JPH08334357A - Present location calculating device - Google Patents

Abstract

PURPOSE: To quickly calculate the present location of a vehicle along a road after the vehicle makes a U-turn. CONSTITUTION: A microprocessor 214 selects the locations obtained by matching the locations found by moving the candidate points decided last time by the traveling distance of its own vehicle to a road in accordance with a prescribed standard and other locations which are not matched to the road as candidate points and calculates the present location of its own vehicle, based on the reliability of each candidate point. When the vehicle makes a U-turn, the microprocessor 214 sets the reliability of the candidate points which are not matched to the road at a lower level while the vehicle travels a prescribed distance so that the location of the vehicle along the road can be calculated quickly as the present location of the vehicle. The reliability of each candidate point is determined, based on the correlation between the candidate point and the road and the reliability of the candidate point from which the candidate point is generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mounted on a moving body such as a vehicle and measures the traveling distance and traveling direction of the moving body.
Accordingly, the present invention relates to a current position calculation device that calculates the current position of the moving body.

[0002]

2. Description of the Related Art In a conventional current position calculating device for calculating the current position of a vehicle traveling on a road, the current position of the vehicle is the traveling direction of the vehicle measured by a direction sensor such as a gyro and a vehicle speed sensor or a distance sensor. It is calculated based on the traveling distance of the vehicle measured by.

The traveling distance of the vehicle is generally measured by measuring the output shaft of the transmission or the rotation speed of the tire, and the distance is a distance that the vehicle travels per rotation of the tire. It is calculated by multiplying by.

Further, as described in Japanese Patent Application Laid-Open No. 63-148115, within a predetermined range centered on the provisional current position of the vehicle, which is determined based on the present position obtained last time, the traveling distance of the vehicle and the amount of change in direction. By extracting the road from the road map and correcting the current position on the road with the highest correlation based on the correlation between the temporary current position and each extracted road, the error of the current position obtained from the traveling direction and traveling distance of the vehicle There is known a technique for correcting the. Further, as such a correlation between the provisional current position and the road, the distance between the provisional current position and the road, the heading difference of the vehicle and the heading difference of the road are often used.

According to the so-called map matching technique, in which the obtained current position of the vehicle is corrected so as to match the road, the accuracy of the current position calculation can be improved.

[0006]

By the way, a plurality of systems for calculating a position which is a candidate for the current position by the map matching technique are provided with reference to a plurality of different candidate points which may be the current position. , It is expected that the current position can be calculated better by considering the candidate points calculated by each system as the candidate points calculated from the more reliable candidate point positions, which are considered to have higher reliability. it can. This is because the position evaluated as the current position becomes more diverse and the past history can also be evaluated.

Here, in the case of calculating the candidate points in each system in this way, if there is no road having a high correlation with the provisional current position, the position on the road obtained by the map matching technique is determined. Alternatively, it is not appropriate to calculate only the position as a candidate point, and it is considered appropriate to estimate the provisional current position itself as a candidate point. Further, in this case, if the past history is not evaluated, the position on the road whose correlation with the provisional current position obtained as a candidate point by the map matching is higher than a predetermined reference is determined by the road map. Since the good result was obtained in the evaluation, the reliability of the candidate point as the current position is higher than the reliability of the candidate point which is the provisional current position where such evaluation has not been performed. I can think.

Further, in the above-described map matching technique, it is conceivable that the direction of the road is determined based on the traveling direction of the vehicle in order to reduce the amount of processing and to obtain the better current position. . That is, the direction of the road is set to the direction in which the vehicle can travel when the vehicle advances without U-turning, out of the two directions in the opposite direction that the road can take, or in the opposite direction that the road can take. Of the two azimuths, the azimuth closer to the vehicle may be used as the azimuth of the road to obtain the above-described correlation between the temporary current position and the road.

However, in this way, the vehicle is
If the vehicle is turned on, the correlation between the heading of the vehicle and the heading of the road will be significantly different and the correlation will be low. Therefore, the current position of the vehicle is calculated as the position on the road that was traveling before the U-turn. In many cases it does not fit. Also, in the U-turn process, the heading difference between the road and the vehicle becomes large, and the current position of the vehicle may not be obtained as the position on the road that was traveling before the U-turn. .

