. In step S1, the correction unit 42 stores the moisture amount detection value, which is the detection result of the moisture amount detector 3, in the storage unit of the correction unit 42 for each detection period. After that, in step S2, the correction unit 42 determines whether the moisture amount detection values for a certain period have been stored in the storage unit of the correction unit 42.

[0048] If the moisture amount detection values for a certain period have been stored, in step S3, the correction unit 42 calculates the average value of the plurality of moisture amount detection values in the certain period as the moisture amount specific value. On the other hand, if the moisture amount detection values for a certain period have not been stored, the correction unit 42 ends the processing.

[0049] When the correction unit 42 calculates the moisture content specific value, in step S4, it determines whether the moisture content specific value is outside the moisture content reference range. That is, in step S4, the correction unit 42 determines whether the moisture content specific value corresponds to a value greater than the upper limit value of the moisture content reference range or a value less than the lower limit value of the moisture content reference range.

[0050] When the moisture content specific value is outside the moisture content reference range, the correction unit 42 calculates correction information based on the moisture content specific value in step S5. On the other hand, when the moisture content specific value is within the moisture content reference range, the correction unit 42 determines that calculation of correction information is unnecessary and ends the process.

[0051] After the correction unit 42 calculates the correction information in step S5, the correction unit 42 transmits the correction information to the determination unit 43 in step S6 and ends the process.

[0052] Next, the processing operation of the determination unit 43 in the vehicle detection system 1 will be described. FIG. 8 is a flowchart showing the processing operation of the determination unit 43 in FIG. 2. The determination unit 43 acquires a change amount detection value from the change amount detection unit 41 in step S11. After that, the determination unit 43 determines whether it has received correction information from the correction unit 42 in step S12.

[0053] When the determination unit 43 has received correction information from the correction unit 42, the determination unit 43 maintains the change amount detection value as it is and specifies it as a comparison detection value in step S13, and corrects the change amount reference threshold based on the correction information and specifies it as a comparison threshold.

[0054] On the other hand, when the determination unit 43 has not received correction information from the correction unit 42, the determination unit 43 maintains the change amount detection value as it is and specifies it as a comparison detection value in step S14, and maintains the change amount reference threshold as it is and specifies it as a comparison threshold.

[0055] After that, in step S15, the determination unit 43 determines whether the comparison detection value is greater than the comparison threshold value.

[0056] When the comparison detection value is greater than the comparison threshold value, the determination unit 43 transmits the vehicle detection signal to the information reading device 5 in step S16. On the other hand, when the comparison detection value is less than or equal to the comparison threshold value, the determination unit 43 determines that the vehicle 7 is not in the detection area 9 and ends the process.

[0057] In the information reading device 5, when receiving the vehicle detection signal from the determination unit 43, it is determined whether the identification information read from the wireless communication unit matches the registered information. When the identification information matches the registered information, a permission signal is transmitted from the information reading device 5 to the determination unit 43. On the other hand, when the identification information does not match the registered information, the permission signal is not transmitted from the information reading device 5 to the determination unit 43.

[0058] After transmitting the vehicle detection signal to the information reading device 5, the determination unit 43 determines in step S17 whether it has received a permission signal from the information reading device 5.

[0059] When the determination unit 43 receives a permission signal from the information reading device 5, the determination unit 43 transmits a gate opening signal to the gate device 6 in step S18. As a result, in the gate device 6, the gate bar 62 moves from the gate closed position to the gate open position. Therefore, the vehicle 7 can pass through the gate device 6.

[0060] On the other hand, when the determination unit 43 does not receive a permission signal from the information reading device 5, the determination unit 43 does not transmit a gate opening signal to the gate device 6 and ends the process. As a result, in the gate device 6, the position of the gate bar 62 remains at the gate closed position. Therefore, the state where the passage of the vehicle 7 is blocked by the gate device 6 is maintained.

[0061] After the determination unit 43 transmits the gate open signal to the gate device 6, in step S19, the determination unit 43 acquires a change amount detection value from the change amount detection unit 41. After that, in step S20, the determination unit 43 determines whether it has received correction information from the correction unit 42.

