JP2009008573A - Navigation device, navigation method, and navigation program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a navigation device capable of providing an optimum route while taking into account of a traffic lane of the own vehicle. <P>SOLUTION: The navigation device performing optimum route guidance to a destination on the basis of road data includes: a positioning part detecting an own vehicle position and velocity; a traffic lane determination part specifying the traffic lane of the own vehicle from the own vehicle position detected by the positioning part; a route search part searching for a first route having the optimum route costs to the destination and a second route in which the traffic lane of the own vehicle specified by the traffic lane determination part is taken into account, on the basis of the road data; a route estimation part estimating the first route and the second route about the route costs corrected on the basis of the traffic lane specified by the traffic lane determination part and the own vehicle position; and a route display part displaying at least the route with higher evaluation from among the first route or the second route. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a navigation device that guides a user to a destination and displays a most recommended route on a display device.

  In recent years, in navigation devices mounted on vehicles, for example, when traveling on a first route, a second route different from the first route is searched and a second point is approached when a certain point (branch point) is approached. A navigation device that displays a route has been proposed (see, for example, Patent Document 1).

JP 2001-304890 A

  However, in conventional navigation devices, the accuracy of positioning of the own vehicle position is not sufficient, and thus the traveling lanes on each road are not particularly considered. When there are a plurality of traveling lanes, a lane change may be required for branching to the road of the route to be selected at the next intersection. Sufficient time is required to safely change the lane. Even if the distance as a whole route is short, a route with a short time to lane change in the current traveling lane is not preferable for safety. Accordingly, there is a need for a navigation device that searches for and displays a route that can safely change lanes in consideration of the traveling lane.

  An object of the present invention is to provide a navigation device that displays information on a route most recommended to a user in an easy-to-understand manner in consideration of the current travel lane.

A navigation device according to the present invention is a navigation device that performs optimal route guidance to a destination based on road data,
A positioning unit that detects the vehicle position and speed;
A lane determination unit that identifies the traveling lane of the vehicle from the vehicle position detected by the positioning unit;
A route search unit that searches for a first route having an optimum route cost to the destination based on the road data, and a second route in consideration of the traveling lane of the host vehicle identified by the lane determination unit;
A route evaluation unit that evaluates the first route and the second route for a route cost that is corrected based on the travel lane specified by the lane determination unit and the vehicle position;
Of the first route or the second route, a route display unit that displays a route having at least a higher evaluation,
Is provided.
With the above configuration, it is possible to perform route evaluation in consideration of the traveling lane.

The road data may include information on a plurality of road links in which road branch points are nodes and roads between the nodes are road links.
Furthermore, the route search unit
In the road data, a route having the lowest route cost from the plurality of routes including the plurality of road links from the road link to which the vehicle position is matched to the destination is defined as the first route. You may search.
In addition, the route search unit
Temporarily changing the cost of the road link next to the current road link in the first route to the cost of the next road link by changing the cost obtained by changing the cost of the next road link according to the identified current driving lane. Change to
Excluding the first route, a route with the lowest cost to the destination is selected from a plurality of routes consisting of a plurality of road links from the road link to which the vehicle position is matched to the destination. You may search as two paths.

In the search for the second route, the route search unit,
Changing the cost of the next road link to the cost of the next road link by changing the cost of the next road link after the current road link in the first route to a predetermined cost, and temporarily changing the road data;
The second route different from the first route may be searched.

In the search for the second route, the route search unit,
A predetermined additional cost is calculated according to the identified current travel lane, and a cost obtained by adding the predetermined additional cost to the cost of the road link next to the current road link in the first route is the next road link. To change the cost of the road data temporarily,
The second route different from the first route may be searched.

In the search for the second route, the route search unit,
Of a plurality of road links branched from the next node of the current road link, a route passing through a road link different from the next road link in the first route may be searched for as the second route.

  The route search unit may search for the first route and the second route according to a distance to a next node. The route search unit may search for the first route and the second route each time the travel lane is changed.

The route evaluation unit
Based on the driving lane in the current road link, considering the difficulty of lane change, the cost of changing the current road link cost is changed to the current road link cost and the road data is temporarily Change to
Calculating the route cost of the first route, including the total cost of each road link of the first route;
Calculating the route cost of the second route, including the total cost of each road link of the second route;
The route cost of the first route and the route cost of the second route may be compared to determine a route with a low route cost.

The route evaluation unit
In calculating the route cost of the first route,
Calculate the lane change factor according to the lane change difficulty required to move from the driving lane on the current road link to the next road link,
The cost obtained by multiplying the lane change coefficient by the distance to the next node may be set as the cost of the current road link.

The route evaluation unit
In calculating the route cost of the second route,
Calculate the lane change factor according to the lane change difficulty required to move from the driving lane on the current road link to the next road link,
The cost obtained by multiplying the lane change coefficient by the distance to the next node may be set as the cost of the current road link.

The route display unit
When the route evaluation unit determines that the second route has a higher evaluation than the first route, the second route may be displayed in addition to the first route.
As described above, the second route is displayed when the evaluation is high, while the second route is not displayed when the second route is not recommended, thereby preventing the user from being confused.

