JP2010134662A - System and method for detecting deterioration - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a deterioration detection system for detecting deterioration of communicating performance of a roadside machine to perform maintenance thereof before becoming uncommunicable due to failure. <P>SOLUTION: A traffic state acquisition part 15 obtains traffic state information for traffic state within a receiving area A based on sensor information obtained form a vehicle sensor 7 set on a road. A prediction part 16 predicts, based on the obtained traffic state information, a receiving scheduled frequency Q or the number of receipt of radio signal transmitted from an onboard machine 2 existing in the receiving area A by a roadside machine 1 in a predetermined period. A deterioration detection part 17 estimates deterioration of the communicating performance of the roadside machine 1 by comparing the receiving scheduled frequency Q with an actual receiving frequency or the number of actual receipt of the radio signal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a deterioration detection system and a deterioration detection method for detecting deterioration in communication performance of a roadside communication device.

In recent years, for the purpose of promoting traffic safety and preventing traffic accidents, an intelligent road traffic system (ITS) that receives information from infrastructure devices installed on the road and uses this information to improve vehicle safety. (Intelligent Transport System) has been studied (for example, see Patent Document 1).
This traffic system is mainly realized by a plurality of roadside communication devices as communication devices on the infrastructure side and an in-vehicle communication device (mobile terminal) that is a communication device mounted on each vehicle. Communication combinations include road-to-road communication between roadside communication devices, road-to-vehicle (or vehicle-road) communication between roadside communication devices and in-vehicle communication devices, and vehicle-to-vehicle communication between in-vehicle communication devices. .

Japanese Patent No. 2806801

  A roadside communication device is installed at each intersection of a road, for example, and other roadside communication devices installed in the neighborhood or the same intersection receive information transmitted from a roadside communication device installed at a certain intersection Can do. Such road-to-road communication is performed, and road-to-vehicle communication is performed between the roadside communication device and the vehicle-mounted communication device of the vehicle traveling around the roadside communication device. It becomes possible to notify the information of the part which is a blind spot beforehand, and the traffic accident in an intersection can be prevented beforehand.

However, roadside communication devices are installed outdoors, for example at intersections, and when used for a long period of time, analog circuits and amplifiers etc. provided in roadside communication devices deteriorate, the frequency fluctuates, The communication area decreases and the communication margin decreases.
If the roadside communication device is left as it is, the deterioration progresses, and wireless communication with other communication devices becomes impossible (fails). In this case, many reception errors occur in the communication device that is in communication with the faulty roadside communication device. For example, the occurrence rate of the reception error is larger than a predetermined threshold value. By detecting this, the other communication device can detect that the roadside communication device has failed.

However, when repair or replacement is performed after detecting that a roadside communication device has failed and communication is disabled, the operation of the roadside communication device may be suspended for a long period of time.
Therefore, the present invention can detect the deterioration of the communication performance of the roadside communication device, and enables the maintenance of the roadside communication device before the roadside communication device fails and becomes unable to communicate. It aims to provide a method.

  (1) The present invention is a deterioration detection system that detects a deterioration in communication performance of a roadside communication device having a reception area on a road that can receive a radio signal transmitted from an in-vehicle communication device. A traffic condition acquisition unit for acquiring traffic condition information relating to the traffic condition in the reception area based on sensor information obtained from an installed vehicle sensor; and in the reception area based on the acquired traffic condition information A radio signal transmitted from the in-vehicle communication device existing in the vehicle, the prediction unit for predicting the scheduled number of times the roadside communication device receives within a predetermined period, the scheduled reception number, and the transmission from the in-vehicle communication device A deterioration test for estimating the deterioration of the communication performance of the roadside communication device by comparing the received radio signal with the actual number of times the roadside communication device actually received within the predetermined period. Characterized in that a part.

According to the present invention, when the traffic condition acquisition unit acquires the traffic condition information related to the traffic condition in the reception area based on the sensor information obtained from the vehicle sensor, the prediction unit is based on the acquired traffic condition information. Thus, the estimated number of times the roadside communication device receives the radio signal transmitted from the in-vehicle communication device existing in the reception area within a predetermined period is predicted.
The sensor information obtained from the vehicle detector is, for example, the number of vehicles that have passed through the detection area of the vehicle detector per unit time and the traveling speed of the vehicle. And the said traffic condition information is the information about the number of vehicles and driving speed which exist in the receiving area of a roadside communication apparatus.

Then, when the prediction unit predicts the scheduled reception number, the deterioration detection unit compares the scheduled reception number with the actual reception number actually received by the roadside communication device within the predetermined period. Here, if the communication performance of the roadside communication device is deteriorated (performance is lowered) and the reception area is narrowed, the actual number of receptions is reduced. For this reason, when the deterioration detection unit determines that the actual number of receptions is less than the scheduled number of receptions (for example, greater than or equal to the threshold) by the comparison, the deterioration detection unit determines the deterioration of the communication performance of the roadside communication device. presume.
Thus, since the degradation of the roadside communication device can be estimated, the roadside communication device can be maintained before the roadside communication device whose degradation has been estimated fails and communication becomes impossible. Failure can be prevented.

