Road monitoring system, road monitoring device, road monitoring method, and road monitoring program

Abstract

(Problem) To improve the accuracy of vehicle speed calculation. (Solution) The present invention extracts, on the basis of an optical signal received from an optical fiber cable laid in a road, a first pattern according to the traveling state of a vehicle on the road in a first time range and a first distance range, generates, on the basis of the first pattern, a second pattern in which the number of time points included in the first time range or the number of positions included in the first distance range has been decreased, and calculates the traveling speed of the vehicle on the road on the basis of the second pattern.

Description

[Technical field]

[0001] The present invention relates to a technique for monitoring the operation of a vehicle using, for example, an optical fiber sensor. [Background technology]

[0002] Optical fiber sensing is a technology that uses optical fiber as a sensor for vibration, temperature, strain, etc. One application of optical fiber sensing is bird's-eye view monitoring of traffic flow. Here, bird's-eye view monitoring of traffic flow means bird's-eye view monitoring of traffic flow conditions at a certain point in time (e.g., vehicle speed, congestion, etc.) in a certain geographical area (e.g., a map).

[0003] Generally, traffic flow on expressways is monitored using existing sensors such as traffic meters and CCTV (Closed-circuit Television). However, there is a problem in that a huge number of sensors are required to install sensors so as to avoid blind spots.

[0004] Therefore, optical fiber sensing can be used as a complementary technology to existing sensors, instead of installing a huge number of sensors. In bird's-eye view monitoring of traffic flow using optical fiber sensing, the vibrations generated by the running of vehicles are continuously measured over time and distance to grasp the running trajectory of the vehicles. The traffic flow conditions are monitored by calculating traffic information such as the vehicle speed from this running trajectory. In order to monitor traffic flow with high accuracy, it is necessary to accurately grasp the running trajectory of the vehicles.

[0005] An example of a technology for bird's-eye view monitoring of traffic flow using optical fiber sensing is disclosed in Patent Document 1. In the road monitoring system of Patent Document 1, optical fiber cables laid along the road are used as a sensing medium to detect vibrations caused by vehicles traveling. This enables the road monitoring system of Patent Document 1 to monitor the traffic conditions of vehicles traveling on the road. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2020 / 116030 Summary of the Invention [Problem to be solved by the invention]

[0007] In optical fiber cables laid along roads, the way vibrations are transmitted to the optical fiber cables changes depending on "the method of laying the optical fiber cables in ducts, racks, etc., and the speed and weight of vehicles traveling on the road" (hereinafter referred to as "laying conditions"). For example, when a truck is traveling, large vibrations are generated due to its heavy weight. Therefore, vibrations may be measured not only around the vehicle but also over a wide area. In optical fiber sensing, the vehicle's travel trajectory is extracted from the measured vibration information, and traffic information such as the travel speed is calculated from the travel trajectory. However, in the technology disclosed in Patent Document 1, when vibrations during vehicle travel are measured over a relatively wide area, the travel trajectory becomes unclear and cannot be extracted well, resulting in a problem that accurate traffic information cannot be calculated.

[0008] The present invention has been made in consideration of the above-mentioned problems, and has as its main object to improve the accuracy of vehicle speed calculation. [Means for solving the problem]

[0009] In one aspect of the present invention, a road monitoring system includes an optical fiber cable laid on a road, a receiving means for receiving an optical signal from the optical fiber cable, a pattern extraction means for extracting a first pattern corresponding to a vehicle's traveling state on the road in a first time range and a first distance range based on the received optical signal, a pattern conversion means for generating a second pattern based on the first pattern by reducing the number of time points included in the first time range or the number of positions included in the first distance range, and a calculation means for calculating the vehicle's traveling speed on the road based on the second pattern.

[0010] In one aspect of the present invention, a road monitoring device includes a receiving means for receiving an optical signal from an optical fiber cable laid on a road, a pattern extraction means for extracting a first pattern corresponding to a vehicle's traveling state on the road in a first time range and a first distance range based on the received optical signal, a pattern conversion means for generating a second pattern based on the first pattern by reducing the number of time points included in the first time range or the number of positions included in the first distance range, and a calculation means for calculating the vehicle's traveling speed on the road based on the second pattern.

[0011] In one aspect of the present invention, a road monitoring method extracts a first pattern corresponding to a vehicle's traveling state on a road in a first time range and a first distance range based on an optical signal received from an optical fiber cable laid on the road, generates a second pattern based on the first pattern by reducing the number of points in time included in the first time range or the number of positions included in the first distance range, and calculates the vehicle's traveling speed on the road based on the second pattern.

