JP3660393B2 - Current position calculation device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a current position calculation device that is mounted on a moving body such as a vehicle and measures a traveling distance, a traveling direction, and the like of the moving body, thereby calculating a current position of the moving body.
[0002]
[Prior art]
In a current position calculation device for calculating a current position of a vehicle traveling on a conventional road, the current position of the vehicle is determined by a vehicle traveling direction measured by an orientation sensor such as a gyro and a vehicle measured by a vehicle speed sensor or a distance sensor. It is calculated based on the travel distance.
[0003]
Further, the travel distance of the vehicle is generally obtained by measuring the output shaft of the transmission or the rotation speed of the tire and multiplying the rotation speed by a distance coefficient that is the distance the vehicle travels per rotation of the tire. It is demanded by.
[0004]
Further, as described in JP-A-63-148115, roads within a predetermined range centered on the temporary current position of the vehicle determined based on the current position obtained last time, the travel distance of the vehicle, and the amount of directional change are roads. By extracting the map and correcting the current position on the road with the highest correlation based on the correlation between the provisional current position and the extracted roads, the current position error obtained from the traveling direction and the traveling distance of the vehicle is corrected. Technology is known. In addition, as the correlation between the temporary current position and the road, a distance between the temporary current position and the road, a traveling direction of the vehicle, and a road direction difference are often used.
[0005]
According to a so-called map matching technique that corrects the obtained current position of the vehicle so as to match such a road, the accuracy of the current position calculation can be increased.
[0006]
[Problems to be solved by the invention]
By the way, a plurality of systems for calculating positions that are candidates for the current position by map matching technology are provided for each of a plurality of different candidate points that may be the current position, and the candidate points calculated by each system are calculated. By calculating the final current position from among them according to the reliability of each candidate point, it can be expected that the current position can be calculated better. This is because the position to be evaluated as the current position becomes more diverse.
[0007]
Here, in this way, when calculating candidate points in each system, if there is no road highly correlated with the temporary current position, the position on the road obtained by the map matching technique, or It is not appropriate to calculate only the position as a candidate point, and it is considered appropriate to estimate the temporary current position itself as a candidate point.
[0008]
In this case, the candidate point generated this time from the candidate point on the road obtained by the previous map matching technique can be expected to be a position on the road connected to the road on which the candidate point obtained last time is located . Therefore, when obtaining new candidate points from the candidate points on the road obtained by the previous map matching technology, the candidate points obtained previously from the road for which the temporary current position and the correlation are to be obtained by the map matching technology are obtained. Only roads that connect to the road where is located can be limited.
[0009]
On the other hand, when a new candidate point is obtained from the candidate point which is the provisional current position obtained last time, the road cannot be limited in this way. Therefore, for the candidate points is a tentative current position previously determined, load of the map matching process, becomes larger.
[0010]
As described above, when a plurality of systems for calculating positions that are candidates for the current position are provided, the amount of processing becomes larger than when only one system is provided.
[0011]
Therefore, for example, when traveling on a highway or the like at a high speed, is also conceivable that the process can not meet in between. This is because the current position calculation device generally displays a map around the current position together with the calculated current position, but when the vehicle travels at high speed, the displayed map must be updated frequently. This is because the amount of processing cannot be ignored.
[0012]
On the other hand, it is not preferable to simply reduce the number of systems in such a case. This is because the probability that the current position cannot be obtained correctly increases greatly as the number of systems decreases.
[0013]
Therefore, the present invention provides a current position calculation device capable of reducing the current position calculation processing load without significantly reducing the reliability of the current position calculation when the current position calculation processing load increases. With the goal.
[0014]
[Means for solving the problems]
To achieve the above object, the present invention is a current position calculation device that is mounted on a vehicle and calculates the current position of the vehicle,
Direction detection means for detecting the traveling direction of the vehicle;
A distance calculating means for calculating a travel distance of the vehicle;
Storage means for storing road maps;
Means for determining whether the vehicle has turned a predetermined angle or more based on the traveling direction of the vehicle;
The temporary current position obtained by adding the relative displacement of the vehicle obtained from the traveling direction and the travel distance to the candidate point of the vehicle obtained as a possible position of the previous vehicle, and the temporary current position and the road on the road map A candidate point calculation means for calculating, as a new candidate point, the temporary current position and a position on the road having a correlation degree equal to or greater than a predetermined reference value,
A reliability calculation means for calculating the reliability as the current position of each candidate point;
Among the calculated new candidate point, and means for calculating the most reliable candidate point as the current position,
When an arbitrary candidate point and a candidate point calculated based on the candidate point are set as a candidate point of the same system, the candidate point of the same system is set as a position on the expressway while the vehicle travels a predetermined distance. In addition to being calculated as display candidate points, the reliability is obtained as a predetermined number of candidate points with higher reliability among the candidate points obtained as positions on the expressway and positions on the expressway. A current position calculation device characterized by comprising candidate point restriction means for setting a predetermined number of candidate points with higher reliability among the candidate points that have not been used as candidate points obtained this time and deleting the remaining candidate points provide.