  In addition, the prediction unit may obtain the scheduled number of receptions as a certain value. In this case, the deterioration detection unit may determine whether the difference from the actual number of receptions is within a predetermined threshold. The degradation of communication performance may be estimated. Alternatively, the prediction unit may determine the expected number of receptions as a numerical range having a predetermined width.In this case, based on whether the actual reception number is within the numerical range, the deterioration detection unit You may estimate the degradation of the communication performance of a roadside communication apparatus. As described above, the comparison by the deterioration detection unit includes both means as described above.

For example, there are the following methods for predicting the scheduled number of receptions by the prediction unit.
The expected number of in-vehicle communication devices existing in the reception area and in the vicinity thereof is calculated from the mounting rate of the in-vehicle communication devices in the vehicle and the number of vehicles that are given in advance and periodically updated. A table (information) in which the number of in-vehicle communication devices and the scheduled number of receptions are associated is prepared in advance, and the reception is scheduled based on the calculated expected number of in-vehicle communication devices by referring to the table. This is a method of calculating the number of times.
Or, for example, in a period of one week or January, the traffic condition and the actual number of actual receptions are stored as statistical data, and the scheduled number of receptions based on past statistical data in traffic conditions similar to the current traffic condition May be predicted.

  (2) Therefore, the deterioration detection system further includes a storage unit that stores correspondence information in which the traffic state information and the scheduled number of receptions are associated, and the prediction unit includes the acquired traffic By adopting a configuration that predicts the scheduled number of receptions based on the situation information, the prediction unit can predict the scheduled number of receptions.

  (3) The deterioration detection system further includes an identification information acquisition unit that acquires identification information of the in-vehicle communication device included in the wireless signal transmitted by the in-vehicle communication device, and the prediction unit acquires Based on the identification information, the number detection unit that detects the number of receptions of a radio signal transmitted from the one in-vehicle communication device within the predetermined period, and the scheduled number of receptions based on the detected number of receptions It is preferable to have a correction unit for correction.

In the reception area of the roadside communication device, when a radio signal is transmitted from the in-vehicle communication device a plurality of times within the predetermined period and the roadside communication device receives the radio signal a plurality of times, the number of in-vehicle communication devices Even if there is one, the multiple receptions are included in the actual reception count. In this case, even if the roadside communication device is normal, there is a discrepancy between the actual reception count and the scheduled reception count.
However, when the identification information acquisition unit acquires the identification information of the in-vehicle communication device, the number detection unit of the prediction unit detects the number of receptions of the radio signal transmitted from the one in-vehicle communication device within a predetermined period. , It can be seen that the wireless signal transmitted from the one in-vehicle communication device is received a plurality of times, the correction unit of the prediction unit corrects the scheduled reception number, the deterioration detection unit and the actual reception number Therefore, it is possible to compare the corrected scheduled number of receptions and improve the determination accuracy.

  (4) Further, the present invention is a deterioration detection method for detecting deterioration in communication performance of a roadside communication device having a reception area on a road that can receive a radio signal transmitted from an in-vehicle communication device, Based on sensor information obtained from a vehicle sensor installed on a road, traffic condition information related to traffic conditions in the reception area is acquired, and based on the acquired traffic condition information, the traffic condition information is present in the reception area. Predicting the scheduled number of times the roadside communication device receives a radio signal transmitted from the vehicle-mounted communication device within a predetermined period, and calculating the scheduled reception frequency and the radio signal transmitted from the vehicle-mounted communication device to the roadside The deterioration of the communication performance of the roadside communication device is estimated by comparing the actual number of receptions received by the communication device within the period.

According to the present invention, when traffic condition information related to traffic conditions in a reception area is acquired based on sensor information obtained from a vehicle sensor, the traffic condition information is present in the reception area based on the acquired traffic condition information. The estimated number of times that the roadside communication device receives a radio signal transmitted from the in-vehicle communication device within a predetermined period is predicted. When the scheduled reception frequency is predicted, the scheduled reception frequency is compared with the actual reception frequency actually received by the roadside communication device within the predetermined period. Here, if the communication performance of the roadside communication device is deteriorated (performance is lowered) and the reception area is narrowed, the actual number of receptions is reduced. For this reason, when it is determined by the comparison that the actual number of receptions is less than the scheduled number of receptions (for example, greater than or equal to the threshold), the deterioration of the communication performance of the roadside communication device is estimated.
Thus, since the degradation of the roadside communication device can be estimated, the roadside communication device can be maintained before the roadside communication device whose degradation has been estimated fails and communication becomes impossible. Failure can be prevented.

