JPH05303329A - Current position display of mobile - Google Patents

Abstract

(57) [Summary] [Purpose] The present position correction operation is realized without causing problems such as dropped candidates, subtlety of threshold setting, and parameter priority order. [Configuration] Roads L _{0 to} L ₅ to be subjected to map matching are searched from the map data, and each road is evaluated on the θ′-d ′ plane. θ ′ is a standardized value of the angle between the trajectory of the estimated position and the road, and d ′ is a standardized value of the length of the perpendicular line drawn from the estimated position to the road. Road L ₀ having a distance R ₀ of the smallest origin of each road L ₀ ~L ₅ is selected as the matching road is subjected to the calculation of the correction coordinate. [Effect] Since the geometrical relationship between the locus of the current position and each road is evaluated in a multi-dimensional space composed of multiple parameters, candidate drop and subtle threshold setting are eliminated, and parameter priority is given. There is no need to consider the ranking.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting a moving distance and a traveling direction of a moving body and estimating and displaying a current position, that is, a current position display device for the moving body.

[0002]

2. Description of the Related Art A current position display device has been conventionally known in order to support the operation of a moving body such as an automobile. The current position display device is a device that sequentially detects a moving distance and a traveling direction of a moving body by a distance sensor, an azimuth sensor, and the like, estimates the current position based on the detection result, and then displays the current position. When displaying the current position, the current position is corrected by collating with the map information. This correction is called map matching.

FIG. 9 shows a flow of position correction processing according to a conventional example. The processing shown in this figure is, for example, the method disclosed in "A method of map matching for car navigation", Denron Theory C, Vol. 111, No. 2, Miyata et al., 1991.

This system assumes a vehicle traveling on a road as a moving body. In this method, all roads included in the road information are targeted when correcting the current position obtained by estimation. Further, one road is selected from the roads included in the map information (100), and d is calculated for this road (102). d is the length of the perpendicular line drawn from the current position obtained by estimation to the selected road. Next, the d determined by the threshold determination by the threshold d _th (104), added to the selected road in step 100 to one of the candidate road when the result d ≦ d _th of this determination is satisfied (106). Step 104
If the condition is not satisfied at step 106
After the processing of (1) is completed, the process proceeds to step 108.

In step 108, it is judged whether or not the processes in steps 100 to 106 have been completed for all the roads included in the map information. As a result, if it is determined that the processing has been completed for all roads, step 10
The candidate road with the smallest θ is selected from the candidate roads selected by 6 as the matching road (110). θ is the angle formed by the locus of the current position and the road.

Then, the current position is corrected based on the matching road determined in step 110 (112). That is, since the outputs of the distance sensor and the azimuth sensor include an error, the current position is corrected so that the estimated position is on the matching road by compensating for the error. The current position obtained by this processing, that is, the corrected position is given to the image display device and is displayed on the screen together with the map information, for example.

[0007]

By using such a method, it is possible to correct the present position obtained by estimation on the road. However, in such a scheme,
Even if θ is very small and is actually a matching road, d> d _th is not selected as a candidate road, and it may be shaken off from the matching road selection targets. Further, since whether or not the road is a candidate road is determined depending on the setting of the threshold value d _th , a process of increasing or decreasing d _th may be necessary depending on the case. As described above, when the parameters of a plurality of processes are evaluated sequentially, complicated problems such as the evaluation contents and the priority order of the parameters occur.

The present invention has been made to solve the above problems, and by correcting the current position without performing a sequential evaluation,
An object of the present invention is to provide a current position display device for a moving body, which is capable of more accurate current position correction without leakage from candidate roads.

[0009]

In order to achieve such an object, the device of the present invention has a geometrical relationship in which the locus of the current position is associated with each of a plurality of roads selected from the map information. The present invention is characterized in that an optimum road is determined by evaluating whether or not it is present in a multidimensional space, and the present position obtained by estimation is corrected so that the road is located on the determined road.

Further, the second aspect of the present invention is characterized in that a road is selected from a predetermined range on the map information centering on the present position obtained by the estimation and is used for evaluation in the multidimensional space. ..

Then, the third aspect of the present invention obtains the standardized value θ'of the angle formed by each road selected from the map information and the locus of the moving body, and estimates the length of the perpendicular line from the present position to each road. Then, the standardized value d'of
It is characterized in that the road having the smallest distance R from the origin on the plane is determined as the optimum road.