The route display unit
If it is determined that the vehicle position detected by the positioning unit is matched not with the road link in the first route but with the road link in the second route, the second route is changed to the first route. May be displayed.
In addition, when it is detected that the vehicle is traveling on the second route, the guidance display is switched from the first route to the second route so that the user can smoothly travel on the second route. The guidance can be continued.

A navigation method according to the present invention is a navigation method for performing optimum route guidance to a destination based on road data,
Detecting the vehicle position and speed;
Identifying the traveling lane of the vehicle from the detected vehicle position;
Based on the road data, searching for a first route having an optimum route cost to the destination and a second route considering the travel lane of the identified own vehicle;
Evaluating the first route and the second route for the route cost corrected based on the identified travel lane and the vehicle position;
Of the first route and the second route, displaying at least the route with the highest evaluation;
including.

  A navigation program to be executed by a computer according to the present invention includes each step of the navigation method. The navigation program may be stored in a computer-readable recording medium.

  According to the navigation device of the present invention, the first route having the optimum route cost to the destination is searched, and the second route different from the first route is searched in consideration of the current traveling lane. Then, the route cost of the first route corrected based on the driving lane and the route cost of the second route are evaluated, and the second route is displayed when the second route has a higher evaluation than the first route. To do. Thereby, the user can select a route without confusion.

  Hereinafter, a navigation device and a navigation method according to embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, substantially the same members are denoted by the same reference numerals.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of navigation device 100 according to Embodiment 1 of the present invention. The navigation device 100 includes a storage device 101, a positioning unit 102, a lane determination unit 103, a route search unit 104, a route evaluation unit 105, a route display unit 106, and a control unit 107.

Below, each structural member which comprises this navigation apparatus 100 is demonstrated.
<Storage device>
The storage device 101 stores data such as road data, index data, map data such as intersection names, and voice data for voice guidance. For example, the road data basically includes a node indicating the position of a branch point such as an intersection or a turning point, and road link information indicating a network between the nodes. The road link information of the road data preferably stores information on the number of lanes and width, road type such as highways, national roads, and general roads, and width information. Furthermore, it is preferable that the road link information of the road data stores regulation information such as one-way traffic, road type such as toll road, distance, travel time, and the like. The index data stores facility names, facility addresses, telephone numbers, and facility types.
The storage device 101 includes a hard disk drive, various media such as a DVD and a memory card, or a flash memory.

<Positioning unit>
The positioning unit 102 performs a positioning process for detecting the vehicle position, speed, and direction, and a matching process for specifying a traveling road. The positioning unit 102 generally includes a GPS receiver, a vehicle speed sensor, a gyro sensor, and the like. Note that the positioning unit 102 may be configured to process signals from a GPS receiver, a vehicle speed sensor, a gyro sensor, or the like connected to the navigation device 100. The GPS receiver receives signals from GPS satellites managed by the United States to detect position and velocity. Similar systems include Gronas of Russia and Galileo planned by Europe. These systems are satellite navigation systems generally called GNSS (Global Navigation Satelite System). In the present embodiment, description will be made using GPS, but it may be replaced with another GNSS.

  From the GPS satellite, satellite orbit information and time information are transmitted using a 1.57542 GHz carrier wave. A GPS receiver receives radio waves from a satellite and first specifies the transmission time of the satellite. The distance from the satellite to the receiver is calculated by comparing the transmission time of the satellite and the reception time of the receiver. The satellite position is calculated by using the satellite transmission time and orbit information. Thus, by obtaining the position of the satellite and the distance to the receiver for a plurality of satellites, the absolute position of the receiver can be obtained from the principle of triangulation.

  In the carrier wave, a Doppler shift frequency is generated by a change in the relative speed between the satellite and the receiver. By receiving the signal, this Doppler shift frequency can be detected, and the relative velocity between the satellite and the receiver is obtained. Since the velocity of the satellite is obtained from the differential component of the orbit information, the velocity component in the satellite direction of the receiver can be obtained by subtracting the satellite velocity from the calculated relative velocity. By obtaining the velocity component in the satellite direction for a plurality of satellites, the absolute velocity and direction of the receiver can be calculated.

  A vehicle speed sensor in a navigation device generally uses a vehicle speed pulse. The vehicle speed pulse is a pulse that is output every time a rotation of the tire is detected and the vehicle rotates by a certain angle, and the speed is calculated by differentiating the pulse with a unit time. Since the vehicle speed pulse changes not only with the vehicle type and tire diameter, but also with tire wear, tire pressure, number of passengers, etc., there is a method to automatically calculate the coefficient to convert to distance using the speed output by GPS. It is common.

  The gyro sensor detects an angular velocity at the time of turning of the vehicle, and obtains a relative angle by integrating. Various sensors exist as gyro sensors, and gyro sensors that detect Coriolis force using a vibrator are widely used for navigation. Since the gyro sensor calculates a relative angle, an initial direction is required to calculate the direction. Generally, the initial azimuth is determined using GPS, and the absolute azimuth is obtained by integrating the output of the gyro sensor.