  According to the present invention, the roadside communication device can be maintained before the roadside communication device whose communication performance is estimated to be deteriorated and becomes incapable of communication. Therefore, the roadside communication device can be prevented from being broken. Become. After a roadside communication device breaks down and communication becomes impossible, the operation of the roadside communication device may be stopped for a long period of time. Can be prevented.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Transportation system]
FIG. 1 is a schematic diagram of a road where a transportation system is provided, and FIG. 2 is an explanatory diagram illustrating a part of FIG. 1 (a part surrounded by a two-dot chain line) in an enlarged manner.
The traffic system includes a plurality of roadside communication devices (hereinafter referred to as “roadside machines”) 1. In FIG. 1, roadside machines 1 </ b> A to 1 </ b> I are shown as roadside machines 1. The transportation system also includes a vehicle detector 7 that senses a vehicle 5 (see FIG. 2) traveling on the road. In FIG. 1, one vehicle detector 7 is shown as a representative in the vicinity of the roadside machine 1A, but the traffic system has a plurality of vehicle detectors.

  Furthermore, the traffic system has a central control device 4 of a traffic control center that supervises a plurality of roadside devices 1 and vehicle detectors 7. The roadside device 1 and the vehicle detector 7 are connected to the central control device 4 of the traffic control center. Between the central control device 4 and each of the roadside device 1 and the vehicle detector 7 are wired or wireless. Communication is possible. In addition, communication between the roadside device 1 and the vehicle sensor 7 is possible by wire or wireless.

  The vehicle 5 is equipped with an in-vehicle communication device (hereinafter referred to as “in-vehicle device”) 2. The in-vehicle device 2 transmits a radio signal. The roadside device 1 (1A) is installed at an intersection (including the vicinity of the intersection) J, and can communicate with the in-vehicle device 2. That is, the roadside device 1 (1A) is set to have a communication area (transmission area and reception area A) in a predetermined area on the road, and is transmitted from the vehicle-mounted device 2 of the vehicle 5 that has entered the reception area A. Wireless signals can be received. Communication between the roadside device 1 and the vehicle-mounted device 2 is referred to as “road-to-vehicle communication”.

In addition, each vehicle-mounted device 2 can communicate with other vehicle-mounted devices 2 in addition to communication with the roadside device 1, and can exchange information between the vehicle-mounted devices 2. This communication between the in-vehicle devices 2 is referred to as “vehicle-to-vehicle communication”.
Furthermore, the roadside machine 1 (for example, the roadside machine 1A) can communicate with other roadside machines (roadside machines 1B, 1C, 1D, 1E), and can exchange information between the roadside machines 1. It is. Communication between the roadside devices 1 is referred to as “roadside communication”.
In addition, the frequency which a traffic system uses is a 720 MHz band, for example, and there exist 2.4 GHz and 5 GHz band especially in road-to-road communication.

The vehicle detector 7 can be a camera type, an ultrasonic type, an optical type, or the like, and is provided separately from the roadside device 1 and senses the vehicle 5 traveling on the road where the vehicle detector 7 is installed. In FIG. 2, the vehicle sensor 7 includes a sensing head 7 a and a sensor control unit 7 b, and the sensor control unit 7 b obtains the number of vehicles 5 that have passed the sensing area and the speed of the vehicle 5. it can. Information (sensing information) about the obtained number and speed is transmitted to the central controller 4 and the roadside machine 1 (1A). Therefore, the roadside device 1 (1A) can receive a radio signal (radio information) from the in-vehicle device 2 mounted on the vehicle 5 and also receives sensing information of the vehicle 5 via the vehicle sensor 7. can do.
When the vehicle sensor 7 is an ultrasonic type or an optical type, the vehicle-mounted device 2 transmits, for example, near infrared rays and senses it in addition to the type in which the sensing head 7a detects the vehicle 5 by transmitting ultrasonic waves and near infrared rays. It may be of the type sensed by the head 7a.

In the present embodiment, as an example of the road structure, a grid structure in which a plurality of roads in the north-south direction and a plurality of roads in the east-west direction intersect is assumed. Accordingly, four roads RE, RW, RN, and RS are connected to one intersection J from four directions of east, west, north, and south.
In FIG. 2, at each intersection J, four (plural) traffic signal lamps 20a, 20b, 20c, and 20d are installed for each of four roads RE, RW, RN, and RS.
In addition, there are obstacles such as buildings at the corners of each intersection. The road structure is not limited to the above.

  As shown in the block diagram of FIG. 3, each roadside device 1 includes a communication device body 10 and an antenna 11 connected to the communication device body 10. The antenna 11 is installed in each of the traffic signal lamps 20a, 20b, 20c, and 20d (antennas 11a, 11b, 11c, and 11d). The communication device main body 10 can communicate with the central control device 4 of the traffic control center that controls the traffic system. The communication device body 10 includes a wireless unit (transmission / reception unit) 12 and a control unit 13 that performs control related to communication. The control part 13 consists of a microcomputer etc. which have CPU, and can perform various processes with the memorize | stored program.

