JP4594785B2 - Navigation device - Google Patents

Description

  The present invention relates to a technique that is mounted on a moving body such as a vehicle and calculates and displays the current position of the moving body.

  Patent Document 1 discloses a vehicle according to the relative position from the current position of the vehicle obtained last time based on the traveling direction of the vehicle measured by an orientation sensor such as a gyro and the traveling distance of the vehicle measured by a vehicle speed sensor or a distance sensor. A position detection method is disclosed in which the current position of the vehicle is estimated on the road in the map data by obtaining the current virtual position and matching the virtual current position with the road position in the map data.

  The technique described in Patent Document 1 extracts all roads within a predetermined range centered on the virtual current position of the vehicle determined based on the amount of change in travel direction and travel distance, and each of all the extracted roads Calculate the correlation coefficient with the virtual current position of the vehicle, select the road corresponding to the correlation coefficient indicating the least error relative to the virtual current position as the road where the vehicle is located, and place it on the selected road Estimate the current position of the vehicle.

  The correlation coefficient is calculated based on, for example, the difference in orientation between the extracted orientation of each road and the orientation of the vehicle at the virtual current position, the distance from the virtual current position to each road, and the like.

JP-A-63-148115

  By the way, in a so-called Y-shaped branch where one road branches into two, if the angle between the two branched roads is small, the difference in direction between the two roads and the distance to the position of each road Since the difference is small, the difference between the correlation coefficients of the two roads with respect to the virtual current position may be small. For this reason, even if the current position is estimated on one road due to variations in measurement values due to measurement errors of direction sensors and distance sensors, the current position of the vehicle on the other road is estimated at the next estimation timing. May be estimated. Thereby, although the vehicle is traveling on one road, the current position of the vehicle is estimated on different roads at each estimation timing, and the vehicle may behave unnaturally.

  The present invention has been made in view of the above circumstances, and an object of the present invention is that the current position of the detected vehicle jumps between two branched roads after passing through a Y-shaped branch road. Is to suppress the behavior.

  In order to solve the above problems, in the present invention, a plurality of candidate points are calculated on the road from the virtual current position calculated based on the relative displacement of the vehicle, and the reliability is highest among the plurality of calculated candidate points. When displaying candidate points, out of the plurality of calculated candidate points, the reliability of the first candidate point, which is a candidate point obtained based on the current position of the vehicle calculated last time, and other than the first candidate point When comparing the reliability of the second candidate point, which is a candidate point, the orientation difference between the link where the first candidate point is located and the link where the second candidate point is located is equal to or less than a predetermined angle. Then, after adding a predetermined first bias value to the reliability of the first candidate point, the reliability of the first candidate point is compared with the reliability of the second candidate point, If the heading difference is larger than a predetermined angle, the reliability of the first candidate point is Of on obtained by adding a second bias value smaller than the bias value, comparing the reliability of the first candidate point and the reliability of the second candidate points.

  In addition, the present invention is a navigation device that is mounted on a vehicle, for example, calculates the current position of the vehicle and displays it on a display device, and stores the link data of each link constituting the road on the map. Virtual current position calculation means for calculating the virtual current position of the vehicle based on measured values of the travel distance and traveling direction of the vehicle since the candidate point was calculated for each candidate point calculated last time. For each virtual current position, candidate point calculation means for calculating the current candidate point using the virtual current position and link data of each link stored in the map storage means, and the candidate for each current candidate point Based on the reliability calculation means for calculating the reliability indicating the certainty of the point as the current position and the reliability calculated by the reliability calculation means, the candidate point having the highest reliability among the current candidate points And a current position determining means for determining the display candidate point that is the current position of the vehicle to be displayed on the display device, and displaying the determined display candidate point on the display device. When comparing the reliability of the first candidate points that are candidate points obtained based on the previous display candidate points, the reliability of the first candidate points is compared and the reliability of the first candidate points is compared. And the reliability of the second candidate point that is a candidate point other than the first candidate point, the link where the first candidate point is located and the link where the second candidate point is located If the azimuth difference is equal to or smaller than a predetermined angle, the reliability of the first candidate point and the second candidate point are obtained by adding the predetermined first bias value to the reliability of the first candidate point. If the heading difference is greater than a predetermined angle After adding a second bias value smaller than the first bias value to the reliability of the first candidate point, the reliability of the first candidate point is compared with the reliability of the second candidate point A navigation device is provided.

