JPH0833302B2 - Position detection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting device, and more particularly to a position detecting device for detecting the position of a vehicle traveling at an arbitrary point in a road traffic network. .

<Prior Art> Conventionally, as a method of detecting the position of a vehicle traveling at an arbitrary point of a road traffic network, a distance sensor, an azimuth sensor, and a process of performing necessary processing on output signals from both sensors. A dead reckoning method is proposed, which includes a device and obtains current position data of a vehicle while accumulating an amount of change in distance and an amount of change in heading caused by traveling of the vehicle. There is a problem that the error that the azimuth sensor necessarily has is accumulated as the running continues, and the error included in the obtained current position data is also accumulated.

In consideration of such problems and on the premise that the vehicle travels on the road, the current position data obtained based on the dead reckoning is compared with the road traffic network data stored in advance in the memory. However, a map matching method is proposed in which the amount of deviation of the current position data from the road is calculated as a cumulative error, and the cumulative error is corrected for the current position data to match the current position data with the road data. (U.S. Pat. No. 3,789,198, JP-A-5
8-99715, JP-A-58-113711, and "LA
NDFALL A HIGH-RESOLUTION AUTOMATIC VEHICLE-LOCAT
ION SYSTEM ", D.KING, GEC Journal of Science & Technol
See ogy, Vol.45, No.1,1978).

Specifically, in the position detection method described in U.S. Pat.No. 3,789,198, based on the traveling distance data of the vehicle obtained by the distance sensor and the traveling direction data of the vehicle obtained by the azimuth sensor. Calculate the current position data of the vehicle,
The calculated current position data is compared with the road position data stored in the memory in advance, and if the difference between the two data is within a predetermined threshold, the current position data is corrected so that it is located on the closest road. On the contrary, when the difference between the two data is equal to or larger than the predetermined threshold value, no correction is performed at all, and the correction is performed with high accuracy as a whole to display the accurate current position.

In the position detection method described in JP-A-58-99715, the current position data is updated by calculating the distance change amount component in the coordinate axis direction of the road map every time the vehicle travels a predetermined distance, and the current position data is When the vehicle is deviated from the road, the position data on the nearest road is simply used as the current position data to accurately display the current position.

In the position detection method described in Japanese Patent Laid-Open No. 58-113711, the error of the direction sensor that detects the traveling direction based on the geomagnetism is compared with the curvature obtained based on the traveling direction and the curvature of the road. By doing so, it is attempting to make an accurate display of the current position.

LANDFALL A HIGH-RESOLUTION AUTOMATIC VEHICLE
-In the position detection method described in LOCATION SYSTEM, the road traffic network is grasped as a non-branching portion and a plurality of typical branching portions, and one of the branching portions travels toward the other branching portion. In the case where the vehicle is traveling, the distance to the other branch is calculated based on the signal from the distance sensor, and if it is determined that the vehicle has reached the branch, the change in the traveling direction thereafter is detected by the direction sensor. Thus, the current position of the vehicle is accurately displayed as a position on the road by determining which branch exit the vehicle is heading for.

<Problems to be Solved by the Invention> In any of the position detection methods described above, when the road traffic network is relatively simple, it is possible to correct the increase in the accumulated error and accurately determine that the vehicle is traveling on the road. Although it is possible to display the current position on the vehicle, for example, when approaching a truck, running under an elevated road, or crossing a railroad crossing, due to the influence of the external magnetic field, the error rate is higher than that of the distance sensor. The accumulated error due to the large azimuth sensor will be included in the current position data of the vehicle as an error that is hard to recover, and if the current position data is simply corrected by matching it to the closest road, There is a problem that it may be displayed as a state in which the vehicle is traveling on a road that is completely different from the road on which the vehicle is traveling.

Further, even in a distance sensor that detects the traveling distance of a vehicle, the cumulative error may exceed an allowable marginal error due to the influence of tire air pressure and the like, and in this case also, the same as in the above case. You will have a problem.