Further, in such a case, in the relationship of the reliability described above, the provisional current position is continuously calculated as the current position for a while, and the current position cannot be returned to the traveling road. Sometimes.

In such a case, the current position, which has lost sight of the current position, is displayed even though the driver has just returned to the road on which he / she has traveled until then. The position will be displayed.

Therefore, the present invention provides a present position calculating device capable of promptly calculating the present position on the road on which the vehicle is traveling even when the vehicle makes a U-turn. To aim.

[0013]

In order to achieve the above object, the present invention is a current position calculating device mounted on a vehicle for calculating the current position of the vehicle, and an azimuth detecting means for detecting a traveling azimuth of the vehicle. A distance calculation means for calculating the travel distance of the vehicle, a storage means for storing a road map, a means for determining whether or not the vehicle has turned a predetermined angle or more based on the traveling direction of the vehicle, and a previous vehicle exists. A temporary current position obtained by adding the relative displacement of the vehicle obtained from the traveling direction and the traveled distance to the candidate point of the vehicle obtained as a possible position, and the road map read from the temporary current position and the road map. And a position on the road having a degree of correlation with the provisional current position and the traveling direction of the vehicle, which is obtained by collating the traveling direction with the traveling direction, as a new candidate point. And any When the complementary points and the candidate points calculated based on the candidate points are the candidate points of the same system, new candidate points obtained by collating the temporary current position with the road map read from the road map. Reliability of the new candidate point is calculated based on the correlation degree between the road where the new candidate point exists and the corresponding virtual current position and the correlation degree of the candidate point of the same system as the new candidate point obtained in the past. Then, the reliability of the new candidate point which is the provisional current position, the correlation degree of a predetermined value given to the new candidate point, and the candidate point of the same system as the new candidate point obtained in the past Of the new candidate points calculated based on the actual result of the correlation degree, and a means for calculating the candidate point having the highest reliability among the calculated new candidate points as the current position. If the vehicle turns more than a certain angle, While traveling a fixed distance, the correlation degree of the new candidate point which is the virtual current position calculated based on the candidate point calculated as the previous current position or the track record of the correlation degree of the system of the new candidate point is relatively low. Provided is a current position calculation device characterized by setting to a value.

[0014]

According to the present position calculating device of the present invention, it is determined whether or not the vehicle has made a U-turn by determining whether or not the vehicle has turned by a predetermined angle or more based on the traveling direction of the vehicle. , U-turn, it is possible to determine the correlation degree of a new candidate point which is a virtual current position calculated based on the candidate point calculated as the previous current position or the system of the new candidate point. By setting the correlation degree record to a relatively low value, the candidate points in the series of candidate points, which are virtual current positions calculated from the candidate points previously calculated as the current position, will be calculated simultaneously on the road. It is made easier to calculate the candidate point of the position of as the current position. This makes U
After that, the current position can be displayed on the road promptly.

[0015]

Embodiments of the present invention will be described below.

FIG. 1 is a block diagram showing the configuration of the present position calculating apparatus according to the embodiment of the present invention. FIG.
As shown in FIG. 1, the current position calculation device 10 includes an angular velocity sensor 11 that detects a change in traveling direction by detecting a yaw rate of the vehicle, a geomagnetic sensor 12 that detects a traveling direction of the vehicle by detecting geomagnetism, A vehicle speed sensor 13 that outputs pulses at time intervals proportional to the rotation of the output shaft of the vehicle transmission is provided.

Further, a display 17 for displaying a map around the current position and a mark indicating the current position, a switch 14 for receiving a command for switching the scale of the map displayed on the display 17 from a user (driver), and digital map data. CD-ROM 15 for storing the
A driver 16 for reading map data from the ROM 15. Further, the controller 18 for controlling the operation of each peripheral device described 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 a highway or a general road. A highway flag indicating whether or not is included.

The controller 18 includes an A / D converter 19 for converting the signal (analog) of the angular velocity sensor 11 into a digital signal, and an A / D converter 20 for converting the signal (analog) of the geomagnetic sensor 12 into a digital signal. , Vehicle speed sensor 1
A counter 26 that counts the number of pulses output from the CPU 3 every 0.1 seconds, a parallel I / O 21 that inputs whether or not the switch 14 is pressed, and a DMA (that transfers the map data read from the CD-ROM 15 ( Direct Memory Acce
ss) It has a controller 22 and a display processor 23 for displaying a map image on the display 17.