  A method of calculating the position using the speed and direction output from the vehicle speed sensor and the gyro sensor is generally called dead reckoning navigation. The dead reckoning feature is that by integrating the relative position change from the initial position, the position can be determined with very high precision when viewed in a short time without being affected by the surrounding environment. Since the error is also integrated, it is necessary to periodically correct the error. On the other hand, in a satellite navigation system such as GPS, since the propagation distance from the satellite is measured every time, errors do not accumulate, but are greatly affected by the reception environment. In the positioning process, the current position can be calculated with high accuracy by effectively utilizing the features of dead reckoning navigation and GPS (satellite navigation).

  Further, in the matching process in the positioning unit 102, the road that is running is specified using the map data stored in the storage device 101 from the road data and the position and direction data output by the positioning process.

<Lane judgment part>
The lane determination unit 104 identifies the lane in which the vehicle on which the navigation device 100 is mounted is traveling. Alternatively, the traveling lane may be determined using the vehicle position and road data. Here, the node stored in the road data basically means the center of the road, and its coordinate information is stored. Therefore, each road link is considered to represent the center of the road as well. If it is assumed that there is no error in the own vehicle position and road data calculated by the positioning process of the positioning unit 102, the distance between the own vehicle position and the road link obtained by the positioning process is considered as the distance from the center of the road. Usually, since each lane of a road is configured with a width of 3.0 to 3.5 m, it is possible to estimate a lane that is running from a distance from the center of the road.

  Currently, there is basically only one road lane link for each road in the road data. However, there is a possibility that road data for each lane will be developed as road data is developed in the future. is there. In that case, the traveling lane can be easily specified from the own vehicle position calculated by the positioning process.

  As another method, a road lane may be specified by obtaining white line information on a road using an imaging device such as a camera and performing image processing. Alternatively, the traveling lane may be specified using another method.

<Route search unit>
The route search unit 104 searches for the first route with the lowest route cost, which is the optimum travel route for the destination set by the user, and the second route in consideration of the current travel lane.
The destination is set by selecting from the name of index data stored in the storage device 101, selecting from a telephone number, selecting from an address, or selecting directly from map data. It may be performed by any method.

<Search for the first route>
The route search unit 104 first selects a route with the lowest route cost to the destination from a plurality of routes including a plurality of road links from the road link to which the vehicle position is matched to the destination in the road data. Search as a route. This route cost is calculated by attaching a cost for each link and each node. The link cost is calculated by multiplying the corresponding link by cost parameters such as the link distance, the number of lanes, and the width. In addition, the node cost is set depending on whether a right / left turn is required at each node, the presence / absence of a traffic light, and the like. In calculating the link cost, a coefficient corresponding to the link type may be multiplied. As the link type, for example, a link of a general road, a link of a toll road (hereinafter referred to as a normal toll road) whose charge varies depending on the distance, a link of a toll road with a uniform charge, or the like may be used.

  When searching for a route, the shortest route search is usually performed under distance priority conditions, but the present invention is not limited to this. For example, a search condition selected by the user from different search conditions such as toll road priority, general road priority, and time priority may be received. As a result, the route cost can be calculated based on the search condition required by the user. For example, in the case of a search under distance priority conditions, a link cost based on the link distance of a road link is used, and in the case of a search under time priority conditions, a link cost based on the time required for road links is used. Route search.

  The route search method is not limited to the Dijkstra method used for the shortest route search, and for example, an all-search method for searching for all routes from the vehicle position to the destination may be used. Alternatively, other search methods may be used.

<Search for the second route>
The route search unit 104 searches for a second route different from the first route. That is, the route search unit 104 changes the distance obtained by changing the distance of the road link next to the current road link in the first route according to the identified current driving lane to the distance of the next road link. Change road data temporarily. Next, the first route is excluded from a plurality of routes consisting of a plurality of road links from the road link to which the vehicle position is matched to the destination, and the route with the smallest total distance of the road links to the destination is selected. Search as two paths.

An outline of a procedure for searching for the second route in the route search unit 104 will be described.
a) First, the distance L1 to the next branch point (node) is calculated from the road data and the vehicle position. For example, in the case of 50 km / h, the search for the second route is performed only when the distance L1 to the branch point is within the range of a certain distance and in the range of 100 m to 500 m. On the other hand, when the distance L1 to the branch point is outside the above range, for example, the travel lane cannot be changed substantially within 100 m, or the travel lane can be changed with a sufficient margin such as 500 m or more. It is considered possible. In this case, the process ends without searching for the second route.
Here, the search for the second route is not performed when the distance L1 from the node is not within the range of the fixed distance, but the range of the fixed distance will be described later in the description of the navigation method.

When the distance L1 to the branch point is within the range of 100 m to 500 m, it may be confirmed whether the second route has been searched. If the second route is not searched, or if it is determined that the vehicle position specified by the matching process of the positioning unit 102 does not exist on the second route even if already searched, the second route is searched again. It is good.
Note that the route search unit 104 may search for the first route and the second route according to the distance to the next node. Alternatively, the first route and the second route may be searched each time the travel lane is changed.

  b) Change the distance changed to the distance of the next road link by changing the distance of the road link next to the current road link in the first route by a predetermined multiple, and change the road data temporarily. A second route different from the one route is searched. Thus, by changing the link distance of the next road link in the first route to be longer, it is different from the next road link of the first route among a plurality of road links branched from the next node of the current road link. It makes it easy to search a route passing through a road link as a second route. The search procedure for the second route is not limited to the above example, and the search procedure in the second embodiment to be described later may be adopted.