Even if the probability of occurrence of the above problem is low, once it occurs, the vehicle position will be detected subsequently based on inaccurate current position data. There is a problem that all the detected vehicle position data becomes inaccurate, and improvement has been demanded for further improving the detection accuracy as a vehicle position detection method.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a position detection device capable of accurately detecting the current position of a vehicle without being affected by complication of a road traffic network or the like. I am trying.

<Means for Solving Problems> A position detecting device of the present invention for achieving the above-mentioned object includes a traveling distance detecting means (1), a traveling direction detecting means (2), and a road map memory (3). ) And the estimated position calculating means (4), and is present within the range of the limit error of the estimated position, which is caused by the error of the traveling distance component and the error of the traveling direction component accumulated as the vehicle travels. With respect to the road, the correlation coefficient calculating means (5) for registering the road and calculating the correlation coefficient corresponding to the road based on the error of the estimated position of the vehicle with respect to the road, and for each predetermined timing, Correlation coefficient evaluation means for comparing the correlation coefficients with each other, selecting a correlation coefficient indicating that the error for the road is the smallest, and determining the current position of the vehicle on the road corresponding to the selected correlation coefficient ( 6) with and the current position of the vehicle The correlation coefficient of the road that was not determined as the position is
When the value is out of the range of the predetermined threshold value or when a difference of a predetermined value or more is generated compared to the correlation coefficient for other roads, the correlation coefficient for the road which is not deleted is calculated as the above correlation coefficient. It is adapted to be updated by the means (5) (Claim 1).

The “correlation coefficient” may be a function of the correlation coefficient value obtained by the calculation and the correlation coefficient value calculated before that (claim 2).

When the correlation coefficient showing the smallest error and the correlation coefficient showing the second smallest error are exchanged, the correlation coefficient evaluation means (6) gives a predetermined hysteresis characteristic to the correlation coefficient. It may be selected (Claim 3).

The correlation coefficient calculating means (5) is configured to measure the traveling distance at predetermined time intervals,
Alternatively, the correlation coefficient may be calculated by obtaining the change amount of the azimuth (claim 4).

The correlation coefficient calculation means (5) calculates the travel distance for each predetermined distance,
Alternatively, the correlation coefficient may be calculated by obtaining the change amount of the azimuth (claim 5).

Further, when the vehicle is traveling in the state where only one road is registered, when the rotation angle data of the vehicle becomes a predetermined value or more, the registration of the traveling road is deleted, and the correlation coefficient calculating means. (5) may calculate a correlation coefficient for a road branching from the deleted road that exists within the margin of error (claim 6).

Further, when the vehicle is traveling in the state where only one road is registered, the registration of the traveling road is deleted when passing through the branch, and the correlation coefficient calculation means (5) A correlation coefficient may be calculated for a road branching from the deleted road existing within the range (claim 7).

<Operation> With the above position detecting device, on the road map existing within the range of the marginal error of the estimated position, which is generated as a result of the error of the traveling distance component and the error of the traveling direction component accumulating as the vehicle travels. The correlation coefficient is calculated based on the error of the estimated position of the vehicle with respect to the road, and its variation is monitored, and the correlation coefficient that shows the smallest error with respect to the road is selected and set to the selected correlation function. The position of the vehicle on the corresponding road can be output as the current position.

Then, in this case, when the correlation coefficient is out of the range of the predetermined threshold value, or when there is a difference of a predetermined value or more compared with the correlation coefficient for other roads, the corresponding correlation coefficient is deleted. Therefore, the data stored as the vehicle travels can be reduced, and the final selection of the correlation coefficient can be facilitated.

Furthermore, the correlation coefficient for roads that have not been erased is
Since the correlation coefficient calculation means updates the error, the error for other roads is relatively lower than the error for the road that has the smallest error until now even though the vehicle is not traveling. In this case, the position of the vehicle can be transferred to the other road.