  According to the present invention, it is possible to increase the possibility that a candidate point on the same road as the position previously calculated as the current position of the vehicle is calculated as the current position of the current vehicle. Accordingly, it is possible to suppress the current position of the vehicle detected after passing through the Y-shaped branch road from jumping on two branched roads, and the current position of the vehicle can be determined based on the actual behavior of the vehicle. Can be displayed.

  The first embodiment of the present invention will be described below.

  FIG. 1 is a system configuration diagram of a navigation system 10 according to an embodiment of the present invention. The navigation system 10 is mounted on a vehicle, for example, and includes a sensor 11, a display device 12, and a navigation device 20.

  The sensor 11 is a GPS receiver, an acceleration sensor, a direction sensor, a vehicle speed sensor, or the like, and measures the current position of the vehicle relative to the geodetic satellite, the traveling direction of the vehicle, the moving distance of the vehicle, and the like.

  The navigation device 20 stores map data including road data, calculates the relative displacement of the vehicle based on the measurement signal from the sensor 11, and based on the map data and the calculated relative displacement, the current position of the vehicle. Is calculated and displayed on the display device 12.

  The display device 12 displays the current position of the vehicle as an image, but has a function of reproducing sound, and reproduces the voice guidance and the like generated together with the current position of the vehicle by the navigation device 20 together with the current position of the vehicle. May be.

  Next, the navigation device 20 will be described in more detail. The navigation device 20 includes a branch table update unit 200, a branch table storage unit 201, a virtual current position calculation unit 202, a candidate point calculation unit 203, a reliability calculation unit 204, a current position determination unit 205, and a map storage unit 206.

  The map storage unit 206 stores map data and link data obtained by approximating roads with line segments called a plurality of links. Each link is associated with the length of the link on the map, the start point coordinates and the end point coordinates of the link, and the like. The navigation device 20 stores only link data in the map storage unit 206, calculates the current position of the vehicle based on the link data, and displays the calculated current position together with the map data acquired from the outside. May be displayed.

  When the vehicle passes near a branch point of a road, the branch table storage unit 201 displays identification information of candidate points calculated on links corresponding to each of a plurality of roads connected to the branch point. Is stored in association with the coordinates on the map corresponding to. Further, the branch table storage unit 201 stores the effective distance subtracted according to the travel distance of the vehicle in association with the coordinates of each branch point. The effective distance is set when the coordinates of the branch point are registered.

  For example, the virtual current position calculation unit 202 calculates the travel distance traveled by the vehicle per unit time based on the measurement signal from the sensor 11. Then, for each candidate point calculated last time, the virtual current position calculation unit 202 calculates the relative displacement of the vehicle based on the measured values of the travel distance and the traveling direction of the vehicle from the candidate point, and the previous calculation is performed. The virtual current position of the vehicle is calculated by moving the position of the vehicle from the candidate point by the calculated relative displacement.

  The candidate point calculation unit 203 refers to the map storage unit 206 and, for each virtual current position calculated by the virtual current position calculation unit 202, is a link within a predetermined range from the virtual current position, and the virtual current position A link whose azimuth difference with the traveling azimuth of the vehicle at the position is within a predetermined angle is extracted, and the current candidate point is calculated on the extracted link. When there is no link within the predetermined range from the virtual current position, the candidate point calculation unit 203 calculates the virtual current position as the current candidate point in the free state.

  In addition, the candidate point calculation unit 203, when a plurality of candidate points are calculated from one virtual current position, that is, when the link where the previous candidate point serving as the calculation source of the virtual current position is branched In addition to the identification information of the plurality of candidate points calculated from the virtual current position, the coordinates of the branch point of the link are notified to the branch table update unit 200.

The reliability calculation unit 204 calculates the reliability of each of the current candidate points calculated by the candidate point calculation unit 203. Specifically, the azimuth difference θ between the traveling direction of the vehicle at the virtual current position calculated by the virtual current position calculation unit 202 and the direction of the link where the current candidate point calculated by the candidate point calculation unit 203 is located, and Based on the distance L from the virtual current position to the link where the current candidate point is located, the reliability calculation unit 204 calculates the error cost ec of each candidate point using, for example, the following relational expression.
ec = αθ + βL
Here, α and β are weighting factors.

