JP3634006B2 - 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]
In addition, 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, a road within a predetermined range centered on the current position of the vehicle determined based on the travel distance and the direction change amount is extracted from the road map, and the estimated position and the extraction are extracted. A technique for correcting an error in the current position obtained from the traveling direction and the traveling distance of the vehicle by correcting the current position on the road having the highest correlation based on the correlation between the roads is known. In addition, as the correlation between the estimated position and the road, a distance between the estimated 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 for correcting the current position of the obtained 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]
Since the map matching technique described above corrects the current position based on the road map, it is assumed that the road map is accurate.
[0007]
On the other hand, in reality, there may be a newly created road that is not on the road map. In such a case, when the vehicle travels on this road, the map matching technique described above will be used. If the upper position is calculated as the current position, the current position is obtained on another road existing on the map, not on the road that is actually traveling.
[0008]
Therefore, the present invention correctly estimates whether the vehicle has traveled on a newly created road that is not on the road map, and if it is estimated that the vehicle has traveled on the newly created road, The object is to suppress the position on the road calculated by matching being selected as the current position.
[0009]
[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;
Road mapIn advanceMemorydoingStorage means;
Advancing direction and mileage at the current vehicle position obtained last timeSeparatedAdd the relative displacement of the vehicleVirtual current position calculating means for calculating the virtual current position of the vehicle by
By comparing the virtual current position calculated by the virtual current position calculating means with the road map stored in the storage means, Sequentially, the position where the vehicle existsageMost likelyThe current position on the road included in the road mapCurrent position estimating means for estimating;
Detected by direction detection meansThe traveling direction of the vehicle,An azimuth difference detecting means for detecting a road vehicle azimuth difference which is an azimuth difference with the azimuth of the road including the current position of the vehicle estimated by the current position estimating means;
Control means for repeatedly executing calculation of the virtual current position by the virtual current position calculation means, estimation of the most probable current position by the virtual current position estimation means, and detection of road vehicle azimuth difference by the azimuth difference detection means,
An average heading difference calculating means for calculating an average heading difference that is an average of the latest five road vehicle heading differences;
An azimuth difference fluctuation calculating means for calculating an azimuth difference fluctuation which is an azimuth difference between the road vehicle azimuth difference detected last by the azimuth difference detecting means and the average azimuth difference calculated by the average azimuth difference calculating means;
The second road vehicle orientation difference detected by the orientation difference detection means is larger than the first threshold orientation difference, and the orientation difference fluctuation calculated by the orientation difference fluctuation calculation means is smaller than the first threshold orientation difference. Regardless of the position where roads should be displayed if they are larger than the threshold direction difference of,Current position calculating means for calculating the virtual current position calculated by the virtual current position calculating means as the current position of the vehicle;
WithA current position calculating device is provided.
[0010]
[Action]
According to the present position calculation apparatus according to the present invention, it is determined that the vehicle has turned with respect to the road, and the difference between the traveling direction of the vehicle and the most probable road direction is equal to or greater than a predetermined value. If the vehicle travels on a newly created road that is not on the road mapNotoA position where the estimated vehicle exists by comparing the virtual current position estimated by adding the relative displacement of the vehicle obtained from the traveling direction and the traveling distance with the road map read from the road mapageThe most probable position on the road, that is, the position obtained by map matching is not set as the current position, and the virtual current position is set as the current position as it is.
[0011]
According to the present invention having such a configuration, the vehicle has traveled on a newly created road that is not on the road map due to the difference between the turning with respect to the road, the traveling direction of the vehicle, and the road direction. It is possible to correctly estimate whether or not.
[0012]
For example, turning to the road occurs even by mere meandering, but in meandering, the difference between the traveling direction of the vehicle and the road direction does not increase so much. According to the present invention that considers both of the differences, it is not erroneously determined that the vehicle has traveled on a newly created road that is not on the road map. On the other hand, since the turning with respect to the road is taken into consideration, the road heading and road heading of the vehicle have increased due to an error in the road direction on the road map and a steady error of the sensor for detecting the direction In some cases, it is not erroneously determined that the vehicle has traveled on a newly created road that is not on the road map.
[0013]
In addition, when it can be determined that the vehicle has traveled on a newly created road that is not on the road map in this way, the relative position of the vehicle is determined without using the position obtained by map matching as the current position. The position obtained from the position can be used as it is as the current position.