In addition, the roadside device 1 can perform communication by the time division multiplexing method. For this purpose, the control unit 13 manages time division slots. The slot management may be performed by the wireless unit 12.
The roadside device 1 can perform broadcast communication (one-to-many communication) with respect to the in-vehicle device 2 and can simultaneously transmit traffic information and the like to the in-vehicle devices 2 existing around.

  In FIG. 3, the vehicle-mounted device 2 includes a communication device main body 20 and an omnidirectional antenna 21 connected to the communication device main body 20. Similar to the communication device main body 10 of the roadside device 1, the communication device main body 20 includes a wireless unit 22 and a control unit 23 that performs control related to communication. The control part 23 consists of a microcomputer etc. which have CPU, and can perform various processes with the memorize | stored program.

  Moreover, the vehicle equipment 2 can perform vehicle-vehicle communication between vehicle equipment by a carrier sense system other than communication with the roadside machine 1. FIG. Since the antenna 21 of the in-vehicle device 2 is omnidirectional, it can receive radio waves regardless of the direction of the roadside device 1 or another in-vehicle device 2.

In the communication system of the traffic system configured as described above (communication system between roads, road vehicles, and vehicles), the TDMA system and the CSMA / CA system are combined in the MAC layer. That is, a time zone (first time zone) for the roadside device 1 to transmit a signal is secured, and a TDMA system is adopted for allocation of slots of the plurality of roadside devices 1 in the first time zone. ing.
The remaining second time zone other than the first time zone is a time during which the vehicle-mounted device 2 can transmit a signal, and vehicle-to-vehicle communication using, for example, the CSMA / CA method is performed in the second time zone. .

Thereby, in the first time zone, road-to-road communication between the roadside devices 1 and road-to-vehicle communication in which a signal is sent from the roadside device 1 to the vehicle-mounted device 2 are performed. In the second time zone, road-to-vehicle communication in which a signal is sent from the vehicle-mounted device 2 to the roadside device 1 and vehicle-to-vehicle communication between the vehicle-mounted devices 2 are performed. In the first time zone, the in-vehicle device 2 is prohibited from transmitting signals.
Thus, the quality of the signal transmitted from the roadside device 1 is ensured by giving the time (first time zone) during which the roadside device 1 transmits the signal preferentially.

Further, all the roadside devices 1 have a function of synchronizing the time in order to control the timing of signal transmission. And each roadside machine 1 can obtain the information (allocation information) regarding the time allocation of the first time zone (and the second time zone) by communication from the central control device 4 of the traffic control center. The storage unit 14 (see FIG. 3) of each roadside device 1 can store this allocation information.
And each roadside machine 1 synchronizes time, and transmits the said allocation information in communication area (to vehicle equipment 2 in a communication area).

Accordingly, each roadside device 1 sharing the allocation information can perform one or both of road-to-road communication and road-to-vehicle communication in a designated slot in the first time zone.
On the other hand, the in-vehicle device 2 obtained by receiving the allocation information includes a time zone (first time zone) in which the roadside device 1 transmits a signal and a communicable time in which the in-vehicle device 2 can transmit the signal. You can know the zone (second time zone). Thereby, the onboard equipment 2 can perform one or both of the inter-road communication and the inter-vehicle communication in the second time zone.

  The roadside device 1 can receive radio signals transmitted to the roadside device 1 by the vehicle-mounted device 2 at various positions in the reception area A for road-to-vehicle communication. The radio signal transmitted by the in-vehicle device 2 can be intercepted even in the time zone (the second time zone) in which the vehicles communicate with each other. That is, even if the radio signal transmitted by the vehicle-mounted device 2 is information for mobile communication (vehicle-to-vehicle communication) that the vehicle-mounted devices 2 directly perform without passing through the roadside device 1, the roadside device 1 Information for this mobile communication can be intercepted.

Moreover, the vehicle equipment 2 is performing vehicle-to-vehicle communication by the carrier sense system, and the vehicle equipment 2 may transmit a radio signal a plurality of times until it passes through the reception area A of the roadside device 1. . In particular, when the number of vehicles 5 mounted with the vehicle-mounted device 2 is large and the traffic situation is congested or congested, the time until one vehicle-mounted device 2 passes through the reception area A becomes longer. The number of times the in-vehicle device 2 transmits a radio signal increases. In this case, the frequency | count of reception which the roadside machine 1 receives a radio signal increases.
Conversely, when the number of vehicles 5 equipped with the vehicle-mounted device 2 is small and the traveling speed is high, the vehicle 5 passes through the reception area A in a short time. The number of times 2 can transmit a radio signal is reduced. In this case, the frequency | count of reception which the roadside machine 1 receives a radio signal decreases. However, even if the number of vehicles 5 is small, when the speed is low, the number of times the roadside device 1 receives a radio signal tends to increase.

