JPS62269300A - Navigation apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a navigation device that uses a traffic monitoring device whose installation location is stored in a database to confirm the current location of a vehicle.

U Prior Art] Current location display devices that display the current location of a vehicle on a map on the screen of a receiver are used to display the shortest distance to the destination and road conditions in today's world, where the main road network and connected branch roads are well developed. It is attracting a great deal of interest as a means of determining the shortest travel time based on this. The current value confirmation method used by this type of current location display device is two methods: radio navigation, which detects radio waves from an absolute position reference such as a satellite and constantly determines the absolute position while driving; The result is quite different depending on which method of navigation is used, estimating based on distance and heading.

For estimated navigation, which can be achieved at a much lower cost than radio navigation, direction detection based on geomagnetism is often used. For example, in the conventional navigation device l shown in Fig. 3, the geomagnetic sensor that detects this geomagnetism is the direction sensor 2. used as. In addition to the direction sensor 2, the navigation device (2) shown in the figure includes a distance sensor 3 that detects the travel distance by integrating the distance calculated based on the travel speed of the vehicle;
More specifically, a storage device 4 that stores map data describing roads and their surroundings is connected to the current location estimating circuit 5. The current location estimation circuit 5 estimates the current location based on information from the direction sensor 2 and the distance sensor 3, and uses a method of estimating the current location based on an extension of the travel route up to that point. The driving route obtained by connecting the current location estimated by the current location estimation circuit 5 with the current location obtained in the past with a line is written on the map of the vicinity of the location read from the storage device 4,
It is displayed on the screen of a display device 6 connected to the current location estimation circuit 5.

[Problems to be Solved by the Invention] In the above-mentioned conventional navigation device I, since the direction sensor 2 that detects earth's magnetism is affected by the magnetism of the vehicle itself, there is no problem as long as the magnetization state of the vehicle does not change. However, in reality, when a vehicle passes near a railroad crossing, elevated track, or power transmission line, the amount of magnetization changes due to the influence of a strong electromagnetic field, causing disturbance to the direction sensor 2. . Such disturbances are particularly noticeable when driving in urban areas, and are one of the reasons why dead reckoning navigation is inferior to radio navigation in terms of absolute accuracy.

Therefore, in order to compensate for these drawbacks of dead reckoning navigation, a transmitter embedded in an intersection, etc., for example, is used as a position reference comparable to the absolute position reference of a satellite, etc., and radio waves of a specific frequency emitted by this transmitter are used as a position reference. , is received by a receiver installed under the floor of the vehicle, and at the time of reception, the display on the display device that had previously displayed the vehicle's driving position on the map is corrected, and the vehicle's current location is displayed at the nearest intersection from there. A method of correcting to a certain position has been proposed.

This type of correction method is disclosed in, for example, Japanese Patent Application Laid-Open No. 59-152482.
``Map Display Device for Vehicles,'' etc., but since it is assumed that a transmitter that emits radio waves of a specific frequency is embedded in an intersection, government agencies in charge of road administration and private sectors It is essential for all organizations to work together to realize a unified standard, and unlike the case of using existing equipment, political factors are also involved, so there are problems such as there is little possibility of realizing it for the time being, if not in the future.

[Means for Solving the Problems] This invention solves the above problems, and includes a current location estimation circuit that estimates the current location of the vehicle based on the travel direction and distance traveled so far, and a road a receiver that receives ultrasonic signals transmitted by a traffic monitoring device that monitors traffic;
Calibrating the estimated current location by the current location estimation circuit based on a database in which the installation location of the traffic monitoring device is stored in advance as location data on a map and current location data determined from the ultrasonic signal received by the receiver. The present invention is characterized in that it is configured by providing a calibration circuit that performs the following steps.

[Operation] The present invention reads position data indicating the installation location of a traffic monitoring device stored in a database in advance from the database based on an ultrasonic signal transmitted by the traffic monitoring device, and reads out the read position data. By calibrating the current location estimated by the current location estimation circuit as a reference, errors in dead reckoning navigation are successively corrected.

[Example] Hereinafter, an example of the present invention will be described with reference to FIG. 1.2. 1 and 2 are a schematic configuration diagram showing an embodiment of the navigation device of the present invention and a flowchart for explaining an operation program, respectively.

In FIG. 1, a navigation device 11 includes a current location estimation circuit 12 that estimates the current location of the vehicle based on the travel direction and distance traveled so far, and an ultrasonic signal transmitted by a traffic monitoring device 10 installed near an intersection. a receiver I3 that receives
, a filter circuit 14 that removes unnecessary signals contained in the output of this receiver 13 , an amplifier 15 that amplifies the output of this filter circuit 14 , and a vehicle that detects the output of the amplifier 15 and detects the location where the traffic monitoring device 10 is installed. a passage detection circuit 16 that detects passing through the intersection, and a database 17 in which all the installation locations of the insect monitoring device 10 are stored as position data Pi (Xi, Yi) on an X-Y two-dimensional coordinate map. and a calibration circuit 18 that calibrates the estimated current location estimated by the current location estimation circuit 12 based on the location data stored in the database I7.

In addition, in the case of this embodiment, the database 17 is as follows:
An optical disk capable of high-density information recording is used as read-only memory (ROM), and one position data can be stored in three
By storing it as 2-bit digital data, for example, the land of Japan can be divided into land units of 0.5 mm square, and each divided unit can be stored with a code attached.

By the way, the operation of the navigation device 11 is performed according to the flowchart shown in FIG.

First, in step (101), the receiver 13
When it is determined that the ultrasonic signal exceeding a certain level has been received by the passage detection circuit 16, in step (102)
provides a calibration command to the calibration circuit 18.

