JPH05173474A - Present position display method for moving body - Google Patents

Abstract

PURPOSE:To shorten the execution time for a map matching processing at the time of displaying the present position of a moving body on a road map reflected on a screen. CONSTITUTION:In the case an actuating condition for a map matching processing is satisfied, in a step 3, the advance direction at every interval determined in advance is checked, while following in the direction for running along a running locus read out in a step 2, and encoding is executed by allowing a code allocated at every direction in advance to correspond successively. In a step 5, a candidate road for executing pattern matching with the running locus is extracted successively, and in a step 6, encoding is executed by the same method as the step 3. In a step 7, a pattern matching processing of each code of the encoded running locus and the encoded candidate road is executed. By encoding the running locus and the candidate road at the time of map matching processing, and executing pattern matching of each code, a processing quantity of data becomes smaller than that of pattern matching of each graphic, and the map matching processing can be executed efficiently.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for displaying the current position of a mobile unit on a road map displayed on the screen.

[0002]

2. Description of the Related Art With the recent development of car electronics, the traveling distance and the traveling direction of a moving body such as an automobile are detected by self-contained navigation sensor devices, and the current position of the moving body such as an automobile is detected from the detected values. Attention has been focused on a current position display device that enables a driver to confirm the present position by displaying the obtained present position on a map that is displayed in advance. In such a current position display device, due to the measurement accuracy of each detection device, positioning errors accumulate as a moving body such as an automobile travels,
Since there is a problem that the current position displayed on the map gradually deviates from the actual current position, it is possible to obtain it by recording and holding the road pattern on the map and the measured current position of the moving body such as a car. A so-called map matching process has been considered in which an error is corrected by performing pattern matching with a pattern of a traveled locus. That is, from the road network within a predetermined area including the current position, all candidate roads that have the same length as the travel locus are extracted, and pattern matching processing is performed on each candidate road and the travel locus, The candidate road with the highest degree of similarity is regarded as the road currently running, and the current position is moved to that road.

[0003]

However, in the above-mentioned conventional correction, when the pattern matching between the figures of the traveling locus and the candidate road is executed, the data processing amount is larger than that of the code pattern matching, so that the map matching is performed. The processing requires a lot of time, and particularly when the road network around the current position is complicated, the number of candidate roads becomes huge and the map matching processing requires a long time.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to reduce the execution time of the map matching process by performing efficient pattern matching.

[0005]

In order to achieve this object, a technical solution of the present invention is to provide a running locus pattern and a candidate road pattern in a map matching process of a current position display device of a mobile body. While maintaining the characteristics as a figure, the coding is performed according to a predetermined rule, and pattern matching between the codes is performed. Also,
Secondly, the chain coding is performed in the coding. Third, use dynamic programming as pattern matching. Fourth, chain coding is used for coding, and dynamic programming is used for pattern matching.

[0006]

According to the present invention, in the map matching process, the running locus as the graphic information and the candidate road on the map are converted into a character string by the above method, and pattern matching is performed between the character strings. Therefore, the pattern matching is simplified and the execution time of the map matching process is shortened as compared with the case of handling the graphic information.

[0007]

An embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a block connection diagram of an apparatus for implementing a method for displaying a current position of a moving body according to an embodiment of the present invention.

In FIG. 1, 1 is a self-contained navigation sensor device for detecting and outputting the traveling distance and traveling direction of a moving body, 2 is a map information storage medium in which map information is stored, and 3 is from the map information storage medium 2. The storage medium reproducing device 4 for reading out the necessary map information displays the map image of the read out map information on the screen, and the same position as the current position of the mobile body from the signal processing device 5 is followed on the same screen. The display device 5 to be displayed on the top sequentially calculates the current position of the moving body using the value from the self-contained navigation sensor device 1, and a map for displaying the current position is displayed on the storage medium reproducing device 3 as a map storage medium. 2, the map and the current position are displayed on the display device 4 according to the movement of the moving body, and the calculated current position is sequentially output to a traveling locus recording device described later, and if necessary. A signal processing device having a temporary storage location for the map matching process, which corrects the current position by using the map matching process, 6 sequentially stores the current position of the moving body obtained by the signal processing device 5, and moves. This is a running locus recording device that records and holds them as a running locus of the body.