[0012] In one aspect of the present invention, a non-transitory computer-readable medium stores a road monitoring program that causes a computer included in a road monitoring device to execute the following processes: extracting a first pattern corresponding to the vehicle's driving state on the road in a first time range and a first distance range based on an optical signal received from an optical fiber cable laid on the road; generating a second pattern based on the first pattern by reducing the number of time points included in the first time range or the number of positions included in the first distance range; and calculating the vehicle's driving speed on the road based on the second pattern. Effect of the Invention

[0013] According to the present invention, there is an effect that the accuracy of vehicle speed calculation can be improved. [Brief description of the drawings]

[0014] [Figure 1]1 is a block diagram showing an example of the configuration of a road monitoring system according to a first embodiment of the present invention. [Diagram 2] 4 is a flowchart showing an operation in the first embodiment of the present invention. [Diagram 3] FIG. 11 is a block diagram showing an example of the configuration of a road monitoring system according to a second embodiment of the present invention. [Figure 4] 10 is a flowchart showing an operation in a second embodiment of the present invention. [Diagram 5] 1 is a schematic diagram showing an example of a travel path in which an amount of environmental variation caused by a vehicle traveling on a road is measured by an optical fiber sensor; [Figure 6] FIG. 2 is a schematic diagram showing an example of an ideal travel path; [Figure 7] FIG. 13 is a schematic diagram showing an example of an unclear travel path; [Figure 8] FIG. 13 is a schematic diagram showing an example in which a travel trajectory with an erroneous inclination is extracted from an unclear travel trajectory; [Figure 9] 11A to 11C are schematic diagrams showing an operation of clarifying an unclear travel path. [Figure 10] FIG. 11 is a block diagram showing an example of the configuration of a road monitoring system according to a third embodiment of the present invention. [Figure 11] 13 is a flowchart showing an operation in a third embodiment of the present invention. [Figure 12] 1 is a schematic diagram showing an example of a data width in the distance and time directions of a travel trajectory; FIG. [Figure 13] FIG. 13 is a block diagram showing an example of the configuration of a road monitoring system according to a fourth embodiment of the present invention. [Figure 14] 13 is a flowchart showing an operation in a fourth embodiment of the present invention. [Figure 15] 11A to 11C are schematic diagrams showing an operation of clarifying an unclear travel path. [Figure 16] 1 is a block diagram showing an example of a hardware configuration capable of realizing a road monitoring device in each embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In all the drawings, the same components are denoted by the same reference numerals, and the description thereof will be omitted as appropriate. [First embodiment] A first embodiment of the present invention, which is the basis of each embodiment of the present invention, will be described. [Configuration Description] Fig. 1 is a block diagram showing an example of the configuration of a road monitoring system according to a first embodiment of the present invention. As shown in Fig. 1, a road monitoring system (100) according to the present embodiment includes an optical fiber cable (11) and a road monitoring device (120).

[0016] The optical fiber cable (11) is an optical fiber cable for communication, and is laid on the road.

[0017] The road monitoring device (120) includes a receiving unit (150), a pattern extracting unit (220), a pattern converting unit (230), and a calculating unit (240).

[0018] The receiving unit 150 receives an optical signal from the optical fiber cable 11. Here, the optical signal received by the receiving unit 150 is a time series of detection values ​​(hereinafter referred to as "environmental fluctuations") detected in the optical fiber cable 11. The environmental fluctuations change according to vibrations occurring in the environment in which the optical fiber cable 11 is installed. The environmental fluctuations are, for example, backscattered light of a signal transmitted to the optical fiber cable 11. The time series of the environmental fluctuations is a superposition of pulses caused by vibrations occurring independently at each position in the length direction of the optical fiber cable 11, and the pulse width is sufficiently short compared to the time width required for the pulse to propagate, and the pulses are sufficiently coarse. In this case, since the propagation speed of the pulses is constant, the timing at which each pulse is detected can be associated with the position at which each pulse is generated in the optical fiber cable 11. When a vehicle passes a specific position on a road, vibrations occur in the road, and pulses of the environmental fluctuations are generated in the optical fiber cable 11 laid on the road due to the road vibrations.

[0019] The pattern extraction unit (220) extracts a first pattern according to a vehicle traveling state on a road in a first time range and a first distance range based on the received optical signal, where the first pattern is a time series of environmental variation amounts in which each environmental variation amount is associated with its occurrence position.

[0020] The pattern conversion unit (230) generates a second pattern by reducing the number of time points included in the first time range or the number of positions included in the first distance range based on the first pattern.

[0021] Here, the "distance range" refers to a distance range in the length direction of the optical fiber cable (11). The "number of positions" refers to the number of distance units included in a certain "distance range". The number of "distance units" is determined when associating the timing at which each pulse is detected with the generation position of each pulse in the optical fiber cable (11), as described above. For example, a case will be described where the "distance range" is the first distance range. In this case, if the width of the first distance range is 1 kilometer and the "distance unit" in the length direction of the optical fiber cable (11) is 10 meters, the number of positions included in the first distance range is 1000 / 10=100, or 100.

[0022] Moreover, a "time range" is a time range in which a series of time series of environmental fluctuations are detected. A "number of time points" is the number of detection periods between each time series included in a certain "time range." For example, a case will be described where the "time range" is a first time range. In this case, if the width of the first time range is 10 minutes and the detection period between each time series is 1 minute, the number of time points included in the first time range is 10 / 1=10, or 10.