<Route evaluation unit>
The route evaluation unit 105 evaluates the first route and the second route that have already been searched in consideration of the current travel lane of the vehicle identified by the lane determination unit 104 and the vehicle position. The route evaluation unit performs the following procedures to evaluate the first route and the second route.
a) Based on the driving lane in the current road link, considering the difficulty of lane change, the distance changed by the distance of the current road link is changed to the distance of the current road link, and the road data is temporarily Change to
b) The total distance of each road link of the first route is calculated as the route cost of the first route.
c) The total distance of each road link of the second route is calculated as the route cost of the second route.
d) The route cost of the first route is compared with the route cost of the second route, and a route with a low route cost is determined.

  The route evaluation unit 105 is periodically activated during route guidance, and the interval depends on processing performed by other members, but may be activated at intervals of 1 to 3 seconds. It is not activated when route guidance is not performed.

In addition, the route evaluation unit 105 corrects the link distance of the current road link by using the lane change coefficient in order to consider the difficulty level of the lane change in the current road link, and the first route and the second route. Used for evaluation. The lane change coefficient is an index representing the difficulty level of lane change. When there are a plurality of lanes, in order to change lanes, complicated confirmation and operation such as confirmation of surrounding vehicles and determination of lane change timing are required. Therefore, a certain amount of time is required to change the lane safely.
However, it may be necessary to change lanes in order to turn right or left according to the route guidance of the navigation device. In this case, there is no problem if the driver can make a lane change with a margin in advance, but there is a possibility that sufficient time cannot be taken for the lane change due to various situations.
Therefore, the route search unit 104 searches for a second route in consideration of the traveling lane in advance, and the route evaluation unit 105 calculates a lane change coefficient indicating the degree of difficulty of lane change, and uses this lane change coefficient. The first route and the second route are evaluated in consideration of the difficulty of lane change. Specifically, the first route and the second route are evaluated with respect to the route cost corrected by the current travel lane and the time to the next right / left turn branch point (node), which is easier for the user to travel. Determine if it is a route.

<Route display section>
The route display unit 106 displays at least one of the first route and the second route. The route display unit 106 displays map coordinates around the current position, and displays the vehicle position on the map in an easy-to-understand manner for the user. Further, when the route search unit 104 searches for the first route and the second route, the route display unit 106 makes it easy to understand at least one of the first route and the second route by changing the color of the road data on the map. indicate. As a result, the user can be correctly guided to the destination.

  The route display unit 106 can be configured by a display device such as a liquid crystal display. Furthermore, by adopting a touch panel or the like, it can also serve as an operation unit of the navigation device.

  If it is determined that the vehicle position detected by the positioning unit 102 is matched not with the road link in the first route but with the road link in the second route, the user replaces the first route with the first route. It is considered that two routes were selected. In this case, the route display unit 106 displays the second route as the first route.

<Control unit>
The control unit 107 controls the operation of the entire navigation device 100. The control unit 107 includes a CPU or MPU, a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. When the CPU or MPU executes a program stored in the ROM, the operation of each functional block shown in FIG. 1 is controlled. The CPU and MPU use the RAM as a work area during execution of the program.

<Navigation method>
Hereinafter, a navigation method by the navigation device 100 according to the embodiment of the present invention will be described with reference to the flowchart of FIG.
(A) The current vehicle position and travel lane are acquired (S01).
(B) The destination setting is accepted (S02).
(C) A first route having an optimum route cost from the vehicle position to the destination is searched (S03). A detailed flowchart is shown in FIG.
(D) A second route different from the first route is searched (S04). Detailed flowcharts are shown in FIGS.
If the current driving road is a one-lane or one-lane road and there is no need to change lanes, this second route search step is not necessary, and steps S04 to S05 are not necessary. . In this case, the first route may be displayed at step S06.
(E) The first route and the second route are evaluated (S05). Detailed flowcharts are shown in FIGS.
(F) A route is displayed based on the evaluation result (S06). A detailed flowchart is shown in FIG.
As described above, the optimum route to the destination can be displayed with guidance.

  FIG. 2 is an example of road data, and there are road links from link 001 to link 008. For example, the link distance of each road link from link 001 to link 008 is set as shown in Table 1 below.

FIG. 4 is a flowchart showing details of the first route search step S03 of FIG. Here, for the sake of explanation, an all-search method for searching for all routes from the vehicle position to the destination is used.
(A) Using the road data, all combinations of a plurality of road link sequences constituting a route from the vehicle position to the destination are extracted (S11). According to Figure 2, from the current location to the destination,
i) Link 001 → Link 002 → Link 003 → Link 004 → Link 005
ii) Link 001 → Link 006 → Link 007 → Link 008 → Link 005
There are two routes. Here, other routes are not considered.
(B) The route cost of each road link row is calculated (S12). Here, the link distance of each road link is used as the link cost, and the node cost is not considered. The route cost in this case is expressed as the total distance of each road link. For example, the total distance of the route i) is 2000 m, and the total distance of the route ii) is 2400 m.
(C) Comparing the route costs of all the road link sequences, the road link sequence having the minimum route cost is set as the first route (S13). Here, since the total distance of each road link is used as the route cost, when the total distance between the route i) and the route ii) is compared, the road link sequence i), link 001 → link 002 → link. 003 → link 004 → link 005 is obtained as the first route with the shortest total distance.
As described above, the first route with the minimum route cost can be searched.