The controller 18 also has a microprocessor 24 and a memory 25. The microprocessor 24 outputs the signal of the angular velocity sensor 11 obtained through the A / D converter 19, the signal of the geomagnetic sensor 12 obtained through the A / D converter 20, and the output pulse of the vehicle speed sensor 13 counted by the counter 26. Number, whether or not the switch 14 is pressed through the parallel I / O 21, and the map data from the CD-ROM 15 obtained through the DMA controller 22 are received and processed based on those signals, The current position is calculated and displayed on the display 17 via the display processor 23. The display of the vehicle position is performed by superimposing an arrow mark or the like on the map which is already displayed on the display 17, as shown in FIG. This allows the user to know the current position of the vehicle on the map. The memory 25 is
It includes a ROM that stores a program that defines the contents of processing (described later) for realizing such operations, and a RAM that is used as a work area when the microprocessor 24 performs the processing.

The operation of the present position calculating device 10 thus configured will be described below.

First, the processing for obtaining the current position will be described.

A processing procedure of processing for accumulating the turning amount of the vehicle of FIG. 3 will be shown.

The process shown in FIG. 3 is a process which is started and executed every time the vehicle travels for 2 m, and whether the vehicle turns later while U-turning the turning amount of the vehicle while turning. This is a process required to determine whether or not.

In this process, when the vehicle is not turning (step 302), only the process of maintaining the flag flag at 0 is performed (step 306).

Further, in this process, during the period when the vehicle is turning, the fl is the first process performed during that period.
ag is set to 1 (step 304), and in the subsequent processing, processing for accumulating the difference between the current vehicle orientation θnow and the vehicle orientation θold at the previous processing in θ (step 305).

When the vehicle has finished turning (step 307), the flag is set to 2 (step 30).
8). When the flag is set to 2, FIG.
In the process of, the θ and the vehicle speed are determined.

However, in the process of FIG. 3, no process is performed while the flag is set to 2 (step 301). This is to prevent the value of the flag from changing or the value of the accumulated θ from changing before the determination of θ and the vehicle speed is executed in the processing of FIG. 11 described above. The flag set to 2 will be initialized to 0 when the determination of θ and the vehicle speed is executed in the process of FIG. 11.

That is, in this process, during the period other than the period from the end of the turn to the execution of the process performed after the end of turn in FIG. 11, the turning amount is θ during the turn, and the process is performed during the turn. The amount of turning is accumulated, and fla is recorded at the end of the turning.
Set g to 2.

Whether or not the vehicle is turning can be determined by whether or not the difference between the current vehicle azimuth and the average of the vehicle azimuths during the past predetermined distance travel is a certain value or more.

Next, FIG. 4 shows a processing procedure of the current position calculation processing performed by the microprocessor 24 to calculate the current position.

The process shown in FIG. 4 is a process which is started and executed every time the vehicle travels 20 m, and is matched at one or a plurality of positions matched by map matching on the road or at the road. This is a process in which one or a plurality of non-existing positions are obtained as one or a plurality of candidate points in which a vehicle may exist, and the most likely current position is selected as a display candidate point from among these. The display candidate point is a position displayed as the current position.

However, this processing is not executed while the vehicle is turning.

In this process, first, the traveling distance R from the execution of the previous process to the present and the current traveling direction θcar of the vehicle are read (step 401). Next, based on those values, the amount of movement of the vehicle is obtained separately in the latitude and longitude directions.

Further, the moving amount in each of these directions is added to the position of each candidate point found in the previous process, and it is estimated that the current vehicle exists for each candidate point found in the previous process. The virtual current position (A), which is the position to be set, is obtained (step 402). The candidate points are one or a plurality of positions found in steps 403 and 404 described later as positions that can be candidates for the current position in this processing, and details of how to find them will be described later.

If there is no candidate point obtained by the previous process for obtaining the candidate point of the vehicle, such as immediately after the start of the apparatus, the position set separately is used as the position of the previously obtained candidate point. Then, the virtual current position (A) is obtained.

Then, a road search process for matching with a road is executed only for the free state candidate points, which will be described later, obtained by the previous process, and one or more candidate points and their reliability trst are obtained. Required (Step 4
03). The free state candidate points refer to the candidate points that could not be matched on the road as described above, and the reliability refers to the certainty as the current position of each candidate point, the details of which will be described later. The details of the search candidate point selection process executed in step 403 will also be described later.