[0015]
[Action]
According to the present position calculation device according to the present invention, when an arbitrary candidate point and a candidate point calculated based on the candidate point are set as candidate points of the same system, the same while the vehicle travels a predetermined distance. When the candidate points of the system are calculated as positions on the expressway and continue to be calculated as display candidate points, the reliability of the candidate points obtained as positions on the expressway is a predetermined number of higher ranks. The candidate points and a predetermined number of candidate points with higher reliability among the candidate points that were not obtained as positions on the expressway are set as the candidate points obtained this time, and the remaining candidate points are deleted.
[0016]
That is, when a candidate point of a certain system that moves continuously on a connected road is calculated as a candidate point that is most correlated with the road more than a predetermined distance (ie, a display candidate point), It can be considered that the probability that the candidate point is correct is high. Further, it can be considered that the probability that the vehicle is traveling on the road where the candidate points of the system are moving is high.
[0017]
Therefore, in such a case, candidate points of the system and candidate points with higher reliability on the same road as the road are selected as candidate points that serve as a reference for obtaining the next candidate point. Further, in consideration of the case where no vehicle is present on the road, a predetermined number of candidate points not on the road are also selected in the order of reliability. The remaining candidate points are deleted to reduce the processing load for the next candidate point calculation.
[0018]
On the other hand, if it cannot be considered as described above, if the number of candidate points is reduced, the reliability of the current position calculation is significantly reduced, so the number of candidate points is not reduced.
[0019]
Also, if you are not driving on a highway, it is considered that there is a margin in processing capacity, so in such a case, candidate points should be set like this so that the correct current position can be calculated with better probability Do not reduce.
[0020]
By doing so, the processing load is reduced without significantly reducing the reliability of the current position calculation at high speeds on highways where the processing amount of the device increases without significantly reducing the reliability of the current position calculation. can do.
[0021]
【Example】
Examples of the present invention will be described below.
[0022]
FIG. 1 is a block diagram showing a configuration of a current position calculation apparatus according to an embodiment of the present invention. As shown in FIG. 1, the current position calculation device 10 includes an angular velocity sensor 11 that detects a change in traveling azimuth by detecting a yaw rate of the vehicle, and a geomagnetic sensor 12 that detects a traveling azimuth of the vehicle by detecting geomagnetism. And a vehicle speed sensor 13 that outputs pulses at time intervals proportional to the rotation of the output shaft of the vehicle transmission.
[0023]
Further, a display 17 for displaying a mark or the like indicating a map and current position around the current position, a switch 14 for accepting an instruction switching the scale of the map displayed on the display 17 from the user (driver), the digital map data storage A CD-ROM 15 is provided, and a driver 16 for reading map data from the CD-ROM 15 is provided. Moreover, the controller 18 which controls operation | movement of each peripheral apparatus shown above is provided. In the present embodiment, the digital map data described above includes road data composed of coordinates indicating the ends of a plurality of links, road width data indicating the road width of the road, and the road is an expressway or a general road. The expressway flag etc. which indicate are included.
[0024]
The controller 18 includes an A / D converter 19 that converts a signal (analog) of the angular velocity sensor 11 into a digital signal, an A / D converter 20 that converts a signal (analog) of the geomagnetic sensor 12 into a digital signal, and a vehicle speed sensor. A counter 26 that counts the number of pulses output every 13 seconds, a parallel I / O 21 that inputs whether or not the switch 14 is pressed, and a DMA that transfers map data read from the CD-ROM 15 ( (Direct Memory Access) controller 22 and display processor 23 for displaying a map image on display 17.