[0023] Similarly to the first pattern, the second pattern is a time series of environmental fluctuation amounts in which each environmental fluctuation amount is associated with its occurrence position. However, the number of environmental fluctuation amounts included in the time series of environmental fluctuation amounts (the number of positions and Number of points ) are different.

[0024] The calculation unit (240) calculates the vehicle's traveling speed on the road based on the second pattern. Here, the calculation unit (240) detects a change over time in the location where vibration occurs in the optical fiber cable (11) (i.e., the traveling of the vehicle) by continuously detecting a time series of the environmental fluctuation amount. The calculation unit (240) calculates the vehicle's traveling speed based on, for example, the traveling trajectory of the vehicle in the second pattern. The calculation unit (240) calculates the vehicle's traveling speed by, for example, linearly approximating the traveling trajectory. [Explanation of operation] FIG. 2 is a flow chart showing the operation in the first embodiment of the present invention.

[0025] First, the pattern extraction unit (220) extracts a first pattern corresponding to the vehicle's traveling state on the road in a first time range and a first distance range, based on the received optical signal (step S210).

[0026] Next, the pattern conversion unit (230) generates a second pattern by reducing the number of time points included in the first time range or the number of positions included in the first distance range based on the first pattern (step S220).

[0027] Next, the calculation unit (240) calculates the vehicle's traveling speed on the road based on the second pattern (step S230). [Effect description] As described above, in the road monitoring device (120) of this embodiment, the pattern extraction unit (220) extracts a first pattern according to the vehicle's traveling state on the road in the first time range and the first distance range based on the received optical signal. Then, the pattern conversion unit (230) generates a second pattern by reducing the number of time points included in the first time range or the number of positions included in the first distance range based on the first pattern. Here, the vehicle's traveling trajectory in the second pattern is narrower than the vehicle's traveling trajectory in the first pattern. The calculation unit (240) calculates the vehicle's traveling speed on the road more accurately based on the second pattern, which is narrower than the vehicle's traveling trajectory in the first pattern, than when based on the first pattern. Therefore, the road monitoring device (120) of this embodiment has an effect of improving the accuracy of vehicle speed calculation.

[0028] The pattern conversion unit (230) may determine the number of time points included in the first time range or the number of positions included in the first distance range so that the vehicle travel trajectory in the second pattern does not disappear. In this case, the road monitoring device (120) in this embodiment has an advantage of being able to suppress failure in calculating the vehicle speed.

[0029] Also, the optical signal in a second time range included in the first time range or in a second distance range included in the first distance range may be set to zero. In this case, the road monitoring device (120) in this embodiment has an advantage of being able to reduce the amount of calculation and memory capacity. [Second embodiment] A second embodiment of the present invention based on the first embodiment of the present invention will be described. [Configuration Description] FIG. 3 is a block diagram showing an example of the configuration of a road monitoring system according to a second embodiment of the present invention. The road monitoring system (105) of this embodiment acquires a time series of detection values ​​(environmental fluctuation amounts) detected in the optical fiber cable (11), which change according to vibrations occurring in the environment in which the optical fiber cable (11) is laid. Here, the environmental fluctuation amounts are the magnitude of backscattered light of a transmission signal in the optical fiber cable (11). In this embodiment, when a vehicle passes at a specific position on the road, vibrations of the road occur, and pulses of the environmental fluctuation amounts occur in the optical fiber cable (11) laid on the road due to the road vibrations. The road monitoring system (105) then continuously detects the time series of the environmental fluctuation amounts to detect a time change in the position where the vibrations occur in the optical fiber cable (11) (i.e., the running of the vehicle). The road monitoring system (105) then calculates traffic information including the running speed of the vehicle based on the time series of the environmental fluctuation amounts. The traffic information may further include information such as vehicle intervals, vehicle acceleration, the number of vehicles, or the running direction of the vehicles. The road monitoring system (105) includes an optical fiber cable (11) and a road monitoring device (125).

[0030] The road monitoring device (125) has a transmitter (13), a circulator (14), a receiving section (155), and an output section (113).

[0031] The transmitter (13) transmits light pulses through an optical path to a circulator (14).

[0032] The circulator (14) outputs the optical pulse transmitted from the transmitter (13) to the optical fiber cable (11), and outputs the backscattered light of the optical pulse returning from the optical fiber cable (11) to the receiving section (155) via an optical path.

[0033] The receiving unit (155) calculates traffic information based on the backscattered light received from the circulator (14), and outputs the calculated traffic information to the output unit (113).

[0034] The output unit (113) outputs the traffic information to the outside.

[0035] The receiving unit (155) has a detector (16), a data processing unit (17), a memory (18), a data format changing unit (195) (an example of a pattern extraction unit and a pattern conversion unit), a trajectory extraction unit (110) (an example of a calculation unit), a data extraction unit (111) (an example of a calculation unit), and a traffic information calculation unit (112).

[0036] The detector (16) converts the backscattered light of the received optical pulse into an electrical signal, and outputs the converted electrical signal to a data processing unit (17).

[0037] The data processing unit (17) converts the input analog electrical signal into digital data to obtain the amount of environmental fluctuation, and outputs it to a memory (18).

