JP2800534B2 - Vehicle position detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle position detecting apparatus mainly used for accurately determining a current position of a moving body such as an automobile running on a road.

[0002]

2. Description of the Related Art An example of a conventional vehicle position detecting device is disclosed in Japanese Patent Application Laid-Open No. 2-21717. FIG. 9 is a block diagram showing the configuration of the prior art.

The vehicle speed sensor 1 outputs a pulse signal for each unit traveling distance in accordance with the rotation of a tire. By counting the number of pulses, the traveling distance of the vehicle can be known. The azimuth sensor 2 is the turning angular velocity (yaw rate) of the vehicle
And outputs a signal proportional to the turning angle of the vehicle.
The road data is read from the CD-ROM 6 which is a map information storage medium, and is input to the arithmetic processing unit 5. Operation SW3
Is to write road correction information into the semiconductor memory 4 when the road shape at the time of creation of the CD-ROM 6 is different from the current road shape. The output signals of the vehicle speed sensor 1 and the azimuth sensor 2 are input to the arithmetic processing unit 5, where the position of the vehicle is XY
It is obtained by sequential calculation on the coordinates. The road data stored in the semiconductor memory 4 or the CD-ROM 6 is used. The position information calculated by the arithmetic processing unit 5 every time the vehicle travels a unit distance is displayed on the display device 7.

[0004] According to the conventional example, the function of correcting road data is configured as follows. This is because the road data stored in the CD-ROM is created based on information such as the road shape at a certain point in the past, so that data relating to the newly opened road is not described, and the newly added CD is added. -Aims to solve the problem of having to replace it with a ROM.

If there is an error in the road data read from the CD-ROM, the user inputs a correct road shape by using the operation switch. The input new data is stored as corrected road data on a writable and erasable recording medium such as a semiconductor memory together with information on a range that needs to be corrected. Then, when a certain range of road data is read, it is determined from the range whether or not the corrected road data stored in the semiconductor memory exists. The reason for storing the range of the corrected road data is to use it for this determination. If the corrected road data exists, the data is read from the semiconductor memory, and if not, the data is read from the CD-ROM.

With the above-described configuration, even when the road shape is changed, only the changed portion is stored in the semiconductor memory so that accurate road display can be performed without changing the CD-ROM.

[0007]

In such a vehicle position detecting apparatus according to the prior art, the user must correct the road data. Therefore, correction of a complicated part where there are many intersections requires a great deal of effort. Further, since the road data used for the map matching processing for obtaining the current position on the road by comparing the traveling locus of the vehicle with the road shape has a larger amount of information than the road data for displaying information related to road connection, the amount of information is further increased. There is a problem that a great deal of labor is required and accurate position detection cannot be performed unless the user corrects the position correctly.

[0008]

In order to solve the above-mentioned problems, according to the present invention, as a first means, there is provided an inconsistent area detecting means for detecting an inconsistent area between road data and a running locus from a result of a map matching operation. And an inconsistent area storing means for storing the area, and an inconsistent area determining means for inhibiting a matching operation in the inconsistent area.

As a second means, an inconsistent area detecting means for detecting an inconsistent area between the road data and the traveling locus from the result of the map matching operation, an inconsistent area storing means for storing the traveling locus together with the area, It is characterized by having a matching prohibited area determining means for prohibiting a matching operation in the matching area.

[0010]

According to the first means, the area having an error in the road data is automatically determined at the time of the map matching calculation, and the map matching in the area is prohibited at the next and subsequent runs, thereby affecting the error of the road data. However, accurate position detection can be performed.

According to the second means, the running locus when it is determined that there is an error in the road data is simultaneously stored, so that the map matching is prohibited only when the vehicle travels on the same road and in the same direction in the same area as that time. However, accurate position detection can be performed without being affected by errors in road data.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a hardware configuration diagram of a vehicle position detecting device applied to an embodiment of the present invention. Reference numeral 1 denotes a high-precision direction sensor. In this embodiment, an optical fiber gyro (hereinafter, referred to as an optical fiber gyro) is used.
Optical gyro). In addition, for example, a vibration rate gyro, a gas rate gyro, or the like is used.
Reference numeral 2 denotes a distance sensor which outputs a number of pulse signals corresponding to the rotation of the tire. Reference numeral 3 denotes a road data storage device which uses, for example, a CD-ROM disk storing road data and a CD-ROM player for reading the road data. Reference numeral 4 denotes an I / O for reading sensor data and road data by an arithmetic processing unit.
This is a microcomputer provided with O. Reference numeral 5 denotes a storage device such as a semiconductor memory used for storing an inconsistent area described later. Reference numeral 6 denotes a display device such as a display.