  In the above example, the link cost is calculated using only the link distance of each road link as the route cost, and the node cost is not particularly considered, but is not limited thereto. For example, in addition to the link distance, a cost based on the number of lanes, the width, etc. may be given as the link cost. Furthermore, a node cost based on whether or not a right / left turn is required at each node, the presence or absence of a traffic light, and the like may be given.

  In the above example, the search is performed under the distance priority condition. However, the search is not limited to this, and the search may be performed under the time priority condition. In this case, the first route is searched using the required time at each road link instead of the link distance as the link cost.

  Furthermore, the route search method is not limited to the case of full search as described above, and for example, the search may be performed using the Dijkstra method used for the shortest route problem. Still another search method may be used.

FIG. 6 is a flowchart showing details of the second route search step S04 in FIG.
(A) The road data is temporarily changed by doubling the link distance of the road link next to the current road link with which the vehicle position in the first route is matched (S21). In other words, in order to search for a second route different from the first route, instead of performing a route search under exactly the same conditions as the search for the first route, the link distance of the road link next to the first route is changed. Yes.
Specifically, for the road data in FIG. 5 (a), as shown in FIG. 5 (b), the link distance between link 002 and link 003 is doubled (link 2 is 600 m, link 3 is 1000 m). The road data is temporarily changed.
(B) Using the temporarily changed road data, all combinations other than the first route are extracted from a plurality of road link sequences constituting the route from the vehicle position to the destination (S22). In the case of the road data in FIG.
(I) road link sequence (link 001-link 002-link 003-link 004-link 005);
(Ii) There is a road link sequence (link 001-link 006-link 007-link 008-link 005).
Since (i) the road link sequence is the first route, in the case of FIG. 2, (ii) the road link sequence is substantially only.

(C) The route cost of each road link row is calculated (S23). Here, the link distance of each road link is used as the link cost, and the node cost is not considered. The route cost in this case is expressed as the total distance of each road link. In this case, of the two road link strings in FIG. 2, (ii) the total distance of the road link strings is 2400 m. For reference, the total distance of the (i) road link train that is the first route is 2800 m.
(D) The road link row that minimizes the route cost of all road link rows is set as the second route. Here, since the total distance of each road link is used as the route cost, the total distance is compared, and the road link sequence having the shortest total distance is set as the second route (S24). In the example of FIG. 2, since there is only (ii) a road link string as a route other than the first route, (ii) the road link string becomes the second route.
Thus, the second route can be searched. Thereby, for example, by increasing the link distance of the road link of the first route among the road links branched at the next node, the second route passing through another road link different from the first route can be searched.

  In the above example, a road link sequence other than the first route is searched for a second route different from the first route. However, since the temporarily changed road data is used, the first route A search may be performed for all road link sequences including the road link sequence. In this case, when the road link sequence having the shortest total distance is the same as the road link sequence of the first route, it may be determined that the search for the second route has failed.

FIG. 10 is a step showing details of step S05 for evaluating the first route and the second route of FIG.
(A) The route cost of the first route is evaluated based on the vehicle position and the travel lane (S41). The details are shown in FIG.
(B) The route cost of the second route is evaluated based on the vehicle position and the travel lane (S42). The details are shown in FIG.
(C) A route with a smaller route cost is determined between the route cost of the first route and the route cost of the second route (S43).
As described above, a route having a low route cost can be evaluated among the first route and the second route.

FIG. 11 is a flowchart showing details of step S41 for evaluating the route cost of the first route of FIG.
(A) A lane change coefficient is calculated according to the traveling lane and speed of the own vehicle (S51).
The calculation of the lane change coefficient will be described below with reference to FIGS. 8 (a) and 8 (b).
First, the travel lane determined by the lane determination unit 103 is read, and the own vehicle position and speed data detected by the positioning unit 102 are read.
Next, a lane change coefficient is calculated using the current vehicle position and speed data. The lane change coefficient is a numerical value of the degree of difficulty for changing the lane, and specific examples are shown in FIGS. 8 (a) and 8 (b). FIG. 8A shows the distance L1 from the current position specified in the matching process to the next left / right turn branch, that is, the distance to complete the lane change and the speed, and is necessary to complete the lane change. It is a figure which shows the relationship with time to become. This time is obtained by dividing the distance L1 to the branch by the speed. FIG. 8B is a diagram illustrating an example of the lane change coefficient set based on the distance L1 to the branch and the speed.