[0038] The memory (18) accumulates data (environmental variation amount data) representing a time series of environmental variation amounts for a predetermined period of time in a format that allows calculation of the position at which each environmental variation amount occurs.

[0039] The data format conversion unit (195) determines the distance and time range for which traffic information should be calculated (traffic information calculation range). The data format conversion unit (195) also derives a range of environmental variation data that corresponds to the distance and time range (trajectory extraction range) used to extract a vehicle's travel trajectory, which is obtained by extending the traffic information calculation range in the distance and time directions. The data format conversion unit (195) also copies the environmental variation data of the derived range to a storage area for the trajectory extraction range in the memory (18). The data format conversion unit (195) also reduces the copied environmental variation data so that the distance width and time width of the trajectory extraction range are the same as those before the extension.

[0040] A locus extraction unit (110) extracts a traveling locus based on the environmental variation data stored in a storage area for the locus extraction range.

[0041] A data extraction unit (111) calculates the vehicle's traveling speed based on the extracted data representing the traveling locus.

[0042] A traffic information calculation unit (112) generates traffic information based on the vehicle's traveling speed, the vehicle's traveling path, and the like. [Explanation of operation] The operation of the road monitoring system (105) will be described with reference to Figures 3 and 4. Figure 4 is a flow chart showing the operation in the second embodiment of the present invention.

[0043] First, the data processing unit (17) acquires a time series of environmental fluctuations caused by vibrations applied to the optical fiber cable (11) by the running of the vehicle (step S01). Here, based on the time difference between the transmission of an optical pulse and the reception of backscattered light, it is possible to associate the timing at which each environmental fluctuation is detected with the location at which each environmental fluctuation occurs in the optical fiber cable (11). Thus, the data processing unit (17) makes it possible to calculate the location at which each environmental fluctuation occurs, for example, by associating the amount of environmental fluctuation at the time when an optical pulse is transmitted with information on the time when the optical pulse is transmitted.

[0044] Next, the memory (18) accumulates the acquired environmental variation amount data for a predetermined period of time in a format that allows calculation of the occurrence position of each environmental variation amount (step S02). The memory (18) accumulates environmental variation amount data in which, for example, the amount of environmental variation at the time when an optical pulse is transmitted is associated with information on the time when the optical pulse is transmitted.

[0045] Next, the data format conversion unit 195 determines the traffic information calculation range (step S03). The data format conversion unit 195 determines the traffic information calculation range based on, for example, settings held by the road monitoring device 125.

[0046] Next, the data format conversion unit (195) derives a range of environmental variation data corresponding to the trajectory extraction range. Then, the data format conversion unit (195) copies the derived range of environmental variation data to a storage area for the trajectory extraction range in the memory (18) (step S04). Here, the trajectory extraction range includes the traffic information calculation range and is wider than the traffic information calculation range.

[0047] Next, the data format change unit (195) reduces the copied environmental variation data so that the distance width and time width of the trajectory extraction range are the same as those before the extension (step S05). Here, the traffic information calculation range is, for example, a range of 1 km and 1 minute when calculating traffic information including an average vehicle speed of 1 km (kilometer) x 1 minute, and a range of 2 km and 2 minutes when calculating traffic information of 2 km x 2 minutes. For example, when the distance width and time width of the trajectory extraction range are each extended to twice the traffic information calculation range, the environmental variation data included in the storage area of ​​the trajectory extraction range is thinned out by half in both the distance and time directions. More specifically, for example, environmental variation data corresponding to odd-numbered distances and odd-numbered times is deleted.

[0048] Next, the trajectory extraction unit (110) extracts a traveling trajectory based on the environmental variation data stored in the storage area of ​​the trajectory extraction range (step S06). The trajectory extraction unit (110) extracts the traveling trajectory, for example, by linearly approximating a band of values ​​(high values) larger than a predetermined threshold value in the environmental variation data distributed on a plane whose axes are distance and time, using the least squares method.

[0049] Next, the data extraction unit 111 calculates the vehicle's traveling speed based on the extracted data representing the traveling trajectory (step S07). The data extraction unit 111 calculates the vehicle's traveling speed based on, for example, the gradient of the above-mentioned approximation line.

[0050] Next, the traffic information calculation unit (112) generates traffic information including, for example, an average vehicle speed, based on the vehicle travel speed calculated in step S07 and the vehicle travel path extracted in step S06 (step S08). [Effect description] Next, the effect of this embodiment will be described with reference to Figs. 5 to 9. In Figs. 5 to 9, the vertical axis of the graph is time, and the horizontal axis of the graph is distance. In the graphs of Figs. 5 to 9, the solid line represents the vehicle's travel trajectory, the shaded band represents the high value of the environmental variation amount, and the dashed line represents the vehicle's travel trajectory extracted from the environmental variation amount. Fig. 5 is a schematic diagram showing an example of a travel trajectory in which the environmental variation amount generated by the vehicle traveling on the road is measured by an optical fiber sensor. Fig. 6 is a schematic diagram showing an example of an ideal travel trajectory. Fig. 7 is a schematic diagram showing an example of an unclear travel trajectory. Fig. 8 is a schematic diagram showing an example in which a travel trajectory with an incorrect inclination is extracted from an unclear travel trajectory. Fig. 9 is a schematic diagram showing an operation of clarifying an unclear travel trajectory.