The calibration circuit 18 that received the calibration command performs the following step (+0
In 3), the current location estimating circuit 12 sets the condition that the distance from the current location determined at the hour of the previous revolution matches the travel distance within a certain tolerance range, even though the current location estimation circuit 12 is an extension of the travel route that has been estimated so far. The position data of the traffic monitoring device IO located at a lower position is read out from the database 17.

In this readout, the corresponding position data may not exist, and even if it exists, the corresponding position data may be single or multiple, so the following step (104) The determination is made at (+05).

If it is determined in step (+04) that the corresponding position data does not exist, it means that an error has occurred in the previous estimated navigation, and in step (+06), the position data obtained several times in the past will be included. , the estimated travel route is corrected.

On the other hand, if the corresponding position data exists, the number of position data is determined in step (105J), but the determination in step (+05) is based on the fact that there are multiple locations ahead in the direction of travel, such as in the city center. Traffic monitoring device 10
This is important to prevent malfunctions in areas where there is a high concentration of locations, and here we will explain the case where there is only one piece of location data.

There is one traffic monitoring device 10 waiting in front of the vehicle in the direction of travel.
If there is only one base, the corresponding position data is also single, there is no error in the direction estimation by the estimated navigation up to that point, and there is no need to correct the travel route, so step (107)
, the current location estimation circuit 12 certifies the direction estimation up to that point, and at the same time, regardless of the presence or absence of an error in distance estimation, the calibration circuit 18 calculates the estimated current location at the time it receives the calibration command based on the corresponding location data. Replace with confirmed current location. As a result, the passing points of the vehicle are successively calibrated and determined.

Further, if two or more position data are obtained in step (+05), it means that two or more traffic monitoring devices 10 are installed in the direction of travel of the vehicle, and all of them are connected to the traffic monitoring device 10 that passed last time. A case is assumed in which the vehicle is located at a distance and further along the extension of the traveling direction. Therefore, in response to the problem of how to process two or more pieces of current location data obtained under such circumstances, in this embodiment, as shown in step (108), when multiple pieces of current location data are obtained simultaneously, Then, the calibration work was temporarily suspended, and then the traffic M
A method is adopted in which the current location is identified by waiting for single location data to be obtained at step (+05) when passing the monitoring device 0. Although this is a city center, the probability that two or more traffic monitoring devices 10 will occur several times in a row in the same direction of travel and at the same distance from the current location is extremely low. This is because even if the calibration is interrupted, the accumulation of estimation errors is ultimately prevented by the travel route correction process in step (+06).

In this way, the navigation device II reads the position data indicating the installation location of the traffic monitoring device 10 stored in the database 17 in advance from the database 17 based on the ultrasonic signal transmitted by the traffic monitoring device 0. Since the current location estimated by the current location estimation circuit 12 is calibrated based on the read position data, the accumulation of estimation errors, which is a drawback of dead reckoning navigation, can be avoided when the vehicle passes by the traffic monitoring device IO. A public facility called a traffic monitoring device 10, which can be corrected at any time and whose installation is being promoted to eliminate traffic congestion at intersections, is used as a type of address display device with a clear installation location, and is highly accurate. Since it is possible to confirm the current location with a high degree of accuracy, and the number of data that can be stored in the database 17 can be expected to increase naturally in the future, it will finally be possible to narrow the accuracy difference with radio navigation, and what is more, radio navigation is different from radio navigation. In addition to requiring an incomparably low-cost equipment configuration, it can be used not only in areas governed by common traffic laws, but also on a global scale that transcends national borders by using optical discs with sufficient storage capacity as the storage medium for database I7. It is not just a dream to use this system, but it is possible to provide a navigation system that is extremely practical for the future.

In the above embodiment, an optical disk is used as a storage medium for storing the installation location of the traffic monitoring device 10, but other types of storage medium such as a magnetic tape or a floppy disk may also be used.

[Effects of the Invention J As explained above, the present invention allows location data indicating the installation location of a traffic monitoring device stored in a database in advance to be exchanged! The configuration is such that the ultrasonic signal transmitted by the IM monitoring device is read from the database, and the current location estimation circuit calibrates the estimated current location based on the read position data, which eliminates the accumulation of estimation errors that are a drawback of dead reckoning navigation. Traffic monitoring devices, which can be corrected every time a vehicle passes by the device, are being installed in a public facility called a traffic monitoring device, which is being promoted in order to eliminate congestion at intersections. It can be used as a type of address display device to confirm the current location with extremely high accuracy, and the number of data that can be stored in the database can be expected to increase naturally in the future, so the difference in accuracy with radio navigation will finally be narrowed. In addition, it requires a low-cost equipment configuration that is incomparable to radio navigation.
By using optical discs with sufficient storage capacity as storage media for databases, it is possible to use them not only in regions governed by common traffic laws, but also on a global scale that transcends national borders, and is highly realistic for the future. This provides excellent effects such as being able to provide a navigation device with high performance.

[Brief explanation of the drawing]

1.2 are a schematic configuration diagram and a flowchart for explaining an operation program, respectively, showing an embodiment of the navigation device of the present invention, and FIG. 3 is a schematic configuration diagram showing an example of a conventional navigation device. . ■0, traffic monitoring device, 11 navigation device,
+2. ,,Current location estimation circuit,13. ,. Receiver, +6. , ,passage detection circuit, +7. , database, 18. ,,calibration circuit.

Claims (1)

[Claims] a current location estimation circuit that estimates the current location of the vehicle based on the travel direction and distance traveled; a receiver that receives ultrasonic signals transmitted by a traffic monitoring device that monitors road traffic volume; A calibration circuit is provided for calibrating the estimated current location by the current location estimation circuit based on a database in which the installation location of the monitoring device is stored as location data on a map, and current location data determined from the ultrasonic signal received by the receiver. navigation device.