The lane change coefficient can be set as follows by comparing the time required for the distance to the branch and the standard time when the standard time necessary for safely changing the lane is set. Here, the standard time required for the user to change lanes without stress is defined as 36 seconds, for example. The standard time is not limited to 36 seconds. This time of 36 seconds can be optimized by experiments or the like. Basically, if the time to complete the lane change is shorter than the standard time of 36 seconds, the difficulty will increase proportionally. Conversely, if it is longer than 36 seconds, the difficulty will not change. I think.
i) If the time to branch is sufficiently longer than the standard time, the lane change coefficient can be set to 1.0.
ii) If the time to branch is shorter than the standard time, the lane change coefficient is set to an appropriate value larger than 1.0.
Note that the lane change coefficient in FIG. 8B is an example, and is determined from the relationship with the standard time as a reference, and becomes a different numerical value when the standard time setting or the like is changed.
For example, when the distance L1 to the branch is 300 m and the speed is 50 km / h, the lane change coefficient is 1.7 as shown in FIG.

(B) The distance obtained by multiplying the current road link distance with which the vehicle position is matched by the lane change coefficient is set as the current road link distance (S52). FIG. 9A shows the link distance of each road link in the same default road data as in Table 1 above. The default link distance of the road link 001 to which the current vehicle position is matched is 300 m. In the first route, it is necessary to turn left from the next branch (node) and move to the next road link 0002. Therefore, the number of necessary lane changes, that is, the difficulty of changing lanes differs depending on the current travel lane. It is necessary to modify the default link distance according to the travel lane as follows.
i) In the case of the left lane When the current driving lane is the left lane, there is no need to change the lane, so there is no need to multiply the lane change coefficient, and the link distance of the road link 001 need not be corrected. Therefore, the link distance remains at the default of 300 m.
ii) In the case of the central lane When the current driving lane is the central lane, it is necessary to change the lane once, and the link distance of the road link 001 is corrected by multiplying by the lane change factor 1.7. Accordingly, the link distance is 510 m.
iii) In the case of the right lane If the current driving lane is the right lane, it is necessary to change the lane twice, and the link distance of the road link 001 is corrected by multiplying the lane change factor 1.7 twice. Therefore, the link distance is 867 m.
FIG. 9B is an example of road data in which the link distance of the current road link 001 is corrected according to the current travel lane. The following route cost is evaluated using the corrected link distance as the link distance of the road link 001.

(C) The distance of the road link after the next node in the first route is added to calculate the total distance of the first route as the route cost (S53).
i) In the case of the left lane When the current driving lane is the left lane, the link distance of the road link 001 is 300 m which is the same as the default, and the route cost which is the total distance of the first route is 2000 m.
ii) In the case of the central lane If the current driving lane is the central lane, it is necessary to change the lane to the left once, so the corrected link distance of the road link 001 is 510 m, which is the total distance of the first route A certain route cost is 2210 m.
iii) In the case of the right lane If the current driving lane is the right lane, the lane change must be made twice, so the corrected link distance of the road link 001 is 867 m, which is the total distance of the first route The route cost is 2567 m.
As described above, the route cost, which is the total distance of the first route, can be evaluated so as to reflect the difficulty of changing the lane according to the current travel lane.

FIG. 12 is a flowchart showing details of step S42 for evaluating the route cost of the second route of FIG.
(A) A lane change coefficient is calculated according to the traveling lane and speed of the own vehicle (S61). Since the calculation of the lane change coefficient is substantially the same as the lane change coefficient calculation step S51 in the first route, the description thereof is omitted. Therefore, the lane change coefficient has the same value as in FIG.
In the example of FIG. 2, the road link 006 next to the second route may go straight ahead with the road link 001. Furthermore, it is necessary to turn right to the next road link 007 at the next branch. Further, a lane change coefficient is obtained from the distance L2 to the next branch and the traveling speed. In this example, the distance L2 is the sum of the road link 001 and the road link 006, and is 1300 m. When traveling at a speed of 50 km / h, the time required for branching is approximately 93.5 seconds, which is sufficiently longer than the reference time of 36 seconds. Therefore, since it is considered that the lane change can be safely performed regardless of which lane the current travel lane is, the lane change coefficient is 1.0.
In the above-described example, it is considered that any lane can go straight on the current road link 001. However, if the current road link 001 has a limited number of lanes that can go straight, it is based on the degree of difficulty in changing the lane according to the current lane in the same manner as the calculation of the lane change coefficient in the first route. What is necessary is just to calculate a lane change coefficient.

(B) The distance obtained by multiplying the current road link distance with which the vehicle position is matched by the lane change coefficient is set as the current road link distance (S62). Since the lane change coefficient is 1.0 for the current road link 001 and the next road link 006 as described above, the respective link distances are 300 m and 1000 m as default.
(C) The distance of the road link after the next node in the second route is added to calculate the total distance of the second route as the route cost (S63). The route cost, which is the total distance of the second route, is 2400 m.
As described above, the route cost, which is the total distance of the second route, can be evaluated so as to reflect the difficulty of changing the lane according to the current travel lane.