  As is clear from the above relational expression, the error cost ec increases as the values of the orientation difference θ and the distance L increase. In addition, when the traveling direction of the vehicle at the virtual current position is close to the direction of the link where the current candidate point is located and the virtual current position is located on the link where the current candidate point is located, the error cost ec approaches zero.

Next, the reliability calculation unit 204 adds the error cost ec of the current candidate point to the error cost ec accumulated up to the previous candidate point based on, for example, the following relational expression, The accumulated error cost ec (n) is calculated.
ec (n) = (1-k) ec + kec (n-1)
Here, ec represents the error cost of the current candidate point, ec (n−1) represents the accumulated error cost at the previous candidate point, and k represents a weighting coefficient greater than 0 and smaller than 1.

Next, the reliability calculation unit 204 calculates the reliability trust of the current candidate point from the accumulated error cost ec (n) of the current candidate point, for example, based on the following relational expression.
trust = 100 / (1 + ec (n))
As is clear from the above relational expression, as the accumulated error cost ec (n) increases, the reliability trust decreases and approaches zero. On the other hand, as the accumulated error cost ec (n) decreases, the reliability trust increases and approaches 100.

  When the candidate point calculation unit 203 calculates a free state candidate point as the current candidate point, the reliability calculation unit 204 assigns a predetermined value as an error cost to the free state candidate point, Based on the error cost, the reliability for the free candidate point is calculated.

  The branch table update unit 200, when notified from the candidate point calculation unit 203 of the coordinates of the link branch point together with the identification information of the plurality of candidate points calculated from one of the previous candidate points, The point identification information is stored in the branch table storage unit 201 in association with the coordinates of the branch point. At this time, the branch table updating unit 200 stores the effective distance in association with the coordinates of the branch point.

  In addition, the branch table update unit 200 subtracts the effective distance stored in the branch table storage unit 201 last time at a predetermined timing such as the timing at which the virtual current position calculation unit 202 calculates the virtual current position. Subtract the distance traveled by the vehicle. Then, the candidate point and the coordinates of the branch point whose effective distance is 0 or less are deleted from the branch table storage unit 201.

  Based on the reliability calculated by the reliability calculation unit 204, the current position determination unit 205 displays the current position of the vehicle that causes the display device 12 to display the candidate point with the highest reliability among the candidate points calculated this time. Is determined as a display candidate point, and the determined display candidate point is displayed on the display device 12.

  Specifically, the candidate point with the highest reliability among the candidate points calculated this time is selected, and the selected candidate point is selected if it is a candidate point calculated from the previous display candidate point. The candidate point is determined as the current display candidate point and displayed on the display device 12. If the selected candidate point is not a candidate point calculated from the previous display candidate point, the following processing is performed.

  When comparing the reliability of candidate points that are not in the branch table storage unit 201 or are not associated with the coordinates of the same branch point in the branch table storage unit 201 with reference to the branch table storage unit 201, The current position determination unit 205 compares the reliability calculated by the reliability calculation unit 204.

  When comparing the reliability of the first candidate points that are associated with the coordinates of the same branch point in the branch table storage unit 201 and obtained based on the previous display candidate point, the current position The determination unit 205 compares the reliability of the first candidate points.

  The reliability of the first candidate point and the reliability of the second candidate point that is a candidate point other than the first candidate point are associated with the coordinates of the same branch point in the branch table storage unit 201. In the case where the comparison is made and the azimuth difference between the link where the first candidate point is located and the link where the second candidate point is located is equal to or smaller than a predetermined angle, the current position determination unit 205 After adding a predetermined first bias value to the reliability of the candidate points, the reliability of the first candidate point is compared with the reliability of the second candidate point.

  Corresponding to the coordinates of the same branch point in the branch table storage unit 201, the reliability of the first candidate point and the reliability of the second candidate point which is the current candidate point other than the first candidate point , And when the azimuth difference between the link where the first candidate point is located and the link where the second candidate point is located is larger than a predetermined angle, the current position determination unit 205 After adding a second bias value smaller than the first bias value to the reliability of the first candidate point, the reliability of the first candidate point is compared with the reliability of the second candidate point. .