In the present invention, identification information is assigned to each roadside device 1 in advance, and the storage unit 14 in each roadside device 1 stores its own identification information (ID information) and other roadside devices. The identification information of the machine 1 is also stored. And the roadside machine 1 can transmit a radio signal including its own identification information.
Also, identification information is assigned to each in-vehicle device 2 in advance, and a storage unit (not shown) in each in-vehicle device 2 stores its own identification information (ID information). And the vehicle equipment 2 can transmit a radio signal including self identification information.

[Deterioration detection system]
As described above, the traffic system includes the plurality of roadside machines 1 and the vehicle detectors 7, which are controlled by the central controller 4. And this traffic system is provided with a deterioration detection system S for detecting the deterioration of the communication performance of the roadside machine 1 (see FIG. 3). In the embodiment of FIG. 3, the deterioration detection system S is provided in the communication device main body 10 of each roadside machine 1 (all roadside machines 1 in FIG. 1). The deterioration detection system S includes a programmable microcomputer having a CPU and a storage unit.
In the following description, a case where a deterioration in communication performance in the roadside device 1A of FIG. 1 is detected will be described. In this case, from the position (intersection) where the antenna 11 of the roadside machine 1A is installed, toward the position where the vehicle detector 7 is installed on the upstream side in the traveling direction of the vehicle 5 and the antenna 11 is installed. The vehicle 5 is configured to sense the traveling vehicle 5.

The storage unit 19 provided in the deterioration detection system S stores programs for executing predetermined functions. And the deterioration detection system S is provided with the traffic condition acquisition part 15, the prediction part 16, the deterioration detection part 17, and the identification information acquisition part 18 as a function part performed by this program. These functional units will be described later. The storage unit 19 and the storage unit 14 include storage devices such as a ROM and a RAM that store various types of information and computer programs.
In addition, although the case where the deterioration detection system S is provided in the roadside machine 1 is shown in FIG. 3, the deterioration detection system S may be provided in the central controller 4 or each of the deterioration detection systems S. The functional unit may be provided separately for the roadside machine 1 and the central control device 4. Each functional unit may be included in the control unit 13 of the communication apparatus main body 10.

FIG. 4 is an explanatory diagram for explaining the function of the deterioration detection system S. FIG. 4A shows a state before the communication performance of the receiving device of the roadside device 1 installed on the road is deteriorated, and FIG. 4B shows the deteriorated state. Note that the reception system of the roadside device 1 includes, for example, an analog circuit or an amplifier on the signal reception side of the wireless unit 12.
The function of the deterioration detection system S will be described with reference to FIGS.

When the vehicle sensor 7 is a camera type, the sensing head 7a is a camera, and the sensor control unit 7b is a sensor of the vehicle 5 that passes through the sensing area B of the vehicle sensor 7 (see FIG. 4A). Information can be easily detected. As described above, the sensor information is information on the number of vehicles 5 that have passed through the sensing area of the vehicle sensor 7 during a unit time (for example, one minute) and the speed of the vehicles 5. The speed of the vehicle 5 can be an average speed.
Even when the vehicle sensor 7 is an ultrasonic type or an optical type, the sensing information detected by the sensor control unit 7b is that of the vehicle 5 that has passed through the sensing area B (see FIG. 4A) for a unit time. Number and speed. In this case, the speed is obtained by providing a plurality of sensing heads 7a, for example.

And the sensor information regarding a sensing result is transmitted to the roadside machine 1, and the traffic condition acquisition part 15 acquires the said sensing information. And the traffic condition acquisition part 15 acquires the traffic condition information regarding the traffic condition (the number of vehicles and speed) of the vehicles 5a-5d which exist in the reception area A of the roadside machine 1 based on the acquired sensing information.
For this purpose, the traffic condition acquisition unit 15 acquires information about the size of the reception area A (the length in the vehicle traveling direction) when the roadside machine 1 is normal from the storage unit 19. Based on the information on the area and the acquired sensing information, the traffic condition acquisition unit 15 performs calculation processing to determine the number of vehicles 5 that are considered to exist in the reception area A of the roadside machine 1. Can be estimated. In addition, since the sensing area B of the vehicle sensor 7 is included in the reception area A of the roadside device 1, the traffic condition acquisition unit 15 determines the speed of the vehicle 5 in the sensing area B as the vehicle 5 in the reception area A. Can be regarded as the speed of. The acquisition of traffic condition information will be described later.

Based on the traffic condition information acquired by the traffic condition acquisition unit 15, the prediction unit 16 generates a radio signal transmitted from the in-vehicle device 2 existing in the reception area A of the roadside device 1. The machine 1 has a function of predicting the scheduled number of times of reception Q received within a predetermined period (predetermined time t: for example, the same one minute as the unit time).
For this purpose, the storage unit 19 stores correspondence information (FIG. 5) in which the traffic situation information is associated with the scheduled number of times of reception Q. And the prediction part 16 can estimate the said frequency | count of reception Q based on the acquired said traffic condition information.
For example, when the traffic situation information acquired by the traffic situation acquisition unit 15 indicates that the number of vehicles 5 in the reception area A is four and the average speed is 60 km / h, according to the correspondence information in FIG. The prediction unit 16 can predict that the scheduled number of receptions Q = 4.