Also, if a function of the past correlation coefficient and the current correlation coefficient is taken and the function value is the object of comparison, it is possible to obtain a stable magnitude without being affected by the local correlation magnitude relationship. The correlation coefficient can be selected based on the relationship, and the position of the vehicle with respect to the road corresponding to the selected correlation coefficient can be output.

Further, if the correlation coefficient showing the smallest error and the correlation coefficient showing the second smallest error are exchanged, if the correlation coefficient is selected with a predetermined hysteresis characteristic, the It is possible to select a correlation coefficient based on a stable magnitude relationship and to output the position corresponding to the selected correlation coefficient with respect to the road as the current position without being affected by the magnitude relationship of the correlation coefficient.

In addition, when the vehicle is traveling in the state where only one road is registered, the registration of the traveling road is deleted when the rotation angle data of the vehicle exceeds a predetermined value, and the deleted road. If the correlation coefficient is calculated for the road that branches from, the road that was originally running after the turn at the intersection can be deleted, so the data saved as the vehicle runs can be reduced. It is possible to facilitate the final selection of the correlation coefficient.

In addition, when traveling with only one road registered, the registration of the traveling road is deleted when passing through the branch, and the relationship between the road branched from the deleted road is correlated. By calculating the number, it is possible to delete the road that was originally running after passing the intersection, so it is possible to reduce the data saved as the vehicle runs, and to determine the final correlation coefficient. Selection can be facilitated.

<Example> Hereinafter, an example will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an embodiment of the position detecting device of the present invention. The position detecting device comprises a traveling distance detecting portion (1), a traveling direction detecting portion (2), and a road traffic network within a predetermined range. Road map memory (3) that stores in advance, traveling distance detection signals, traveling direction detection signals output from both detection units (1) and (2), and map data stored in the road map memory (3) , And an estimated position calculation unit (4) for calculating an estimated position by inputting evaluation data output from a correlation coefficient evaluation unit (6) described later, and the road map memory (3).
A correlation coefficient calculation unit (5) that calculates the correlation coefficient by inputting the map data stored in the above and the position data output from the estimated position calculation unit (4), and the correlation coefficient calculation unit (5) The correlation coefficient evaluation unit (6) which receives the correlation coefficient calculated by the above and evaluates the magnitude relationship of the correlation coefficient and outputs the current position.

More specifically, the traveling distance detection unit (1)
Has, for example, a photoelectric switch that detects the rotation of the wheel, obtains the number of rotations of the wheel by counting the number of output pulse signals from the photoelectric switch with a counter, and for the count data output from the counter, A so-called wheel speed sensor may be used to calculate the travel distance per unit time by multiplying a predetermined constant indicating the outer circumference of the wheel by a multiplier, but the travel speed of the vehicle can be calculated based on Doppler shift or the like. It is possible to use a conventionally known structure such as a vehicle speed sensor configured to calculate and integrate the running distance.

The traveling direction detector (2) can use a geomagnetic sensor that outputs rotation angle data per unit time by detecting, for example, a horizontal component of geomagnetism, but a gyro or the like can also be used. Examples of this gyro include a vibration gyro, an optical fiber gyro, and a differential wheel speed sensor. It is also possible to employ a combination of the geomagnetic sensor and the gyro.

The road map memory (3) previously stores road map data over a predetermined range (combined data of points and lines indicating directions of roads, distances between branch portions, etc.), and semiconductor memory, Cassette tapes, CD-ROMs, etc. can be used.