[0025]
The controller 18 further includes a microprocessor 24 and a memory 25. The microprocessor 24 outputs a signal from the angular velocity sensor 11 obtained through the A / D converter 19, a signal from the geomagnetic sensor 12 obtained through the A / D converter 20, and an output pulse from the vehicle speed sensor 13 counted by the counter 26. Number, whether or not the switch 14 is input via the parallel I / O 21, the map data from the CD-ROM 15 obtained via the DMA controller 22 is received, and processing based on these signals is performed. The current position is calculated and displayed on the display 17 via the display processor 23. As shown in FIG. 2, the vehicle position is displayed by superimposing an arrow mark or the like on a map already displayed on the display 17. Thereby, the user can know the current position of the vehicle on the map. The memory 25 includes a ROM that stores a program that defines the contents of processing (to be described later) for realizing such an operation, and a RAM that is used as a work area when the microprocessor 24 performs processing. Yes.
[0026]
Hereinafter, the operation of the current position calculation device 10 configured as described above will be described.
[0027]
First, the current position calculation process for obtaining the current position will be described.
[0028]
FIG. 3 shows a processing procedure of the current position calculation process.
[0029]
The process shown in FIG. 3 is a process that is activated and executed every time the vehicle travels 20 m, and is one or a plurality of positions matched by map matching on the road, or 1 or not matched on the road In this process, a plurality of positions are obtained as one or a plurality of candidate points where a vehicle may exist, and the most likely current position is selected as a display candidate point. The display candidate point is a position displayed as the current position.
[0030]
In this process, first, the travel distance R from the previous process execution time to the present, the current vehicle travel direction θcar, and the map data are read (steps 301 and 302).
[0031]
Next, map matching processing is performed (step 303).
[0032]
The processing procedure of this map matching process is shown in FIG.
[0033]
As shown in the figure, in this process, first, based on the previously read travel distance R and travel azimuth θcar, the travel distance of the vehicle is obtained separately in the latitude and longitude directions. Further, the amount of movement in each direction is added to the position of each candidate point obtained in the previous process, and the position where the current vehicle is estimated to exist corresponding to each candidate point obtained in the previous process. A virtual current position (A) is obtained (step 402). Candidate points, in this process, but one or more positions determined in step 403 and 404 to be described later as a position that can be a candidate for the current position, it will be detailed later its Determination.
[0034]
If there is no candidate point obtained by the process of obtaining the previous candidate point of the vehicle, such as immediately after the start of the device, the virtual current position is set using the position set separately as the position of the previously obtained candidate point. The position (A) is obtained.
[0035]
Subsequently, road search processing for matching with roads is executed only for candidate points in a free state, which will be described later, obtained in the previous process, and one or a plurality of candidate points and their reliability trst are obtained ( Step 403). The candidate point in the free state refers to a candidate point that could not be matched on the road as described above, and the reliability refers to the probability as the current position of each candidate point, details of which will be described later. Details of the search candidate point selection process executed in step 403 will also be described later.
[0036]
Next, after the search candidate point selection process is executed, a road search process for performing matching with a road is executed only for candidate points in a matching state (to be described later) obtained in the previous process, and one or more Candidate points and their reliability trst are obtained (step 404). The candidate point in the matching state refers to a candidate point matched by map matching on the road, and details of how to find it will be described later.
[0037]
Next, these new candidate points are sorted according to the value of the reliability trst corresponding to each of the candidate points obtained by the above processing (step 405), and the candidate point C having the highest reliability value is As display candidate points CD, that is, candidate points for display on the display 17, the position, accumulated error cost es described later, reliability, a status flag indicating whether it is in a matching state or a free state, etc. In addition to being stored in a predetermined area of the RAM of the memory 25, the positions of candidate points other than the display candidate points, the accumulated error cost es, the reliability trst, the status flag, etc. are also stored in the predetermined area of the RAM (step 406).
[0038]
Finally, the coordinate data of the display candidate point is output (step 407), and the process ends.
[0039]
Next, only the previous candidate point in the matching state in step 404 and the road search processing for matching with the road that is performed only for the previous candidate point in the free state in step 403 of the map matching process (FIG. 4). The details of the road search processing for matching with the road to be performed will be described.
[0040]
First, the road search process in step 404 will be described.
[0041]
FIG. 5 shows details of the road search process in step 404.
[0042]
This process is performed for each candidate point in the matching state obtained in the previous map matching process.