Alternatively, the correspondence information may be a function, the function may be stored in the storage unit 19, and the prediction unit 16 may obtain the scheduled reception count Q using the function based on the traffic situation information. In this case, assuming that the size of the reception area A at normal time is L (m), the number of vehicles 5 is N (units), and the average speed is v (km / h), the scheduled reception number Q is
Q = k × L × N / v (k is a coefficient)
It can be a function. This function is proportional to the number N of vehicles 5 and inversely proportional to the average speed v.
In this manner, the prediction unit 16 can predict the scheduled reception frequency Q based on the acquired traffic condition information based on the data as shown in FIG. 5 or the function.

  Further, since the wireless signal transmitted from the vehicle-mounted device 2 includes identification information (ID information) of the vehicle-mounted device 2, the identification information acquisition unit 18 receives the wireless signal from the roadside device 1. Has a function of acquiring identification information of the in-vehicle device 2 included in the wireless signal transmitted by the in-vehicle device 2. In this case, the prediction unit 16 includes a number detection unit 16a and a correction unit 16b as part of the functional unit.

Based on the identification information of the in-vehicle device 2 acquired by the identification information acquisition unit 18, the number-of-times detection unit 16a receives the radio signal transmitted from one in-vehicle device 2 within the predetermined period (one minute) ( Hereinafter, it has a function of detecting the duplicate reception count).
For example, in FIG. 4A, the vehicle 5a that has entered the reception area A transmits a radio signal to the roadside device 1 within the reception area A, for example, three times (multiple times) within the predetermined period. Assume that the roadside device 1 has received all three radio signals. In addition, when the vehicle-mounted devices 2 of the other vehicles 5b, 5c, and 5d transmit the wireless signal to the roadside device 1 only once within the predetermined period, and the roadside device 1 receives the wireless signal, respectively. To do.

In this case, the roadside device 1 actually transmits the radio signal from the vehicle-mounted device 2 of the vehicle 5a three times and the radio signal (one time each) from the vehicle-mounted device 2 of the vehicles 5b, 5c, and 5d within a predetermined period. The radio signals are received and received six times in total, but six vehicles equipped with the vehicle-mounted device 2 are not present in the reception area A.
4A, according to the sensor information by the vehicle sensor 7, the number of vehicles in the reception area A is four (5a, 5b, 5c, 5d). According to the traffic condition information to be acquired, there are four vehicles 5, and the prediction unit 16 is expected to have a scheduled reception count Q of four.
However, as described above, the vehicle-mounted device 2 of one vehicle 5a transmits the radio signal three times in the reception area A, and the roadside device 1 has received all of this, so the scheduled number of receptions Q (= 4 times) ) And the actual reception count R (= 6) actually received by the roadside device 1 (radio unit 12) are different.

  However, according to the number detection unit 16a, if the identification information of the vehicle-mounted device 2 is referred to, the vehicle-mounted device 2 of one vehicle 5a transmits a radio signal multiple times (three times) in the reception area A, and the roadside It is possible to detect that the machine 1 is receiving this, and in this case, the number detection unit 16a can detect that the number M of duplicate receptions is 3 (R = 3).

Therefore, the correction unit 16b of the prediction unit 16 has a function of correcting the scheduled reception number Q based on the duplicate reception number M detected by the number detection unit 16a.
This is because, as described above, even if the prediction unit 16 predicts that the number of vehicles 5 is four and the scheduled number of times of reception Q is four based on the traffic condition information, the roadside device 1 actually receives it. However, the correction unit 16b adds one less number (M-1) to the number of duplicate receptions M for each in-vehicle device 2 to the initial scheduled number of receptions Q. The arithmetic processing to be performed is performed.
That is, when the number of duplicate receptions M detected by the number detection unit 16a is 3, the number of times of initial reception is Q = 4, and the number of duplicate receptions M is one less (M-1 = 3-1 =) 2 Is added, and the corrected scheduled reception count Q1 is set to 6 (Q1 = 6). As a result, the discrepancy between the corrected scheduled reception count Q1 and the actual reception count R is eliminated.

The deterioration detection unit 17 counts the actual number of receptions R that the roadside device 1 (wireless unit 12) actually received a radio signal transmitted from the in-vehicle device 2 within the predetermined period (predetermined time t: 1 minute). To do. Then, the deterioration detection unit 17 estimates the deterioration of the communication performance of the roadside device 1 by comparing the scheduled reception number Q predicted by the prediction unit 16 with the actual reception number R.
In addition, when the correction unit 16b corrects the scheduled reception count Q, the corrected scheduled reception count Q1 is employed.