The estimated position calculation unit (4) calculates the distance based on the distance data Δl output from the traveling distance detection unit (1) and the rotation angle data Δθ output from the traveling direction detection unit (2). East-West component Δx (= Δl × cos
θ) and the north-south direction component Δy (= Δl × sin θ) are calculated, and the above-mentioned respective components Δx, Δy are added to the previous estimation data (Px ′, Py ′) to obtain the current estimated position data ( Px, Py) and corresponds to the above distance data for the marginal errors (including distance error, rotation angle error, and road map error) that the previous estimated position data may have By adding the increment of the marginal error, the marginal error that the current estimated position data may have is calculated. Further, a curve (including a branch) is detected based on the distance data Δl and the rotation angle data Δθ, and the estimated position data (Px, Px) among the map data read from the road map memory (3) is detected.
Roads existing within the range of the marginal error around y) are registered in a memory (not shown), and positions on all roads can be displayed on a display (not shown).

The correlation coefficient calculation unit (5) calculates the similarity between the movement of the estimated position calculated by the estimated position calculation unit (4) and the road in the road map memory (3). More specifically, the correlation coefficient changes as the vehicle travels, and the shape of the correlation coefficient is based on the distance from the estimated position of the vehicle to the road, as is known. (See Japanese Patent Application Laid-Open No. 61-56910) or based on orientation difference (Japanese Patent Application Laid-Open No. 58-113711).
(See the official gazette).

For example, if the previous correlation coefficient is γi, j and the correlation coefficient obtained by this calculation is γj, the new correlation coefficient γi + 1, j is γi + 1, j = A × γi, j + B × γj (Where j is the index indicating the registered road, A is the previous correlation coefficient, B is the weighting coefficient of the current correlation coefficient, and A = B = 0.5. Then it will be a simple average). In particular,
The correlation coefficient corresponding to the road with the smallest error with respect to the road is the largest. However, it is also possible to make the correlation coefficient corresponding to the road having the smallest error with respect to the road the smallest by changing the calculation standard of the correlation coefficient.

The correlation coefficient evaluation unit (6) evaluates the magnitude relationship between the correlation coefficients corresponding to the roads, and stores the road and the position on the road corresponding to the largest correlation coefficient as the actual position. , It will update the registration of other roads and delete them depending on the conditions. More specifically, the relationship between the correlation coefficients is evaluated at predetermined timings, the roads corresponding to the correlation coefficient smaller than the predetermined threshold are deleted, and the registration is not deleted. The correlation coefficient corresponding to the road is sequentially updated to a new correlation coefficient in the correlation coefficient calculation unit (5) thereafter, and the above evaluation is performed again. Then, by performing the above-described series of evaluation operations, only one road is finally left under the influence of road branching and the like, and the remaining position on the road continues to be displayed as the current position.

Regarding the position detecting operation by the device having the above configuration,
This will be described in detail with reference to FIGS.

First, a description will be given based on the examples of FIG. 2 and FIG.

FIG. 2 is a diagram showing a part of the road traffic network. Among a number of roads, only roads L0, L1, L2, L3 are shown, and as shown by the broken line S, the road L0 is shown. Is shown running from L1 to L1. The alternate long and short dash line T
Indicates a trajectory of an estimated position, E indicates a marginal error, a, b, c, d indicate branches or curves, and γ0, γ1, γ2, γ3 indicate correlation coefficients corresponding to each road.

Further, FIG. 3 is a diagram showing a change in the correlation coefficient γ when the vehicle travels as indicated by a broken line S in FIG.
l1, l2, ... In are shown as the correlation coefficient update times.

Therefore, while traveling on the road L0,
Until it is determined that the vehicle has entered the road L1 through the branch a (until the rotation angle data exceeds a predetermined value), only the interphase coefficient γ0 is large and the other interphase coefficients γ1, γ2, γ3 are small. (See area R1 in FIG. 3). That is, since the rotation angle data is small until passing the branch a, it is not necessary to consider the influence of other roads at all, and only the traveling distance on the road L0 needs to be taken into consideration. The position data calculated by the section (4) may be corrected so as to be the position data on the road L0. Then, the current position of the vehicle can be confirmed by displaying the position together with the road map on a display device (not shown) based on the corrected position data.