Next, after the search candidate point selection processing is executed, the road search processing for matching with the road is executed only for the candidate points in the matching state, which will be described later, obtained in the previous processing, and 1 Alternatively, a plurality of candidate points, their accumulated error cost, and reliability trst are obtained (step 404). The candidate point in the matching state refers to a candidate point matched on the road by map matching, and details of how to obtain it will be described later.

Next, it is determined whether the vehicle has U-turned,
Cumulative error cost es when the vehicle is U-turned
And a process for correcting the reliability trst (step 4
05). Details of this processing will be described later.

Then, 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 406), and the candidate point C having the largest reliability value C As a display candidate point CD, that is, a candidate point to be displayed on the display 17, its position, cumulative error cost es described later, reliability, a state flag indicating whether it is in the matching state or the free state, etc. Are stored in a predetermined area of the RAM of the memory 25, and 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 4
07). In this embodiment, the data related to the seven candidate points can be stored. Therefore, as a result of executing the map matching process, the number of candidate points is 8
If more than one is calculated, of these, the reliability tr
Various data related to the seven candidate points in the order of increasing value of st will be stored in a predetermined area of the RAM of the memory 25.

Finally, the coordinate data of the display candidate points are output (step 408), and the process ends.

Next, in the current position calculation process (FIG. 4), the road search process for matching the road with only the last free candidate point in step 403, and the previous matching state in step 404. The details of the road search processing for matching with the road, which is performed only with respect to the candidate points of, will be described.

First, the road search processing in step 404 will be described.

FIG. 5 shows details of the road search processing in step 404.

This processing is performed for each candidate point in the matching state obtained in the previous current position calculation processing.

In this road search processing, first, a map around the virtual current position (A) obtained corresponding to the previous candidate point of the matching state of the processing target is obtained from the CD-ROM 1
5 through the driver 16 and the DMA controller 23 (step 501).

Then, the link in which the previous candidate point in the matching state to be processed is located or the link connected to this link in front of the vehicle is selected and taken out (step 502).

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. The one expressed by the coordinates of is used. For example, the link 53 has its start point (x3,
It is represented by y3) and the end point (x4, y4).

Next, from the links extracted in step 502, the vehicle travels on the link in the two directions opposite to each other, if the vehicle continues traveling without U-turning. Only the links whose directions are within the predetermined vehicle direction and the predetermined direction are selected (step 503). Here, as mentioned above, the direction of the link is
Since the vehicle is set to the direction in which the vehicle will travel on the link when the vehicle is traveling without U-turn, the direction of the vehicle after the U-turn and the direction of the link where the vehicle was located immediately before the U-turn. The direction is almost opposite. Therefore, in this step, the link in which the vehicle was located immediately before this U-turn is not selected. Similarly, the link in which the vehicle was located immediately before the U-turn was connected to the link ahead of the vehicle in front of the U-turn in the traveling direction, and the vehicle direction after the U-turn was also significantly different. As a result, these links will not be selected either. As described above, when the link to be selected does not exist, the virtual current position (A) becomes a free state candidate point.

When a link can be selected, a vertical line is drawn from the virtual current position (A) for all the selected n extracted links, and the length of the vertical line L (n) is obtained. (Step 504). In addition, candidate points corresponding to each link are set. All of these candidate points are candidate points in a matching state matched with the road. However, at this point, the positions of the candidate points in the matching state are not yet determined.

By the way, even if it is not after the U-turn, it is the link in which the candidate point in the previous matching state to be processed, which is selected in step 503, is located or the link connected to this, It is conceivable that there is no link whose difference between the vehicle heading and the traveling direction is less than or equal to a predetermined value. In this case, the virtual current position (A) is also the next candidate point calculated from a certain candidate point. Such candidate points are also free state candidate points.

Next, for each candidate point, the error cost e
c, the cumulative error cost es, and the reliability trst are calculated (step 505).

That is, first, the error cost value ec (n) defined by the following equation is calculated for all candidate points.