[0062] When the determination unit 43 has received correction information from the correction unit 42, in step S21, the determination unit 43 maintains the change amount detection value as it is and specifies it as a detection value for comparison, and corrects the change amount reference threshold based on the correction information and specifies it as a comparison threshold.

[0063] On the other hand, when the determination unit 43 has not received correction information from the correction unit 42, in step S22, the determination unit 43 maintains the change amount detection value as it is and specifies it as a detection value for comparison, and maintains the change amount reference threshold as it is and specifies it as a comparison threshold.

[0064] After that, in step S23, the determination unit 43 determines whether the detection value for comparison is less than or equal to the comparison threshold.

[0065] When the detection value for comparison is less than or equal to the comparison threshold, in step S24, the determination unit 43 transmits a gate close signal to the gate device 6. As a result, in the gate device 6, the gate bar 62 moves from the gate open position to the gate close position. On the other hand, when the detection value for comparison is greater than the comparison threshold, the determination unit 43 repeats the processing from step S19 to step S23 until the detection value for comparison becomes less than or equal to the comparison threshold. After that, the processing of the determination unit 43 ends.

[0066] In such a vehicle detection system 1, based on the moisture content specific value obtained from the detection result of the moisture content detector 3, the correction unit 42 can calculate correction information. When the determination unit 43 receives the correction information from the correction unit 42, it corrects the change amount reference threshold based on the correction information to specify a comparison threshold, and maintains the change amount detection value as it is to specify a comparison detection value. The determination unit 43 detects the presence or absence of the vehicle 7 in the detection area 9 by comparing the comparison detection value with the comparison threshold. Therefore, even when the change amount detection value changes due to a change in the moisture content of the soil, by correcting the change amount reference threshold, a comparison threshold corresponding to the change in the change amount detection value can be specified. Thereby, the magnitude relationship between the comparison detection value and the comparison threshold can be made less susceptible to changes in the moisture content of the soil. Therefore, the presence or absence of the vehicle 7 can be detected more accurately.

[0067] Also, the moisture content of the soil is likely to be different, for example, between winter and the rainy season, and changes greatly over the course of a year. In the present embodiment, since the magnitude relationship between the comparison detection value and the comparison threshold is less susceptible to changes in the moisture content of the soil, it is possible to eliminate the need to adjust the sensitivity for detecting the vehicle 7 throughout the year.

[0068] Also, the correction unit 42 determines the necessity of calculating the correction information by comparing the moisture content specific value with the moisture content reference range. When the correction unit 42 determines that it is necessary to calculate the correction information, it calculates the correction information. Therefore, it is possible to prevent the correction unit 42 from calculating unnecessary correction information, and the processing burden on the correction unit 42 can be reduced.

[0069] Also, the determination unit 43 corrects the change amount reference threshold based on the correction information. The correction information is information that makes the comparison threshold larger than the change amount reference threshold when the moisture content specific value is larger than the upper limit value of the moisture content reference range, and makes the comparison threshold smaller than the change amount reference threshold when the moisture content specific value is smaller than the lower limit value of the moisture content reference range. Therefore, even when the moisture content of the soil changes and the change amount detection value changes, a comparison threshold corresponding to the change in the change amount detection value can be specified.

[0070] Further, the specific moisture content value is the average value of the detection results of the moisture detector 3 over a certain period. Therefore, the frequency of the process for calculating the specific moisture content value can be reduced, and the processing burden on the correction unit 42 can be alleviated. Also, even when the moisture content of the soil changes suddenly, the sudden change in the moisture content can be made less likely to affect the specific moisture content value, and the correction information can be calculated more accurately.

[0071] In the first embodiment, the change amount reference threshold is the value to be corrected, and the change amount detection value is a fixed value. However, the change amount detection value may be the value to be corrected, and the change amount reference threshold may be a fixed value. That is, when the determination unit 43 receives the correction information from the correction unit 42, the determination unit 43 may correct the change amount detection value based on the correction information to specify the comparison detection value, and maintain the change amount reference threshold as it is to specify the comparison threshold.