[0012]

In the present invention, first, the geometrical relationship of the locus of the current position with respect to each road is evaluated in a multidimensional space. Each road to be evaluated is selected from within a predetermined range on the map information with the current position obtained by estimation as the center, as described in claim 2, for example.
Further, as the multi-dimensional space relating to the evaluation, for example, claim 3
As described in (3), a θ′-d ′ plane composed of the normalized value θ ′ of the angle and the normalized value d ′ of the length of the perpendicular is used.
In the present invention, the optimum road is determined by such an evaluation, and the present position obtained by estimation is corrected so as to be located on this road. Therefore, unlike the conventional method, there is no need to perform the threshold value determination, so that problems such as subtlety of threshold value setting and dropping of candidates do not occur. Further, it is not necessary to consider the priority order of the parameters related to the evaluation.

Further, in the second aspect, the road to be evaluated in the multidimensional space is selected from within a predetermined range on the map information with the current position obtained by the estimation as the center. Therefore, the process is simplified as compared with the case where all the roads included in the map information are targeted.

In the third aspect, the θ'-d 'plane composed of the angle normalized value θ'and the perpendicular length normalized value d'is used as a multidimensional space for evaluation. As described above, since the normalized values θ ′ and d ′ of both are used instead of the angle θ and the length d of the perpendicular, the units of both are
Inequality in evaluation due to differences in properties etc. is eliminated.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a current position display device according to an embodiment of the present invention. The device shown in this figure is mounted on a vehicle that runs on a road, for example, an automobile. The apparatus of this embodiment includes a distance sensor 1 as a means for detecting a moving distance and an azimuth sensor 2 as a means for detecting a traveling direction.

The distance sensor 1 and the azimuth sensor 2 are each connected to the current position calculating means 3. The current position calculation means 3 inputs the outputs of the distance sensor 1 and the azimuth sensor 2 at a predetermined timing t _n (n = 1, 2, ...) And estimates the current position at that point. The current position obtained by the estimation, that is, the estimated position P _n is output to the map matching means 4.

Here, the output of the distance sensor 1 represents the moving distance L of the moving body from the previous measurement timing t _n-1 to the current measurement timing t _n , and the output of the azimuth sensor 2 is this time. The traveling direction θ _car of the moving body at the measurement timing t _n is shown. The current position calculation means 3 uses the previously estimated position P _n (x _n-1 , y _n-1 ) and L and θ thereof.
_{From car} , the estimated position P _n (x
Guess _n-1 , y _n-1 ).

X _n = x _{n -1} + L cos θ _car y _n = y _{n -1} + L sin θ _{car The} map matching means 4 collates the estimated position P _n obtained by the current position calculation means 3 with the map data and corrects the position P. Correct to _{r + 1} . The map data is read from the map data storage device 5 via the storage device interface 6. That is, the map data read from the distance data storage device 5 includes, for example, road-related information as shown by the solid line in FIG. The map matching means 4 corrects the estimated position P _n to obtain the corrected position P _{r + 1} so as to compensate the error of the estimated position P _n caused by the error of the map sensor 1, the error of the orientation sensor 2, and the like.

The map matching means 4 has a correction position P.
_{r + 1} is output to the image display device 7 and displayed on the screen. At that time, a map is displayed on the screen of the image display device 7 based on the map data read from the map data storage device 5, and the driver of the vehicle or the like can see the current vehicle from the screen of the image display device 7. You can get information such as where you are.

The feature of this embodiment is that
This is the operation of the map matching means 4, that is, the operation of obtaining the corrected position P _{r + 1} by collating the estimated position P _n obtained from the current position calculating means 3 with the map data obtained from the map data storage device 5. This operation is shown in FIGS.

First, FIG. 3 shows a flow of operation of the map matching means 4 in this embodiment, that is, a flow of position correction processing. As shown in this figure, the map matching means 4 of the present embodiment first searches for roads from the map data read from the map data storage device 5 (200). Roads to be searched are, for example, as shown in FIG. 4, roads L _{0 to} L ₅ existing in a predetermined range (range indicated by a broken line) from the estimated position P _n .

Next, the map matching means 4 calculates θ and d for each of the roads L _{0 to} L ₅ obtained by the search (202). As shown in FIG.
Is the angle between the path of the estimated position P _n and the road, and d is the length of the perpendicular line from the estimated position P _n to the road. More specifically, the angle θ is the direction θ of the vector P _r P _n connecting the _road direction θ _road and the estimated position P _n from the previous corrected position Pr.
_It is the difference with _rn .