[0051] First, a general road monitoring technology will be described. As shown in Fig. 5, a vehicle travels along an optical fiber cable. In this case, ideally, the travel trajectory is extracted at a position and with a gradient that coincides with the high value of the environmental variation data, as shown by the dashed line in Fig. 6. However, depending on the laying conditions of the optical fiber cable, environmental variation data with a wide range may be acquired, as shown in Fig. 7, making the travel trajectory unclear. In such a situation, the travel trajectory may be extracted with a gradient different from the environmental variation data, as shown by the dashed line in Fig. 8, and erroneous traffic information may be calculated.

[0052] On the other hand, in this embodiment, as shown in Fig. 9, the traffic information calculation range is extended in terms of both distance and time, and a copy of the environmental variation amount data in the extended range is reduced to the same size as before the extension, thereby extracting a travel trajectory. As a result, even if the environmental variation amount showing a high value is wide and unclear, the width of the travel trajectory is narrowed and clarified. As a result, this embodiment has the effect of extracting a travel trajectory with a correct slope from the environmental variation amount data, and improving the calculation accuracy of traffic information including information related to vehicle speed.

[0053] The contents of this embodiment are not limited to the above description.

[0054] In the above description, an example is shown in which the environmental fluctuation data included in the traffic information calculation range is extended in both the distance and time directions and reduced to the same size as before the extension. However, in this embodiment, the data may be extended only in the distance direction or only in the time direction and reduced only in the extended direction. In this case, the embodiment has the effect of reducing the amount of calculation.

[0055] In the above description, the traffic information calculation unit (112) generates traffic information including an average speed and the like based on the travel path in step S07, but the travel path may be output without generating traffic information. In this case, the present embodiment has an advantage that the travel status of each vehicle can be monitored. [Third embodiment] A third embodiment of the present invention based on the second embodiment of the present invention will be described. [Configuration Description] 10 is a block diagram showing an example of the configuration of a road monitoring system according to the third embodiment of the present invention. The road monitoring system (106) of this embodiment acquires a time series of environmental fluctuations in an optical fiber cable (11). The road monitoring system (106) includes the optical fiber cable (11) and a road monitoring device (126).

[0056] The road monitoring device (126) has a transmitter (13), a circulator (14), a receiving section (156), and an output section (113).

[0057] The receiving unit (156) has a detector (16), a data processing unit (17), a memory (18), an extension amount calculation unit (80) (an example of a pattern conversion unit), a data format conversion unit (196) (an example of a pattern extraction unit and a pattern conversion unit), a trajectory extraction unit (110) (an example of a calculation unit), a data extraction unit (111) (an example of a calculation unit), and a traffic information calculation unit (112).

[0058] The extension amount calculation unit (80) extracts the number of positions or the number of points in time (referred to as a "trajectory distance width" and a "trajectory time width") that indicate high values ​​of the environmental variation amount data that are consecutively arranged in the direction of distance or time, respectively, included in the traveling trajectory in the environmental variation amount data stored in the memory (18). Then, the extension amount calculation unit (80) acquires the minimum trajectory distance width and the minimum trajectory time width. Then, the extension amount calculation unit (80) determines the smaller of the minimum trajectory distance width and the minimum trajectory time width as the extension ratio. Here, the extension ratio is an extension ratio of the distance width and the time width of the trajectory extraction range with respect to the traffic information calculation range, which is used to determine the trajectory extraction range in step S09 (corresponding to step S04 in the first embodiment) described later. Then, the extension ratio is determined to avoid a case where the distance width and the time width of the traveling trajectory after the reduction become less than 1 as a result of the reduction of the trajectory extraction range in step S05 (same as in the first embodiment) described later, and the traveling trajectory is lost. However, in this embodiment, when the extension ratio becomes 1, the trajectory extraction range is not substantially extended or reduced. Therefore, in this embodiment, the extension ratio is set to 2 or more. That is, in this embodiment, it is set to be possible to use environmental fluctuation amount data having resolution in the distance and time directions such that the minimum trajectory distance width and the minimum trajectory time width are both 2 or more. Alternatively, in this embodiment, when the extension ratio becomes 1, the occurrence of an error may be displayed, and subsequent processing may be interrupted.

[0059] The data format conversion unit (196) determines a traffic information calculation range, and determines a trajectory extraction range based on the extension ratio determined by the extension amount calculation unit (80). Then, the data format conversion unit (196) derives a range of environmental variation amount data corresponding to the trajectory extraction range, and copies the environmental variation amount data of the derived range to a storage area for the trajectory extraction range on the memory (18).

[0060] The other configurations are the same as those of the second embodiment. [Explanation of operation] The operation of the road monitoring system (106) will be described with reference to Figures 10 and 11. Figure 11 is a flow chart showing the operation in the third embodiment of the present invention.