FIG. 1 is a block diagram of a vehicle position detecting apparatus applied to a first embodiment of the present invention.

In FIG. 1, reference numeral 101 denotes a high-accuracy azimuth sensor. In this embodiment, an optical gyro is used. Reference numeral 102 denotes a distance sensor that uses a wheel speed sensor or a vehicle speed sensor. 10
Reference numeral 3 denotes a current position estimating unit that calculates the current position of the vehicle with respect to the reference position and the travel locus from the direction sensor and the distance sensor. Reference numeral 109 denotes a map storage unit that stores road data described on a map. Reference numeral 108 denotes road data selection means for selecting road data to be used for map matching calculation. Numeral 105 denotes a map matching calculating means, which performs pattern matching based on a running locus which is a locus formed by the current position of the vehicle calculated by the current position estimating means 103 and the current position from the past and the road data obtained by the road data selecting means 108. To correct the current position of the vehicle on the road.
Reference numeral 106 denotes an inconsistent area detecting means for detecting an area in which the road data and the traveling locus are not well matched at the time of map matching calculation.
In the inconsistent area storage means. Reference numeral 104 denotes a matching prohibited area determining unit that determines whether or not the map matching calculation is to be performed by determining whether the current position is within the mismatched area. An output unit 110 displays the current position of the vehicle calculated by the current position estimation unit 103 or the map matching calculation unit 105 on a display mounted on the vehicle.

The operation of the vehicle position detecting device according to the first embodiment configured as described above will be described below.
Although the present invention can be realized by hardware, this embodiment describes a case where processing is performed by software using a microcomputer or the like. In the first embodiment, a region having an error in the road data is automatically determined at the time of the map matching calculation, and the map matching in the region is prohibited at the next and subsequent runs, thereby providing a highly accurate road data unaffected by the road data error. The purpose is to perform position detection.

Normally, errors in road data are partial, and when a high-precision azimuth sensor such as an optical gyro is used, the trajectory of the vehicle can be detected very accurately. Error of typical road data can be detected. However, in order to reliably detect an error in the road data, it is necessary to confirm that the trajectory and the shape of the road data match before and after the erroneous portion. Therefore, a process for detecting an erroneous portion at the time of map matching calculation, storing the position thereof, and prohibiting the map matching calculation when passing through the same area again, thereby preventing erroneous correction to an erroneous portion of road data. Is required.

FIG. 4 is a flowchart showing the procedure of position detection in the first embodiment, and the operation will be described according to the flowchart. When installing the equipment, it is necessary to set the initial position,
The coordinates of the position of the vehicle are manually input or set by external information such as radio navigation, but once set, it is not necessary to reset it by storing the position where the vehicle stopped last time. Setting is unnecessary. Similarly, when a sensor for detecting the turning angle of a vehicle such as an optical gyro or a vibration rate gyro is used as the direction sensor, once the manual setting or the direction setting based on external information is performed, the setting of the absolute direction is usually unnecessary. .

In step 401, each time the vehicle travels a unit distance (for example, 5 m), the traveling direction and the traveling distance of the vehicle are detected. When an optical gyro is used for the direction sensor, the traveling direction D
Is D = D '+ Ta (1). D 'is the absolute azimuth obtained up to the previous time, T
a is a turning angle detected by the optical gyro while traveling a unit distance.

In the next step 402, the estimated position of the vehicle is calculated by the following equation using the estimated position of the vehicle obtained up to the previous time as a reference position.

X = X ′ + LcosD (2) Y = Y ′ + LsinD (3) where X, Y Estimated position coordinates of vehicle X ′, Y ′ Previous estimated position coordinates of vehicle L Section traveling The distance D is the traveling direction. In step 403, the estimated position coordinates are sequentially stored, and a running locus is created by complementing a straight line between the coordinates. In step 404, it is determined whether or not the estimated position calculated in step 402 is within a matching prohibited area described later. If it is within the matching prohibited area, the estimated position calculated in step 402 is displayed in step 407, and one process ends. If it is outside the matching prohibited area, the position is detected by the map matching calculation in step 405, the detected position is displayed in step 406, and one process is terminated.