[0072] When the change amount detection value is the value to be corrected and the change amount reference threshold is a fixed value, the correction value as the correction information is a negative value when the specific moisture content value is greater than the upper limit value of the moisture content reference range, and a positive value when the specific moisture content value is less than the lower limit value of the moisture content reference range. Also, in this case, when the correction value is a positive value, the determination unit 43 makes the comparison detection value larger than the change amount detection value, and when the correction value is a negative value, the determination unit 43 makes the comparison detection value smaller than the change amount detection value. That is, the correction unit 42 calculates, as the correction information, information for making the comparison detection value smaller than the change amount detection value when the specific moisture content value is greater than the upper limit value of the moisture content reference range, and making the comparison detection value larger than the change amount detection value when the specific moisture content value is less than the lower limit value of the moisture content reference range.

[0073] Even in this way, the change amount detection value can be corrected based on the specific moisture content value, and the comparison detection value with the influence of the change in the moisture content of the soil suppressed can be specified. Therefore, the magnitude relationship between the comparison detection value and the comparison threshold is less likely to be affected by the change in the moisture content of the soil, and the presence or absence of the vehicle 7 can be detected more accurately. Also, the adjustment of the sensitivity for detecting the vehicle 7 can be made unnecessary throughout the year.

[0074] Also, in Embodiment 1, a correction value added to or subtracted from a value to be corrected is used as correction information. However, the correction information is not limited to this. For example, a magnification factor for the value to be corrected may be used as correction information. When the change amount reference threshold is the value to be corrected, a magnification factor is used as correction information such that when the specific water content value is greater than the upper limit value of the water content reference range, the comparison threshold is made greater than the change amount reference threshold, and when the specific water content value is less than the lower limit value of the water content reference range, the comparison threshold is made less than the change amount reference threshold. Also, when the change amount detection value is the value to be corrected, a magnification factor is used as correction information such that when the specific water content value is greater than the upper limit value of the water content reference range, the comparison detection value is made less than the change amount detection value, and when the specific water content value is less than the lower limit value of the water content reference range, the comparison detection value is made greater than the change amount detection value. Even in this case, the magnitude relationship between the comparison detection value and the comparison threshold is less likely to be affected by changes in the soil water content, and the presence or absence of the vehicle 7 can be detected more accurately. Also, it is possible to eliminate the need to adjust the sensitivity for detecting the vehicle 7 throughout the year.

[0075] Also, in Embodiment 1, the average value of the detection results of the water content detector 3 over a certain period is used as the specific water content value. However, it is not limited to this. For example, the detection result of the water content detector 3, that is, the water content detection value may be used as the specific water content value as it is.

[0076] Also, in Embodiment 1, the loop coil 2 and the water content detector 3 are buried in the soil at a position farther from the parking lot than the gate device 6. However, the loop coil 2 and the water content detector 3 may be buried in the soil at a position closer to the parking lot than the gate device 6. In this case, the detection area 9 is set above the road surface 8 at a position closer to the parking lot than the gate device 6. In this way, the vehicle 7 when leaving the parking lot can be detected at the entrance and exit of the parking lot.

[0077] In addition, in Embodiment 1, the loop coil 2 and the moisture detector 3 may be buried in the soil at any position farther from the parking lot than the gate device 6 and at any position closer to the parking lot than the gate device 6. In this case, two vehicle detection devices 4 corresponding to the respective loop coils 2 at positions farther from the parking lot than the gate device 6 and at positions closer to the parking lot than the gate device 6 are installed on the side of the road surface 8. In this way, it is possible to detect the entry and exit of the vehicle 7 respectively, or to detect before and after the entry of the vehicle 7 respectively.

[0078] In addition, in Embodiment 1, the information reading device 5 is separate from the vehicle detection device 4. However, the information reading device 5 may be incorporated into the vehicle detection device 4.

[0079] In addition, the function of the vehicle detection device 4 according to Embodiment 1 is realized by a processing circuit. FIG. 9 is a configuration diagram showing a first example of a processing circuit that realizes the function of the vehicle detection device 4 according to Embodiment 1. The processing circuit 100 of the first example is dedicated hardware.