In the above structure, the signal processing device 5 sequentially calculates the current position using the value from the self-contained navigation sensor device 1 and outputs the value to the traveling locus recording device 6, and
A map for displaying the current position of the moving body is read from the map information storage medium 2 using the storage medium reproducing device 3, and the map and the current position of the moving body are displayed on the display device 4 in an overlapping manner, which will be described later. Map matching processing by the method,
Correct the current position.

The specific operation of the map matching process will be described below with reference to the flowchart of FIG.

First, step 1 of the flowchart of FIG.
Then, the moving distance of the moving body after the end of the previous map matching process and the distance between the road and the current position displayed on the display device 4 are sequentially inspected, and the moving body sets a preset distance (for example, about several kilometers). Or when the distance between the current position and the road on the map exceeds a preset error, the process from step 2 onward is performed.

In step 2, the traveling locus recorded and held in the traveling locus recording device 7 is read out by a predetermined distance, and in step 3, the traveling locus read in step 2 is set in the traveling direction. Encoding is performed by checking the traveling direction at predetermined intervals (for example, about several meters) while tracing, and sequentially associating the codes assigned in advance for each direction.

The concrete encoding method of step 3 is executed by, for example, using chain encoding in which the traveling direction is divided into eight directions and the codes are assigned to the respective directions.

Chain coding will be described with reference to FIG. As shown in FIG. 3A, a traveling locus of a predetermined distance for pattern matching is drawn on a plane subdivided at predetermined intervals K. The subdivided parts will be called cells. Figure 3 (b)
As shown in FIG. 3, attention is paid to the continuous cells including the traveling locus, and the centers of the cells are connected by arrows in the traveling order. Figure 3
As shown in (c), such an arrow is called a direction vector, the direction vector a is made to correspond to the code 0, and similarly, the direction vector b is made to be the code 1, the direction vector c is made to the code 2, and the direction vector d. To 3, the direction vector e to a code 4, the direction vector f to a code 5, the direction vector g to a code 6, and the direction vector h to a code 7. Encoding is performed by recording codes for the direction vector in order from the start point. For example, in the case of FIG. 3B, the traveling locus is coded as in (Equation 1).

[0015]

[Equation 1]

In the chain coding, it is not necessary to actually prepare a plane to draw a traveling route, and the change in the traveling locus in each direction is sequentially examined. When the amount of change in a certain direction exceeds a predetermined interval, It may be encoded by assigning a character code indicating the direction of change.

The result of step 3 is stored in a temporary storage location of the signal processing device 5 in step 4.

In step 5, candidate roads for pattern matching with the traveling locus are sequentially extracted. For example, execute as follows. When the map matching process is started because the mobile body has moved a predetermined distance, every time step 5 is executed, the current position corrected and confirmed by the map matching process performed last time is used as a starting point in advance. Roads on the map having a determined distance are sequentially extracted and sent to step 6 as candidate roads. If the distance between the current position of the moving body and the road on the map is greater than or equal to a predetermined error, the road with a predetermined distance is corrected using the current position that has been corrected and confirmed in the past map matching process. The roads are sequentially extracted and sent to step 6 as candidate roads.

In step 6, the candidate roads sequentially obtained in step 5 are encoded in the same manner as in step 3.

In step 7, pattern matching processing is performed between the encoded traveling locus stored in the temporary storage location of the signal processing device 5 in step 4 and the encoded candidate road obtained in step 6.

A specific pattern matching method will be described below. For pattern matching between encoded data, for example, a dynamic programming method is used. The encoded travel locus (Equation 2) and the encoded candidate road (Equation 3) are expressed as follows, respectively.

[0022]

[Equation 2]

[0023]

[Equation 3]

Here, as the quantity representing the distance between the codes, for example,

[0025]

[Equation 4]

Then, in pattern matching using dynamic programming, for example, an initial condition is set.

[0027]

[Equation 5]

As a recurrence formula (Equation 6)

[0029]

[Equation 6]

This is performed by sequentially calculating Finally, (Equation 7) is obtained.