[0014]
【Example】
Examples of the present invention will be described below.
[0015]
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.
[0016]
Also, a display 17 for displaying a map around the current position, a mark indicating the current position, and the like, and a command for switching the scale of the map displayed on the display 17 are used.The(Switch 14 received from the driver) andIA CD-ROM 15 for storing digital map data and a driver 16 for reading the map data from the CD-ROM 15 are 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.
[0017]
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.
[0018]
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.
[0019]
Hereinafter, the operation of the current position calculation device 10 configured as described above will be described.
[0020]
First, the process for obtaining the current position will be described.
[0021]
FIG. 3 shows a processing procedure of processing performed by the microprocessor 24 to calculate the current position.
[0022]
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.
[0023]
In this process, first, the vehicle orientation θcar and map data are read (steps 301 and 303).
[0024]
Then, a map matching process (step 304) is executed.
[0025]
The map matching process is a process for obtaining the candidate points described above.
[0026]
FIG. 4 shows a processing procedure of the map matching process.
[0027]
In this process, the travel distance R from the previous execution of the map matching process to the present and the current travel direction θcar of the vehicle are read (step 401). Next, based on these values, the movement amount of the vehicle is obtained separately in the latitude and longitude directions.
[0028]
Furthermore, the amount of movement in each direction is added to the position of each candidate point obtained in the previous map matching process, and there is a current vehicle corresponding to each candidate point obtained in the previous map matching process. A virtual current position (A) that is an estimated position is obtained (step 402). The candidate points are one or a plurality of positions obtained in steps 403 and 404, which will be described later, as positions that can be candidates for the current position in the map matching process. Details of how to obtain the candidate points will be described later.The
[0029]
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.
[0030]
Next, a road search process for matching with a road is executed only for candidate points in a free state, which will be described later, obtained in the previous map matching 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.
[0031]
Next, after the search candidate point selection process is executed, a road search process for matching with a road is executed only for candidate points in the matching state described later obtained in the previous map matching process, and 1 or A plurality of 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.
[0032]
Then, these new candidate points are sorted according to the value of the reliability trst corresponding to each of the candidate points obtained in steps 403 and 404 (step 405), and the candidate point C having the highest reliability value is obtained. The display candidate point CD, its position, accumulated error cost es, which will be described later, reliability, a status flag indicating whether it is in a matching state or a free state, and the like are 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, and the like are also stored in a predetermined area of the RAM (step 406).
[0033]
Next, in the map matching of FIG. 4, the road search processing for matching with the road only for the previous candidate point in the free state in step 403 and the previous candidate point in the matching state in step 404 are performed. Details of the road search processing for matching with the road will be described.
[0034]
First, the road search process in step 404 will be described.
[0035]
FIG. 5 shows details of the road search process in step 404.
[0036]
This process is performed for each candidate point in the matching state obtained in the previous map matching process.
[0037]
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).
[0038]
Then, the link where the previous candidate point in the matching state to be processed is located or a link connected to this link is selected and taken out (step 502).
[0039]
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).
[0040]
Next, from the links taken out in Step 502, only those links whose direction of the link is within the predetermined vehicle direction and a predetermined value are selected (Step 503), and the selected n pieces taken out are selected. For all links, a perpendicular line is taken from the virtual current position (A), and the length of the perpendicular line L (n) is obtained (step 504).
[0041]
Next, an error cost value ec (n) defined by the following equation is calculated for all links selected in step 503 based on the lengths of these perpendicular lines. 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, L (n) is the distance from the virtual current position (A) to the link, that is, the length of the perpendicular, and α and β are weighting factors. 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.
[0042]
Next, according to the calculated error cost ec (n) and the accumulated error cost es of the previous candidate point to be processed, the accumulation of each link selected in step 504 is defined by the following equation: Error cost es (n) is calculated (step 505).
[0043]
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. Further, based on the calculated accumulated error cost es (n), the reliability trst (n) defined in the following equation is calculated (step 505).
[0044]
trst (n) = 100 / (1 + es (n))
However, the reliability of the candidate point generated from the candidate point selected as the previous display candidate point is obtained by the following equation.