Next, the map matching means 4 standardizes θ and d. This is because the angle θ and the length d have different units and properties, and standardization eliminates inequality in evaluation. For example, as shown in FIGS. 6A and 6B,
The standard deviation of θ is σ ₁ and the standard deviation of d is σ _2, and θ ′ = θ / σ ₁ d ′ = d / σ ₂ and the standardized values θ ′ and d ′ are obtained.

Further, the map matching means 4 has a θ'-
On the d ′ plane, the distance R between each road L _{0 to} L ₅ and the origin is calculated (6). That is, R = (θ ′ ² + d ′ ² ) ^1/2 is calculated for each of the roads L _{0 to} L ₅ . Figure 4
In the case of the example shown in FIG. 7, the distance R ₀ between the road L ₀ and the origin is smaller than the other roads L _{1 to} L ₅ as shown in FIG.
The map matching means 4 is a road with the smallest distance R,
That is, the road L ₀ is selected as the matching road (20
8), the estimated position P _n is corrected based on the positional relationship with the road L ₀ . That is, the coordinates of the corrected position P _{r + 1} are calculated (210). This is shown in FIG.

Therefore, according to the present embodiment, the candidate roads are not narrowed down by using only d as a parameter, for example. Further, since the threshold value determination is not performed, problems such as subtlety of threshold value setting do not occur. Furthermore, 2
Since the evaluation is performed using the dimensional θ′-d ′ plane,
There is no need to consider the priority order. In addition, since θ and d are standardized and used, inequality in evaluation does not occur.

[0027]

As described above, according to the present invention,
Since roads that use map matching are determined by evaluation in a multidimensional space, problems such as candidate dropping and subtlety in threshold setting do not occur, and the current position is corrected more accurately. be able to.

Further, according to claim 2, since the roads to be evaluated are selected centering on the present position obtained by the estimation, the process is simpler than the case where all the roads are selected. Then, a high-speed current position correction operation is performed.

According to claim 3, the standardized value θ '
And d ′ are used, the present position can be accurately corrected without causing inequality in evaluation due to the difference in the property of each parameter.

[Brief description of drawings]

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

FIG. 2 is a diagram showing the meaning of position correction in this embodiment.

FIG. 3 is a flowchart showing a flow of position correction processing by a map matching means in this embodiment.

FIG. 4 is a diagram showing a road search operation in this embodiment.

FIG. 5 is a diagram showing a calculation method of θ and d in this embodiment.

6A and 6B are diagrams showing a road data distribution in this embodiment, FIG. 6A is a diagram before standardization, and FIG. 6B is a diagram after standardization.

FIG. 7 is a diagram showing an example of positioning of roads on the θ ′ and d ′ planes in this embodiment.

FIG. 8 is a diagram showing calculation of correction coordinates in this embodiment.

FIG. 9 is a flowchart showing a flow of position correction processing according to a conventional example.

[Explanation of symbols]

1 distance sensor 2 azimuth sensor 3 present position calculation means 4 map matching means 5 map data storage device 6 storage device interface 7 image display device P _n estimated position P _{r + 1} corrected position L _{0 to} L ₅ road θ locus of moving body Angle formed by the road d Length of the perpendicular line dropped from the estimated position to the road Normalized value of θ ′ θ Normalized value of d ′ d R θ ′ and distance between each road on the d ′ plane

Claims (3)

[Claims] 1. A means for detecting a moving distance and a traveling direction of a mounted moving body, a means for estimating a current position of the moving body based on the detected moving distance and a traveling direction, and a moving body based on the estimated current position. In the present position display device of the moving body, the locus of the present position is obtained by a means for obtaining the locus of, the means for collating the obtained locus with map information and correcting the present position, and means for displaying the obtained present position The optimal roads are determined by evaluating in a multidimensional space what geometric relationship each of the roads has with each of the roads selected from the map information, and it is assumed that the roads are located on the determined roads. A current position display device for a mobile body, characterized in that the current position is corrected by correcting the current position obtained by. 2. The current position display device for a mobile body according to claim 1, wherein a road is selected from a predetermined range on map information centering on the current position obtained by estimation, and evaluation is performed in the multidimensional space. A current position display device for a mobile body, which is characterized in that 3. The current position display device for a mobile body according to claim 1, wherein a standardized value θ ′ of an angle formed by each road selected from the map information and the trajectory of the mobile body is obtained, and the current is obtained by estimation. The normalized value d ′ of the length of the perpendicular line from each position to each road is obtained, and the road having the smallest distance R from the origin on the θ′-d ′ plane is determined as the optimum road. A current position display device for a moving body, characterized by performing evaluation in a three-dimensional space.