  Thus, by comparing the reliability of each candidate point calculated this time, the current position determination unit 205 determines the candidate point with the highest reliability as the current display candidate point, and determines the determined display candidate point. It is displayed on the display device 12.

  FIG. 2 is a conceptual diagram for explaining the processing performed by the candidate point calculation unit 203. First, the candidate point calculation unit 203 is connected to the link 300 in which the previous candidate point 400 is located among the links within the predetermined range 60 from the virtual current position 401 calculated by the virtual current position calculation unit 202. Extract links. In the example illustrated in FIG. 2, the links 306 and 307 are removed, and the links 301, 302, 303, 304, and 305 are extracted by the candidate point calculation unit 203.

  Then, the candidate point calculation unit 203 further extracts, from the extracted links, links whose azimuth difference from the traveling direction of the vehicle at the virtual current position 401 is within a predetermined angle. In the example illustrated in FIG. 2, the link 303 is removed, and the links 301, 302, 304, and 305 are extracted by the candidate point calculation unit 203.

  Next, the candidate point calculation unit 203 follows the extracted link from the previously calculated candidate point 400 for the travel distance of the vehicle since the previous candidate point 400 was calculated, and the current candidate points 402 and 403. Is placed on the link. In the example illustrated in FIG. 2, the candidate point calculation unit 203 arranges the current candidate point 402 along the links 300 and 304 at a position advanced from the previous candidate point 400 by the travel distance R, and links 300 and 301. Then, the current candidate point 403 is arranged at a position advanced by the travel distance R from the previous candidate point 400.

  In addition, there is no link within a predetermined range from the virtual current position, there is no link within a predetermined angle with the traveling direction of the vehicle at the virtual current position, or the link where the previous candidate point is located When there is no connected link, the candidate point calculation unit 203 calculates the virtual current position 401 calculated by the virtual current position calculation unit 202 as the current candidate point in the free state.

  FIG. 3 shows an example of the structure of data stored in the branch table storage unit 201. The branch table storage unit 201 includes a record 2013. Each record 2103 is the effective distance 2011 subtracted according to the travel distance of the vehicle, and the current candidate point identification information calculated on the link corresponding to each of the plurality of roads connected to the branch point Candidate point ID 2012 is stored in association with branch point coordinates 2010.

  By referring to the branch table storage unit 201, the current position determination unit 205 can determine whether each candidate point is associated with the same branch point coordinate.

  When the branch table update unit 200 registers the effective distance in the branch table storage unit 201 in association with the branch point coordinates, the candidate point corresponding to the candidate point ID is on the expressway and on the general road. Different effective distances may be registered depending on the case. For example, the branch table update unit 200 sets the effective distance to 2 km when the candidate point corresponding to the candidate point ID is on the expressway, and sets the effective distance to 700 m when the candidate point is on the general road, respectively. Register with.

  In this embodiment, when one current candidate point is calculated from one previous candidate point, the identification information of the current candidate point inherits the identification information of the previous candidate point. On the other hand, when two or more current candidate points are calculated from one previous candidate point, the identification information of one of the current candidate points inherits the identification information of the previous candidate point, and other current candidate points The point identification information is newly generated. Each candidate point is associated with at least information for distinguishing whether it was calculated last time or this time.

  4, FIG. 5, and FIG. 6 are conceptual diagrams for explaining how the branch table storage unit 201 is updated.

  In the link configuration as shown in FIG. 4A, when the vehicle passes near the branch point of the road, the branch point 51 in the link data corresponding to the branch point of the road is determined based on the previous candidate point 410. The current candidate points 411 and 412 are arranged on the connected links, respectively. At this time, the branch table update unit 200 registers a record 2013 as shown in FIG. 4B in the branch table storage unit 201.

  Here, when the candidate point 410 has an ID of A, the candidate point calculation unit 203 generates, for example, the branch candidate point ID of the candidate point 411 from the candidate point 410 when generating the candidate points 411 and 412 from the candidate point 410. As a takeover A, a new branch candidate point ID B is assigned to the candidate point 412. In this example, when a new branch point coordinate is registered in the branch table storage unit 201, the branch table update unit 200 registers 700 m as an effective distance associated with the branch point.