[0045]
trst (n) = 100 / (1 + es (n)) + B
Here, B is a predetermined bias value. As described above, the bias value is added to the candidate points generated from the display candidate points because a series of candidate points selected as display candidate points (the candidate points and the candidate points generated from the candidate points are the same series). This is to prevent excessive change. That is, when there is a series of similar reliability generated each time, the series of candidate points selected as display candidate points changes frequently, but such a change is the current position to be displayed as described later. This is not preferable because it causes the position jump. Therefore, by adding a bias to the candidate points born from the display candidate points, it is selected as the display candidate points until it is determined to some extent that there is a difference in reliability and one series will be correct. The change of the series of candidate points is suppressed.
[0046]
As is clear from the above equation, as the accumulated error cost ec (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.
[0047]
By performing such processing, the reliability trst (n) relating to each of 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 is obtained. It is done.
[0048]
Next, the points advanced by the length corresponding to the distance R traveled by the vehicle along the n links selected in step 503 from the previous candidate points to be processed are set as new candidate points ( Step 506). Therefore, when there are a plurality of links (n is a plurality) selected in step 503,, NNew candidate points C (n) are generated. In other words, a plurality of new candidate points may be generated for each candidate point in the previous matching state.
[0049]
Then, the accumulated error cost es (n) of each of the n links selected in step 503 is set as the accumulated error cost of the new candidate point C (n) obtained by moving the distance R along the link.
[0050]
An example in which candidate points are sequentially obtained by the above processing is shown in FIGS.
[0051]
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 map matching process. In such a case, the link 64 connected from the virtual current position (A) to the link 61 where the candidate point 62 is located, and the difference between the direction and the vehicle direction is equal to or less than a predetermined value, 65, and the distances L (1) and L (2) from the current position A to the links 64 and 65 are calculated, and the calculated distances and the angles θ (1) and θ (2) of the links 64 and 65 are calculated. And the related error cost, accumulated error cost, and reliability are calculated based on the vehicle orientation θcar and the like. 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.
[0052]
In the next map matching process, as shown in FIG. 8, the new virtual current position (A) for the candidate point 66 on the link 64 is represented at the position indicated by the point 71, while the link 65 It is assumed that a new virtual current position (A ′) is represented at a position indicated by a point 72 with respect to the upper 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 orientation θcar, etc., the related error cost, accumulated error cost and reliability are calculated. In addition to 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.
[0053]
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.
[0054]
Now, the candidate points obtained by the processing as described above are all matching points that are matched on the road.
[0055]
On the other hand, the link selected in step 503 is the link where the candidate point of the previous matching state to be processed is located, or the 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.
[0056]
Such candidate points are candidate points that have not been matched on the road, and are candidate points in a free state. Here, in step 505, the candidate point in the free state is given a constant value larger than the error cost given to the candidate point in the matching state as the error cost ec (n).
[0057]
The details of the road search process for matching with the road performed only for the previous candidate point in the matching state in step 404 of FIG. 4 have been described above.
[0058]
Next, the details of the road search process for performing matching with the road only on the candidate points in the free state, which will be described later, obtained in the previous map matching process in step 403 in FIG. 4 will be described.
[0059]
FIG. 10 shows a processing procedure of road search processing for the previous candidate point in the free state.
[0060]
This process is performed for each candidate point in the free state obtained in the previous map matching process.
[0061]
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.
[0062]
The difference between these two processes is that in the road search process, the link where the candidate point obtained by the process for obtaining the candidate point of the previous vehicle is located, or the link connected to this, is extracted, and from these links, While a link whose orientation difference from the sensor orientation is within a predetermined value is selected (steps 502 and 503 in FIG. 5), in the candidate point road search process in the free state, the virtual current position (A) is the center. All the links within the preset distance D are extracted, and a link whose orientation difference from the sensor orientation is within a predetermined value is selected from these links (step 1202).
[0063]
That is, in the processing of steps 502 and 503 in FIG. 5, it is sufficient to take out a single link or several links extending from the branch point. However, in the processing of step 1202 in FIG. A link to be extracted is determined from road data in the map corresponding to the data.
[0064]
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 link equal to or smaller than a predetermined value exists, the intersection of the perpendicular line drawn from the virtual current position to the link and the link 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.
[0065]
Also, if there is no link within the predetermined range D from the virtual current position (A) with respect to the candidate point in the free state, the difference between the direction and the traveling direction of the vehicle does not exceed the predetermined value, it corresponds to the virtual current position Only the points to be selected are candidate points in the free state.
