JP2010287206A - Traffic information estimation apparatus, computer program for traffic information estimation, and traffic information estimation method - Google Patents

Abstract

To appropriately estimate traffic information, link travel speed is converted into speed information.
A traffic information estimation device for estimating traffic information of an estimation target road link based on traffic information of another road link, and a link travel speed indicating a vehicle speed on the other road link Conversion units 17b and 18b are provided for converting into speed information that takes a value corresponding to the magnitude of travel speed. The conversion units 17b and 18b perform the conversion using the conversion information 19 for converting the link travel speed into the speed information. The conversion information 19 indicates that the rate of change in the speed information relative to the change in the link travel speed is higher in the speed range of the free travel speed where the vehicle can be in the free travel state than in the speed region lower than the free travel speed region. It is set to be smaller.
[Selection] Figure 4

Description

  The present invention relates to a traffic information estimation device for estimating traffic information, a computer program for traffic information estimation, and a traffic information estimation method.

As a technology for providing road traffic information to drivers, VICS (Vehicle Information and Communication System: “VICS” is a registered trademark of the foundation) is widely known.
This VICS tabulates traffic information including traffic congestion and link travel time on each route based on fixed point observation information consisting of the number of vehicles, vehicle speed, etc. collected from various roadside sensors (vehicle detectors, loop coils, etc.). The traffic information is provided to the driver by wide-area communication such as narrow-area communication using beacons or FM broadcasting.

As another technique for providing road traffic information to a driver, a traffic information estimation system using a probe car (hereinafter referred to as a probe system) is also known.
For example, as shown in Patent Documents 1 and 2, this probe system uses a vehicle (probe vehicle) that actually travels on a road as a moving body sensor, and wirelessly communicates probe information such as the current vehicle position and time. Are collected from each probe vehicle to generate road traffic information.

Japanese Patent Laid-Open No. 5-151696 Japanese Patent Laying-Open No. 2005-4467

  However, even if the VICS and the probe system are used, traffic information cannot be obtained for road links for which no data is obtained from either the VICS or the probe system.

Therefore, for road links for which data is not obtained from either the VICS or the probe system (estimation target road links), it is conceivable to estimate the traffic information based on the traffic information of other road links. For example, the traffic information on the road link connected to the estimation target road link or other related road link is correlated with the traffic information of the estimation target road link. By using such a correlation, the traffic information of the estimation target road link can be supplemented using the traffic information of another road link.
As a result, for road links for which no data is obtained from either the VICS or the probe system, the traffic information is complemented and the area coverage of the road links that can provide the traffic information can be increased.

  However, when the speed of a vehicle on a road link is handled as traffic information, if the traffic information is estimated at the speed [km / h], the following problem occurs.

That is, for example, as shown in FIG. 30, a road link is configured, links A and B are highways with a speed limit of 100 km / h, and link C is a general road with a speed limit of 60 km / h. Further, it is assumed that the road is free in any of links A, B, and C, and the vehicle is in a free-running state.
It is assumed that the speed (link travel speed) is detected as 100 km / h for the links A and B, and the speed (link travel speed) is detected as 60 km / h for the link C. In this case, there is a difference in speed between the links A and B and the link C, but this is only due to the difference in the speed limit of the road, and as the degree of congestion (traffic volume) of the road, The links A, B, and C are considered to be almost the same.

  However, when trying to estimate the speed of the road link (estimation target road link) related to the links A, B, C based on the speeds of the links A, B, C, the links A, B, and C The present inventors have found that there are problems that it is difficult to obtain an appropriate estimated value due to the different speeds, and that a processing time for obtaining an appropriate estimated value becomes long.

Therefore, an object of the present invention is to provide means for reducing the above-described problem when the road link speed (link travel speed) itself is used.
Another object of the present invention is to provide a new technique for estimating traffic information of an estimation target road link based on traffic information of another road link.

(1) The present invention is a traffic information estimation device for estimating traffic information of an estimation target road link based on traffic information of another road link, and a link travel speed indicating a vehicle speed on the other road link. Is converted into speed information that takes a value corresponding to the magnitude of the link travel speed, and the speed information converted by the conversion section is used as traffic information of the other road link, and the estimation target road link An estimation unit that estimates the traffic information of the vehicle, and the conversion unit performs the conversion using conversion information for converting a link travel speed into the speed information. In the speed region of the free travel speed where the free travel state can be in the free travel state, the rate of change in the speed information relative to the change in the link travel speed is smaller than in the speed region lower than the free travel speed region It is the traffic information estimating device according to claim set in Kunar so.

  According to the present invention, the conversion information is the speed information for the change in the link travel speed in the speed range of the free running speed where the vehicle can be in the free running state, compared to the speed area lower than the free running speed area. Since the change rate is set to be small, the road condition can be expressed more appropriately by the speed information.

(2) The conversion information includes a link travel in a speed region of a free travel speed where the vehicle can be in a free travel state and a near-zero speed region where the link travel speed is near zero, compared to a speed region between the two regions. It is preferable that the speed information change ratio is set to be small with respect to the speed change. In this case, the road condition can be expressed more appropriately.

(3) From another viewpoint, the present invention is a traffic information estimation device that estimates traffic information of an estimation target road link based on traffic information of another road link, and the speed of the vehicle on the other road link. Using the speed information converted by the conversion unit as the traffic information of the other road link, the conversion unit that converts the link travel speed indicating the link travel speed into speed information that takes a value corresponding to the magnitude of the link travel speed, An estimation unit that estimates traffic information of the estimation target road link, and the conversion unit performs the conversion using conversion information for converting link travel speed into the speed information, The conversion information is a traffic information estimation device that is set such that the rate of change in the speed information with respect to the change in the link travel speed decreases as the link travel speed increases. .
According to the present invention, the conversion information is set so that the rate of change in the speed information with respect to the change in the link travel speed decreases as the link travel speed increases. Can express.

(4) It is preferable that the conversion information is set as a function in which the rate of change in the speed information with respect to the change in the link travel speed monotonically decreases as the link travel speed increases.

(5) When the link travel speed is x and the speed information is y, the conversion information is preferably set as the following function.
y = exp (-(x / a)) (where a is an arbitrary positive number)

(6) When the traffic information of one or a plurality of the other road links is obtained, the estimation unit sets each of the estimation targets using the remaining one or a plurality of road links for which the traffic information is not obtained as the estimation target road links. The traffic information of the road link is estimated according to the estimation order, and the estimation unit gives the highest priority to the estimation target road link directly connected to the other road link from which the traffic information is obtained. The estimation order is preferably determined so that the estimation target road link having a larger number of road links intervening with the other road links from which information is obtained has a later order.
In this case, the traffic information is estimated in order from the road link closest to the road link from which the traffic information was obtained.

(7) The estimation unit is connected to each node for each of a plurality of road links, and a link-node connection table storing information indicating a node to which a link end of each road link is connected. It is preferable that a node-link connection table storing information indicating a road link is included, and the estimation order is determined using the link-node connection table and the node-link connection table. Since the link-node connection table and the node-link connection table clarify the road link connection relationship, the estimation order can be easily determined.

(8) In the traffic information estimation device of the present invention, the estimation unit that estimates the traffic information of the estimation target road link based on the traffic information of the other road link uses the estimation target road link from the traffic information of the other road link. When the traffic link traffic information that can be the estimation target road link is obtained, the calculation for estimating the traffic information of the other link is performed. Traffic information is stored as learning data, and a learning unit is provided that optimizes the estimation parameter using the stored learning data.

  In this case, the learning parameter is optimized by the learning unit, and traffic information can be estimated more appropriately.

(9) It is preferable that the actual measurement value is obtained from probe information transmitted from the probe vehicle.

(10) It is preferable that the estimation parameter includes a weight to be multiplied by traffic information of another road link.

(11) The present invention further includes a link travel speed calculation unit that calculates a link travel speed for a road link from probe information including a position and time of the probe vehicle, and the link travel speed calculation unit includes the probe vehicle First probe information transmitted when the vehicle is present at the first position; second probe information transmitted when the probe vehicle is moved from the first position and is present at the second position; Is configured to calculate a link travel speed for a road link existing between the first position and the second position, and the link travel speed calculation unit further includes the first position and When the distance between the second positions is equal to or smaller than a set minimum distance, the probe information transmitted when the distance is between the first position and the second position and / or the second position. Using the probe information transmitted when present in a position of Rimosaki is a device that is configured to calculate a link travel speed of the road link.

