JPH06288781A - Vehicle position detecting device - Google Patents

Abstract

PURPOSE:To improve the accuracy of detecting the present position of a vehicle position detector. CONSTITUTION:The signals from a wheel speed sensor 1 and an azimuth sensor 2 are processed by a vehicle signal processing device 3 to obtain the travel vector. A micro map matching position detecting device 4 calculates the present position by the dead-reckoning navigation based on the travel vector, and matching is executed with the road data stored in the CD-ROM 8. A reliability evaluating device 9 evaluates the reliability of the matching, and when the reliability is low, a macro map matching position detecting device 11 is started. The macro map matching position detecting device 11 executes the pattern matching with the road data based on the pattern data of the travel locus which are prepared by the travel vector by a travel locus recording device 10. The present position corrected by the pattern matching is given to the micro map matching position detecting device 4, and displayed as the present position 6 by a display device 5.

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 device for detecting where a vehicle is currently traveling, such as a so-called navigation system.

[0002]

2. Description of the Related Art Conventionally, a vehicle position detecting device mounted on a vehicle and displaying a current position of the vehicle in an image in real time has been commercialized. The current position of the vehicle is calculated according to so-called dead reckoning. Dead reckoning in a vehicle is
The moving distance and the azimuth from the determined position are calculated by combining the travel vectors detected based on the signal from the sensor mounted on the vehicle.

When the current position is detected only by dead reckoning, the detection error of the sensor is accumulated. Map matching is performed in order to avoid the accumulation of errors and improve the detection accuracy of the current position. Map matching uses the fact that a vehicle runs on a road in principle. The running locus obtained by dead-reckoning is compared with the shape of the road to identify the road on which the vehicle is running and correct the error. Figure 7 for example
As shown in (a), the vehicle travels on the road La and Pa
It is assumed that the current position is Pa0 starting from. Starting point P
Proceed from a to Pa5 and Pa4, and on Pa3 the road La
Corrected to the upper position. Further, the process proceeds to Pa2 and Pa1, and the current position Pa0 is corrected to the position on the road La again.

[0004]

In the conventional position detecting device, local map matching is performed to correct the current position. Therefore, although map matching is possible within a certain range as shown in FIG. 7A, map matching may not always be possible as shown in FIG. 7B. That is, even if the first position Pb is on the road Lb, Pb5, Pb
No correction can be made on the road Lb from 4, Pb3, Pb2, Pb1 to Pb0 at the current position, and a route different from the apparent road Lb is passed. Thus, once a mismatch occurs, it is difficult to recover, and in the worst case, the results diverge.

An object of the present invention is to provide a vehicle position detecting device capable of improving the detection accuracy when the error becomes large only by the local map matching.

[0006]

The present invention relates to a vehicle position detecting device for detecting the current position of a traveling vehicle, and a vehicle signal processing means for deriving a signal representing a traveling vector according to the traveling of the vehicle. In response to the vehicle signal, the current position of the vehicle is calculated based on dead reckoning, and the current position calculated by performing local map matching with prestored road data is corrected. 1
The position detecting means, the reliability evaluating means for evaluating the reliability of the current position detected by the first position detecting means, and the reliability detecting means activated in response to the output from the reliability evaluating means, and detected by the first position detecting means. When the reliability of the current position is low,
A vehicle position detecting device comprising: a second position detecting unit that detects the current position by correcting the current position based on global position data.

The second position detecting means of the present invention, in response to the vehicle signal, synthesizes the travel vectors to create pattern data representing a travel locus, and performs pattern matching with pre-stored road data. It is characterized in that the current position is corrected by.

The second position detecting means of the present invention is G
It is characterized in that the current position is corrected by receiving radio waves from the PS satellite.

[0009]

According to the present invention, the first position detecting means calculates the current position of the vehicle on the basis of dead reckoning, and performs local map matching with prestored road data for correction. The second position detection means is activated when the reliability of the current position detected by the first position detection means is low, and corrects the current position based on the global position data. When the reliability is high by the local map matching, the first position detecting means detects the current position, and when the reliability becomes low, the current position is corrected. This can improve the detection accuracy of the current position. While the reliability of the current position detected by the first position detecting means is high, the correction by the second position detecting means is not performed, so that the rapid processing can be performed.

Further, according to the present invention, the second position detecting means synthesizes the travel vectors to create pattern data representing a travel locus, and performs pattern matching with the road data stored in advance. Since the patterns formed by roads are finite, it is easy to find global similarity by performing overall pattern matching.