FIG. 5 is a flowchart showing the procedure of the map matching calculation in the first embodiment, and the operation of the map matching calculation will be described in detail in accordance with the flowchart. As will be described in detail later, since the road data is obtained by linearly approximating the shape of the road, a straight line portion of the road generally has higher accuracy than a bent portion. Therefore, in order to match with the road data, a straight traveling portion is required in the traveling locus, and step 50 is performed.
In step 1, it is determined whether or not the vehicle is traveling straight. For example, when the change angle of the traveling azimuth in the 50 m section is 5 ° or less, the straight traveling state is set. Step 5 if the vehicle is straight ahead
The process proceeds to step 02 and thereafter. If the vehicle is not traveling straight, the estimated position of the vehicle is displayed in step 511, and one process is terminated. In step 502, the road data used by the map matching calculation means is read. It is assumed that the road data exists within La (for example, 50 m) from the estimated position of the vehicle and is closest to the estimated position. This La may be enlarged or reduced according to the traveling distance, traveling time, or turning angle of the vehicle.

The map matching calculation means mainly calculates a correlation between a traveling locus and road data and sets a position on a road when there is one or more turns between two straight sections.
In order to advance the current position on the road when the vehicle is straight ahead, it is determined in step 503 whether or not there has been a bend within a predetermined distance (for example, 200 m) in the past. This is determined, for example, based on whether the change angle of the traveling azimuth in that section is 10 ° or less. If the vehicle turns, the process proceeds to step 504. If the vehicle does not turn, the current position on the currently running road is moved by the travel distance in step 512, the position is output, and the process ends.

In this embodiment, a map matching operation is performed using points on the road data. In step 504, a process of selecting a map evaluation point from a map evaluation range, which is a portion of the road data with a small error, is performed. First, an error in the road data will be described.

In the case of Japan, the road data is based on a topographic map issued by the Geospatial Information Authority of Japan, etc., and the shape of the road described on the map is approximated by a straight line.
It is stored in a map storage medium such as a D-ROM.

There are various storage methods, such as storing a vector as a line segment and storing the starting point and the ending point of the vector. However, all methods are the same in that a road is approximated by a straight line. Even if it is a straight line approximation, the shape can be approximated by approximating it with a very short straight line. However, since the data amount increases, the data amount and accuracy are actually compromised by a practical line. Therefore, the difference between the road data and the road shape especially near the intersection becomes large (see FIG. 6A). Therefore, in step 504, it is determined that the error amount of the road data satisfying the following two conditions is small.

However, one road vector data is referred to as a road segment. 1) The length of the road segment is longer than Ld (e.g., 100 m) 2) The difference between the direction of the target road segment and the directions of the road segments connected before and after it is greater than a predetermined value (e.g., 20 °). Since the coordinates and azimuth accuracy of the midpoint of the line segment are considered to be the highest among the small road segments, the midpoint of the road segment that satisfies the above conditions is used as the map evaluation point. Next, in step 505, it is determined whether two map evaluation points have been obtained before and after the turning. If it is obtained, a matching operation of the map and the trajectory is performed in step 506, and if it is not obtained, the estimated position is output in step 511, and the process ends.

The matching calculation method in step 506 will be described below with reference to FIG. FIG. 6A shows an example of the road data, and the line segment connecting the points is the above-mentioned road line segment. The traveling locus when the vehicle travels from A to F on such road data is indicated by broken lines in FIG.
2 is the straight section before and after the bend). The dashed line in FIG.
The actual shape of the road shown in FIG. Since the road data is created from the center line of the actual road, the shape error at the intersection becomes large. The error between C and D in FIG. 6A is a typical example of the road data error near the intersection. The map evaluation points obtained in step 504 are shown in FIG.
(C) M1 and M2, and the azimuth at M1 is θ.
Now, one point in the straight traveling portion S1 of the traveling locus before turning is made to coincide with the coordinates of M1. If there is a large error in the traveling direction, the traveling path may be made coincident with M1 and the path may be rotated so that the direction at the point coincident with M1 becomes θ. Thus, the absolute coordinates of each point on the traveling locus can be determined. Next, the shortest distance d between M2 and the trajectory is determined (FIG. 6).
(D)). The point of the rectilinear portion S1 to be matched with M1 is shifted by a predetermined distance (for example, 10 m) within a predetermined range SA (for example, 200 m), and d is obtained again. Then, when the minimum d is given, the coordinates of M1 are given to the point that matches M1 to determine the tip of the traveling locus, that is, the coordinates of the current position.