  According to the present invention, even when the distance between the first position and the second position is short, it is possible to calculate a more accurate link travel speed by increasing the distance. This technique can also be used for calculating the link travel time.

(12) The present invention is a computer program for causing a computer to function as the device described in any one of (1) to (11) above.

(13) The present invention relates to a traffic information estimation method for estimating traffic information of an estimation target road link based on traffic information of another road link, the link travel speed indicating a vehicle speed on the other road link. Is converted into speed information that takes a value corresponding to the magnitude of the link travel speed, and the converted speed information is used as traffic information of the other road link to estimate the traffic information of the estimation target road link. And converting the link travel speed into speed information is performed using conversion information for converting the link travel speed into speed information, and the conversion information is used for free travel in which the vehicle can be in a free travel state. The speed range is set so that the rate of change in the speed information relative to the change in speed is smaller than in the speed range that is slower than the free running speed range. It is the traffic information estimating method comprising.

(14) From another viewpoint, the present invention is a traffic information estimation method for estimating traffic information of an estimation target road link based on traffic information of another road link, and the speed of the vehicle on the other road link. The link travel speed indicating the link travel speed is converted into speed information that takes a value corresponding to the magnitude of the link travel speed, and the converted speed information is used as traffic information of the other road link, Estimating the traffic information, wherein the conversion from the link travel speed to the speed information is performed using conversion information for converting the link travel speed into the speed information, and the conversion information includes the link travel speed The traffic information estimation method is characterized in that the rate of change in the speed information with respect to the change in the link travel speed is set to be smaller as the value is increased.

  The rate of change in the speed information relative to the change in the link travel speed is smaller in the speed area of the free running speed where the vehicle can be in the free running state than in the speed area slower than the free running speed area. Or by setting the ratio of the change in speed information to the change in link travel speed as the link travel speed increases, the road condition can be expressed more appropriately by the speed information. .

1 is an overall configuration diagram of a traffic information system. It is a block diagram of a traffic information estimation apparatus. It is a block diagram of an input information processing part. It is a figure which shows conversion information. It is explanatory drawing for calculating | requiring a link travel speed from probe information. It is a flowchart which shows the traffic information estimation process procedure. It is a block diagram of a neural network. It is a figure which shows the example of a road link. It is a figure which shows the initial state of an estimation database. It is a figure which shows the initial state of a weight database. It is a figure which shows the VICS information and probe information which were acquired as input information. It is a figure which shows the estimation database after the 1st update. It is a figure which shows the estimation database after the 2nd update. It is a figure which shows the estimation database after the 3rd update. It is a figure which shows the part extracted by taking a snapshot. It is a figure which shows the database for learning. It is a flowchart which shows a learning process. It is a figure which shows the other example of conversion information. It is a figure which shows the other example of conversion information. It is a figure which shows the other example of conversion information. It is a figure which shows the other example of conversion information. It is a figure which shows the other example of a road link structure. It is a figure which shows an estimation order determination process. It is a figure which shows the other example of an estimation database structure. It is a table which shows the related road link of a link end unit. It is a structural diagram of a link-node connection table and a node-link connection table. It is a structural diagram of a link-node connection table and a node-link connection table. It is a structural diagram of a link-node connection table and a node-link connection table. It is a structural diagram of a link-node connection table and a node-link connection table. It is a figure for demonstrating the problem in the case of estimating with speed.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
[1. overall structure]
FIG. 1 shows a traffic information system including a traffic information estimation device (central device) 1 according to an embodiment of the present invention. In addition to the traffic information estimation device 1, the traffic information system includes a probe vehicle 3 equipped with an in-vehicle device 2, a roadside communication device 4 that wirelessly communicates with the in-vehicle device 2, and a roadside sensor 5.

  The traffic information estimation device 1 indicates, for example, one of various functions in the central device, and the central device 1 acquires traffic information (observation information) such as VICS information and probe information and provides it to the vehicle. It has a function of generating traffic information for provision for the purpose. The central device 1 may perform various traffic processing such as traffic signal control and traffic control based on the traffic information.

  The traffic information estimation device (central device) 1 is configured by a computer having a processing device and a storage device. A computer program for causing the computer to function as the traffic information estimation device (central device) is stored in the storage device. It is remembered. This computer program is executed by the processing device, and the processing device performs functions as the traffic information estimation device (central device) 1 by inputting and outputting to the storage device and the like. Note that the functions of the traffic information estimation apparatus (central apparatus) 1 described below are realized by the computer program unless otherwise specified.

  The in-vehicle device 2 generates probe information as observation information of the probe vehicle 3 and wirelessly transmits it to the roadside communication device 4. The probe information is traffic information including the position of the probe vehicle, the passing speed of the position, the vehicle ID of the probe vehicle, and the like. The probe information may include other information such as the speed of the probe vehicle. The position of the probe vehicle is calculated based on the GPS signal received by the GPS receiver included in the in-vehicle device 2.

  The roadside communication device 4 transmits / receives information to / from the in-vehicle device 2 by wireless communication. Specifically, the roadside communication device 4 receives probe information as observation information transmitted by the in-vehicle device 2 and transfers the probe information to the traffic information estimation device (central device) 1. Further, the roadside communication device 4 can acquire traffic information for provision to the vehicle from the traffic information estimation device (central device) 1 and transmit the traffic information to the in-vehicle device 2. The roadside communication device 4 and the traffic information estimation device 1 are connected by a communication line.

  The roadside sensor 5 is for detecting traffic information as observation information, for example, a vehicle detector for ultrasonically detecting a vehicle passing directly below, a loop coil for detecting the vehicle by inductance change, or It consists of an image sensor that measures the traffic volume and vehicle speed by image processing of the camera video, and is installed on expressways and major trunk roads for the purpose of measuring the number of vehicles flowing into the intersection and the vehicle speed. .

  The roadside sensor 5 transmits the detected observation information 6 to the VICS center server via the communication line, and the VICS center server 6 generates VICS information based on the observation information of the roadside sensor 5. This VICS information is transmitted to the traffic information estimation device 1 via a communication line.

The VICS information is traffic information including traffic jams and link travel times on each road link. Since the VICS information is updated by obtaining observation information from the roadside sensor 5 every 5 minutes, high-density information can be obtained in time. However, the roadside sensor 5 is not installed on all roads (20% or less on main roads), and the area coverage rate is low.
On the other hand, since the probe information is acquired from the probe vehicle 3 traveling on the road, the area coverage rate can be increased. However, since the penetration rate of the in-vehicle device 2 to become the probe vehicle 3 is still low, only low-density data can be obtained in time.

  That is, when a road link is set on a road in a predetermined area, traffic information (VICS information) is always obtained for each VICS information update unit time for a road link from which VICS information is obtained. On the other hand, as for road links for which VICS information cannot be obtained, there are road links for which probe information can be obtained as traffic information, and road links for which probe information cannot be obtained for each VICS information update unit time. become.

[2. Details of Traffic Information Estimator]
[2.1 Overall configuration of estimation device]
The traffic information estimation device 1 according to the present embodiment estimates the traffic information of a road link for which neither VICS information nor probe information is obtained, and complements the traffic information of the road link, so that all road links in the predetermined area Generate traffic information. In this way, by supplementing road link traffic information for which neither VICS information nor probe information can be obtained, more accurate traffic information can be provided to the vehicle (navigation system), or traffic control can be performed with high accuracy. Is possible.
In the following, a road link for which VICS information or probe information is not obtained and traffic information needs to be estimated and complemented is referred to as “estimation target road link”.

  As shown in FIG. 2, the traffic information estimation device 1 learns an estimation engine (estimation unit) 11 for estimating traffic information of an estimation target road link and a parameter (estimation parameter) used for estimation. And a learning engine 12.

  The traffic information estimation device 1 accumulates data used for learning in the learning engine 12 among the estimation database (traffic information database) 13 for accumulating traffic information estimated by the estimation engine 11 and data in the estimation database 13. A learning database 14 and a weight database (estimated parameter database) 15 for accumulating estimated parameters (in this embodiment, “weight”).

[2.2 Input information processing section]
Furthermore, the traffic information estimation device 1 according to the present embodiment performs input processing on VICS information and probe information (hereinafter, referred to as “input information” when both information are collectively) acquired by the traffic information estimation device 1. A processing unit 16 is provided.