[0031]

[Equation 7]

(Equation 7) is an encoded travel locus (Equation 2).
This is a quantity that indicates the distance between both patterns after optimally time-normalizing the candidate road coded as (Equation 3) to remove distortion. Therefore, (Equation 7) can be used as the similarity between patterns. Here, the smaller the value of (Equation 7), the higher the degree of similarity. The recurrence formula used for pattern matching may be one that satisfies the conditions of dynamic programming.

In step 8, if the pattern matching value obtained in step 7 is within a predetermined allowable value (the degree of similarity is high), the process proceeds to step 9; otherwise, the process proceeds to step 10.

In step 9, the candidate roads that have been subjected to the pattern matching with the traveling locus in step 7 and the result of the pattern matching are stored in the temporary storage location of the code processing device 5.

In step 10, it is checked whether or not the pattern matching between the traveling locus and all the candidate roads is completed. If the pattern matching is completed, the process proceeds to step 11. If it is not completed, the process returns to step 5 and the next candidate road Then, a series of processing from step 6 to step 9 is performed.

After the pattern matching between the traveling locus and all the candidate roads is completed, the number of candidate roads stored in step 9 is checked in step 11, and steps 12, 13, and 14 are determined according to the number. Run.

If there is no selected candidate road (step 12), the current position is displayed on the display device 4 without being corrected and the current position is recorded in the temporary storage location of the signal processing device 5.

If the number of selected candidate roads is one (step 13), the candidate road is regarded as the road currently running.
The current position on the road is estimated, the current position is displayed on the display device 4, the current position inside the signal processing device 5 is corrected, and the current position is corrected to a temporary storage location of the signal processing device 5. Record the position.

If the number of the candidate roads selected is plural (step 14), the one having the highest degree of similarity among the candidate roads is set as the road currently being traveled, and the current position on the road is estimated. The current position is displayed on the display device 4, the current position inside the signal processing device 5 is corrected, and the corrected current position is recorded in a temporary storage location of the signal processing device 5.

As described above, according to the present embodiment, during the map matching process, the traveling locus and the candidate road are coded, and the pattern matching between the codes is performed.
Compared with pattern matching between figures, the amount of data processing is small, and map matching processing can be performed efficiently.

[0041]

As described above, according to the present invention, in the method for displaying the current position of a moving body, when performing map matching processing,
By encoding the traveling locus and the candidate road while retaining the characteristics as a line figure pattern and performing pattern matching between the encoded data, the amount of data processing is significantly reduced, and map matching processing is performed. Can be done efficiently.

[Brief description of drawings]

FIG. 1 is a block connection diagram of a device that realizes a method for displaying a current position of a moving body according to an embodiment of the present invention.

FIG. 2 is a flowchart of map matching processing in the same device.

FIG. 3 is a conceptual diagram of chain coding in the same device.

[Explanation of symbols]

 1 Self-contained navigation sensor device 2 Map information storage medium 3 Recording medium playback device 4 Display device 5 Signal processing device 6 Running track recording device

Claims (3)

[Claims] 1. A current position of a moving body is sequentially calculated while detecting a running distance and a traveling direction of the moving body, the value is sequentially recorded and saved as a running locus, and map information is stored in advance. When displaying the current position of the moving object displayed on the same screen while following the movement of the moving object, the map image of the map information and the current position of the moving object read from the map information storage medium For all the roads that can be traveled around the current position stored in the recorded and saved track information and map information, the traveling direction at predetermined intervals is checked while following the traveling direction, and it is determined in advance for each direction. The corresponding loci by sequentially corresponding codes,
And all the roads that can be traveled are coded, and the coded pattern of the traveled trajectory of the encoded moving body and all the roads that can be traveled around the current position is matched, and the road that is currently running A method for displaying the current position of a moving body, which comprises estimating the current position and correcting the current position. 2. The method for displaying the current position of a moving body according to claim 1, wherein chain coding is used for coding the traveling locus and all the roads that can travel. 3. The method for displaying the current position of a mobile body according to claim 1, wherein dynamic programming is used for pattern matching between the travel locus formed into a character string and all the roads that can travel.