[0066]
The error cost ec, the accumulated error cost es, and the reliability trst of each candidate point are obtained by adding the bias B to the reliability trst of the candidate point generated from the display candidate point. This is exactly the same as that described in the road search process for the candidate point.
[0067]
The map matching process in FIG. 4 has been described above.
[0068]
Now, returning to FIG. 3, in this way the map matching process304When a display candidate point is obtained, a candidate point that is not matched by map matching on the road is selected as a display candidate point (hereinafter, this candidate point is referred to as a “free state candidate point”). (Step 305), if selected, variables n and i are initialized to 0 in step 307.TheIn step 325, the display candidate point data is output and the process ends.
[0069]
In addition, this time, the display candidate point selected by the map matching process 304 is selected as the previous display candidate point.Matching stateIf it is not a candidate point born from the candidate point (step 306), variables n and i are initialized to 0 in step 307.TheIn step 325, the display candidate point data is output and the process ends.
[0070]
On the other hand, in other cases, when the road vehicle heading difference θn has not reached six, the heading difference between the vehicle heading θcar and the road where the display candidate point exists is sequentially stored in θ0 to θ5 as the road car heading difference. (Steps 330, 332, and 334).Further, until six road vehicle orientation differences θn are accumulated, the parameter θ representing the difference between the past five road vehicle orientation differences θ0 to θ4 and the current road vehicle orientation difference θ5 is maintained at 0.In step 325, the display candidate point data is output and the process ends.
[0071]
However, the accumulated θn value is used when a candidate point in a free state is obtained as a display candidate point in the map matching process 304 or when a candidate point generated from the previous display candidate point is not selected. All of n and i are cleared to 0 in step 307.
[0072]
Next, if six road vehicle heading differences θn are accumulated, the step309, 311, 313 deletes θ 0 out of the six vehicle orientations θ 0 to θ 5 accumulated at that time and sets θ 1 to θ 5 as oneZThen, θ1 to θ5 are set as new θ0 to θ4, the current vehicle direction θcar is taken in, the current road vehicle direction difference is obtained, and this is set as new θ5 (step 315). Then, in step 317, the average value θave of the five previous road vehicle heading differences (θ0 to θ5) is obtained, and step 319 is the current road car heading difference θ5 and the road car heading difference obtained in step 317. The difference θ between the average values of the two is obtained.
[0073]
In the departure determination process (step 323), it is determined whether or not the vehicle has traveled on a road that is not on the map. If the vehicle travels, a process for changing display candidate points is performed.
[0074]
FIG. 11 shows a processing procedure of this deviation determination processing.
[0075]
In this process, the current road vehicle heading difference θ5 is larger than a predetermined threshold θth1 (step 1101), and the current road vehicle heading difference θ5 varies with respect to the average of five past road vehicle heading differences θave. When θ is larger than a predetermined threshold θth2 (step 1102), it is determined that the vehicle has traveled on a road that is not on the map. However, θth1> θth2.
[0076]
When it is determined that the vehicle is not traveling on a road that is not on the map, the process ends without performing other processes so as to maintain the display candidate points obtained by the map matching process.
[0077]
On the other hand, if it can be determined that the vehicle has traveled on a road that is not on the map, the virtual current position (A) obtained from the previous display candidate is not generated as a candidate point in the free state. In this case, it is generated as a candidate point in a free state.
[0078]
Then, the candidate point in the free state at the virtual current position (A) obtained from the previous display candidate point is set as the current display candidate point. Further, the accumulated error cost es of the candidate point in the free state is set to the same value as the accumulated error cost es of the previous display candidate point, and the reliability trst is obtained again as described above. A value (a value such that the reliability of this display candidate point is higher than that of other candidate points) is added, and this is set as the reliability of this candidate point.
[0079]
And about this display candidate point, the state flag which shows whether it is a matching state or a free state, and the accumulation error cost es are memorize | stored in the predetermined area | region of RAM, and a process is complete | finished.
[0080]
When such departure determination processing 323 is completed, in step 325, display candidate point data that has been changed or not changed by the departure determination processing 323 is output, and the processing of FIG.
[0081]
As a result of the above processing, the road vehicle heading difference is turned to the road of the vehicle (the variation θ of the current road vehicle heading difference θ5 in step 1102 with respect to the average θave of the past five road vehicle heading differences is a predetermined threshold value θth2. If the current road vehicle heading difference θ5 caused by (when larger) becomes larger than the predetermined threshold θth1 (step 1101), that is, the driver turns the vehicle with respect to the road heading on the map. In this case, it can be estimated that the vehicle has traveled on a road not on the map.