  The input information processing unit 16 performs processing for generating “speed information” of each link from the input information. The generated “speed information” is given to the estimation database 13 to update the estimation database 13. Used.

The input information processing unit 16 includes a VICS information processing unit 17 that generates “speed information” from the acquired VICS information, and a probe information processing unit 18 that generates “speed information” from the acquired probe information. .
The VICS information processing unit 17 calculates a link travel speed calculation unit 17a that calculates the link travel speed of the road link from the link travel time included in the VICS information, and a speed that converts the link travel speed into “speed information” of the link. And an information conversion unit 17b.

  The link travel speed calculation unit 17a of the VICS information processing unit 17 divides the link length of the road link for which the link travel speed is to be calculated by the link travel time of the road link, so that the link travel speed [km / h] Is calculated. The link lengths of all road links in the target area are set in the device 1 in advance.

  The speed information conversion unit 17b of the VICS information processing unit 17 converts the link travel speed obtained by the link travel speed calculation unit 17a into an index value (speed index information) called “speed information”. This conversion is performed by the speed information conversion unit 17 b referring to the “speed-speed information” conversion information 19 preset in the apparatus 1. The “speed-speed information” conversion information 19 is set as shown in FIG. 4 and will be described later in detail.

  The link travel speed calculation unit 18b of the probe information processing unit 18 calculates the link travel speed of the road link for which the link travel speed is to be calculated based on the position and time included in the probe information. A method for calculating the link travel speed [km / h] from the probe information will be described later.

  Similar to the speed information conversion unit 17b of the VICS information processing unit 17, the speed information conversion unit 18b of the probe information processing unit 18 converts the link travel speed into “speed information”. The processing content is the same as that of the speed information conversion unit 17b.

[2.3 Speed information]
The “speed information” is an index value that takes a value according to the size of the link travel speed. In this embodiment, the speed information takes a value from 0 to 1, and “speed information” = 0 is the link travel speed = 100 [km / H] and higher speeds, “speed information” = 1 corresponds to link travel speed = 0 [km / h].

However, the “speed information” in the present embodiment is not simply inversely proportional to the link travel speed. That is, as shown in FIG. 4, the link travel speed-speed information relational expression is different depending on a plurality of speed regions of the link travel speed.
More specifically, the plurality of speed regions are a first speed region (near zero speed region) having a link travel speed of 0 [km / h] to about 10 (more strictly 10.53) [km / h]. ), A second speed region in which the link travel speed is about 10 (more precisely 10.5) [km / h] to about 60 (more precisely 57.9) [km / h], the link travel speed is about These are the three speed regions of the third speed region (free travel speed region) exceeding 60 (more precisely, 57.9) [km / h].

  The first speed region is set as a near-zero speed region where the vehicle speed is 0 or a value close thereto, and such a speed region value is detected when the road is congested. The third speed region is set as a speed region that is equal to or higher than the speed limit (60 km / h) of a general road. When the road is relatively smooth and the vehicle can be in a free-running state, such a speed region is set. The value of is detected. The second speed area is set as an intermediate area between the first and third speed areas.

  If the value of the horizontal axis (link travel speed) in FIG. 4 is x and the value of the vertical axis (speed information) is y, the relational expression of link travel speed-speed information in the first speed region is y = 1− (x / 1000), the relational expression of the link travel speed-speed information in the second speed region is set to y = 1.2- (x / 50), and the link travel speed-speed information of the third speed region is The relational expression is set to y = 0.1− (x / 1000).

As described above, the link travel speed-speed information relationship line is focused on the third speed area and the second speed area. In the third speed area (inclination = 1/1000), the second speed area (inclination = 1/1000). 50), the negative slope is smaller.
That is, in the third region, which is a free speed region in which the vehicle can be in a free-running state, the rate of change in the speed information (y) with respect to the change in the link travel speed (x) (as compared to the lower second speed region) (Negative slope) is smaller.

In addition, the link travel speed-speed information relational line is focused on the first speed area and the second speed area. In the first speed area (inclination = 1/1000), the second speed area (inclination = 1/50). The inclination is smaller than that.
That is, in the first region where the vehicle speed is near zero, the rate of change in the speed information (y) with respect to the change in the link travel speed (x) (negative slope) compared to the higher-speed second speed region. Is getting smaller.

  According to the conversion information 19 set as described above, in addition to an element of simply “speed”, the road information is busy and traffic jams, or the road is empty and the vehicle is in good condition. It is also possible to have an element of the degree of traffic congestion (the degree of traffic flow).

For example, if the road travel speed is 100 km / h on a road link with a speed limit of 100 km / and the road travel speed is 60 km / h on a road link with a speed limit of 60 km / h, the speed difference is 40 km / h. Although there are vehicles on all road links, all are considered to be free-running.
On the other hand, when the link travel speed of one road link is 60 km / h and the link travel speed of the other road link is 20 km / h, the difference in speed is 40 km / h as described above. However, although the vehicle is flowing smoothly on the former road link, the latter road link is considered to be congested.

In this way, when the link travel speed reaches the free travel speed range, the relationship between the number of vehicles on the road (congestion) and the link travel speed becomes relatively low, which may be caused by other factors such as the road speed limit. The link speed is likely to change.
For this reason, for example, assuming a case where traffic information (link travel speed) of an estimation target road link is to be estimated from traffic information (link travel speed) of other related road links, the third of other road links The influence of the difference in the link travel speed in the speed region (free travel speed region) on the estimated value of the link travel speed of the estimation target road link is smaller than the difference in the link epidemic speed in the slower second speed region.

In the first speed region, as in the third speed region, when the speed is 0 to 10 [km / h], the road is considered to be considerably congested at any speed. The difference in the link travel speed in the area is less meaningful than the difference in the link epidemic speed in the high-speed second speed area.
The speed information of the present embodiment takes the above into consideration, and the traffic information of the estimation target road link can be accurately estimated by reducing the slopes of the first and third speed regions.

Further, as a result of reducing the slopes of the first and third speed regions, the slope of the second speed region is increased, and the difference in the link travel speed in the second speed region can be more emphasized in the index of speed information. .
For example, when the link travel speed (x) in the range of 0 to 100 km / h is associated with the speed information with one relational expression y = 1− (x / 100), the speed is in the range of 10 to 60 km / h. Of course, the slope is (1/100), but in the case of FIG. 4, the slope is (1/50). Therefore, in the speed information obtained from FIG. 4, the link travel speed at 10 to 60 km / h can be more accurately indexed. As a result, it is possible to improve the estimation accuracy of the traffic information of the estimation target road link.

[2.4 Calculation of link travel time from probe information]
FIG. 5 shows a method for calculating the link travel speed [km / h] from the probe information in the link travel speed calculation unit 18a.
As shown in FIG. 5, in the case where there are six road links L1 to L6, the probe vehicle 3 is used to calculate the link travel speed of the road link L4 toward the right side of the figure (direction of arrow A). The first probe information pr1 transmitted while the vehicle is located at the road link L3 (first position) immediately before the traveling direction, and the road link L5 (first The second probe information pr2 transmitted while being located at (2 position) is used.

  The distance D between the first position where the first probe information pr1 is transmitted and the second position where the second probe information pr2 is transmitted is determined by the position indicated by the first probe information pr1 and the position indicated by the second probe information pr2. . In addition, the time T required to move from the first position to the second position is determined by the time indicated by the first probe information pr1 and the time indicated by the second probe information pr2. By dividing the distance D by the time T, the travel speed of the section (normal speed calculation section) between the first position and the second position is obtained. Normally, this travel speed is regarded as the link travel speed on the road link L4 between the first position and the second position.

However, when the distance between the first position and the second position (distance of the normal speed calculation section) is equal to or less than the set minimum distance (for example, 1 km), the speed calculation section becomes long. Another piece of probe information used for calculating the link travel speed of the road link L4 is selected.
Specifically, when the distance of the normal speed calculation section is equal to or less than the minimum distance, the link travel speed calculation unit 18a has the vehicle positioned on the road link L2 (front position) one before in the vehicle traveling direction. The probe information pr0 transmitted at times and the probe information pr2 transmitted when located on the road link LL5 are used. As a result, the travel speed for the extended speed calculation section from the front position to the second position is obtained, and this travel speed is calculated as the link travel speed of the road link L4 between the front position and the second position. I reckon.