A specific example of the degradation detection method for the roadside machine 1 executed by the degradation detection system S configured as described above will be described. FIG. 6 is a flowchart for explaining the deterioration detection method. This will be described with reference to FIGS.
The vehicle sensor 7 senses the vehicle 5 in the sensing area B (step S1 in FIG. 6). The vehicle sensor 7 (sensor control unit 7b) obtains the number of vehicles 5 that have passed the sensing area B per unit time and the speed (average speed) of the vehicles 5. Sensing information about the number and speed is transmitted to the degradation detection system S of the roadside machine 1 (step S2).

When the roadside device 1 receives the sensor information, the traffic condition acquisition unit 15 acquires the sensor information, and based on the sensor information, the traffic condition of the vehicle 5 existing in the reception area A of the roadside device 1 ( Traffic status information relating to the number N and the average speed v) is acquired (step S3).
Explaining a specific example, the traffic condition acquisition unit 15 acquires from the storage unit 19 information related to the size of the reception area A (the length L in the vehicle traveling direction) when the roadside machine 1 is normal (FIG. 4A). To do. The traffic condition acquisition unit 15 regards the average speed of the vehicle 5 in the sensing area B obtained by the vehicle detector 7 as the average speed v of the vehicle 5 in the reception area A.
Then, the time required for the vehicle 5 to pass through the reception area A is determined based on the size (length L) of the reception area A and the average speed v. And the traffic condition acquisition part 15 acquires (estimates) the number N of the vehicles 5 which exist in the reception area A by counting the number of the vehicles 5 which passed the sensing area B during the calculated | required time. be able to.

The prediction unit 16 is based on the traffic condition information (number N and average speed v) acquired by the traffic condition acquisition unit 15 and is transmitted from the in-vehicle device 2 existing in the reception area A of the roadside device 1. Predicted number of times of reception Q that the roadside device 1 receives the signal within a predetermined period (1 minute) is predicted (step S4).
The prediction unit 16 may predict the scheduled reception frequency Q based on the correspondence information in FIG. 5, or may predict the scheduled reception frequency Q based on the function.

  Then, the prediction unit 16 determines whether or not the scheduled reception count Q needs to be adjusted (step S5). The case where adjustment is necessary is, for example, a case where the traveling speed of the vehicle 5 is low even if the number of the vehicles 5 present in the reception area A is small. This can be determined based on the acquired traffic situation information.

  Even if the number of vehicles 5 present in the reception area A is small, the number of receptions actually received by the roadside device 1 tends to increase when the traveling speed of the vehicles 5 is low. Therefore, as shown in FIG. 5, the correspondence information includes information on the coefficient k corresponding to the speed. The coefficient k is a value for increasing the (basic) scheduled reception number N in FIG. 5 in order to adjust the scheduled reception number Q (step S6). That is, the prediction unit 16 (correction unit 16b) may adjust the scheduled reception frequency Q by multiplying the (basic) scheduled reception frequency Q by the coefficient k according to the speed v in the traffic situation information.

For example, even if the number N of traffic status information is small (for example, four), if the speed v is less than 30 km / h, the prediction unit 16 determines the (basic) scheduled number of receptions Q = 4 Is multiplied by a coefficient k = 3 to adjust the scheduled reception count Q to 12 (step S6).
In the following description, it is assumed that the speed is v = 60 km / h and the scheduled number of receptions Q is 4.

Then, the deterioration detection unit 17 counts the actual number of receptions R that the roadside device 1 (the radio unit 12) actually received the radio signal transmitted from the in-vehicle device 2 within a predetermined period (predetermined time t: 1 minute). (Step S7).
At the same time, since the roadside device 1 has acquired the identification information (ID information) of the in-vehicle device 2 from the in-vehicle device 2, the correction is performed by the correction unit 16b (step S8). This corrects the scheduled reception frequency Q as described above based on the duplicate reception frequency M detected by the frequency detection unit 16a of the prediction unit 16. If correction is not necessary, the correction process is not executed.

  Here, FIG. 4B shows a state in which the communication performance of the receiving device of the roadside device 1 has deteriorated (performance has deteriorated). In this case, since the reception area A is narrower than that in the normal state of FIG. 4A, the radio signals transmitted from the vehicle-mounted device 2 of the vehicle 5a and the vehicle-mounted device 2 of the vehicle 5d far from the antenna 11 are Machine 1 can no longer receive. Examples of the reception system device of the roadside device 1 include an analog circuit and an amplifier on the signal reception side of the wireless unit 12.

  Even in this case, the vehicle detector 7 can obtain the same sensing information as in FIG. 4A, and can obtain the same traffic situation information as in FIG. According to the traffic condition information, the number of vehicles 5 per minute passing through the reception area A before deterioration is 4, and the average speed is 60 km / h. According to the correspondence information in FIG. When the number of times Q is 4, the prediction unit 16 can predict.

  However, in the case of FIG. 4B, the roadside device 1 can no longer receive the radio signals transmitted by the vehicle-mounted device 2 of the vehicle 5a and the vehicle-mounted device 2 of the vehicle 5d that are distant from the antenna 11, and therefore for 1 minute. In addition, the number of times the roadside device 1 actually receives a radio signal from the in-vehicle device 2 decreases. That is, the actual number of receptions R counted by the deterioration detection unit 17 in step S7 is smaller than that in the case of FIG.