Next, when the road L1 is entered through the branch a, the correlation coefficient γ is calculated by the correlation coefficient calculation unit (5) for each road existing within the range of the limit error E (third Based on the calculated correlation coefficient (see area R2 in the figure), the correlation coefficient evaluation unit (6) evaluates. That is, which position has the highest similarity to the road is evaluated. More specifically, since the rotation angle data is equal to or larger than the predetermined value, the correlation coefficient γ0 for the road L0 can be ignored any longer, and conversely, the road for which the branch for the road L0 exists within the range of the limit error E. The correlation coefficient for L1, L2, L3 must be evaluated. In FIG. 3, the correlation coefficients γ2 and γ3 are larger than the correlation coefficient γ1 at the beginning of passing the branch a, but this is due to an error by the traveling direction detection unit (2). is there. However, regarding the correlation coefficient γ2 with respect to the road L2, the direction detected by the traveling direction detection unit (2) after passing the curve b and the road L2
However, the correlation coefficient γ3 with respect to the road L3 is also significantly different from the direction of the road L3 after passing through the branch c. Since the direction is greatly deviated from the direction of, the correlation coefficient γ1 on the road L1 hardly changes. On the contrary, based on the relatively large correlation coefficient γ1, The position on the road L1 can be discriminated as the current position and can be displayed on a display device (not shown) together with the road map. That is, the current position is displayed corresponding to the road L0 until reaching the branch a, and the current position is displayed on the road L2 after passing the branch a until the position on the road L2 passes the curve b. The current position is displayed correspondingly, and the position on the road L2 is the curve b.
The current position is displayed in correspondence with the road L3 from the time when the position on the road L3 passes the branch c until the position on the road L3 passes the branch c after the position on the road L3 passes the branch c. The current position can be displayed in correspondence with the above.
In FIG. 3, when the position on the road L1 is determined as the current position, the interphase coefficient γ1 has the maximum value (for example, 1.
It is set to 0).

Therefore, thereafter, the same processing is performed again using the display position on the road L1 as a reference, so that the accurate current position can be sequentially displayed as the vehicle travels.

Incidentally, when the correlation coefficient γ becomes equal to or less than a predetermined threshold value (not shown), the registration of the road corresponding to the corresponding correlation coefficient may be deleted, and further, the difference between the correlation coefficients may be predetermined. The registration of the road corresponding to the smaller correlation coefficient may be deleted when the threshold value is equal to or more than the threshold value.

Also, in the case of the above example, the highest correlation coefficient changes from γ2 to γ3, γ1, and the display on the display device also moves in order from the road L2 to L3, L1. However, when the order of the correlation coefficients is reversed, by providing a predetermined hysteresis characteristic, it is possible to prevent the display on the display device from changing rapidly and frequently on different roads. .

 Next, a description will be given based on FIGS. 4 and 5.

Fig. 4 is a diagram showing a part of the road traffic network.
Only 1 and L2 are shown, and as shown by the broken line S, the vehicle is traveling through the roads L0 to L1. In addition, the one-dot chain line T indicates the trajectory of the estimated position, E indicates the marginal error, a, b, and c indicate branches or curves, and γ0,
γ1 and γ2 represent correlation coefficients corresponding to each road.

Further, FIG. 5 is a diagram showing a change in the correlation coefficient γ when the vehicle travels as indicated by a broken line S in FIG.
l1, l2 ... ln are shown as the correlation coefficient update points.

Therefore, while traveling on the road L0,
Until it is determined that the road L1 is entered through the branch a (until it is determined that the branch a is passed based on the distance data), only the interphase coefficient γ0 is large, and the other interphase coefficients γ
1, γ2 is small (see region R1 in Fig. 5). That is, branch a
Since the rotation angle data is small until passing through, it is not necessary to consider the influence of other roads at all, and only the traveling distance on the road L0 needs to be taken into consideration. Therefore, the estimated position calculation unit (4) It is only necessary to correct the position data calculated in the above so as to become the position data on the road L0. Then, the current position of the vehicle can be confirmed by displaying the position together with the road map on a display device (not shown) based on the corrected position data.