  The reason for using the extended speed calculation section when the distance of the normal speed calculation section is short is as follows. That is, when the speed calculation section is short, the time required to move in the speed calculation section is greatly affected by the stop time due to the traffic signal. In other words, even if the time required to pass the speed calculation section is, for example, 2 minutes, the time when the vehicle actually traveled is 1 minute, and the remaining 1 minute is a waiting time due to a signal. obtain. On the other hand, another vehicle passing through the same speed calculation section does not stop by a signal, and the time required to pass through the speed calculation section may be one minute. Thus, if the speed calculation section is short, an error due to the influence of waiting for a signal becomes large, and accurate speed calculation becomes difficult.

  On the other hand, if it is a speed calculation section where the distance is sufficiently long and it is necessary to pass many traffic signals (intersections), the waiting time due to one of the traffic signals is almost all of the vehicles. To occur evenly. The error due to signal waiting is small.

Thus, as in the present embodiment, when the distance of the normal speed calculation section is short, the speed can be calculated with higher accuracy by calculating the speed in the extended speed calculation section.
Even if the distance of the normal speed calculation section is short, if the number of vehicles is large (for example, 10 or more), the time required to pass through the speed calculation section is determined by a probe from a plurality of vehicles. By averaging with information, the error can be reduced. Therefore, it is expanded only when the normal speed calculation section is not more than the set minimum distance and the number of probe vehicles per unit time (the number of probe information) is not more than the set minimum number. Speed calculation in the calculated speed calculation section may be performed.

  In the above example, the extended speed section is from the front position (road link L2) to the second position (road link L5), but instead of the second position, the traveling direction is more than the second position. It is good also as a point ahead (road link L6). Further, the extended speed section may be between the first position (road link L3) and the previous position (road link L6).

[2.5 Processing by the traffic information estimation device 1]
[2.5.1 Outline of estimation process]
FIG. 6 shows a traffic information estimation method by the traffic information estimation apparatus 1. First, initial values are set in the estimation database (traffic information database) 13 and the weight database 15 (step S1).

  And if the traffic information estimation apparatus 1 acquires VICS information and probe information, the input information processing part 16 will produce | generate the speed information of each road link from VICS information and probe information (step S2). However, the road links for which speed information can be acquired in step S2 are a part of all road links in the target area, and there are road links for which speed information cannot be obtained in step S2.

  Subsequently, the speed information obtained in step S2 is set in the estimation database 13, and the estimation database DB4 is updated (step S3). Then, the estimation engine 11 estimates speed information about the road link for which speed information is not obtained based on the content of the estimation database 13 updated in step S3, and sets the estimated speed information in the estimation database 13. Then, the estimation database 13 is updated (step S4). By this step S4, speed information (a mixture of measured values and estimated values) for all road links in the target area is obtained.

The speed information for all road links obtained in step S4 is output to the outside of the device (step S5). Specifically, it is displayed on the display of the device 1 or output as information to be provided to the in-vehicle device 2.
A part of the content of the estimation database 13 updated in step S4 is accumulated as a snapshot in the learning database 14 and used as learning data by the learning engine 12 (step S6).

  The processes in steps S2 to S6 are repeatedly executed every time speed information is generated. The input information processing unit 16 acquires the VICS information and the probe information in accordance with the update period (for example, 5 minutes) of the VICS information, and generates the speed information. It is repeatedly executed in accordance with the update cycle (for example, 5 minutes).

[2.5.2 Model for speed information estimation]
FIG. 7 shows a neural network for the estimation engine 11 to estimate speed information of the estimation target road link. The illustrated neural network generates an output value y by multiplying each of N input signals x _i (i: 1 to N) having values of 0 to 1 by weights w _i (w _i : 0 to 1). It is configured as a simple perceptron.
Here, the input signal x _i is speed information of a road link other than the estimation target road link (a road link connected to the estimation target road link), and the output value y is speed information of the estimation target road link. .

Further, the weight w _i is a value indicating how much the speed information of each of the plurality of road links other than the estimation target road link is reflected, and the road link having a high correlation with the estimation target road link (for example, A road link that constitutes the same road as the estimation target road link and is adjacent to the estimation target road link) should be set to a larger value, and a road link having a lower correlation should be set to a smaller value.

However, in FIG. 7, unlike a general simple perceptron, an independent parameter w ₀ that is added to a node without being multiplied by the input signal x _i is provided. This independent parameter w ₀ expresses a factor (for example, a difference in speed limit between road links) that a factor other than speed information in a road link other than the estimation target road link gives to the speed information of the estimation target road link. Speed information can be estimated with high accuracy. Further, when learning the estimation parameter (weight), the estimation parameter is easily converged to the optimum value, and the learning process can be performed easily or at high speed.

  As described above, in order for the estimation engine 11 to obtain the speed information of a certain estimation target road link, the speed information of another road link whose correlation with the estimation target road link is recognized to some extent, and the other road It is only necessary to obtain a weight indicating how much the link speed information is reflected in the speed information of the estimation target road link. The speed information of such other road links is accumulated in the estimation database (traffic information database) 13, the weights are accumulated in the weight database 15, and the estimation engine 11 obtains necessary information from both the databases 13 and 15. get.

  Note that the neural network for estimating the velocity information is not limited to a single-layer perceptron as shown in FIG. 8, and may be a multilayer perceptron having an input layer, an intermediate layer, and an output layer. When configured as a multilayer perceptron, the speed information of the estimation target road link can be appropriately obtained even when the speed information has a non-linear relationship between the estimation target road link and another road.

[2.5.3 Details of estimation processing]
Here, a road link connected as shown in FIG. 8 is assumed. In FIG. 8, Vx indicates road link speed information (value of 0 to 1). The subscript x in Vx indicates the link number of the road link and takes a value of 1 to 24. That is, in FIG. 8, there are 24 road links with link numbers 1 to 24. Moreover, the arrow direction of each link shows the traveling direction of the vehicle.

In FIG. 8, road links (link numbers x = 1 to 10) indicated by solid-line arrows are links from which VICS information can be acquired, for example, road links corresponding to expressways and main trunk roads. Moreover, the road link (link number x = 11-24) shown by the dotted line arrow is a link from which VICS information cannot be acquired, and is, for example, a general road other than a highway or a main trunk road. A road link indicated by a dotted arrow may be an estimation target road link of speed information. That is, the road link indicated by the dotted arrow is not the estimation target road link when the probe information is obtained, and is the estimation target road link when the probe information is not obtained.
Even if the VICS information can be acquired, if the VICS information cannot be acquired for some reason, it is treated as an estimation target road link.

Hereinafter, the speed information estimation procedure will be described in detail with reference to the road link in FIG. 8 and with reference to FIG. 6 again.
First, initial values are input to the estimation database (traffic information database) 13 and the weight database 15 by the device administrator (step S1).

  As shown in FIG. 9, the estimation database 13 has data items of “check” 31, “speed information” 32, “related road link information” 33, “link length” 34, and “learning?” The value of each data item can be stored for each road link (link number).

Among the data items, “check” 31 is an item indicating whether or not the speed information of each road link is updated and the order of update. “Speed information” 32 is an item in which speed information of each road link is set.
The “related road link information” 33 indicates a road link (related road link) correlated with each road link, and here indicates a road link (link number) connected to each road link. .

The “related road link information” 33 is divided into five types of “reverse”, “A order”, “A reverse”, “B order”, and “B reverse”.
“Reverse” indicates a link number of a road link opposite to an arbitrary road link. For example, for a road link with link number 1, the road link with link number 8 becomes a “reverse” road link.
“A order” is a road link connected in the forward direction behind a certain road link. For example, for the road link with link number 1, the road links with link numbers 12, 7, and 15 are “A order”. It becomes the road link.
“A reverse” is a road link connected in the reverse direction behind a certain road link. For example, for the road link with link number 1, the road links with link numbers 11, 15, and 13 are “A reverse”. It becomes the road link.

“B order” is a road link connected in the forward direction in front of a certain road link. For example, for the road link with link number 1, the road links with link numbers 4 and 9 are “B order”. It becomes a link.
“B reverse” is a road link connected in the reverse direction in front of a certain road link. For example, for the road link with link number 1, the road links with link numbers 3 and 6 are “B reverse”. It becomes a link.

  Of the data items, “link length” 34 indicates the link length of each road link. “Learning?” 35 indicates whether or not the speed information of each road link is data (learning data) for learning by the learning unit 20 (learning engine 12). Takes a value of 1. “0” indicates that the speed information of the road link is not the learning data, and “1” indicates that the speed information of the road link is the learning data.