Ec (n) = α × | θcar−θ (n) | +
β | L (n) | Here, θcar represents the vehicle direction at the virtual current position (A). Further, θ (n) is the azimuth 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 lengths of perpendicular lines, and α and β are It is a weighting factor. The values of these weighting factors may be changed depending on which of the deviation in the direction of travel and the direction of the road, and the deviation between the current position and the road, which is more important in selecting the road above the current position. For example, when a road whose direction is close to the traveling direction is important, α is increased.

In this error cost calculation, the error cost ec (n) for the candidate points in the free state is relatively larger than the average value of the error costs that may be given to the candidate points in the matching state. Give the value directly.

Next, the calculated error cost ec (n)
And the cumulative error cost es of the previous candidate point to be processed, the cumulative error cost es (n) of each candidate point defined by the following formula is calculated.

Es (n) = (1−k) × es + k × ec (n) Here, k is a weighting 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 this process. Then, based on the calculated cumulative error cost es (n), the reliability trst (n) defined by the following formula is calculated (step 507).

Trst (n) = 100 / (1 + es (n)) As apparent from the above equation, the accumulated error cost ec
The reliability trst increases as (n) increases.
(N) decreases and approaches 0 (zero). On the other hand, as it becomes smaller, the reliability trst (n) increases, and its value approaches 100.

By performing such processing, the candidate points on the n links that are connected to the link in which the previous candidate point to be processed exists and the direction of the link is close to the vehicle direction and the free state. The reliability degree trst (n) of the candidate point is obtained.

Then, from the previous candidate point to be processed, along the n links selected in step 503, the points advanced by the length corresponding to the distance R traveled by the vehicle are set in the link. The position of the selected candidate point is set (step 508). Therefore, if there are a plurality of links (n is a plurality) selected in step 503, a plurality of candidate points will be generated. That is, n new candidate points C (n) are generated corresponding to the n links. In other words, a plurality of new candidate points may be generated for each candidate point in the previous matching state.

An example of sequentially obtaining candidate points by the above processing is shown in FIGS.

As shown in FIG. 7, in a certain process, for a certain candidate point 62 existing on the link 61,
It is assumed that the virtual current position (A) is represented by the position indicated by the point 63. In such a case, from the virtual current position (A),
The links 64 and 65 which are connected to the link 61 on which the candidate point 62 is located in the front direction in the vehicle direction and in which the difference between the direction and the vehicle direction is less than or equal to a predetermined value are taken out.
Distance L from current position A to links 64 and 65
(1) and L (2) are calculated, and the calculated distance,
Based on the angles θ (1) and θ (2) of the links 64 and 65, the vehicle direction θcar, and the like, the related error cost, accumulated error cost, and reliability are calculated. Further, based on the traveling distance R of the vehicle previously obtained, the position advanced from the certain candidate point 62 along the links 61 and 64 or the links 61 and 65 by the length corresponding to the traveling distance R is calculated. Then, the points corresponding to this position are set as candidate points 6
6, 67.

In the next processing, as shown in FIG. 8, the new virtual current position (A) is displayed at the position indicated by the point 71 with respect to the candidate point 66 on the link 64, while the link 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 on 65. In this case, from the virtual current position (A), the links 73 and 74 that are connected to the link 64 and have a difference between the azimuth and the vehicle azimuth of a predetermined value or less are taken out, and a new link is created. Link 65 from the virtual current position (A ')
A link 75 connected to the vehicle is taken out such that the difference between the azimuth and the vehicle azimuth is a predetermined value or less. 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. Furthermore, the distance calculated in relation to the current position A and the angle θ1 of the links 73 and 74
Based on (1) and θ1 (2) and the vehicle direction θcar, the related error cost, accumulated error cost and reliability are calculated, and the distance calculated in relation to the current position A ′ and the angle of the link 75 are calculated. Based on θ2 (1) and the vehicle direction θcar, the related error cost, accumulated error cost, and reliability are calculated.

Further, based on the traveling distance R of the vehicle, from the candidate point 66 to the links 64 and 73 or the link 6
4 and 74, or from the candidate point 67 along the links 65 and 75, the position advanced by the length corresponding to the mileage R of the vehicle is calculated, and the point corresponding to this position is calculated, respectively. It will be a new candidate point. FIG. 9 shows the candidate points 81 to 83 newly obtained in this way.

Next, the details of the road search processing for matching the road only with respect to the later-described free state candidate points obtained in the previous current position calculation processing of step 403 of FIG. 4 will be described.