[0082]
In other words, since a turn with respect to the road direction is a condition, if an offset value is added to the sensor output due to an error in the road direction on the road map or the magnetization of the vehicle body, the vehicle is accidentally placed on a road that is not on the map. It is not determined that it has progressed. In addition, since the difference between the direction of the road and the vehicle is a condition, even if a turn with respect to the road direction is performed simply by meandering, it may be erroneously determined that the vehicle has traveled on a road that is not on the map. There is no. In particular, since the determination condition is set so as to satisfy θth1> θth2, a typical case that occurs when traveling to a branched road (traveling to a road that is not on the road map where the road branches on the road map). It is possible to satisfactorily determine the situation, that is, the situation in which the turn of the other relatively small road (the road that did not travel) continues and the direction of the vehicle changes to a direction that is relatively different from the other road direction.
[0083]
In this case, the current position can be calculated not at the position obtained by map matching but at the position according to the behavior of the vehicle obtained from various sensors.
[0084]
In the next calculation of the display candidate points, if the vehicle is traveling on a road that is not actually on the map, the difference between the vehicle direction and the road direction of the road on the map is also the distance from the virtual present (A). The candidate point of the matching state on the road that is larger and is born next time from the current display candidate point is not calculated as the display candidate point, and the free state candidate point that is born next time from the current display candidate point is again displayed as a display candidate. You can expect to be chosen as a point. In addition, since the above-described bias is added to the reliability of the candidate points generated from the display candidate points changed in the deviation determination process 323, the deviation determination process 323 changes the next display candidate point calculation. The display candidate point returns to the candidate point of the candidate point series previously obtained by the map matching process (the reliability will decrease if the vehicle is traveling on a road that is not really on the map). There is little possibility.
[0085]
In the above process, the start of the process of FIG. 3 is suppressed until the vehicle ends the turn from the beginning of the turn, and when the turn is completed, the start of the process of FIG. It may be determined whether the vehicle has traveled on a road that is not on the map when the turn is completed.
[0086]
Hereinafter, the remaining display process for explaining the process of displaying the current position on the display based on the display candidate points obtained by the process of FIG. 3 will be described.
[0087]
FIG. 12 shows a processing procedure for display processing.
[0088]
This process is a routine of the microprocessor 24 that is activated and executed every second.
[0089]
In this process, first, it is determined whether or not the switch 14 has been 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).
[0090]
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) and the current position (B)The map including the map is read (step 1803), and a map with a scale corresponding to the contents of the scale flag switched at step 1802 is displayed on the display 17 in a state as shown in FIG. 2 (step 1804).
[0091]
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. 2 as described above (step 1805). 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).
[0092]
According to the operation as described above, when the vehicle travels on the road a that is not on the map, the vehicle travels for a while on the road b on the map on which the vehicle is not traveling as shown in FIG. 13A. And after that, according to the reliability mentioned above, it prevents the occurrence of strange display such as being displayed so that the current position suddenly moves to any position off this road, As shown in FIG. 13B, the position corresponding to the road a can be displayed as if the vehicle is traveling from the time when the vehicle enters the road a that is not on the map.
[0093]
【The invention's effect】
As described above, according to the present invention, it is correctly estimated whether or not the vehicle has traveled on a newly created road that is not on the road map, and it is estimated that the vehicle has traveled on the newly created road. In this case, it is possible to provide a current position calculation device capable of suppressing the position on the road calculated by map matching from being selected as the current position.
[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 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 a road search process for candidate points in a matching state.
FIG. 5 is a diagram for explaining a road expression format on a road map;
FIG. 6 is a diagram for explaining a link corresponding to a road, a virtual current position, and candidate points;
FIG. 7 is a diagram for explaining a link, a virtual current position, and a candidate point corresponding to a road.
FIG. 8 is a diagram for explaining a link, a virtual current position, and a candidate point corresponding to a road.
FIG. 9 is a diagram for explaining a link corresponding to a road, a virtual current position, and candidate points;
FIG. 10 is a flowchart of a process procedure of a road search process for candidate points in a free state;
FIG. 11 is a flowchart illustrating a processing procedure of departure determination processing for calculating display candidate points;
FIG. 12 is a flowchart illustrating a processing procedure of a current position display process.