  The initial value input in step S1 is performed when the operation of the apparatus 1 is started or reset. Regarding the estimation database 11, among the above data items, “speed information” 32, “related road link information” 33, “link length”. An initial value is set for 34. As an initial value of the “speed information” 32, for example, 0 may be set for all road links. The initial values of “related road link information” 33 and “link length” 34 are set according to the road configuration of the target area. The initial values of “related road link information” 33 and “link length” 34 are not updated even if traffic information (speed information) including VICS information and probe information is acquired.

On the other hand, the value of “speed information” 34 is updated for all road links every time traffic information (speed information) composed of VICS information and probe information is acquired (steps S3 and S4).
The “check” 31 is initialized to 0 each time the traffic information (speed information) is acquired (step S2). “Learning?” 35 is also set to 0 or 1 every time traffic information (speed information) is acquired (step S2), depending on whether or not the speed information of each road link should be learned data. The

As shown in FIG. 10, in the weight database 15, a weight wi used when an estimated value of speed information for each road link is obtained from speed information of other road links is set as an initial value. The weight wi is set to “number of related road links + 1” for each road link. In FIG. 10, w ₀ is an independent parameter, and w _{1 and} subsequent weights are weights to be multiplied by the related road link speed information.

  Since the weight wi that is an estimation parameter is automatically updated to a more appropriate value by learning by the learning engine 12, an appropriate value may be set as an initial value. Therefore, initial setting is easy.

  Now, after performing the above initialization, it is assumed that VICS information and probe information (traffic information) as shown in FIG. 11 have been obtained at a certain point in time for the road link shown in FIG. In FIG. 11, VICS information (link travel time) for road links with link numbers 1 to 10 is obtained, and probe information for road links with link number 20 is obtained. Neither VICS information nor probe information is obtained for other road links. In FIG. 11, probe information about the road link with the link number 20 is indicated by “link travel time” in the same manner as the VICS information for easy notation.

  Further, in the information of FIG. 11, a value “1” indicating that the road link (link number 20) where the probe information exists is set as a learning target is set, and the road link (link number) where the VICS information exists. As for 1 to 10), a value “0” indicating that it is not a learning target is set.

  When the input information as shown in FIG. 11 is acquired, the “travel time” in this information is converted into “speed information” by the input information processing unit 16 (step S2), and the correspondence of the estimation database 13 is determined by the speed information. The “speed information” 32 of the road link to be updated is updated (first update; step S3). For the updated road link, “1” indicating that the speed information has been updated in the first update is set in “check” 31. For the road link whose “learning target” of the input information in FIG. 11 is “1” (here, the road link of link number 20), “learning?” 35 is set to “1”.

  FIG. 12 shows the contents of the estimation database 13 after the first update (set of input information) is performed as described above.

Subsequently, the speed information about the road links (link numbers 11 to 19 and 21 to 24) whose speed information is not updated is estimated, and the estimation database 13 is updated with the estimated value (step S4).
Specifically, first, among the related road links (adjacent road links) of road links (link numbers 1 to 10, 20) in which “1” indicating the previous update is set in the “check” 31 item, A road link (check = 0) for which speed information has not yet been updated based on the current input information (FIG. 11) is extracted. Here, 11 road links of link numbers 12, 15, 11, 13, 19, 18, 17, 21, 21, 24, 14 and 16 are extracted (see FIG. 13). These 11 road links serve as estimation target road links here.

  Then, the estimation engine 11 reads the related road links for each of the 11 estimation target road links from the estimation database 13 and uses the weights (estimation parameters) set for each of the 11 estimation target road links as the weights. Reading from the database 15 and using these, the estimated value of the speed information of each estimation target road link is calculated. The calculated estimated value of the speed information is set in “speed information” of the estimation database 13, and the second update of the speed information is performed. For the updated road link, “2” indicating that the speed information has been updated in the second update is set in “check” 31.

Among the estimation target road links, for example, an arithmetic expression for obtaining an estimated value (V ₁₂ , V ₁₅ , V ₁₁ , V ₁₃ ) of speed information of road links of link numbers ₁₂ , ₁₅ , ₁₁ , and ₁₃ is as follows. It is as follows.
V ₁₂ = w ₀ + w ₁ V ₁₁ + w ₂ V ₁ + w ₃ V ₅ + w ₄ V ₁₃ + w ₅ V ₈ + w ₆ V ₇ + w ₇ V ₁₅
V ₁₅ = w ₀ + w ₁ V ₁₃ + w ₂ V ₂₀ + w ₃ V ₁₆ + w ₄ V ₁₇ + w ₅ V ₁₄ + w ₆ V ₁ + w ₇ V ₁₁
+ W ₈ V ₅ + w ₉ V ₈ + w ₁₀ V ₁₂ + w ₁₁ V ₅
V ₁₁ = w ₀ + w ₁ V ₁₂ + w ₂ V ₈ + w ₃ V ₁₅ + w ₄ V ₇ + w ₅ V ₁ + w ₆ V ₁₁ + w ₇ V _{5
V 13 = w 0 + w 1} V 15 + w 2 V 8 + w 3 V 12 + w 4 V 7 + w 5 V 1 + w 6 V 11 + w 7 V 5
+ W ₈ V ₁₄ + w ₉ V ₁₇ + w ₁₀ V ₁₆ + w ₁₁ V ₂₀

  And among the related road links (adjacent road links) of the road links (link numbers 11 to 19, 21, 24) in which “2” indicating the previous update is set in the “check” 31 item, this input A road link (check = 0) for which speed information has not yet been updated based on the information (FIG. 11) is extracted. Here, two road links with link numbers 22 and 23 are extracted (see FIG. 14). These two road links become the next estimation target road links.

  Then, the estimation engine 11 reads the related road links for each of the two estimation target road links from the estimation database 13 and uses the weights (estimation parameters) set for each of the two estimation target road links as the weights. Reading from the database 15 and using these, the estimated value of the speed information of each estimation target road link is calculated. The calculated estimated value of the speed information is set in “speed information” of the estimation database 13, and the third update of the speed information is performed. As for the updated road link, “3” indicating that the speed information has been updated in the third update is set in “check” 31.

  The above process is repeated until the speed information for all road links is estimated (step S4). Here, since all speed information has been complemented by three updates, the estimation process is terminated.

Then, the contents of the estimation database are output (step S5).
Furthermore, among the road link data of the estimation database 13 for which the estimation process has been completed based on the current input information (FIG. 11), the road link of the link number 20 with “1” set to “Learning?” 35. A snapshot (see FIG. 15) is added to the learning database 14. Here, the snapshot stores “speed information” of a road link having a link number for which “1” is set in “learn?” 35 and “speed information” of a related road link of the road link. It is. Here, the speed information of the road link having the link number for which “1” is set in “Learning?” 35 is a measured value because it is a value obtained from the probe information. In addition, in the “speed information” of the related road link of the road link, an actual measurement value and an estimated value obtained from VICS information are mixed.

A snapshot occurs every time input information is acquired and all road links in the estimation database are updated (steps S3 and S4). This snapshot is generated for a road link for which probe information has been acquired.
Therefore, in the above example, the snapshot is generated only for the road link with the link number 20, but if all the road links in the estimation database are updated many times (steps S3 and S4), the other road links are also snapped. Shots are accumulated. When sufficient time has passed for the input information to be returned to the city, a plurality of snapshots are accumulated for one road link.

FIG. 16 shows the contents of the learning database 14 in which a plurality of snapshots are accumulated for a plurality of road links.
Based on the learning database 14 in which a large number of snapshots are accumulated in this way, the learning engine 12 learns (optimizes) the weights (estimation parameters) stored in the weight database 15 to obtain the weights. The contents of the database 15 are updated.

FIG. 17 shows the procedure of the learning process by the learning engine 12. First, the learning engine 12 sets parameters for learning, such as an allowable error for error determination, the number of intermediate layers constituting the neural network (FIG. 7), and a learning count (step S11).
The learning engine 12 is configured as a neuro engine that optimizes (learns) a neural network as shown in FIG. That is, the learning engine 12 uses the speed information that is an actual measurement value among the snapshots stored in the learning database 14 as a teacher signal, and the speed information about the related road link of the road link having the speed information that becomes the teacher signal. Then, an appropriate neural network for outputting the teacher signal is reconstructed. That is, the learning engine 12 calculates the optimum value of the weight from the learning data including the speed information that is the actually measured value and the speed information about the related road link having the speed information. The optimum weight value can be calculated by, for example, the least square method.