[0043]
In this road search process, first, a map around the virtual current position (A) obtained corresponding to the previous candidate point of the matching state to be processed is read from the CD-ROM 15 using the driver 16 and the DMA controller 23. (Step 501).
[0044]
Then, the link where the previous candidate point in the matching state to be processed is located, or the link connected to the front in the traveling of the vehicle is selected and taken out (step 502).
[0045]
As described above, in this embodiment, the road data is approximated by a plurality of links 51 to 55 connecting two points as shown in FIG. 6, and these links are represented by the coordinates of the start point and the end point. The ones shown are used. For example, the link 53 is represented by its start point (x3, y3) and end point (x4, y4).
[0046]
Next, out of the links taken out in step 502, the direction in which the vehicle should travel when the vehicle travels on the link out of the two opposite directions of the link is obtained. Only the link within the vehicle direction and the predetermined value is selected (step 503), and the perpendicular line L (n) is taken from the virtual current position (A) for all the selected n extracted links. Is obtained (step 504). In addition, candidate points corresponding to each link are set. These candidate points are all matching candidate points matched to the road. However, at this time, the position of the candidate point in the matching state is not yet determined.
[0047]
By the way, the link selected at step 503 where the candidate point of the previous matching state to be processed is located or a link connected thereto, and the difference between the direction and the traveling direction of the vehicle is less than a predetermined value. There may be a case where there is no such link. In this case, the virtual current position (A) is set as the next candidate point calculated from a certain candidate point. Such candidate points are candidate points that have not been matched on the road, and are candidate points in a free state.
[0048]
Next, error cost, accumulated air cost es, and reliability trst are calculated for each candidate point (step 505 ).
[0049]
In this process, an error cost value ec (n) defined by the following equation is calculated for all candidate points.
[0050]
ec (n) = α × | θcar−θ (n) | + β | L (n) |
Here, θcar represents the vehicle direction at the virtual current position (A). Θ (n) is the direction of the link where the candidate point is set, L (n) is the distance from the virtual current position (A) to the link where the candidate point is set, that is, the length of the perpendicular, α and β are It is a weighting factor. The values of these weighting factors may be changed depending on whether the shift in the traveling direction or the direction of the road or the shift in the current position or the road is important in selecting a road on which the current position is located. For example, when importance is attached to a road whose direction is close to the traveling direction, α is increased.
[0051]
Further, in this error cost calculation, a relatively large value is given to the candidate point in the free state as the direct error cost ec (n) compared to the average value of the error cost that may be given to the candidate point in the matching state. .
[0052]
Now, according to the calculated error cost ec (n) and the accumulated error cost es of the previous candidate point, the accumulated error cost es (n) of each candidate point defined by the following equation: Is calculated.
[0053]
es (n) = (1-k) × es + k × ec (n)
Here, k is a weight coefficient larger than 0 and smaller than 1. This accumulated error cost es (n) represents how much the error cost calculated in the previous process is reflected in the error cost calculated in the current process. Furthermore, based on the calculated accumulated error index es (n), that to calculate the reliability trst defined by the following equation (n).
[0054]
trst (n) = 100 / (1 + es (n))
As is clear from the above equation, as the accumulated error cost e s (n) increases, the reliability trst (n) decreases and approaches 0 (zero). On the other hand, as it decreases, the reliability trst (n) increases and its value approaches 100.
[0055]
By performing such processing, the candidate point on the n links that are connected to the link where the previous candidate point to be processed exists and whose link direction is close to the vehicle direction and the candidate point of the free state Reliability trst (n) is obtained.
[0056]
Next, the candidate points set as the links are points that have been advanced from the previous candidate point to be processed by the length corresponding to the distance R traveled by the vehicle along each of the n links selected in step 503. (Step 506 ). Therefore, when there are a plurality of links (n is a plurality) selected in step 503, a plurality of candidate points are generated. That is, n new candidate points C (n) are generated corresponding to n links. In other words, a plurality of new candidate points may be generated for each candidate point in the previous matching state.
[0057]
An example in which candidate points are sequentially obtained by the above processing is shown in FIGS.