FIG. 13 is a diagram showing how the current position is displayed by the process of the current position display process.
[Explanation of symbols]
10 Current position calculation device
11 Angular velocity sensor
12 Direction sensor
13 Vehicle speed sensor
14 switch
15 CD-ROM
16 CD-ROM reader
17 Display
18 Controller

Claims (3)

A current position calculation device that is mounted on a vehicle and calculates a current position of the vehicle,
An azimuth detecting means for detecting a headed direction of the vehicle,
Distance calculation means for calculating a travel distance of the vehicle,
Storage means for storing a road map in advance ;
The current position of the vehicle previously obtained, and the virtual current position calculation means for calculating a virtual current position of the vehicle by adding the relative displacement of the vehicle which is obtained the headed direction and the travel distance or al,
Wherein said virtual current position calculating means and the virtual current calculated position, by collating the said road map said memory means has stored, sequentially, the most probable current position as a position where the vehicle is present Current position estimation means for estimating on a road included in the road map ;
And heading of the vehicle in which the direction detection unit detects the azimuth difference detecting means for detecting a difference between road and vehicle directions is the azimuthal difference between the orientation of the road including the current position of the vehicle current position estimating means has estimated When,
Each of the calculation of the virtual current position by the virtual current position calculation means, the estimation of the most probable current position by the virtual current position estimation means, and the detection of the road vehicle direction difference by the direction difference detection means are repeatedly executed. Control means for causing
An average heading difference calculating means for calculating an average heading difference by averaging the latest predetermined number of the road vehicle heading differences;
An azimuth difference fluctuation calculating means for calculating an azimuth difference fluctuation that is an azimuth difference between the road vehicle azimuth difference detected last by the azimuth difference detection means and the average azimuth difference calculated by the average azimuth difference calculation means;
The latest road vehicle azimuth difference detected by the azimuth difference detection means is greater than a first threshold azimuth difference, and the azimuth difference fluctuation calculated by the azimuth difference fluctuation calculation means is the first threshold azimuth difference. The virtual current position calculated by the virtual current position calculation means is used for the vehicle regardless of the position where the road included in the road map is to be displayed when the difference is larger than the second threshold direction difference that is smaller than Current position calculation means for calculating the current position of
Current position calculating device, characterized in that it comprises a.   The current position calculation device according to claim 1,
  The current position calculating means includes
  The latest road vehicle orientation difference detected by the orientation difference detection means is smaller than the first threshold orientation difference, or the orientation difference calculated by the orientation difference variation calculation means is the second threshold orientation difference. A current position calculation device that calculates the most likely current position estimated on the road included in the road map by the virtual current position estimation unit as the current position of the vehicle.   A current position calculation device that is mounted on a vehicle and calculates a 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;
  The virtual 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 virtual current position is read from the road map. A candidate point calculating means for calculating, as a new candidate point, a position on the road where the vehicle may exist, obtained by collating with the road map
  When an arbitrary candidate point and a candidate point calculated based on the candidate point are set as candidate points of the same system, a new map obtained by comparing the virtual current position with a road map read from the road map Candidate point reliability is calculated based on the correlation between the virtual current position and the road where the new candidate point exists, and the correlation between the candidate points of the same system as the new candidate point obtained in the past And said The reliability of a new candidate point that is the virtual current position, the degree of correlation of a predetermined value given to the new candidate point, and the degree of correlation between candidate points of the same system as the new candidate point obtained in the past Reliability calculation means for calculating based on the results of
  Among the calculated new candidate points, means for calculating the most reliable candidate point as the current position,
  If the candidate point with the highest reliability is a position on the road, whether the vehicle turned with respect to the road based on the direction of travel of the vehicle and the direction of the road where the candidate point with the highest reliability is located Means to determine whether or not
With
  The current position calculation device is a case where it is determined that the vehicle has turned, and the azimuth difference between the traveling direction of the vehicle and the road where the candidate point with the highest reliability is greater than or equal to a predetermined value. In place of the candidate point with the highest reliability, the candidate of the virtual current position calculated from the current position obtained last time is estimated as the current position, and the candidate calculated from the candidate point estimated as the previous current position About the reliability of a point, the present position calculation apparatus characterized by correcting the said reliability to a higher value.

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