  Then, the branch table update unit 200 subtracts all effective distances stored in the branch table storage unit 201 according to the travel distance of the vehicle. Then, as shown in FIG. 5A, when the vehicle passes near the branch point of the road corresponding to the branch point 52, the candidate point calculation unit 203 displays the previous link on the link connected to the branch point 52. Current candidate points 413 and 414 are generated from the candidate point 411, and current candidate point 415 is generated from the previous candidate point 412.

  At this time, for example, the candidate point calculation unit 203 sets the branch candidate point ID of the candidate point 413 as the takeover A from the candidate point 411, sets the branch candidate point ID of the candidate point 415 as the takeover B from the candidate point 412, and sets the candidate point 414 as the candidate point 414. C, which is a new branch candidate point ID, is assigned. The branch table update unit 200 adds the branch candidate point ID of the candidate point branched through the branch point 52 to the branch table storage unit 201 in association with the branch point 52.

  Then, the branch table update unit 200 refers to another record 2013, and the branch candidate point ID associated with the same branch point coordinate as the newly assigned branch candidate point ID is stored in the branch table storage unit 201. If the branch candidate point ID is stored in association with another branch point coordinate, the newly assigned branch candidate point ID is stored in the branch table storage unit 201 in association with the other branch point coordinate.

In the example shown in FIG. 5B, the candidate point ID A that is associated with the same branch point coordinates (X ₂ , Y ₂ ) as the newly assigned candidate point ID C is another Since it is associated with the branch point coordinates (X ₁ , Y ₁ ), the branch table update unit 200 assigns C, which is the newly assigned candidate point ID, to other branch point coordinates (X ₁ , Y ₁ ). Correspondingly, it is stored in the branch table storage unit 201.

  When the vehicle further advances as shown in FIG. 6A, the candidate point calculation unit 203 changes the current candidate points 416, 417, and 418 from the previous candidate points 413, 414, and 415, respectively. Generate. At this time, the branch table update unit 200 subtracts all effective distances stored in the branch table storage unit 201 according to the travel distance of the vehicle, and branches the branch point coordinate record 2013 whose effective distance is 0 or less. Delete from the table storage unit 201.

In the example shown in FIG. 6B, the effective distance associated with the branch point coordinates (X ₁ , Y ₁ ) is 0 or less according to the travel distance of the vehicle. The record 2013 corresponding to the branch point coordinates (X ₁ , Y ₁ ) is deleted from the branch table storage unit 201.

  FIG. 7 is a flowchart showing an example of the operation of the navigation device 20. For example, the navigation device 20 starts the processing shown in this flowchart at a predetermined timing such as when the engine of the vehicle is started.

  First, in the navigation device 20, the virtual current position calculation unit 202 determines whether or not a predetermined time (for example, 100 ms) has elapsed with reference to a timer value (S100). When the predetermined time has not elapsed (S100: No), the virtual current position calculation unit 202 repeats step 100 until the predetermined time elapses.

  When the predetermined time has elapsed (S100: Yes), the virtual current position calculation unit 202 resets and starts the timer, and acquires a measurement signal from the sensor 11 (S101). Then, the virtual current position calculation unit 202 calculates the relative displacement of the vehicle based on the measurement signal acquired from the sensor 11, and determines whether or not the travel distance of the vehicle from the previous time has become a predetermined distance (for example, 20 m) or more. Determine (S102). When the travel distance from the previous time is less than the predetermined distance (S102: No), the virtual current position calculation unit 202 performs the process shown in step 100 again.

  If the travel distance from the previous time is equal to or greater than the predetermined distance (S102: Yes), the navigation device 20 performs a current position calculation process described later (S200), and the virtual current position calculation unit 202 performs the process shown in step 100 again. Do.

  FIG. 8 is a flowchart illustrating an example of the current position calculation process in step 200. First, the virtual current position calculation unit 202 selects one of the previously calculated candidate points, and advances the position of the vehicle by the relative displacement of the vehicle calculated in step 102 of FIG. 7 from the selected candidate point. Thus, the virtual current position corresponding to the selected candidate point is calculated (S201).