  The optimum weight value is calculated until the speed information calculated from the speed information about the related road link approaches the teacher signal and the error from the teacher signal is less than the set allowable error (step S13). ).

  When the weights converge and the learning process ends, the obtained weights are reflected in the weight database 15 and the weight database 15 is updated.

  When input information composed of VICS information and probe information is generated after the weight database 15 is updated, the estimation of the speed information by the estimation engine 11 is performed with higher accuracy using the new weight. Thus, in the traffic information estimation apparatus 1 of this embodiment, the estimation accuracy of traffic information (speed information) naturally improves by continuing operation.

[3. Other examples of speed information]
FIG. 18 shows another example of the “speed-speed information” conversion information described above with reference to FIG.
The conversion information in FIG. 18 uses a natural logarithm. Specifically, if the link travel speed (horizontal axis in FIG. 18) is x and the speed information (vertical axis in FIG. 18) is y, y = It is a function of exp (− (x / 20)). The speed information y in FIG. 18 also takes a value from 0 to 1. Note that the value “20” in this formula is a preferred example and is not limited to “20”, and any positive number a can be adopted.

In the function of y = exp (− (x / 20)), the slope seen from x is obtained by differentiating this expression by x, and is as follows.

As described above, the conversion information in FIG. 18 is set so that the rate of change in the speed information (standardized speed) y with respect to the change in the link travel speed x (the slope seen from x) decreases as the link travel speed x increases. Has been.
That is, in the conversion information in FIG. 18 as well, in the speed region of 60 km / h or higher where the vehicle can be in a free-running state, the link travel speed is lower than that in the lower speed region. Is set so that the rate of change of speed information with respect to change of

  In other words, the conversion information in FIG. 18 is set so that the rate of change in the link travel speed x with respect to the change in the speed information (standardized speed) y (the slope seen from y) increases as the speed information increases. ing.

この場合、ｙからみた傾きは、ｙの逆数に比例することになる。 Here, when the function of FIG. 18 is expressed as a function with respect to y, x = −20 × ln (y). In this case, the slope seen from y is obtained by differentiating this expression with y. It is.

In this case, the slope seen from y is proportional to the reciprocal of y.

As shown in FIG. 18, even if the speed information (standardized speed) changes by the same value by setting the conversion information, the effect on the actual link travel speed depends on the magnitude of the speed information (standardized speed). Different.
For example, consider cases where the speed information is 0.1 and 0.5. In this case, since the slope seen from y is proportional to the reciprocal of y, dx / dy = −20 / 0.1 = −200 and dx / dy = −20 / 0.5 = −40.

  Therefore, when the speed information changes by about 0.01, and when the speed information is higher than 0.1, the change in the link travel speed is −0.01 (dx / dy) = 2 [km / h. ], The speed information of the link travel speed is −0.01 (dx / dy) = 0.4 [km / h]. Becomes relatively small.

  That is, even if the speed information (standardized speed) changes by the same value, the influence on the actual link travel speed is determined by the reciprocal of the speed information (standardized speed). Since the reciprocal of the speed information, which is an inclination, is proportional to the link travel time traveling a unit distance (for example, 1 km), it is effective to use conversion information as shown in FIG. 18 when evaluating the travel time.

  In the conversion information of FIG. 18, the slope as viewed from x decreases monotonously as x increases. In other words, the slope seen from y increases monotonically with increasing y. In this way, by adopting a function in which the slope changes monotonously as conversion information, when the slope is compared at any two points, even if the speed information (normalized speed) changes by the same value, The relationship of “the influence on the actual link travel speed differs depending on the speed information (standardized speed)” is always preferable.

  FIG. 19 shows still another example of conversion information. The conversion information in FIG. 19 is set as a function of y = (1 / x), and, similar to the conversion information in FIG. 18, the slope seen from x is a function that decreases monotonically as x increases. In the case of the conversion information shown in FIG. 19, the speed information changes too much in the region where the link travel speed x is relatively low. To avoid this point, the natural logarithm is used as in the conversion information shown in FIG. Function is preferred.

FIG. 20 shows still another example of conversion information. In the conversion information of FIG. 20, the link travel speed-speed information relationship is linear in each of the region where the link travel speed x is 0 to 60 [km / h] and the region where 60 to 100 [km / h]. The change in inclination is not monotonous, but overall, the inclination changes according to the link travel speed. Specifically, in the region of 60 to 100 [km / h], 0 to 60 [ km / h], the rate of change of the speed information y with respect to the change of the link travel speed x is smaller.
As described above, the conversion information in FIG. 20 is also set so that the rate of change in the speed information with respect to the change in the link travel speed decreases as the link travel speed x increases, and is similar to the conversion information in FIG. In addition, in the speed range of 60 km / h or higher where the vehicle can be in a free-running state, the rate of change in the speed information with respect to the change in the link travel speed is set to be smaller than in the lower speed range. Yes.

  FIG. 21 shows still another example of conversion information. In the conversion information of FIG. 21, the link travel speed has different slopes in the region of 0 to 10 [km / h], the region of 10 to 60 [km / h], and the region of 60 to 100 [km / h]. The rate of change in the speed information with respect to the change in the link travel speed decreases as the link travel speed x increases, and the vehicle is in a free-running state as in the conversion information in FIG. In a speed range of 60 km / h or higher, which is a lower speed range, the rate of change in the speed information with respect to the change in the link travel speed is set to be smaller than that in the lower speed range.

[4. Determination of estimation order of speed information (traffic information)]
Below, in the traffic information estimation apparatus 1 demonstrated previously, when estimating the speed information of a road link, the method to determine the order (estimation order) of the road link which estimates speed information is demonstrated.

Here, a road link connected as shown in FIG. 22 is assumed. In the road link structure shown in FIG. 22, the road link V23 set as the road link in the reverse direction of the road link V22 in the road link structure shown in FIG. 8 is omitted. Instead, the road link V23 is replaced with the road link V14. Are set to be forward and parallel to each other.
In the road link structure of FIG. 22, node numbers 1 to 7 are assigned to the nodes (circles in FIG. 22) to which the link ends of the road links are connected. These nodes indicate connection points between roads indicated by road links, such as intersections.

FIG. 23 shows a road link (estimation target road link) for which the estimation engine 11 cannot obtain VICS information and probe information when the traffic information estimation device 1 acquires VICS information and probe information if present. When traffic information (speed information) is estimated, a procedure for determining the order of road links (estimation order; update order of speed information in the estimation database) for estimating the traffic information is shown.
More specifically, FIG. 23 determines the order of road links for estimating speed information when estimating speed information for road links for which speed information is not obtained in step S3 of FIG. Means are shown.

  When determining the estimation order, the estimation engine 11 first refers to the link-node connection table T1 corresponding to the road link structure as shown in FIG. 22, and the road link from which the speed information is obtained is connected. Nodes are extracted (step S21). The link-node connection table T1 is a table indicating nodes to which road links are connected, and a specific description thereof will be described later. In step S21, extraction is performed excluding the nodes already extracted in the preceding step S21 in the repetition in step S23.

  Here, it is assumed that the VICS information can be acquired for the road links of the link numbers 1 to 10 and the probe information can be acquired for the road link of the link number 20. In this case, since the nodes connected to these road links 1 to 10 and 20 are nodes having node numbers 1 to 4 and 6 as is apparent from FIG. 22, in step S21, the node numbers 1 to 4 are used. And 6 nodes are extracted.

  Subsequently, the estimation engine 11 is connected to the extracted node with reference to the node-link connection table T2 corresponding to the road link structure as shown in FIG. 22, and the speed information in the estimation database is not updated. Is extracted (step S22). The node-link connection table T2 is a table showing road links connected to each node, and a specific description will be given later.

  If the extracted nodes are nodes having node numbers 1 to 4 and 6 as described above, road links having link numbers 11 to 19, 21, 23, and 24 are extracted in step S22. These link numbers 11 to 19, 21, 23, and 24 are road link groups that are estimated first.

  If the road link group extracted as described above is all of the road links for which speed information is not obtained, the estimation order determination process ends. If not, step S21 and step S22 are repeated. In the above example, since not all (the road link with the link number 22 remains), Step S21 and Step S22 are executed again.