[0058]
As shown in FIG. 7, it is assumed that the virtual current position (A) is represented at a position indicated by a point 63 with respect to a certain candidate point 62 existing on the link 61 in a certain process. In such a case, the link is connected forward from the virtual current position (A) to the link 61 where the candidate point 62 is located in the vehicle direction, and the difference between the direction and the vehicle direction is equal to or less than a predetermined value. The links 64 and 65 are taken out, and the distances L (1) and L (2) from the current position A to the links 64 and 65 are calculated, and the calculated distance and the angle θ (1) of the links 64 and 65 are calculated. , Θ (2), vehicle orientation θcar, and the like, the associated error cost, accumulated error cost, and reliability are calculated. Further, based on the travel distance R of the vehicle obtained previously, a position advanced by a length corresponding to the travel distance R from a certain candidate point 62 along the links 61 and 64 or the links 61 and 65 is calculated. The points corresponding to this position are set as candidate points 66 and 67, respectively.
[0059]
In the next processing, as shown in FIG. 8, the new virtual current position (A) is represented at the position indicated by the point 71 with respect to the candidate point 66 on the link 64, while on the link 65. It is assumed that a new virtual current position (A ′) is represented at the position indicated by the point 72 with respect to the candidate point 67. In this case, links 73 and 74 that are connected to the link 64 and whose difference between the azimuth and the vehicle azimuth is equal to or less than a predetermined value are taken out from the virtual current position (A) and new From the virtual current position (A ′), a link 75 connected to the link 65 and having a difference between the direction and the vehicle direction equal to or smaller than a predetermined value is taken out. Next, the distances L1 (1) and L1 (2) from the virtual current position (A) to the links 73 and 74 are calculated, and the distance L2 (1) from the virtual current position (A ′) to the link 75 is calculated. ) Is calculated. Further, based on the distance calculated in relation to the current position A, the angles θ1 (1) and θ1 (2) of the links 73 and 74, the vehicle direction θcar, etc., the related error cost, accumulated error cost and reliability are calculated. In addition to the calculation, the related error cost, accumulated error cost, and reliability are calculated based on the distance calculated in relation to the current position A ′, the angle θ2 (1) of the link 75, the vehicle orientation θcar, and the like.
[0060]
Further, based on the travel distance R of the vehicle, the travel distance R of the vehicle from the candidate point 66, along the links 64 and 73, or along the links 64 and 74, or from the candidate point 67 along the links 65 and 75. A position advanced by a length corresponding to is calculated, and points corresponding to this position are set as new candidate points. FIG. 9 shows the candidate points 81 to 83 newly obtained in this way.
[0061]
Next, the details of the road search process for performing matching with the road only on the candidate points in the free state obtained in the previous map matching process in step 403 in FIG. 4 will be described.
[0062]
FIG. 10 shows a processing procedure of road search processing for the previous candidate point in the free state.
[0063]
This process is performed for each candidate point in the free state obtained in the previous map matching process.
[0064]
As shown in the figure, this process is similar to the road search process for the candidate points in the matching state shown in FIG.
[0065]
The difference between these two processes, the road search processing, the line candidate points obtained in the process of determining a candidate point of the preceding vehicle is positioned or retrieves the line segment to be connected thereto, these On the other hand, in the candidate point road search process in the free state, the virtual current position (in step 502 and 503 in FIG. 5) is selected from the line segments where the azimuth difference with the sensor direction is within a predetermined value (steps 502 and 503 in FIG. 5). All line segments within a preset distance D centered on A) are extracted, and a line segment whose azimuth difference from the sensor orientation is within a predetermined value is selected from these line segments (step 1202). is there.
[0066]
That is, in the processing of steps 502 and 503 in FIG. 5, it is sufficient to extract a single line segment or several line segments extending from the branch point, but in the processing of step 1202 in FIG. The line segment to be extracted is determined from the road data in the map corresponding to the map data.
[0067]
Further, in the road search process for the candidate point in the free state, a difference between the direction and the traveling direction of the vehicle is within a predetermined range D from the virtual current position (A) for the candidate point in the previous free state to be processed. When a line segment equal to or smaller than a predetermined value exists, the intersection of the vertical line drawn from the virtual current position to the line segment and the line segment becomes a candidate point for a new matching state. Further, the virtual current position (A) with respect to the previous free state candidate point to be processed is also a free state candidate point.
[0068]
In addition, if there is no line segment having a difference between the direction and the traveling direction of the vehicle within a predetermined range D from the virtual current position (A) for the candidate point in the free state, the virtual current position is determined. Only the corresponding points are candidate points in the free state.
[0069]
The method of obtaining the error cost ec, the accumulated error cost es, and the reliability trst of each candidate point is exactly the same as that described in the road search process for the candidate point in the matching state.