  Next, the candidate point calculation unit 203 arranges the current candidate point on a link within a predetermined range from the virtual current position calculated in step 201 (S202). Then, the reliability calculation unit 204 calculates the reliability of the candidate points arranged in step 202 (S203). Then, the virtual current position calculation unit 202 determines whether or not the virtual current position has been calculated for all of the previously calculated candidate points (S204). When the virtual current position has not been calculated for all the previously calculated candidate points (S204: No), the virtual current position calculation unit 202 performs the process shown in step 201 again.

  When the virtual current position is calculated for all of the previously calculated candidate points (S204: Yes), the branch table update unit 200 performs a branch table update process to be described later (S300). Then, the current position determination unit 205 performs a current position determination process to be described later (S400), and the process shown in this flowchart ends.

  In step 204, the virtual current position calculation unit 202 may exclude candidate points whose reliability of the previous candidate point is a predetermined value or less from the calculation target of the virtual current position.

  FIG. 9 is a flowchart illustrating an example of the branch table update process. First, the branch table update unit 200 updates the effective distance of each branch point coordinate by subtracting the vehicle travel distance (for example, 20 m) from the previous time from all the effective distances in the branch table storage unit 201 ( S301).

  Next, the branch table update unit 200 deletes the record of the branch point coordinates whose effective distance is 0 or less from the branch table storage unit 201 (S302).

  Then, the branch table update unit 200 adds the new branch point coordinates, candidate point ID, and effective distance received from the candidate point calculation unit 203 to the branch table storage unit 201 (S303), and the processing illustrated in this flowchart ends. To do.

  FIG. 10 is a flowchart illustrating an example of the current position determination process. First, the current position determination unit 205 selects the current candidate point with the highest reliability among the current candidate points arranged by the candidate point calculation unit 203 based on the reliability calculated by the reliability calculation unit 204. (S401).

  Then, the current position determination unit 205 determines whether or not the selected current candidate point is a candidate point calculated from the previous display candidate point (S402). The current position determination unit 205 holds, for example, the ID of the candidate point determined as the previous display candidate point, and compares the held candidate point ID with the ID of the selected candidate point to select the current point selected this time. It is determined whether the candidate point is a candidate point calculated from the previous display candidate point.

  When the selected current candidate point is a candidate point calculated from the previous display candidate point (S409), the current position determination unit 205 determines the selected candidate point as the current display candidate point. Then, the determined display candidate point for this time is displayed on the display device 12, and the processing shown in this flowchart ends.

  When the selected current candidate point is not a candidate point calculated from the previous display candidate point (S402: No), the current position determination unit 205 refers to the branch table storage unit 201 and selects the current candidate selected. It is determined whether or not the point is associated with the same branch point coordinate as the branch point coordinate associated with the current candidate point calculated from the previous display candidate point (S403). If they are not associated with the same branch point coordinates (S403: No), the current position determination unit 205 performs the processing shown in step 409.

  When it is associated with the same branch point coordinates (S403: Yes), the current position determination unit 205 refers to the map storage unit 206, and the link where the selected current candidate point is located and the previous display candidate It is determined whether the azimuth difference calculated from the point and the current candidate point is less than or equal to a predetermined angle (S404). In this example, the predetermined angle is 5 degrees.

  When the azimuth difference is larger than the predetermined angle (S404: No), the current position determination unit 205 calculates a bias value to be added to the reliability, for example, 0 (S405), and performs the process shown in step 407.

  When the azimuth difference is equal to or smaller than the predetermined angle (S404: Yes), the current position determination unit 205 calculates a bias value to be added to the reliability, which is higher than the bias value set in step 405, for example, 2. (S406).

  Then, the current position determination unit 205 adds the bias value calculated in step 405 or 406 to the reliability of the current candidate point calculated from the previous display candidate point, and thus the reliability of the selected candidate point. It is determined whether or not this is the case (S407).

  If the value obtained by adding the bias value to the reliability of the current candidate point calculated from the previous display candidate point is less than the reliability of the selected candidate point (S407: No), the current position determination unit 205 The processing shown in 409 is performed.

  When the value obtained by adding the bias value to the reliability of the current candidate point calculated from the previous display candidate point is equal to or higher than the reliability of the selected candidate point (S407: Yes), the current position determination unit 205 The current candidate point with high reliability is selected (S408), and the process shown in step 402 is performed again.