  In the second step S21, among the nodes to which the road links (link numbers 11 to 19, 21, 23, and 24) extracted in the previous step S22 are connected, the nodes not extracted in the previous step S21 are selected. Extract. Here, nodes with node numbers 5 and 7 are extracted.

  Further, the second step S22 is performed, and the road links connected to the extracted node numbers 5 and 7 are obtained as the road links in which the speed information is not acquired or estimated and the speed information in the estimation database is not updated. The road link of link number 22 is extracted. The road link with the link number 22 is the second estimated road link.

  Here, since the estimation order of all road links in FIG. 22 is determined by repeating step S21 and step S22 twice, the estimation order determination process is terminated in the second step S23.

  As described above, by determining the estimation order, the road link directly connected to the road link (link numbers 1 to 10 and 20) from which the speed information is obtained has the highest priority, and the road from which the speed information is obtained. Estimated order is determined so that the road links with a larger number of road links intervening with the links are later in order, and the road links closer to the road links from which the speed information was obtained are estimated in order from the road links farther away. Ripple.

[5. Generation of connection tables T1, T2]
FIG. 24 shows a modification of the structure of the estimation database 13 shown in FIG. Hereinafter, a method for generating the link-node connection table T1 and the node-link connection table T2 when the estimated database structure shown in FIG. 24 is given will be described.

  First, the estimation database 13 of FIG. 24 includes “estimation order” 31, “standardized speed” (speed information) 32, “link length (km)” 34, “road type” 36, “learning?” 35, “relevant”. It has a data item of “road link information” 33 and can store the value of each data item for each road link (link number).

  In FIG. 24, items having the same names as the data items in FIG. 9 have the same role. Further, “estimation order” 31 in FIG. 24 corresponds to the item of “check” 31 in FIG. Further, “road type” 36 in FIG. 24 indicates a road type such as an expressway or a general road.

“Related road link information” 33 in FIG. 24 is almost the same as that in FIG. 9, but “reverse”, “A order”, “A reverse”, “B reverse”, “B reverse” as shown in FIG. ”Is not the five types, but six types are added with“ order ”. “Forward” indicates a road link parallel to a certain road link in the forward direction (a road link having a common road link rear end and front end). For example, for a road link with a link number 14, a road link with a link number 23 Becomes the “order” road link.
Further, in “related road link information” 33 in FIG. 24, the number of road links belonging to “order”, “A order”, “B order”, “A reverse”, “reverse”, and “B reverse” is recorded. The

  In order to generate the connection tables T1 and T2 from the estimated database structure shown in FIG. 24, first, from the “related road link information” 33 in the estimated database in units of road links as shown in FIG. Such “related road link information” is generated for each road link end.

  Here, each road link has a rear end (A end) and a front end (B end) as road link ends, and the road link connected to the rear end (A end) includes its own link, “order”, There are “reverse”, “A order”, and “A reverse”, and the road link connected to the front end (B end) is the own link, “order”, “reverse”, “B order”, “B reverse”. is there. For example, in the case of the road link with the link number “1”, as the road link (including its own link) connected to the rear end (A end), the link numbers 1, 8, 12, 7, 15, 11, 5, There are 13 road links, and road links (including self-links) connected to the front end (B end) include road links with link numbers 1, 8, 4, 9, 3, and 6.

In this way, the road links connected to the rear end (A end) and the front end (B end) of each road link are extracted from the “related road link information” 33 in units of road links in FIG. Generate to show.
In FIG. 25, the node number (“Node number”) of the node corresponding to the road link end can also be recorded.

Furthermore, the “related road link information” in units of road link ends shown in FIG. 25 is sorted by link number. The item “related road links after sorting” in FIG. 25 indicates the result of sorting for each road link end.
Of these sort results, the same “Node number” is recorded in the same sort result as shown in FIG.

  A link-node connection table T1 shown in FIG. 26A is generated from the “link number” and “Node number” shown in FIG. FIG. 26 shows the node number of the node to which the rear end or front end of the link is connected for each road link. In FIG. 26A, the node number of the node to which the rear end is connected is indicated by a number with parentheses. In the link-node connection table T1, the rear end and the front end of the link to be connected are distinguished. The node number is recorded as attached.

  FIG. 26A shows the node-link connection table T2 generated from the “Node number” and the “related road link after sorting” shown in FIG. In this table T2, in the “Node number” and “Related road link after sorting” shown in FIG. 25, the “Node number” or “Related road link after sorting” is deleted and connected to each node. It shows the road link. In FIG. 26B, the link number of the road link to which the rear end is connected is indicated by a number with parentheses. In the node-link connection table T2, the rear end and the front end of the connected link are distinguished. The link number is recorded so as to be attached.

  Furthermore, both connection tables T1 and T2 each have an item of “estimation order” (update order). This “estimation order” item is used as follows.

  First, regarding the road link shown in FIG. 22, it is assumed that VICS information and probe information are obtained at a certain point in time as shown in FIG. In FIG. 24, VICS information about the road links with the link numbers 1 to 10 is obtained, probe information about the road link with the link number 20 is obtained, and the speed information calculated from the VICS information is “normalized” in the estimation database 13. It is set in the item of “Speed” (speed information). For other road links, neither VICS information nor probe information is obtained.

  For the road link for which the VICS information or the probe information is obtained, “1” is set in the “estimation order” (update order) 31 item of the estimation database 13 as the order indicating the estimation (update).

  Further, as shown in FIG. 26A, for the road link from which VICS information or probe information is obtained, “1” is also set in the “estimated order” (update order) item of the link-node connection table T1. Then, the speed information is set in the item of “standardized speed” (speed information). Note that the initial value of the “estimation order” is “0” in the database 13 and the tables T1 and T2.

  When the link-node connection table T1 in step S21 of FIG. 23 is referred to in the above state, as shown in FIG. 27A, road links (link numbers 1 to 1) from which VICS information or probe information is obtained are obtained. The node numbers of the nodes to which 10 and 20) are connected are extracted. Nodes with node numbers 1, 2, 3, 4, and 6 are extracted as nodes to which the road links with link numbers 1 to 10 and 20 are connected. Note that the extracted node numbers are not limited to those in which “estimation order” is “0” in the node-link connection table T2, but at this point in time, as shown in FIG. Since the “estimated order” is all “0”, the node numbers of all the nodes to which the road links from which the VICS information or the probe information is obtained are connected are extracted in the table T1.

  For the extracted node numbers 1, 2, 3, 4, and 6, as shown in FIG. 27B, “1” is set in the “estimated order” item of the node-link connection table T2. .

  Subsequently, when the node-link connection table T2 in step S22 in FIG. 23 is referred to, roads connected to the nodes having node numbers 1, 2, 3, 4, and 6 as shown in FIG. Road links whose “estimated order” is “0” in the link-node connection table T1 (road links whose “standardized speed” has not been updated) are extracted. Here, road links with link numbers 11 to 19, 21, 23, 24 are extracted.

  For the road links with the extracted link numbers 11 to 19, 21, 23, 24, “2” is set in the “estimated order” item of the link-node connection table T1, as shown in FIG. The

  In the second reference to the link-node connection table T1 in step S21, road links (link numbers 11 to 19, 21, 23, 24 with link numbers 11 to 19, 24, in which “2” is set in the “estimated order” item of the table T1. For the link), nodes that are connected to the link and whose "estimation order" is still "0" in the node-link connection table T2 are extracted. Here, nodes with node numbers 5 and 7 are extracted. For the nodes with the node numbers 5 and 7, the “estimation order” in the node-link connection table T2 is set to “2” (see FIG. 28B).

  In the second reference to the node-link connection table T2 in step S22, as shown in FIG. 28 (b), the nodes (node numbers 5, 5) in which “2” is set in the “estimation order” item of the table T2. With respect to 7), road links connected to nodes that have an “estimated order” of “0” in the link-node connection table T1 are extracted. Here, the road link of link number 22 is extracted. For the road link 22, the “estimated order” in the link-node connection table T1 is set to “3” (see FIG. 29A).

  As shown in FIG. 29 (a), values other than the initial value “0” are set in the “estimation order” of all road links, and the estimation order (update order) of all road links is set to “ It is determined as shown in “estimation order”. Therefore, the estimation order determination process ends (step S23 in FIG. 23), and speed information (standardized speed) is estimated in the determined estimation order.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the meanings described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  For example, other road links (related road links) used for estimating speed information of the estimation target road link are not limited to those connected to the estimation target road link, but are separated from the estimation target road link. However, it may be a road link (for example, a road link parallel to the estimation target road link) whose speed information changes in time.