[0061] The operations in steps S01 and S02 are the same as those in the second embodiment.

[0062] Following step S02, the extension amount calculation unit (80) extracts the trajectory distance width and trajectory time width included in the traveling trajectory in the environmental variation data corresponding to the traffic information calculation range stored in the memory (18), and obtains the minimum trajectory distance width and the minimum trajectory time width.Then, the extension amount calculation unit (80) determines the smaller of the minimum trajectory distance width and the minimum trajectory time width as the extension ratio of the trajectory extraction range to the traffic information calculation range (step S09).Here, for example, if the extension ratio is 2, the distance width and time width of the trajectory extraction range are each extended to twice the traffic information calculation range.

[0063] Next, the data format conversion unit (196) determines the trajectory extraction range based on the extension ratio determined in step S09. Then, the data format conversion unit (196) derives the range of environmental variation amount data corresponding to the trajectory extraction range, copies the environmental variation amount data of the derived range to the storage area of ​​the trajectory extraction range in the memory (18) (step S10), and proceeds to the processing of step S05.

[0064] The operations in steps S05 to S08 are the same as those in the second embodiment.

[0065] The other operations are the same as those in the second embodiment. [Effect description] Next, the effect of this embodiment will be described with reference to Fig. 12. Fig. 12 is a schematic diagram showing an example of the data width in the distance and time directions of a travel trajectory. In Fig. 12, the right side shows that the traffic information calculation range shown on the left side is divided into each environmental variation data. That is, each area divided in a lattice shape shows each environmental variation data.

[0066] In this embodiment, the minimum trajectory distance width and minimum trajectory time width contained in the environmental variation data are obtained. The smaller of these values ​​is then set as the extension factor, and the distance width and time width of the traffic information calculation range are multiplied by this extension factor to calculate the distance width and time width of the trajectory extraction range. The environmental variation data is then divided for each distance and time for which traffic information is calculated, and the divided data is extended to have a distance width and time width multiplied by the extension factor, thereby calculating the environmental variation data of the trajectory extraction range. The environmental variation data of the trajectory extraction range is then reduced to have the same size as before the extension. As a result, the reduction process is performed without erasing the driving trajectory, Environmental change data This makes it possible to narrow and clarify the vehicle travel trajectory that has become unclear due to the widening of the trajectory, making it easier to extract the correct slope of the trajectory from the environmental variation data.

[0067] In this embodiment, as shown in FIG. 12, the distance width and time width included in the environmental variation data stored in the memory (18) are extracted, and the minimum trajectory distance width and the minimum trajectory time width are obtained. Then, the extension amount calculation unit (80) determines the smaller value of the minimum trajectory distance width and the minimum trajectory time width as the extension magnification. In the example shown in FIG. 12, of the two traveling trajectories, the left traveling trajectory has a narrower width, and both its minimum trajectory distance width and minimum trajectory time width are 2, and the extension magnification is 2. When the width of the traffic information calculation range is 1 km×1 minute, the distance width of the trajectory extraction range is 2 km, and the time width is 2 minutes. Then, as described in the second embodiment with reference to FIG. 9, the traffic information calculation range is extended in terms of distance and time, and the copy of the environmental variation data in the extended range is reduced to the same size as before the extension, and then the traveling trajectory is extracted. Thus, even if the travel trajectory in the traffic information calculation range is wide and unclear, the width of the travel trajectory in the reduced trajectory extraction range is narrowed and clarified. As a result, this embodiment has an effect of extracting a travel trajectory with a correct slope from the environmental variation amount data without losing the travel trajectory after reducing the trajectory extraction range, and improving the calculation accuracy of traffic information including information related to vehicle speed.

[0068] The contents of this embodiment are not limited to the above description.

[0069] In the above description, an example is shown in which the environmental fluctuation data included in the traffic information calculation range is extended in both the distance and time directions and reduced to the same size as before the extension. However, in this embodiment, the data may be extended only in the distance direction or only in the time direction and reduced only in the extended direction. In this case, the present embodiment has the effect of reducing the amount of calculation.

[0070] In the above description, the traffic information calculation unit (112) generates traffic information such as an average speed based on the travel path in step S07, but the travel path may be output without generating traffic information. In this case, the present embodiment has an advantage that the travel status of each vehicle can be monitored.

[0071] In the above description, an example is shown in which the extension ratio is calculated from the travel trajectory having the smallest trajectory width of the environmental fluctuation amount data in the traffic information calculation range, but the extension ratio may be calculated from the travel trajectory having the smallest trajectory width of all the accumulated environmental fluctuation amount data. In this case, the present embodiment has the effect of reducing the amount of calculation. [Fourth embodiment] A fourth embodiment of the present invention based on the second embodiment of the present invention will be described. [Configuration Description] 13 is a block diagram showing an example of the configuration of a road monitoring system according to a fourth embodiment of the present invention. The road monitoring system (107) of this embodiment acquires a time series of environmental fluctuations in an optical fiber cable (11). The road monitoring system (107) includes the optical fiber cable (11) and a road monitoring device (127).