[0070]
The map matching process in step 303 in FIG. 3 has been described above.
[0071]
When the map matching process (step 303) ends, whether or not the current display candidate is a candidate point generated based on the candidate point that was the previous display candidate (step 304) is matched with the position on the expressway. It is determined whether or not the matching point is a candidate point (step 305). If the current display candidate is a candidate point that is generated based on the candidate point that has become the previous display candidate and is a matching candidate point that is matched to the position on the expressway, the display candidate continuation distance l is updated by adding the travel distance 20 m from the previous processing to the present (step 306). On the other hand, in other cases, the display candidate continuation distance l is initialized to 0 (step 309).
[0072]
As a result, the display candidate continuation distance l is the candidate of the matching state on the expressway when an arbitrary candidate point and a candidate point generated from the candidate point are the same system so far. It represents the distance that has been selected as a display candidate point.
[0073]
Therefore, in the next step, it is determined whether or not the display candidate continuation distance l is greater than a predetermined threshold value, and the number of candidate points is limited. A candidate number restriction process is performed (steps 307 and 308).
[0074]
FIG. 11 shows a processing procedure for the candidate number limiting process.
[0075]
As shown in the figure, in the process, the candidate points generated in the current map matching process 303 are the highway individual complement HW, which is the number of candidate points that are positions matched to the expressway, and other candidate points. The number GN is obtained respectively (step 1101).
[0076]
Next, it is determined whether the non-highway complement GN exceeds a predetermined upper limit number GNth (for example, 2) (step 1102), and if it exceeds, a candidate point that is not matched with the highway is selected. In order of increasing reliability (step 1103), the upper limit number GNth candidate points are selected in descending order of reliability, and information on candidate points that are not positions matched to the remaining expressway is deleted from the memory (step 1104). ).
[0077]
Next, it is determined whether the highway complement HW exceeds a predetermined upper limit number HWth (for example, 3) (step 1105), and if it exceeds, a candidate point that is a position matched with the highway is determined. In order of increasing reliability (step 1106), the upper limit number HWth candidate points are selected in descending order of reliability, and information on candidate points corresponding to the remaining highways is deleted from the memory (step) 1107).
[0078]
The candidate points that have not been deleted in this way become the previous candidate points that serve as a reference for obtaining new candidate points in the next map matching process 303.
[0079]
In this way, by deleting candidate points when it is considered that the vehicle is traveling on an expressway, the processing load for the next candidate point calculation is reduced. Even if it is considered that the vehicle is traveling on an expressway, the reduction is performed only when the display candidate point is considered to be correct to some extent, so the probability that the calculated current position is erroneous is so high. Don't be.
[0080]
In the map matching process (FIG. 3, step 303), the generated candidate points may be always reduced to a number greater than HWth + GNth in the order of reliability.
[0081]
Hereinafter, based on the display candidate points determined by the current position calculating process of FIG. 3, that describes the processing for displaying the current position on the display.
[0082]
FIG. 12 shows a processing procedure for display processing.
[0083]
This process is a routine of the microprocessor 24 that is activated and executed every second.
[0084]
In this process, first, it is determined whether or not the switch 14 is instructed to change the scale of the map by being pressed by looking at the contents of the parallel I / O 21 (step 1801). If it is pressed (Yes in Step 1801), a predetermined scale flag is set correspondingly (Step 1802).
[0085]
Next, the coordinate obtained by adding the moving amount of the vehicle after the coordinates of the display candidate point obtained from the azimuth and travel distance obtained from the sensor to the coordinates of the display candidate point obtained most recently is output as the current position ( B), a map including the current position (B) and the current position (B) is read (step 1803), and a map of a scale corresponding to the contents of the scale flag switched in step 1802 is displayed on the display 17, for example, FIG. 2 is displayed (step 1804).
[0086]
Then, the position of the current position (B) and the current vehicle orientation θcar are displayed using, for example, the arrow symbol “↑” as shown in FIG. Finally, a north mark indicating north and a distance mark corresponding to the scale are displayed as shown in FIG. 2 so as to be superimposed on these (step 1806).
[0087]
【The invention's effect】
As described above, according to the present invention, when the current position calculation processing load increases, the current position calculation processing load can be reduced without significantly reducing the reliability of the current position calculation. An apparatus can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a current position calculation apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a display example of a map and a current position according to the present embodiment.