  In addition, when you want to reflect the time component in the speed information estimation, you can use road links that change characteristic in time (for example, road links that are crowded only in the morning, road links that are mixed only in the night, etc.) It can also be included in a road link (related road link). In this case, the speed information of the road link that changes temporally is commonly used for all the estimation target road links.

  Furthermore, in this embodiment, only the speed information in the same time zone is used as the speed information of other road links used for estimating the speed information of the estimation target road link. The speed information may be used. For example, in the case of a road link far away from the estimation target road link, there is a time delay until the traffic situation on the road link is reflected on the estimation target road link. Therefore, in the case of a road link far away, for example, more appropriate estimation can be performed by using the speed information of one hour ago for estimation.

  Furthermore, the traffic information to be estimated by the estimation engine 11 of the traffic information estimation apparatus 1 according to the present embodiment is not limited to speed information, but may be other traffic information such as traffic jam information in addition to / in place of the speed information. You can also. In this case, the degree of traffic congestion can be calculated by assigning 1 in the speed information to a busy binary value and 0 as a smooth binary value. Further, when the congestion degree is handled as the traffic information to be estimated, the neural network also requires a threshold for determining one of the two values as an estimation parameter. In this case, the threshold value is also a learning target by the learning unit.

  Furthermore, in the present embodiment, when the speed information is estimated, the road link order (estimation order) for estimating the speed information is determined, but it is not necessary to perform the estimation according to such an estimation order. Although it takes time to perform estimation several times in an arbitrary order, it is possible to obtain the same effect as in the case of estimation according to the estimation order.

  Furthermore, in the traffic information device 1 of the present embodiment, common conversion information may be used for a plurality of road links, or different conversion information may be used depending on road link attributes. The attributes of the road link include, for example, a road type such as a highway / general road, a road speed limit, an average travel speed, a speed variation, a road width, and the like. Furthermore, you may make it use the conversion information which changes with time with respect to the same road link.

  Furthermore, the present specification discloses a plurality of inventions, and each invention is not limited to the description method of the claims, and should be interpreted in the broadest sense according to the technical significance of each invention. It is.

1: Traffic information estimation device, 2: On-vehicle device, 3: Probe vehicle, 4: Roadside communication device, 5: Roadside sensor, 6: VICS center computer, 11: Estimation engine (estimator), 12: Learning engine, 13: Estimation database, 14: learning database, 15: weight database, 16: input information processing unit, 17: VICS information processing unit, 17a: link travel speed calculation unit, 17b: speed information conversion unit, 18: probe information processing unit, 18a: Link travel speed calculation unit, 18b: Speed information conversion unit, 19: Conversion information, 20: Learning unit

Claims (14)

A traffic information estimation device that estimates traffic information of an estimation target road link based on traffic information of another road link,
A conversion unit that converts a link travel speed indicating the speed of the vehicle on the other road link into speed information that takes a value corresponding to the magnitude of the link travel speed;
Using the speed information converted by the conversion unit as traffic information of the other road link, an estimation unit for estimating the traffic information of the estimation target road link;
With
The conversion unit performs the conversion using conversion information for converting link travel speed into the speed information,
The conversion information indicates that the rate of change in the speed information with respect to the change in the link travel speed is smaller in the speed range of the free running speed where the vehicle can be in the free running state than in the speed area lower than the free running speed range. A traffic information estimation device characterized by being set to be.   The conversion information includes a change in the link travel speed in the speed region of the free travel speed where the vehicle can be in a free travel state and the near-zero speed region where the link travel speed is near zero, compared to the speed region between the two regions. The traffic information estimation apparatus according to claim 1, wherein the traffic information estimation apparatus is set so that a rate of change in speed information with respect to the vehicle is small. A traffic information estimation device that estimates traffic information of an estimation target road link based on traffic information of another road link,
A conversion unit that converts a link travel speed indicating the speed of the vehicle on the other road link into speed information that takes a value corresponding to the magnitude of the link travel speed;
Using the speed information converted by the conversion unit as traffic information of the other road link, an estimation unit for estimating the traffic information of the estimation target road link;
With
The conversion unit performs the conversion using conversion information for converting link travel speed into the speed information,
The traffic information estimation device, wherein the conversion information is set such that the rate of change in speed information with respect to change in link travel speed decreases as the link travel speed increases.   4. The traffic information estimation apparatus according to claim 3, wherein the conversion information is set as a function in which a rate of change in speed information with respect to a change in link travel speed monotonically decreases as the link travel speed increases. . If the link travel speed is x and the speed information is y,
The traffic information estimation apparatus according to claim 3 or 4, wherein the conversion information is set as a function described below.
y = exp (-(x / a)) (where a is an arbitrary positive number) When the traffic information of one or a plurality of the other road links is obtained, the estimation unit sets the remaining one or a plurality of road links for which the traffic information is not obtained as the estimation target road links, and sets the estimation target road links. Traffic information is estimated according to the estimated order.
Further, the estimation unit gives first priority to the estimation target road link directly connected to the other road link from which traffic information is obtained, and is interposed between the other road link from which the traffic information is obtained. The traffic information estimation apparatus according to any one of claims 1 to 5, wherein the estimation order is determined so that the estimation target road links having a larger number of road links are in a later order. The estimation unit includes
For each of the plurality of road links, a link-node connection table storing information indicating the node to which the link end of each road link is connected;
For each of the plurality of nodes, a node-link connection table storing information indicating road links connected to each node, and
The traffic information estimation apparatus according to claim 6, wherein the estimation order is determined using the link-node connection table and the node-link connection table. The estimation unit is configured to perform an operation of estimating traffic information of an estimation target road link from traffic information of another road link using an estimation parameter,
When an actual measurement value of traffic information of a road link that can be an estimation target road link is obtained, the actual measurement value and the traffic information of the other link are stored as learning data, and the stored learning data is stored. The traffic information estimation device according to claim 1, further comprising: a learning unit that uses and optimizes the estimation parameter.   The traffic information estimation apparatus according to claim 8, wherein the actual measurement value is obtained from probe information transmitted from a probe vehicle.   The traffic information estimation device according to claim 8 or 9, wherein the estimation parameter includes a weight multiplied by traffic information of another road link. A link travel speed calculation unit that calculates a link travel speed for a road link from probe information including the position and time of the probe vehicle,
The link travel speed calculation unit transmits the first probe information transmitted when the probe vehicle is present at the first position, and when the probe vehicle is moved from the first position and is present at the second position. Based on the second probe information transmitted to the vehicle, and is configured to calculate a link travel speed for a road link existing between the first position and the second position,
Further, the link travel speed calculation unit is present at a position before the first position when the distance between the first position and the second position is equal to or less than a set minimum distance. The link travel speed of the road link is calculated by using the probe information transmitted when the information is transmitted and / or the probe information transmitted when the probe information is present at a position ahead of the second position. Item 11. The traffic information estimation device according to any one of Items 1 to 10.   A computer program for causing a computer to function as the traffic information estimating apparatus according to any one of claims 1 to 11. A traffic information estimation method for estimating traffic information of an estimation target road link based on traffic information of another road link,
Converting link travel speed indicating the speed of the vehicle on the other road link into speed information taking a value corresponding to the magnitude of the link travel speed;
Using the converted speed information as the traffic information of the other road link, estimating the traffic information of the estimation target road link, and
Conversion from link travel speed to speed information is performed using conversion information for converting link travel speed to speed information.
The conversion information is such that the rate of change in the speed information with respect to the change in speed is smaller in the speed region of the free running speed where the vehicle can be in the free running state than in the speed region of lower speed than the free running speed region. The traffic information estimation method characterized by being set to. A traffic information estimation method for estimating traffic information of an estimation target road link based on traffic information of another road link,
Converting link travel speed indicating the speed of the vehicle on the other road link into speed information taking a value corresponding to the magnitude of the link travel speed;
Using the converted speed information as the traffic information of the other road link, estimating the traffic information of the estimation target road link, and
Conversion from link travel speed to speed information is performed using conversion information for converting link travel speed to speed information.
The said conversion information is set so that the rate of change of speed information to change of link travel speed may become small, so that link travel speed becomes large.

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