[0072] The road monitoring device (127) has a transmitter (13), a circulator (14), a receiving section (157), and an output section (113).

[0073] The receiving unit (157) has a detector (16), a data processing unit (17), a memory (18), a data dividing unit (1100) (an example of a pattern conversion unit), a data format changing unit (197) (an example of a pattern extraction unit and a pattern conversion unit), a trajectory extraction unit (110) (an example of a calculation unit), a data extraction unit (111) (an example of a calculation unit), and a traffic information calculation unit (112).

[0074] A data division unit (1100) divides the environmental fluctuation amount data accumulated in the memory (18) into divided data for each traffic information calculation range.

[0075] The data format conversion unit (197) extends the divided data corresponding to the traffic information calculation range in the distance and time directions by a predetermined extension ratio. The data format conversion unit (197) also fills the environmental fluctuation amount data in the extended range of the divided data with zeros. The data format conversion unit (197) also reduces the extended divided data so that the distance width and time width of the extended divided data are the same as those before the extension.

[0076] The other configurations are the same as those of the second embodiment. [Explanation of operation] The operation of the road monitoring system (107) will be described with reference to Figures 13 and 14. Figure 14 is a flow chart showing the operation in the fourth embodiment of the present invention.

[0077] The operations in steps S01 and S02 are the same as those in the second embodiment.

[0078] Following step S02, the data division unit (1100) divides the environmental fluctuation amount data accumulated in the memory (18) into divided data for each traffic information calculation range (step S11).

[0079] Next, the data format changing unit (197) extends the divided data corresponding to the traffic information calculation range in the distance and time directions by a predetermined extension ratio (step S12).

[0080] Next, the data format changing unit (197) fills the environmental variation data in the extended range of the divided data with zeros (step S13). Here, "filling with zeros" means that when the detection value in the environmental variation data varies against the background of the detection value of the noise level, the environmental variation data in the extended range of the divided data is set to the value of the background noise level. When the detection value of the background noise level can be approximated by zero, the value of the background noise level to be set may be zero. Alternatively, the environmental variation data in the extended range of the divided data may be set to a series of values ​​that can be taken by environmental noise data measured at a place and time when the vehicle is not traveling.

[0081] Next, the data format changing unit (197) reduces the extended divided data so that the distance width and time width of the extended divided data are the same as those before the extension (step S14), and proceeds to the process of step S06. Here, the traffic information calculation range is, for example, a range of 1 km and 1 minute when calculating traffic information including an average vehicle speed of 1 km x 1 minute, and a range of 2 km and 2 minutes when calculating traffic information of 2 km x 2 minutes.

[0082] The operations in steps S06, S07, and S08 are the same as those in the second embodiment. [Effect description] Next, the effects of this embodiment will be described with reference to Fig. 15. Fig. 15 is a schematic diagram showing the operation of clarifying an unclear travel path.

[0083] In this embodiment, as shown in FIG. 15, the environmental variation data is divided into divided data for each traffic information calculation range (the left part of FIG. 15). Then, the divided data is extended by a predetermined extension ratio while filling the divided data in the extended range (the upper left, upper right, and lower right areas in the right part of FIG. 15) with zeros. Then, the extended divided data is reduced to the same size as before the extension, and the travel trajectory is extracted. Thereby, even if the environmental variation indicating a high value spreads and becomes unclear, the width of the travel trajectory is narrowed and clarified. As a result, this embodiment has the effect of extracting a travel trajectory with a correct slope from the environmental variation data, and improving the calculation accuracy of traffic information including information related to vehicle speed.

[0084] In addition, in this embodiment, since the environmental variation data corresponding only to the traffic information calculation range is used, the amount of environmental variation data stored in the memory is reduced, and therefore the required memory capacity can be reduced. That is, in the upper left, upper right, and lower right areas in the right part of Fig. 15, the environmental variation data is substituted with zero.

[0085] The contents of this embodiment are not limited to the above description.

[0086] In the above description, an example is shown in which the environmental fluctuation data included in the traffic information calculation range is extended in both the distance and time directions and reduced to the same size as before the extension. However, in this embodiment, the data may be extended only in the distance direction or only in the time direction and reduced only in the extended direction. In this case, the embodiment has the effect of reducing the amount of calculation.

[0087] In the above description, the traffic information calculation unit (112) generates traffic information including an average speed and the like based on the travel path in step S07, but the travel path may be output without generating traffic information. In this case, the present embodiment has an advantage that the travel status of each vehicle can be monitored.

[0088] FIG. 16 is a block diagram showing an example of a hardware configuration capable of realizing a road monitoring device in each embodiment of the present invention.

[0089] The road monitoring device 901 includes a storage device 902, a CPU (Central Processing Unit) 903, a keyboard 904, a monitor 905, and an I / O (Input / Output) device 908, which are connected by an internal bus 906. The storage device 902 stores operation programs for the CPU 903 of the receiving unit 150, the pattern extracting unit 220, the pattern converting unit 230, the calculating unit 240, the receiving units 155, 156, 157, etc. (hereinafter referred to as "receiving units, etc."). The CPU 903 controls the entire road monitoring device 901, executes the operation programs stored in the storage device 902, and executes the programs of the receiving units, etc., and transmits and receives data by the I / O device 908. The internal configuration of the road monitoring device 901 described above is an example. The road monitoring device 901 may have a device configuration in which the keyboard 904 and the monitor 905 are connected as necessary.