FIG. 10 shows a processing procedure of road search processing for the previous candidate point in this free state.

This process is performed for each of the free-state candidate points obtained in the previous map matching process.

As shown, this process is similar to the road search process for candidate points in the matching state shown in FIG.

The difference between these two processes is that, in the road search process, the link at which the candidate point obtained in the previous process for obtaining the candidate point of the vehicle is located or the link connected to this is extracted, From the links, a link whose orientation difference from the sensor orientation is within a predetermined value is selected (steps 502 and 503 in FIG. 5), while in the candidate point road search process in the free state, the virtual current position (A ) Is extracted as a center and all links within a 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).

That is, steps 502 and 503 in FIG.
In the processing of (1), a single link or several links extending from the branch point may be extracted, but in the processing of step 1202 of FIG. 12, road data in the map corresponding to the read map data. From this, the links to be extracted are determined.

In the road search process for the candidate points in the free state, the azimuth and the traveling direction of the vehicle are within a predetermined range D from the virtual current position (A) for the previous candidate point in the free state to be processed. If there is a link whose difference is less than or equal to a predetermined value, the intersection of the perpendicular line drawn from the virtual current position to the link and this link becomes a candidate point for a new matching state. In addition, the virtual current position (A) with respect to the previous candidate point in the free state to be processed is also free.
It becomes a candidate point for the state.

If there is no link whose difference between the heading and the traveling heading of the vehicle is a predetermined value or less within the predetermined range D from the virtual current position (A) for the candidate point in the free state, the virtual current Only points corresponding to positions are free state candidate points.

By the above processing, from the free state candidates generated immediately after the U-turn, generally, the free state candidates which are the virtual current position (A) obtained by using the candidates as reference points. The point and the virtual current position (A) are generated as a candidate point in a matching state on the link before the U-turn or on the link connected to the link in front of the vehicle after the U-turn in the traveling direction. It will be.

Error cost ec of each candidate point, cumulative error
The method for obtaining the cost es and the reliability trst is exactly the same as that described above in the road search processing for the candidate points in the matching state.

The current position calculation process has been described above.

Next, the process of correcting the accumulated error cost and reliability in step 405 of FIG. 4 will be described.

The processing procedure of this processing is shown in FIG. In this process, the vehicle is U-turned for a predetermined distance lth,
The cumulative error cost es of the free state candidate points generated from the previous display candidates is corrected to a larger value, and the reliability tr
A process of recalculating st is performed.

In this process, first, the flag is 2
It is determined whether or not the turning end time is reached (step 1101). If the turning end time is reached, it is determined whether or not there is a free state candidate point generated from the display candidate points (step 1102). , And, if present, further in FIG.
The turning amount θ accumulated in the processing of step 110 is checked (step 110
3), this is the amount that the vehicle can be considered to have turned (160)
More than 200 degrees and less than 200 degrees) and the current vehicle speed is 30k
If m or more, it is considered that the vehicle has U-turned, and fla
g and θ are initialized to 0, the parameter esl is set to 1 (step 1104), and the cumulative error cost es of the free-state candidate points generated based on the candidate points selected as the previously displayed candidate points is set. Is corrected to a large value, and the reliability trst is recalculated based on this value (step 1105).
Now, after being set to l, esl is updated to a value obtained by successively subtracting the travel distance. That is, esl is updated to represent the travel distance after being set to l.

Here, only when the vehicle speed is 30 km / hour or more, it is considered that the vehicle has made a U-turn. At the end of the turn, if the vehicle speed is less than 30 km / h, the turn is made by the U-turn. Instead, since it is considered to be a turn in a parking lot, a free state candidate point that occurs in the parking lot due to the lower reliability due to the processing in (step) 1105 described later becomes difficult to be calculated as a display candidate point. This is to prevent

Even when the flag is 2 and the turning is completed, if there is no free-state candidate point generated based on the candidate point previously selected as the display candidate point (step 1102), If it cannot be considered that U-turned, the flags, θ, and esl are initialized to 0, and the processing ends.

On the other hand, even if the flag is not 2, if esl is larger than 0 and there is a free-state candidate point generated based on the candidate point selected as the previous display candidate point. Since the vehicle has not traveled a certain distance since the turning end, (step 1105) is also executed to correct the accumulated error cost es and the reliability trst. If there is no free-state candidate point generated based on the candidate point previously selected as the display candidate point, e
The sl is initialized to 0 and the processing is terminated.