  The embodiment of the present invention has been described above.

  As is clear from the above description, according to this embodiment, after passing through the Y-shaped branch road, the detected current position of the vehicle jumps between the two branched roads. It can be suppressed.

  In addition, this invention is not limited to said embodiment, Many deformation | transformation are possible within the range of the summary.

  For example, the branch table update unit 200, the virtual current position calculation unit 202, the candidate point calculation unit 203, the reliability calculation unit 204, and the current position determination unit 205 in the navigation device 20 are ASIC (Application Specific Integrated Circuit), FPGA ( It may be realized in hardware by an integrated logic IC such as a field programmable gate array), may be realized in software by a DSP (Digital Signal Processor) or a general-purpose computer, or may be partially hardware or software. You may combine the realized functional block.

1 is a system configuration diagram of a navigation system 10 according to an embodiment of the present invention. 5 is a conceptual diagram for explaining processing performed by a candidate point calculation unit 203. FIG. 4 is a diagram illustrating an example of a structure of data stored in a branch table storage unit 201. FIG. It is a conceptual diagram for demonstrating a mode that a branch table is updated. It is a conceptual diagram for demonstrating a mode that a branch table is updated. It is a conceptual diagram for demonstrating a mode that a branch table is updated. 4 is a flowchart showing an example of the operation of the navigation device 20. It is a flowchart which shows an example of a present position calculation process. It is a flowchart which shows an example of a branch table update process. It is a flowchart which shows an example of a present position determination process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Navigation system, 11 ... Sensor, 12 ... Display apparatus, 20 ... Navigation apparatus, 200 ... Branch table update part, 201 ... Branch table storage part, 2010 ... Branch Point coordinate 2011 ... Effective distance 2012 ... Branch candidate point ID 2013 ... Record 202 ... Virtual current position calculator 203 ... Candidate point calculator 204 ... Reliability Calculation unit 205 ... Current position determination unit 206 ... Map storage unit 300-307 ... Link 400, 402, 403, 410-418 ... Candidate point 401 ... Virtual current position , 50, 51, 52 ... branch point, 60 ... range

Claims (1)

A navigation device that is mounted on a vehicle and calculates a current position of the vehicle and displays it on a display device,
Map storage means for storing link data of each link constituting the road on the map;
For each candidate point calculated last time, virtual current position calculation means for calculating a virtual current position of the vehicle based on measured values of the travel distance and traveling direction of the vehicle since the candidate point was calculated;
For each calculated virtual current position, candidate point calculation means for calculating the current candidate point using link data of each link stored in the virtual current position and the map storage means;
For each of the candidate points this time, reliability calculation means for calculating reliability indicating the certainty as the current position of the candidate points;
Based on the reliability calculated by the reliability calculation means, the display candidate point that is the current position of the vehicle to be displayed on the display device is determined from the current candidate points, and the determined display candidate point is A current position determining means for displaying on the display device,
The current position determining means includes
Until the vehicle travels a predetermined distance after passing the branch point,
Select one candidate point with the highest reliability among the candidate points
If the selected candidate point is a candidate point calculated from the candidate point previously determined as the display candidate point, the selected candidate point is determined as the display candidate point,
If the selected candidate point is not a candidate point calculated from the previously determined candidate point as the display candidate point, the selected candidate point is calculated from the link where the selected candidate point is located and the previously determined candidate point as the display candidate point Determining whether the angle formed with the link where the candidate point is positioned is greater than a predetermined angle;
When the angle formed is equal to or less than a predetermined angle, a predetermined first bias value is added to the reliability of the candidate point calculated from the candidate point previously determined as the display candidate point. The reliability of the selected candidate point is compared with the reliability of the candidate point calculated from the candidate point previously determined as the display candidate point, and the candidate point with the higher reliability is determined as the display candidate point. ,
When the angle formed is larger than a predetermined angle, the reliability of the candidate point calculated from the candidate point previously determined as the display candidate point with a second bias value smaller than the first bias value. In addition, the reliability of the selected candidate point is compared with the reliability of the candidate point calculated from the previously determined candidate point as the display candidate point, and the candidate point with the higher reliability is displayed. A navigation device characterized in that it is determined as a candidate point .

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