[0090] The road monitoring device 901 in each of the above-mentioned embodiments of the present invention may be realized by a dedicated device, but can also be realized by a computer (information processing device) except for the operation of the hardware in which the I / O device 908 executes communication with the outside. In this case, the computer reads the software program stored in the storage device 902 into the CPU 903 and executes the read software program in the CPU 903. In the case of each of the above-mentioned embodiments, the software program includes the above-mentioned programs shown in Figs. 1, 3, 10, and 13, road monitoring device It is sufficient that the description can realize the functions of each part of the above. However, it is also assumed that each part includes hardware as appropriate. In such a case, the software program (computer program) in question can be considered to constitute the present invention. Furthermore, a computer-readable storage medium storing the software program in question can also be considered to constitute the present invention.

[0091] The present invention has been described above by way of example with reference to the above-mentioned embodiments and their modifications. However, the technical scope of the present invention is not limited to the scope described in the above-mentioned embodiments and their modifications. It is clear to those skilled in the art that various modifications or improvements can be made to the embodiments. In such cases, new embodiments with such modifications or improvements may also be included in the technical scope of the present invention. This is clear from the matters described in the claims.

[0092] The present invention can be used in applications of optical fiber sensing such as monitoring road traffic flow, and also in monitoring the movement of moving objects such as train operation monitoring. [Explanation of symbols]

[0093] 100, 105, 106, 107 Road monitoring system 11 Optical fiber cable 120, 125, 126, 127 Road monitoring device 13 Transmitter 14 Circulator 150, 155, 156, 157 Receiver 16 Detectors 17 Data Processing Section 18 Memory 195, 196, 197 Data format change section 110 Trajectory extraction part 111 Data Extraction Unit 112 Traffic information calculation section 113 Output section 80 Extension amount calculation section 1100 Data division part 220 Pattern Extraction Unit 230 Pattern Conversion Unit 240 Calculation Unit

Claims

1. A receiving means for receiving an optical signal from an optical fiber cable laid on a road; a pattern extraction means for extracting a first pattern corresponding to a vehicle traveling state on the road within a first time range and a first distance range based on the received optical signal; a pattern conversion means for multiplying a first time range and a first distance range by an extension ratio, causing the pattern extraction means to extract a first pattern corresponding to the first time range and the first distance range multiplied by the extension ratio, and reducing the first pattern corresponding to the first time range and the first distance range multiplied by the extension ratio by the extension ratio, thereby generating a second pattern; a calculation means for calculating a vehicle traveling speed on the road based on the second pattern; Equipped with A road monitoring device in which the extension ratio is the smaller of the minimum trajectory distance width and the minimum trajectory time width of the optical signal.

2. The optical signal is the backscattered light of the signal transmitted to the optical fiber cable. A road monitoring device according to claim 1.

3. The calculation means calculates the traveling speed of the vehicle based on a traveling locus of the vehicle in the second pattern.

3. A road monitoring device according to claim 1 or 2.

4. The calculation means calculates the traveling speed of the vehicle by linearly approximating the traveling locus. A road monitoring device according to claim 3.

5. The optical signal is set to zero in a second time range included in the first time range or in a second distance range included in the first distance range. A road monitoring device according to any one of claims 1 to 4.

6. A road monitoring device according to any one of claims 1 to 5; The optical fiber cable. A road monitoring system equipped with

7. extracting a first pattern corresponding to a vehicle running state on the road within a first time range and a first distance range based on an optical signal received from an optical fiber cable laid on the road; performing pattern conversion to generate a second pattern by multiplying a first time range and a first distance range by an extension ratio, extracting a first pattern corresponding to the first time range and the first distance range multiplied by the extension ratio, and reducing the first pattern corresponding to the first time range and the first distance range multiplied by the extension ratio by the extension ratio; Calculating a traveling speed of the vehicle on the road based on the second pattern; A road monitoring method, wherein the extension ratio is the smaller of the minimum trajectory distance width and the minimum trajectory time width of the optical signal.

8. The computer in the road monitoring device has extracting a first pattern corresponding to a traveling state of a vehicle on a road within a first time range and a first distance range based on an optical signal received from an optical fiber cable laid on the road; a pattern conversion process of multiplying a first time range and a first distance range by an extension ratio, extracting a first pattern corresponding to the first time range and the first distance range multiplied by the extension ratio, and reducing the first pattern corresponding to the first time range and the first distance range multiplied by the extension ratio by the extension ratio, thereby generating a second pattern; calculating a vehicle speed on the road based on the second pattern; Run the command, A road monitoring program in which the extension ratio is the smaller of the minimum trajectory distance width and the minimum trajectory time width of the optical signal.

Images