FIG. 3 is a flowchart illustrating a processing procedure of a process for calculating a current position.
FIG. 4 is a flowchart illustrating a processing procedure of map matching processing;
FIG. 5 is a flowchart illustrating a processing procedure of a road search process for candidate points in a matching state.
FIG. 6 is a diagram for explaining a road expression format on a road map;
FIG. 7 is a diagram for explaining a line segment corresponding to a road, a virtual current position, and candidate points;
FIG. 8 is a diagram for explaining a line segment corresponding to a road, a virtual current position, and candidate points.
FIG. 9 is a diagram for explaining a line segment corresponding to a road, a virtual current position, and candidate points;
FIG. 10 is a flowchart illustrating a processing procedure of a road search process for candidate points in a free state.
FIG. 11 is a flowchart illustrating a processing procedure for candidate number reduction processing;
FIG. 12 is a flowchart illustrating a processing procedure of current position display processing;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Present position calculation apparatus 11 Angular velocity sensor 12 Direction sensor 13 Vehicle speed sensor 14 Switch 15 CD-ROM
16 CD-ROM read driver 17 Display 18 Controller 24 Microprocessor

Claims (3)

A current position calculation device for calculating a current position of a vehicle,
Direction detection means for detecting the traveling direction of the vehicle;
A distance calculating means for calculating a travel distance of the vehicle;
Storage means for storing road maps;
Means for estimating the virtual current position of the vehicle by using the candidate point, the detected traveling direction, and the calculated travel distance for each candidate point of the vehicle obtained as a position where the vehicle may exist the previous time When,
For each estimated virtual current position, the virtual current position is compared with a road on the road map, and a position on the road having a degree of correlation with the virtual current position equal to or greater than a predetermined reference value is a new candidate. Means for calculating as points;
Means for calculating the reliability of each of the new candidate points;
Means for comparing the reliability of the new candidate point and determining the candidate point having the largest value as a display candidate point indicating the current position of the vehicle;
Each of the plurality of display candidate points determined while the vehicle travels a predetermined distance is a display candidate point calculated based on the virtual current position estimated from the display candidate point immediately before the display candidate point . There, if a display candidate points located either suspended high-speed on the road, a first predetermined number of reliability level among the candidate points determined as a position on the highway from the new candidate point And a second predetermined number of candidate points with higher reliability among candidate points that were not obtained as positions on the expressway as candidate points for determining the next display candidate point And a current position calculating device. A current position calculation device for calculating a current position of a vehicle,
Direction detection means for detecting the traveling direction of the vehicle;
A distance calculating means for calculating a travel distance of the vehicle;
Storage means for storing road maps;
Sequentially, for each candidate point of the vehicle obtained as a position where the previous vehicle may exist, the virtual current position of the vehicle is estimated using the candidate point, the detected traveling direction, and the calculated travel distance The virtual current position and the traveling direction are compared with the road map for each estimated virtual current position, and the virtual current position and the traveling direction have a degree of correlation greater than a predetermined reference value. When the position on the road is obtained, the position on the road is set as a new candidate point, and the candidate point of the vehicle obtained as the position where the previous vehicle may exist is the virtual current position obtained last time And a candidate point calculation means for calculating the virtual current position as a new candidate point when a position on the road having a correlation degree equal to or higher than a predetermined reference value with the virtual current position and the traveling direction is not obtained. When ,
Means for calculating the reliability of each of the new candidate points;
Means for comparing the reliability of the new candidate point and determining the candidate point having the largest value as a display candidate point indicating the current position of the vehicle;
Each of the plurality of display candidate points determined while the vehicle travels a predetermined distance is a display candidate point calculated based on the virtual current position estimated from the display candidate point immediately before the display candidate point . There, if a display candidate points located either suspended high-speed on the road, a first predetermined number of reliability level among the candidate points determined as a position on the highway from the new candidate point And a second predetermined number of candidate points with higher reliability among candidate points that were not obtained as positions on the expressway as candidate points for determining the next display candidate point And a current position calculating device. The current position calculation device according to claim 1 or 2,
The candidate point calculation means obtains only the road connected to the road where the candidate point obtained last time is located on the road map for the vehicle candidate point obtained as the position on the road last time. A current position calculation device characterized in that it is a target to be compared with a virtual current position obtained from a candidate point.

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