FIG. 13 is a flowchart showing details of the route display step S06 in FIG.
(A) The first route is displayed on the route display unit 106, for example, as shown in FIG. 14A (S71).
(B) It is determined whether or not the route cost of the second route is lower than that of the first route (S72). The determination of the route cost is based on the determination in the route evaluation unit 105. For example,
i) If the current lane is the left lane,
Since the route cost of the first route is 2000 m and the route cost of the second route is 2400 m, the route cost of the first route is smaller.
ii) If the current lane is the central lane,
Since the route cost of the first route is 2210 m and the route cost of the second route is 2400 m, the route cost of the first route is smaller.
iii) If the current lane is the right lane,
Since the route cost of the first route is 2567 m and the route cost of the second route is 2400 m, the route cost of the second route is smaller.
(C) When it is determined that the route cost of the second route is lower than the route cost of the first route, for example, in the case of iii), the second route is also displayed as shown in FIG. It is displayed on 106 (S73). On the other hand, when the route cost of the second route is larger than the route cost of the first route, for example, in the case of i) and ii), the second route is not displayed. As a result, it is possible to guide and display the optimum route with the smallest route cost re-evaluated based on the travel lane. As a specific example, when the vehicle position is in the left lane or the center lane as shown in FIG. 14A, the route cost of the first route is smaller than the route cost of the second route. The route is not displayed. On the other hand, when the vehicle position is in the right lane, the route cost of the second route is smaller than the route cost of the first route, so that not only the first route but also the second route is displayed (FIG. 14B). .

  The navigation method described above may be realized as a computer program executed on a computer. This computer program may be executed by the control unit 107, for example. The computer program may be stored in a computer-readable recording medium. As this recording medium, for example, any of an optical recording medium, a magneto-optical recording medium, a magnetic recording medium, a semiconductor storage device, and the like may be used.

  Further, when it is determined that the user has confirmed the first route and the second route and selected the second route, specifically, when it is determined that the user is traveling on the road link 006, The second route is changed to the first route and the guidance display is continued. As a result, navigation can be smoothly continued for the user.

(Embodiment 2)
The navigation method according to the second embodiment differs from the navigation method according to the first embodiment in the second route search step. Specifically, the second route search step is different in that a predetermined addition distance is calculated according to the current travel lane and added to the link distance of the next road link to search for the second route. .

FIG. 7 is a flowchart showing details of another example of the second route search step S04 in the navigation method according to the second embodiment.
(A) A predetermined addition distance to the road link due to the difficulty of changing the lane based on the traveling lane of the own vehicle is calculated (S31). This predetermined added distance corresponds to the difference between the default link distance of the link distance corrected using the lane change coefficient in the evaluation of the first route and the second route of the navigation method of the first embodiment.
For example, when the distance to the branch L1 is 300 m and the speed is 50 km / h, the link distance of the current road link 001 is 300 m when the current driving lane is the left lane as shown in FIG. In the case of the center lane, the value is corrected to 510 m, and in the case of the right lane, the value is corrected to 867 m. Differences from the default link distance are 0 m, 210 m, and 367 m in order. Therefore, when the current lane is the left lane, the predetermined additional distance is 0 m, when the center lane is 210 m, and when the right lane is 367 m.

(B) The road data is temporarily changed by adding the predetermined addition distance to the link distance of the road link next to the road link whose vehicle position is matched in the first route (S32). For example,
i) If the current lane is the left lane,
Since the predetermined addition distance is 0 m, the road data is not changed in this case.
ii) If the current lane is the central lane,
Since the predetermined addition distance is 210 m, the road data is changed by adding 210 m to the link distance of the next road link 002 of the first route.
iii) If the current lane is the right lane,
Since the predetermined addition distance is 367 m, the road data is changed by converting 367 m into the link distance of the road link 002 next to the first route.
(C) Using the road data temporarily changed, all combinations other than the first route are extracted from a plurality of road link sequences constituting the route from the vehicle position to the destination (S33).
(D) The route cost of each road link row is calculated (S34). Here, the total distance of each road link is used as the route cost.
(E) Comparing the route costs of all the road link sequences, the road link sequence having the smallest route cost is set as the second route (S35). Here, since the total distance of each road link is used as the route cost, the road link string having the shortest total distance is set as the second route.
Thus, the second route can be searched efficiently.
The steps (c) to (e) are substantially the same as the steps (b) to (d) of the second route search step in the first embodiment, and the description thereof is omitted. To do.

  According to the navigation method according to the second embodiment, the second route can be searched in consideration of the difficulty of changing the lane according to the traveling lane in advance. Therefore, an effective second route can be efficiently searched even when the first route and the second route are reevaluated.

  As described above, the navigation device according to the present invention searches for the second route in consideration of the travel lane separately from the first route. In addition, periodically evaluate the route cost considering the number of lane changes for traveling the first route from the driving lane of the host vehicle and the route cost corrected considering the number of lane changes for traveling the second route. To do. As a result, an optimum route to the destination can be guided and displayed, so that the user can determine the route to be selected from the current vehicle position. Therefore, this navigation device is useful as a navigation device for guiding a user to a destination in a vehicle or the like.