Further, according to the invention, the second position detecting means receives the radio wave from the GPS satellite and corrects the present position, so that the present position can be detected as an absolute value independently of the traveling state.

[0012]

1 shows a schematic structure of a vehicle position detecting device according to an embodiment of the present invention. The wheel speed sensor 1 derives a signal corresponding to the traveling speed of the vehicle. Direction sensor 2
Is realized by a geomagnetic sensor, a vibration gyro sensor, or the like, and derives a signal indicating the traveling direction of the vehicle. The vehicle signal processing device 3 responds to the traveling speed and the traveling direction of the vehicle and derives a vehicle signal representing a traveling vector of the vehicle. The micro map matching position detecting device 4 which is the first position detecting means calculates the current position of the vehicle by dead reckoning based on the vehicle signal from the vehicle signal processing device 3. The calculated current position is displayed as a current position 6 on a display device 5 such as a cathode ray tube (abbreviation “CRT”) or a liquid crystal display (abbreviation “LCD”). Roads 7 and the like are also displayed on the display unit 5 at the same time. This road data is previously stored in the CD-ROM 8 or the like. The micro map matching position detection device 4 performs map matching between the road data stored in the CD-ROM and the current position calculated by dead reckoning, and corrects the current position if matching is possible. However, matching is not always possible uniquely.

The reliability of the current position detected by the micro map matching position detection device 4 is evaluated by the reliability evaluation device 9. When the reliability is low, the macro map matching position detecting device 11 that performs pattern matching with the road data based on the pattern data of the traveling locus created by the traveling locus recording device 10 is activated. In the macro map matching position detecting device 11 which is the second position detecting means, the pattern data of the traveling locus,
The road data stored in the CD-ROM is globally compared, and the current position is corrected by performing the same pattern matching as in the field of character recognition. The vehicle signal processing device 3, the micro map matching position detection device 4, the reliability evaluation device 9, the traveling locus recording device 10 and the macro map matching position detection device 11 as described above are a multi-processor of the processing device 12 including a CPU and a memory. It is realized by the task program operation. Of course, other configurations such as parallel operation of a plurality of computer devices may be used.

FIG. 2 shows the operation of the configuration shown in FIG. The operation is started from step a1, and the current position is detected by dead reckoning in step a2. In step a3, it is determined whether or not the detected current position can be corrected by micro map matching. If the correction is not possible, the process proceeds to step a4, and it is determined whether or not the distance during which the dead reckoning is continued is equal to or larger than the reference value. When it does not exceed the reference value, the process returns to step a2.

When it is determined in step a3 that the correction by micro map matching is possible, step a5
To perform micro map matching correction. In step a6, the degree of micromap matching is evaluated, and the evaluation value is compared with the reference value. When it is determined that the evaluation value is not lower than the reference value, the process proceeds to step a7. At step a7, the number of candidates to be corrected is obtained. When it is determined that the number of candidates is not greater than or equal to the reference value, the process returns to step a2.

When it is determined in step a4 that the dead reckoning distance is greater than or equal to the reference value, in step a6 it is determined that the evaluation value is less than or equal to the reference value, and in step a7 that the number of candidates is greater than or equal to the reference value. If it is determined that the macro map matching position detection device 11 performs global correction, the process returns to step a8.

FIG. 3 shows the principle of pattern matching in the macro map matching position detecting device 11 shown in FIG. As shown in FIG. 3A, the traveling locus recording device 1
From 0, the history pattern H0, H
It is derived as 1, ... Each history data has data representing distances and azimuths by gathering traveling vectors every moment in the same azimuth range. 3 (b) is shown in FIG. 3 (a).
The road data to be matched with the locus pattern of is shown.
Road data also includes nodes N0, which correspond to intersections globally.
N1, N2, N3 and the link L corresponding to the road between them
It is abstracted like 1, L2, L3. Nodes N0-N3
Is coordinate data representing the position. Links L1 to L
3 has data indicating its length and azimuth.

Global pattern matching is started from the latest history data H0. H0
Can match L1 and L3, and there are two candidates. However, if history data H1 is added, the links that can be matched are L1 and L.
Only in combination with 2. Therefore, the current position is node N
It is determined to be 0. The above is the operation principle of the macro map matching position detection device 11.

In FIG. 4, one history data H10 is 2
It shows the state of matching including one link. That is, in the history data H10 shown in FIG. 4A, the distance is d10 and the azimuth is θ10. On the other hand, FIG. 4 (b)
The links L11 and L12 shown in can be matched. The link L11 has a distance of d11 and an azimuth of θ11. The link L12 has a distance of d12 and an azimuth of θ12. The absolute value of the difference between θ10 and θ11 and θ12 is smaller than a predetermined reference value, and the distance d10 is equal to the distances d11 and d.
When the sum is equal to 12, the history data H1
It is determined that 0 is the sum of the links L11 and L12.