Next, when the road L1 is entered through the branch a, the correlation coefficient γ is calculated by the correlation coefficient calculation unit (5) for each of the roads L1 and L2 existing within the range of the above limit error E ( The area R2 in FIG. 5) is used for evaluation by the correlation coefficient evaluation unit (6) based on the calculated correlation coefficient. That is, which road the similarity is high is evaluated. More specifically, since the vehicle passed the branch a, the correlation coefficient γ0 for the road L0 can be ignored any longer, and conversely, the correlation coefficients for the roads L1 and L2 branched at the branch a are evaluated. Must. In FIG. 5, branch a
At the beginning of passing through, the correlation coefficient γ1 is more
Although slightly larger than 2, both correlation coefficients γ1, γ
Since the difference between 2 is very small, the positions on both roads L1 and L2 are displayed on a display device (not shown). Of course the road
Only the position on L1 may be displayed on a display device (not shown). However, the correlation coefficient γ2 with respect to the road L2 becomes small because the deviation between the direction detected by the traveling direction detection unit (2) and the direction of the road L2 after passing through the curve b becomes small, and the curve c further decreases. After passing through the road, the direction detected by the traveling direction detection unit (2) and the direction of the road L2 are largely deviated from each other, so that the distance is sharply reduced. On the contrary, the correlation coefficient γ1 for the road L1 hardly changes. Therefore, it is possible to determine the position on the road L1 as the current position based on the relatively large correlation coefficient γ1 and display it on the display device (not shown) together with the road map. That is, the current position is displayed in correspondence with the road L0 until reaching the branch a, and the roads L1, L2 or , The current position can be displayed only in correspondence with the road L1, and after the position on the road L2 has passed the curve c, the current position can be displayed only in correspondence with the road L1. In addition, in FIG. 5, when the position on the road L1 is determined as the current position,
The interphase coefficient γ1 is set to the maximum value (for example, 1.0).

Therefore, thereafter, the same processing is performed again using the display position on the road L1 as a reference, so that the accurate current position can be sequentially displayed as the vehicle travels.

The limit error E is different between the above two examples, and is larger in the examples shown in FIGS. 2 and 3, because the straight running distance is larger. However, in the case of general driving in urban areas, etc., it often reaches a branch or a curve before the marginal error E becomes too large, and there are two or more points within the marginal error E in this state. In addition to the fact that there are few roads, and even if there are two or more roads, there is a high probability that the road coefficient corresponding to the actual running will have a larger correlation coefficient. As shown, it is rare to recognize a position on a different road as the current position.

As is clear from the above description, by outputting the current position inside the vehicle, it can be applied to a navigation system that displays the current position and a destination together with a road map to provide route guidance. It is also possible to apply the present invention to a location system that outputs the position to the outside of the vehicle by radio waves and receives the radio waves at one place to grasp the traveling states of many vehicles.

It should be noted that the present invention is not limited to the above-mentioned embodiment, and for example, instead of obtaining and integrating the amount of change in the traveling distance and the bearing for each predetermined distance, the change in the traveling distance and the bearing at each predetermined time. It is possible to obtain and integrate the amount, and it is possible to make various design changes within a range that does not change the gist of the present invention.

<Effects of the Invention> As described above, according to the present invention, the correlation coefficient of the vehicle is estimated based on the error of the estimated position of the vehicle with respect to the road existing within the range of the marginal error on the road map caused by the dead reckoning. It is possible to monitor the fluctuation and select the correlation coefficient that shows the smallest error for the road, output the position on the road corresponding to the selected correlation function as the current position, and set the correlation coefficient to a predetermined value. When the value exceeds the threshold range of, or when there is a difference more than a predetermined value compared with the correlation coefficient for other roads, the data related to the corresponding correlation coefficient is deleted, so it is saved as the vehicle travels. Data can be reduced. The final selection of the correlation coefficient can be facilitated.