[0080] In addition, the processing circuit 100 corresponds to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof.

[0081] In addition, FIG. 10 is a configuration diagram showing a second example of a processing circuit that realizes the function of the vehicle detection device 4 according to Embodiment 1. The processing circuit 200 of the second example includes a processor 201 and a memory 202.

[0082] In the processing circuit 200, the functions of the vehicle detection device 4 are realized by software, firmware, or a combination of software and firmware. The software and firmware are described as programs and stored in the memory 202. The processor 201 reads and executes the programs stored in the memory 202 to realize the functions of the vehicle detection device 4.

[0083] It can also be said that the programs stored in the memory 202 cause the computer to execute the above-described procedures or methods. Here, the memory 202 is, for example, a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), or an EEPROM (Electrically Erasable and Programmable Read Only Memory). Also, a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, a DVD, etc. also correspond to the memory 202.

[0084] Note that, regarding the above-described functions of the vehicle detection device 4, some may be realized by dedicated hardware, and some may be realized by software or firmware.

[0085] In this way, the processing circuit can realize the above-described functions of the vehicle detection device 4 by hardware, software, firmware, or a combination thereof.

[0086] As described above, the configurations shown in the above embodiments are examples of the content of the present disclosure. The embodiments can be combined with other known technologies. It is possible to omit or change a part of the configuration of the embodiments without departing from the gist of the present disclosure.

Explanation of Reference Numerals

[0087] 1 Vehicle detection system, 2 Loop coil, 3 Moisture content detector, 4 Vehicle detection device, 8 Road surface, 9 Detection area, 41 Change amount detection unit, 42 Correction unit, 43 Determination unit.

Claims

1. A loop coil that is buried in soil on which a road surface is formed and generates a magnetic field in a detection area set above the road surface, a moisture content detector that is buried in the soil within a restricted range where the loop coil is accommodated and detects the moisture content of the soil, a vehicle detection device and comprising: The vehicle detection device includes a change amount detection unit, a correction unit, and a determination unit, The change amount detection unit detects a change amount of the inductance of the loop coil as a change amount detection value, A change amount reference threshold value is stored in the determination unit, The determination unit specifies a comparison detection value from the change amount detection value and a comparison threshold value from the change amount reference threshold value, and compares the comparison detection value with the comparison threshold value to detect the presence or absence of a vehicle in the detection area, The correction unit can calculate correction information based on a moisture content specific value obtained from the detection result of the moisture content detector, The determination unit sets one of the change amount detection value and the change amount reference threshold value as a correction target value and the other as a fixed value, When the determination unit receives the correction information from the correction unit, the determination unit corrects the correction target value based on the correction information, maintains the fixed value as it is, and a vehicle detection system that specifies the comparison detection value and the comparison threshold value.

2. A moisture content reference range is stored in the correction unit, The correction unit compares the moisture content specific value with the moisture content reference range to determine the necessity of calculating the correction information, and calculates the correction information when it is determined that the correction information needs to be calculated. The vehicle detection system according to claim 1.

3. The correction target value is the change amount reference threshold value, The correction unit calculates, as the correction information, information for increasing the comparison threshold value to be greater than the change amount reference threshold value when the moisture content specific value is greater than the upper limit value of the moisture content reference range, and decreasing the comparison threshold value to be smaller than the change amount reference threshold value when the moisture content specific value is smaller than the lower limit value of the moisture content reference range. The vehicle detection system according to claim 2.

4. The correction target value is the change amount detection value, The correction unit calculates, as the correction information, information for making the comparison detection value smaller than the change amount detection value when the specific moisture amount is greater than the upper limit value of the moisture amount reference range, and making the comparison detection value greater than the change amount detection value when the specific moisture amount is smaller than the lower limit value of the moisture amount reference range. The vehicle detection system according to claim 2.

5. The vehicle detection system according to any one of claims 1 to 4, wherein the specific moisture amount is an average value of detection results of the moisture detector over a certain period.

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