It is a block diagram which shows the structure of the navigation apparatus which concerns on Embodiment 1 of this invention. It is the schematic which shows an example of road data. It is a flowchart which shows the navigation method which concerns on Embodiment 1 of this invention. It is a flowchart which shows the detail of the search step of the 1st path | route of FIG. (A) is a figure which shows the road link of default road data, (b) shows the road data which changed the distance of the road link following the present road link temporarily for the search of a 2nd path | route. FIG. It is a flowchart which shows the detail of the search step of the 2nd path | route of FIG. It is a flowchart which shows the detail of another example of the search process of the 2nd path | route of FIG. (A) And (b) is a figure which shows an example of calculation of the lane change coefficient which concerns on Embodiment 1 of this invention. (A) And (b) shows an example of correction of the link distance of the present road link according to the present driving lane in evaluation of the 1st course and the 2nd course concerning Embodiment 1 of the present invention. FIG. It is a flowchart which shows the detail of the evaluation step of the 1st path | route of FIG. 3, and a 2nd path | route. It is a flowchart which shows the detail of the route cost evaluation step of the 1st route | root of FIG. It is a flowchart which shows the detail of the path | route cost evaluation step of the 2nd path | route of FIG. It is a flowchart which shows the detail of the display step of the path | route of FIG. (A) And (b) is the schematic which shows an example of the display by the path | route display part of the navigation apparatus which concerns on Embodiment 1 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Navigation apparatus 101 Storage apparatus 102 Positioning part 103 Lane determination part 104 Route search part 105 Route evaluation part 106 Route display part 107 Control part

Claims (15)

A navigation device that provides optimal route guidance to a destination based on road data,
A positioning unit that detects the vehicle position and speed;
A lane determination unit that identifies the traveling lane of the vehicle from the vehicle position detected by the positioning unit;
A route search unit that searches for a first route having an optimum route cost to the destination based on the road data, and a second route in consideration of the traveling lane of the host vehicle identified by the lane determination unit;
A route evaluation unit that evaluates the first route and the second route for a route cost that is corrected based on the travel lane specified by the lane determination unit and the vehicle position;
Of the first route or the second route, a route display unit that displays a route having at least a higher evaluation,
A navigation device comprising: The road data includes information on a plurality of road links in which road branch points are nodes and roads between the nodes are road links.
The route search unit
In the road data, a route having the lowest route cost from the plurality of routes including the plurality of road links from the road link to which the vehicle position is matched to the destination is defined as the first route. As you explore,
Temporarily changing the cost of the road link next to the current road link in the first route to the cost of the next road link by changing the cost obtained by changing the cost of the next road link according to the identified current driving lane. Change to
Excluding the first route, a route with the lowest cost to the destination is selected from a plurality of routes consisting of a plurality of road links from the road link to which the vehicle position is matched to the destination. Explore as two paths,
The navigation device according to claim 1. In the search for the second route, the route search unit,
Changing the cost of the next road link to the cost of the next road link by changing the cost of the next road link after the current road link in the first route to a predetermined cost, and temporarily changing the road data;
The navigation device according to claim 2, wherein the second route different from the first route is searched. In the search for the second route, the route search unit,
A predetermined additional cost is calculated according to the identified current travel lane, and a cost obtained by adding the predetermined additional cost to the cost of the road link next to the current road link in the first route is the next road link. To change the cost of the road data temporarily,
The navigation device according to claim 2, wherein the second route different from the first route is searched. In the search for the second route, the route search unit,
The route that passes through a road link different from the next road link in the first route among the plurality of road links branched from the next node of the current road link is searched for as the second route. 3. The navigation device according to 2.   The navigation device according to claim 2, wherein the route search unit searches for the first route and the second route according to a distance to a next node.   The navigation device according to claim 2, wherein the route search unit searches the first route and the second route each time a traveling lane is changed. The route evaluation unit
Based on the driving lane in the current road link, considering the difficulty of lane change, the cost of changing the current road link cost is changed to the current road link cost and the road data is temporarily Change to
Calculating the route cost of the first route, including the total cost of each road link of the first route;
Calculating the route cost of the second route, including the total cost of each road link of the second route;
The navigation device according to claim 1, wherein the route cost of the first route and the route cost of the second route are compared to determine a route having a low route cost. The route evaluation unit
In calculating the route cost of the first route,
Calculate the lane change factor according to the lane change difficulty required to move from the driving lane on the current road link to the next road link,
The cost obtained by multiplying the lane change coefficient by the distance to the next node is set as the cost of the current road link.
The navigation device according to claim 8. The route evaluation unit
In calculating the route cost of the second route,
Calculate the lane change factor according to the lane change difficulty required to move from the driving lane on the current road link to the next road link,
The cost obtained by multiplying the lane change coefficient by the distance to the next node is set as the cost of the current road link.
The navigation device according to claim 8. The route display unit
The said path | route evaluation part displays said 2nd path | route in addition to said 1st path | route, when it determines with said 2nd path | route being higher evaluation than said 1st path | route. The navigation device described in 1. The route display unit
If it is determined that the vehicle position detected by the positioning unit is matched not with the road link in the first route but with the road link in the second route, the second route is changed to the first route. The navigation device according to claim 10, wherein the navigation device is displayed. A navigation method that provides optimal route guidance to a destination based on road data,
Detecting the vehicle position and speed;
Identifying the traveling lane of the vehicle from the detected vehicle position;
Based on the road data, searching for a first route having an optimum route cost to the destination and a second route considering the travel lane of the identified own vehicle;
Evaluating the first route and the second route for the route cost corrected based on the identified travel lane and the vehicle position;
Of the first route and the second route, displaying at least the route with the highest evaluation;
Including a navigation method.   The navigation program for performing each step of the navigation method of Claim 13 with a computer.   A computer-readable recording medium storing a navigation program for executing each step of the navigation method according to claim 13 on a computer.

Images