In step 507, the azimuth at M2 is compared with the azimuth of the traveling locus separated by d from M2, and when the difference between the azimuths is equal to or greater than Da (for example, 10 °), the estimated position is output in step 511. To end.

When the difference between the directions is equal to or smaller than a predetermined value, in step 508, an inconsistent area between the travel locus used in the map matching calculation and the road data is also detected. A method of detecting a mismatched area will be described in detail with reference to FIG. In FIG. 7A, road data of a certain area is indicated by a solid line, and the actual vehicle is A →
The trajectory when traveling C → F → E is indicated by a broken line. Although roads between ACs are not described in the road data, it is assumed that roads actually exist between ACs. If the distance between ACs is long, the current position may be erroneously detected on a road between BDs, resulting in an error in road data (lack of ACs).
As a result, the position detection accuracy decreases. In the present invention, when the vehicle passes such a point for the first time, the current position is erroneously detected on the road between the BDs. However, when the current position reaches between the CFs, a mismatched area between the ACs is detected and stored. This prevents an erroneous current position from being detected on a road between BDs when passing through the same point in the next and subsequent times.

The matching error SE between the traveling locus and the road data is: SE = dist × derr × fd (4) where dist: the shortest distance from a point on the locus to the road derr: the locus giving the shortest distance and the on-road The azimuth difference fd at a point can be calculated as a coefficient. fd is a coefficient for normalizing the matching error SE between the traveling locus and road data when a correct road is detected to about 1.0, and may be a constant or a variable determined by dist or derr. FIG. 7B is a graph in which the SE is calculated for each point set at regular intervals on the traveling locus, and the traveling distance is plotted on the horizontal axis and the SE is plotted on the vertical axis. In this way, the SE between ACs having an error in the road data is
Becomes larger. Therefore, when the section in which the SE is equal to or more than a predetermined value (changed by fd, but 1.0 in this example) continues for a predetermined distance (for example, 50 m) or more, the area is determined to be a mismatched area. In this example in which the vehicle travels to the point E, the area between ACs is determined to be a mismatch area. When the vehicle is traveling between ACs, the matching error SE increases, but the mismatching area cannot be determined because the vehicle is still in the mismatching area. When the signal passes through the mismatch area and the matching error is reduced again, the mismatch area is determined and detected.

In step 509, the inconsistency area detected in the above processing is set as a non-matching area and stored in a semiconductor memory or the like. The stored matching prohibited area is stored in step 40 of FIG.
4 is used for comparison with the estimated position.

Finally, at step 510, a perpendicular is drawn from the tip of the running locus to the road segment, the foot is detected as the current position, and output as the position on the road. The output position is displayed as the detected position obtained by the map matching calculation in step 406 in FIG.

As described above, according to the present embodiment, once a portion having a large error in the road data is detected by the map matching calculation, the matching calculation in that region is prohibited thereafter, so that the road on the road with a large error is detected. In order to prevent detection of the current position, stable detection of the current position becomes possible. Therefore,
On a frequently used road, highly accurate position detection becomes possible regardless of the accuracy of the road data.

Next, a second embodiment of the present invention will be described. FIG. 2 shows a block diagram of this embodiment. This drawing is the same as FIG. 1 except that the running locus calculated by the current position estimating means 103 is stored together with the mismatched area in the mismatched area storage means 107.

In the second embodiment, the running locus is stored together when the mismatched area is stored, and the execution of the map matching is changed depending on the traveling direction and the passing road even in the same area. An object of the present invention is to perform high-precision position detection that is not affected by errors in road data by prohibiting map matching only when the vehicle has the same traveling locus.

The operation of this embodiment will be described with reference to FIG. FIG. 8A shows the same road data as FIG. 7 with the addition of the road HI. The roads are indicated by solid lines. Also in this example, it is assumed that a road actually exists between ACs. Also, the trajectory of the vehicle traveling in the order of H → I → D → G → F → E is indicated by a broken line. FIG. 8B is a graph in which the matching error between the trajectory and the road data in this example is calculated by using the equation (4) as in the first embodiment. According to this figure, the matching error is always a predetermined value (in this example, 1.
0) Since it is less than or equal to the above, it can be determined that the error of the road data is small, and it is not necessary to prohibit the matching operation.