FIG. 5 shows the history data H2 shown in FIG.
0 indicates a state in which the combination of the two history data shown in (b) is a candidate. That is, although there is one link from the node N20 to the node N21 via the link L21, it is branched from the node N21, and it is not possible to judge which route it is. Node N21
From the route to the node N22 via the link L22 and the route from the link L23 to the node N23 have little change in mutual azimuth and little change in the link distance. In such a case, the route is judged by global pattern matching including more history data.

FIG. 6 shows a schematic structure of another embodiment of the present invention. This embodiment is similar to the embodiment shown in FIG. 1, and the corresponding parts are designated by the same reference numerals. It should be noted that the GPS radio wave of the GPS system is received by the GPS receiver 21 from the antenna 20 and the current position is corrected by this. The operation of the reliability evaluation device 9 is similar to that of the embodiment shown in FIG.

In the above embodiment, the reliability evaluation device 9 judges the reliability by determining the distance traveled by dead reckoning, the evaluation value of the road currently subjected to micromap matching, and the number of candidates for micromap matching. Although the judgment is made in combination, it is needless to say that the judgment may be made in any one or in a combination of two. Of course, the driver may activate the switch by operating the switch when he / she looks at the display 5 and determines that the current traveling state does not match the display state.

Although the macro map matching position detecting device 11 and the GPS receiving device 21 are shown as the second position detecting means, it is also possible to use a position beacon from a sign post installed on the road. Of course.

[0024]

As described above, according to the present invention, the first position detecting means detects the current position by performing dead reckoning and local map matching. When the reliability of the detection of the current position is low, the second position detection means is activated to perform the correction by the global position detection, so that the accuracy of the detected current position is improved. The second position detecting means corrects the current position only when the reliability of the current position detected by the first position detecting means is low, so normally only the first position detecting means needs to operate. Therefore, it is possible to quickly detect the current position. Since the second position detecting means may perform the correction only when the reliability of the current position detected by the first position detecting means is low, it is possible to increase the reliability of the detection by spending sufficient time for the processing.

Further, according to the present invention, the second position detecting means corrects the current position by performing pattern matching between the pattern data representing the traveling locus and the road data stored in advance. It is possible to identify possible roads and intersections and easily correct the current position.

Further, according to the present invention, since the second position detecting means receives the radio wave from the GPS satellite and corrects the present position, the correct correction can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic electrical configuration of an embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the configuration of FIG.

FIG. 3 is a diagram showing the principle of pattern matching in the embodiment of FIG.

FIG. 4 is a diagram showing the principle of pattern matching in the embodiment of FIG.

5 is a diagram showing the principle of pattern matching in the embodiment of FIG.

FIG. 6 is a block diagram showing a schematic electrical configuration of another embodiment of the present invention.

FIG. 7 is a diagram showing the concepts of conventional dead reckoning and map matching.

[Explanation of symbols]

 1 Wheel Speed Sensor 2 Direction Sensor 3 Vehicle Signal Processing Device 4 Micro Map Matching Position Detection Device 5 Display 6 Current Position 7 Road 8 CD-ROM 9 Reliability Evaluation Device 10 Running Track Recording Device 11 Macro Map Matching Position Detection Device 20 Antenna 21 GPS receiver

Claims (3)

[Claims] 1. A vehicle position detecting device for detecting the current position of a vehicle that is traveling, comprising: vehicle signal processing means for deriving a signal representing a traveling vector according to traveling of the vehicle; A first position detecting means for calculating a current position of the vehicle based on dead reckoning, and performing a local map matching with prestored road data to correct the calculated current position; Reliability evaluation means for evaluating the reliability of the current position detected by the position detection means; and reliability of the current position detected by the first position detection means, which is activated in response to the output from the reliability evaluation means. When it is low, the vehicle position detecting device includes a second position detecting unit that detects the current position by correcting it based on the global position data. 2. The second position detecting means, in response to a vehicle signal, synthesizes traveling vectors to create pattern data representing a traveling locus, and performs pattern matching with road data stored in advance. The vehicle position detecting device according to claim 1, wherein the current position is corrected. 3. The vehicle position detecting device according to claim 1, wherein the second position detecting means receives a radio wave from a GPS satellite to correct the current position.