By the above-mentioned processing, when the candidate point in the free state continues to be generated from the previously displayed candidate point after the turning is completed while the vehicle is traveling the distance l after the turning is completed, the reliability of the candidate point in the free state. Since trst is held down to a low value, it becomes difficult to select it as a display candidate point. The cumulative error
The cost es may be corrected, for example, by adding a value according to the value of esl at that time to sequentially reduce the correction amount.

According to the above-described processing, as shown in FIG. 12, the accumulated error cost es of the free-state candidate points 100 generated from the previous display candidate point 0 immediately after the vehicle U-turns is normally set. Correct to a larger value. Therefore, the candidate points 200 in the matching state that occur simultaneously are easier to be selected as the display candidate points than the candidate points in the free state.

Further, from this free state candidate point 100 to the free state candidate point 110 and the matching state candidate point 1
20 are born, and free state candidate points 110 are born to free state candidate points 111, and matching state candidate points 1
When the matching state candidate point 121 is generated from 20, the reliability of the free state candidate point is cumulatively lowered while the free state candidate point is continuously selected as the display candidate point. Will be fixed.

Accordingly, the candidate points 20 in the matching state that are matched as the display candidate points on the road more promptly.
0, 201 will be selected. For example, candidate point 1
11 and the candidate point 211, the reliability of the candidate point 111 is affected by the correction of the accumulated error cost performed at the candidate point 100, the candidate point 110, and the candidate point 111. Since it is only affected by the correction of the accumulated error cost performed at the candidate point 100, it can be expected to have a higher reliability.

Hereinafter, the remaining display processing for explaining the processing of displaying the current position on the display based on the display candidate points obtained by the current position calculation processing of FIG. 4 will be described.

FIG. 13 shows the processing procedure of the display processing.

This processing is a routine of the microprocessor 24 which is activated and executed every one second.

In this process, first, it is judged whether the switch 14 is instructed to change the scale of the map by pressing the switch 14 by looking at the contents of the parallel I / O 21 (step 180).
1). If it is pressed (Yes in step 1801)
s), correspondingly, a predetermined scale flag is set (step 1802).

Next, the coordinates obtained by adding the movement amount of the vehicle after the coordinates of the display candidate point obtained from the azimuth and the traveling distance obtained from the sensor are added to the coordinates of the display candidate point obtained most recently. A map including the current position (B) and the current position (B) is read (step 1803), and a map having a scale according to the content of the scale flag switched in step 1802 is displayed on the display 17, for example, in FIG. It is displayed in the state as shown (step 1804).

Then, the current position (B) is superimposed on the map.
And the current vehicle direction θcar are displayed using the arrow symbol “↑” as shown in FIG. 2 (step 1805). Finally, the north mark indicating north and the distance mark corresponding to the reduced scale are displayed in a superposed manner as shown in FIG. 2 (step 1806).

[0091]

As described above, according to the present invention, even if the vehicle makes a U-turn, the current position can be promptly calculated on the road on which the vehicle is traveling. A calculation device can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a current position calculation device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a display example of a map and a current position according to the present embodiment.

FIG. 3 is a flowchart showing a processing procedure of processing for calculating a current position.

FIG. 4 is a flowchart showing a processing procedure of road search processing for candidate points in a matching state.

FIG. 5 is a diagram for explaining an expression format of roads on a road map.

FIG. 6 is a diagram for explaining a line segment corresponding to a road, a virtual current position, and a candidate point.

FIG. 7 is a diagram for explaining a line segment corresponding to a road, a virtual current position, and a candidate point.

FIG. 8 is a diagram for explaining a line segment corresponding to a road, a virtual current position, and a candidate point.

FIG. 9 is a diagram for explaining a line segment corresponding to a road, a virtual current position, and a candidate point.

FIG. 10 is a flowchart showing a processing procedure of road search processing for a candidate point in a free state.

FIG. 11 is a flowchart showing a processing procedure of processing for calculating an error cost.

FIG. 12 is a diagram for explaining what kind of candidate points are selected as display candidates after U-turn.

FIG. 13 is a flowchart showing a processing procedure of current position display processing.