However, when the vehicle passes through this area in the order of A → C → F → E as in the first embodiment, there is no road data between ACs, so that the area between ACs becomes a mismatched area. Since the road HI passes through the inconsistent region, the matching calculation is not performed in this region despite the high accuracy of the road data. Therefore, map matching is prohibited only when the area is in the mismatched area and has the same travel locus as that at the time of storage.

Since the processing flow is the same as that of the first embodiment, a description will be given with reference to FIGS. Operations other than steps 404 and 509 are the same as those in the first embodiment.
The running locus is created in step 403, and the running locus immediately after entering the mismatched area is stored in step 509 simultaneously with the storage of the mismatched area. Then, step 404
Then, it is determined whether or not the estimated position is within the matching prohibited area and the traveling locus is the same as the stored locus. This 2
The process proceeds to step 407 only when the two conditions are satisfied, and the estimated position is displayed without performing the map matching calculation. Since only the running locus immediately after the estimated position is included in the mismatched area is stored, once it is determined that the map matching calculation is prohibited in step 404, it is determined only by determining whether the estimated position is within the matching prohibited area. I do.

As described above, according to the present embodiment, the matching calculation is prohibited only when traveling on a road with low consistency with the traveling locus even in the same area, so that the current position on the road with a large error is determined. Stable detection of the current position becomes possible to prevent detection. Therefore, on a frequently used road, highly accurate position detection can be performed regardless of the accuracy of the road data.

[0041]

As a first means, a portion having a large error in the road data is detected from the result of the map matching calculation by the mismatched area detecting means, and stored by the mismatched area storage means. Thereafter, the matching prohibition region determination means prohibits the matching calculation in that region, thereby preventing the detection of the current position on a road having a large error, thereby enabling a stable detection of the current position.

As a second means, the inconsistent area storage means stores the inconsistent area and the running locus together, and the inconsistent area determining means determines that the estimated position is in the inconsistent area and has the same running locus as that at the time of storage. Only by banning map matching,
In order to prevent the detection of the current position on a road having a large error, the current position can be detected stably.

[Brief description of the drawings]

FIG. 1 is a block diagram of a vehicle position detecting device according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a vehicle position detecting device according to a second embodiment of the present invention;

FIG. 3 is a configuration diagram of a vehicle position detection device applied to an embodiment of the present invention.

FIG. 4 is a flowchart for explaining the operation of the first embodiment of the present invention;

FIG. 5 is a flowchart for explaining the operation of a map matching operation according to the first embodiment of the present invention;

FIG. 6 is a diagram showing an example of creating road data;

FIG. 7 is an explanatory diagram of the first embodiment.

FIG. 8 is an explanatory diagram of a second embodiment.

FIG. 9 is a configuration diagram of a conventional vehicle position detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Direction sensor 102 Distance sensor 103 Current position estimating means 104 Matching prohibited area judging means 105 Map matching calculating means 106 Mismatched area detecting means 107 Mismatched area storing means 108 Road data selecting means 109 Map storing means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G01C 21/00 G09B 29/00

Claims (2)

(57) [Claims] An azimuth sensor for detecting a traveling azimuth of a vehicle;
A distance sensor that detects a traveling distance of the vehicle, a current position that calculates a traveling locus of the vehicle using the traveling direction detected by the direction sensor and the traveling distance detected by the distance sensor, and calculates an estimated current position of the vehicle. Estimating means, map storing means for storing road data, road data selecting means for selecting road data to be used for map matching calculation from the road data stored in the map storing means, Map matching calculation means for obtaining a current position on a road by a matching calculation; mismatched area detection means for detecting a mismatched area between the traveling locus and the road data at the time of matching calculation by the map matching calculation means; An inconsistent area storing means for storing an area detected by the detecting means; a current position detected by the current position estimating means; and a current position stored in the inconsistent area storing means. A matching prohibiting region judging means for performing execution determination map matching operation by comparing the area, the vehicle position detecting device characterized by having an output means for outputting the presumed current position or the road on the current position. 2. The inconsistent area storage means stores the inconsistent area detected by the inconsistent area detecting means and the running locus detected by the current position estimating means. An area determination for determining whether the estimated position detected by the means is within the mismatched area stored in the mismatched area storage means, and a running locus detected by the current position estimation means is stored in the mismatched area storage means. 2. The vehicle position detecting device according to claim 1, wherein the determination of execution of the map matching calculation is performed by a trajectory determination for determining whether or not the traveling trajectory matches.