Therefore, the deterioration detection unit 17 compares the estimated number of receptions Q predicted (corrected) by the prediction unit 16 with the counted actual number of receptions R (step S9), and estimates the deterioration of the communication performance of the roadside device 1. .
Specifically, when the difference (R−Q) between the scheduled number of receptions Q and the actual number of receptions R is equal to or greater than the threshold value α, the deterioration detection unit 17 deteriorates the communication performance of the reception system device of the roadside device 1. (Step S10). The threshold value α can be set to ± 5% of the scheduled number of receptions Q, for example.
In the above embodiment, the correction processing (step S8) of the scheduled number of receptions Q by the correction unit is performed, but this may be omitted. In this case, it is necessary to change the threshold value α, for example, ± 20% of the scheduled reception count Q.

When it is estimated by the deterioration detection unit 17 that the communication performance of the receiving system of the roadside device 1 has deteriorated (step S10), the deterioration detection unit 17 performs maintenance indicating that the roadside device 1 requires maintenance. Information is created (step S11). This maintenance information is transmitted to the central control device 4 (FIG. 1) of the traffic control center through the radio unit 12 of the roadside machine 1.
Then, the administrator of the traffic control center can perform maintenance on the roadside device 1 whose communication performance is estimated to be deteriorated based on the acquired maintenance information. For this reason, maintenance of the roadside machine 1 can be performed before the roadside machine 1 in which deterioration is estimated fails and communication becomes impossible. That is, it is possible to prevent a failure of the roadside device 1. In addition, after the roadside device 1 breaks down and communication becomes impossible, there is a possibility that the operation of the roadside device 1 may be stopped for a long period of time. Stop can be prevented.

  In addition, with respect to the present invention, the embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is not intended to include the above-described meanings, but is intended to include meanings equivalent to the claims and all modifications within the scope.

It is a schematic diagram of the road where the traffic system is provided. It is explanatory drawing which expands and demonstrates a part of FIG. It is a block diagram of a traffic control center, a vehicle detector, a roadside device, and an in-vehicle device. It is explanatory drawing explaining the function of a deterioration detection system. It is explanatory drawing of the corresponding information with which traffic condition information and the frequency | count of reception were matched. It is a flowchart of a deterioration detection method.

Explanation of symbols

1 Roadside machine (roadside communication device)
2 In-vehicle device (in-vehicle communication device)
DESCRIPTION OF SYMBOLS 5 Vehicle 7 Vehicle detector 15 Traffic condition acquisition part 16 Prediction part 16a Count detection part 16b Correction | amendment part 17 Degradation detection part 18 Identification information acquisition part 19 Storage part A Reception area Q Receipt count R Actual reception count S Deterioration detection system

Claims (4)

A degradation detection system that detects degradation of communication performance of a roadside communication device having a reception area on a road that can receive a radio signal transmitted from an in-vehicle communication device,
A traffic condition acquisition unit for acquiring traffic condition information related to the traffic condition in the reception area based on sensor information obtained from a vehicle sensor installed on the road;
Prediction for predicting the expected number of times the roadside communication device receives a radio signal transmitted from the in-vehicle communication device existing in the reception area within a predetermined period based on the acquired traffic condition information And
By comparing the scheduled number of receptions with the actual number of times the roadside communication device actually received the radio signal transmitted from the in-vehicle communication device within the predetermined period, the communication performance of the roadside communication device A degradation detector for estimating degradation;
A deterioration detection system characterized by comprising: A storage unit that stores correspondence information in which the traffic state information and the scheduled number of receptions are associated;
The deterioration detection system according to claim 1, wherein the prediction unit predicts the scheduled reception frequency based on the acquired traffic condition information. An identification information acquisition unit for acquiring identification information of the in-vehicle communication device included in the wireless signal transmitted by the in-vehicle communication device;
Based on the acquired identification information, the prediction unit detects the number of receptions of a radio signal transmitted from the one in-vehicle communication device within the predetermined period, and based on the detected number of receptions The deterioration detection system according to claim 1, further comprising a correction unit that corrects the scheduled number of receptions. A deterioration detection method for detecting deterioration in communication performance of a roadside communication device having a reception area on a road that can receive a radio signal transmitted from an in-vehicle communication device,
Based on sensor information obtained from a vehicle sensor installed on the road, obtain traffic condition information regarding the traffic condition in the reception area,
Based on the acquired traffic situation information, predicting the scheduled number of times the roadside communication device receives a radio signal transmitted from the in-vehicle communication device existing in the reception area within a predetermined period,
Degradation of the communication performance of the roadside communication device by comparing the scheduled number of receptions with the actual number of times the roadside communication device actually received the radio signal transmitted from the in-vehicle communication device within the period. A degradation detection method characterized by estimating

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