[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 Read Driver 17 Display 18 Controller

Claims (3)

[Claims] 1. A current position calculating device mounted on a vehicle for calculating a current position of the vehicle, comprising: an azimuth detecting means for detecting a traveling azimuth of the vehicle; and a distance calculating means for calculating a traveling distance of the vehicle. A storage means that stores a road map, a means that determines whether or not the vehicle has turned a predetermined angle or more based on the traveling direction of the vehicle, and a candidate point of the vehicle that was previously determined as a position where the vehicle may exist. , A provisional current position obtained by adding the relative displacement of the vehicle obtained from the traveling direction and the traveling distance, a road map read from the provisional current position and the road map, and the traveling direction are obtained by collation, Candidate point calculation means for calculating, as new candidate points, the provisional current position and the traveling direction of the vehicle and the position on the road having a degree of correlation equal to or more than a predetermined reference value, and an arbitrary candidate point and calculation based on the candidate point The symptom When the points are the candidate points of the same system, the reliability of the new candidate point obtained by collating the temporary current position with the road map read from the road map is the existence of the new candidate point. Calculated based on the correlation degree between the road and the corresponding virtual current position and the correlation degree of the candidate points of the same system as the new candidate point obtained in the past, and the new candidate point that is the temporary current position. Reliability calculation of the reliability of the new candidate point based on the correlation value of a predetermined value given to the new candidate point and the past correlation coefficient of the candidate points of the same system as the new candidate point obtained in the past. And a means for calculating the candidate point with the highest reliability among the calculated new candidate points as the current position, wherein the reliability calculation means turns when the vehicle turns a predetermined angle or more. While the vehicle is traveling for a predetermined distance after the end, The present invention characterized by setting the correlation degree of a new candidate point that is a virtual current position calculated based on the calculated candidate point or the actual value of the correlation degree of the system of the new candidate point to a relatively low value. Position calculation device. 2. A current position calculating device which is mounted on a vehicle and calculates a current position of the vehicle, the direction detecting means detecting a traveling direction of the vehicle, and a distance calculating means calculating a traveling distance of the vehicle. A storage means that stores a road map, a means that determines whether or not the vehicle has turned a predetermined angle or more based on the traveling direction of the vehicle, and a vehicle candidate that has been sequentially obtained as a position where the vehicle may previously exist. At the point, the temporary current position obtained by adding the relative displacement of the vehicle obtained from the traveling direction and the traveled distance, the road map read from the road map and the traveling direction are collated, and the temporary current position and the traveling direction are compared. When a position on the road having a degree of correlation greater than or equal to a predetermined reference value 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 vehicle may exist last time is Last time The virtual current position is a new candidate when the position on the road having a degree of correlation greater than or equal to a predetermined reference value with the temporary current position and traveling direction is not obtained. If a candidate point and a candidate point calculated based on the candidate point are defined as a candidate point of the same system, the provisional current position is obtained by collating the road map read from the road map. The reliability of the new candidate point is the correlation between the road on which the new candidate point exists and the corresponding provisional current position, and the correlation of the candidate points of the same system as the new candidate point obtained in the past. The reliability of the new candidate point, which is the provisional current position, is calculated based on the actual performance of the degree, and the correlation between the predetermined value given to the new candidate point and the new candidate obtained in the past. Calculated based on the actual results of the correlation of candidate points in the same system as the points The reliability calculation means has a means for calculating the candidate position with the highest reliability among the calculated new candidate points as the current position, and the reliability calculation means is provided when the vehicle turns a predetermined angle or more. In addition, while the vehicle travels for a predetermined distance after the turning ends, the correlation degree of the new candidate point that is the virtual current position calculated based on the candidate point calculated as the previous current position or the correlation of the system of the new candidate point. A current position calculation device characterized by setting a track record of degrees to a relatively low value. 3. The current position calculation device according to claim 1, wherein the distance calculation means for calculating a traveling speed of the vehicle, and the reliability calculation means are configured such that the vehicle has a predetermined traveling speed equal to or higher than a predetermined speed. Only when the vehicle turns more than a corner, while the vehicle travels a predetermined distance after the turn ends, the correlation degree of the new candidate point which is the virtual current position calculated based on the candidate point calculated as the previous current position or the new candidate. A current position calculation device, characterized in that the track record of the degree of correlation of the point system is set to a relatively low value.