Furthermore, the correlation coefficient for roads that have not been erased is
Since the correlation coefficient calculating means is updated, even if the road pattern in the area where the vehicle travels is complicated, or there are multiple roads in close proximity to each other. However, it is possible to always hold multiple roads including the current position and output the correct position on the road as the current position based on the change of the correlation coefficient, which significantly improves the position detection accuracy and accuracy. be able to.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an apparatus for carrying out the position detecting system of the present invention, FIGS. 2 and 4 are diagrams showing a part of a road traffic network, FIG. 3 and FIG. 5 and FIG. 5 are diagrams showing changes in the correlation coefficient corresponding to FIG. 2 and FIG. 4, respectively. (1) ... running distance detection unit, (2) ... running direction detection unit, (3) ... road map memory, (4) ... estimated position calculation unit, (5) ... correlation coefficient calculation unit, (6) ... Correlation coefficient evaluation unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kunihiko Mitto 1-3-3 Shimaya, Konohana-ku, Osaka-shi, Osaka Sumitomo Electric Industries, Ltd. (56) Reference JP-A 63-115004 (JP, A) JP-A-61-56910 (JP, A)

Claims (7)

[Claims] 1. A road map in which a traveling distance detecting means (1) for detecting a traveling distance of a vehicle, a traveling direction detecting means (2) for detecting a traveling direction of the vehicle, and map data of a predetermined range are stored in advance. The current estimated position of the vehicle is calculated by adding the traveling distance component and the traveling direction component output from both the detection means (1) and (2) to the memory (3) and the conventional vehicle estimated position. In the position detecting device having the estimated position calculating means (4), within the range of the limit error of the estimated position which is generated as a result of accumulating the error of the traveling distance component and the error of the traveling direction component as the vehicle travels. With respect to the road existing in, the correlation coefficient calculating means (5) for calculating the correlation coefficient corresponding to the road is registered based on the error of the estimated position of the vehicle with respect to the road, and at every predetermined timing. ,Up By comparing the correlation coefficient with each other,
A correlation coefficient evaluation means (6) for selecting a correlation coefficient indicating that the error with respect to the road is the smallest and determining the current position of the vehicle on the road corresponding to the selected correlation coefficient; The correlation coefficient of the road not determined as the current position is, when the correlation coefficient is out of the predetermined threshold range,
Alternatively, when a difference of a predetermined value or more is generated as compared with the correlation coefficient for another road, the correlation coefficient for the road that is not deleted is updated by the correlation coefficient calculation means (5). A position detecting device characterized in that 2. The position detecting device according to claim 1, wherein the "correlation coefficient" is a function of a correlation coefficient value obtained by calculation and a correlation coefficient value calculated before that. 3. The correlation coefficient evaluation means (6) has a predetermined hysteresis characteristic when the correlation coefficient showing the smallest error and the correlation coefficient showing the second smallest error are exchanged. The position detecting device according to claim 1, which selects a correlation coefficient. 4. The position detecting device according to claim 1, wherein the correlation coefficient calculating means (5) calculates the correlation coefficient by obtaining the amount of change in the traveling distance and the azimuth at every predetermined time. 5. The position detecting device according to claim 1, wherein the correlation coefficient calculating means (5) calculates the correlation coefficient by obtaining the amount of change in the traveling distance and the azimuth for each predetermined distance. 6. When the vehicle is traveling in the state where only one road is registered, when the rotation angle data of the vehicle exceeds a predetermined value, the registration of the traveling road is deleted, and the correlation The position detecting device according to claim 1, wherein the number calculating means (5) calculates a correlation coefficient with respect to a road branched from the deleted road existing within the range of the marginal error. 7. When traveling in a state where only one road is registered, the registration of the traveling road is deleted when passing through a branch, and the correlation coefficient calculation means (5) The position detecting device according to claim 1, wherein a correlation coefficient is calculated for a road branched from the deleted road existing within a marginal error range.