JP2730093B2 - Car navigation system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an in-vehicle navigation device that detects the position of an own vehicle such as an automobile and displays it together with a nearby map and the like.

[Summary of the Invention]

The present invention relates to an in-vehicle navigation device for detecting and displaying the position of a vehicle, wherein the detected coordinates of the vehicle coordinate detecting means for detecting the coordinates of the vehicle position are determined by a position estimating means from a transmitter installed on the ground. When there is a distance equal to or more than a predetermined value from the coordinate position obtained by the receiving means, the output of the receiving means is adopted as position information, and when the distance is equal to or less than the predetermined value, the output of the own vehicle coordinate calculating means is used as position information. I will adopt it,
The output level of the receiving means is not used in the determination of adoption, so that the position of the own vehicle can be displayed more accurately.

[Conventional technology]

2. Description of the Related Art In recent years, various navigation devices have been developed for use in automobiles. For example, the position of the own vehicle is determined by detecting the direction of travel of the vehicle from the starting point, the amount of travel, and the like, and a road map near the determined own vehicle position is used as a CD RO.
It is conceivable to display on a CRT screen based on information from a large-capacity storage device such as the M device. Such a method of detecting a position from the traveling state of the own vehicle is called an independent navigation method. In the position detection by the independent navigation method, a deviation between an actual traveling position and a detected position occurs as the traveling distance increases. There was a fear. For this reason, it has been proposed to provide a transmitter called a beacon, a signpost, or the like that transmits a radio signal for position estimation containing absolute position information of the intersection at a main intersection, for example. In this case, the position is detected by the autonomous navigation method until the signal from the transmitter is obtained, and when the signal from the transmitter is received by the vehicle, the position indicated by the absolute position information included in the received signal is set to the current position. The position is corrected. By doing so, the displacement of the current position is corrected each time the vehicle passes through the intersection provided with the transmitter.

[Problems to be solved by the invention]

However, if the current position is corrected using a wireless signal from a transmitter such as a beacon, the deviation between the actual position and the detected position may be increased. That is, assuming that the actual running state is as shown in FIG. 2, it is assumed that the car C running on the road R is approaching the transmitting antenna _RA of the coordinate information transmitter. When the car C moves into the service area S to which the radio signal from the antenna _RA reaches, the antenna C _{A of the} navigation device mounted on the car C receives the radio signal, and the antenna R _A is installed. The coordinate information of the position a is obtained, and the position indicated by the coordinate information is set as the current position.

However, since the car C is actually traveling at the position b at the end of the service area S away from the position a of the antenna _RA , the detection position is different from the actual position by the deviation between the points a and b. I will.

Since the service area S is wide, the positional deviation that occurs may be, for example, about 20 m, and the display position on the road map may be the road next to the actual traveling road.

If the receiver for coordinate information reception determines the electric field strength and detects the point that becomes the maximum, a position closer to the transmission antenna _RA can be set as the coordinate position indicated by the reception information. However, such a receiver for judging the electric field strength is expensive, and the car is not necessarily equipped with a transmitting antenna.
It could not be said that it was running at the position closest to _RA , and the error could not be completely eliminated.

In view of the above, an object of the present invention is to provide an in-vehicle navigation device of this kind that can perform a position correction with a position evaluation signal from a transmitter installed on the ground in a favorable manner.

[Means for solving the problem]

As shown in FIG. 1, for example, a vehicle-mounted navigation device according to the present invention includes distance calculating means (3) and (4) for calculating the traveling distance of the own vehicle and azimuth calculating means (5) for calculating the traveling direction of the own vehicle. ), (6), own-vehicle coordinate calculating means (1) for calculating coordinates of the own-vehicle position by distance calculating means (3), (4) and azimuth calculating means (5), (6); Receiving means (7), (8), (9) for receiving the position evaluation signal transmitted from the installed transmitter and converting it into coordinate information, own vehicle coordinate calculating means (1) and receiving means (7) , (8), (9)
Are compared with each other, and when the error exceeds a predetermined value, the output of the vehicle coordinate calculation means (1) is corrected by the output of the receiving means (7), (8), (9), and the error is corrected to a predetermined value. Otherwise, the output of the vehicle coordinate calculating means (1) is employed without correction and is used as it is.
The comparison control means (10) does not consider the output levels of (8) and (9).

[Action]

According to the in-vehicle navigation device of the present invention, it is detected at the time of receiving the position evaluation signal that the detection position of the own vehicle by the self-contained navigation method is smaller than an error caused by a deviation between a transmission point and a reception point of the position evaluation signal. When it is determined that the error of the position detected by self-sustained navigation is smaller, the position is detected by the independent navigation system without correction by the position evaluation signal, and the position of the own vehicle is detected as accurately as possible. I have.

〔Example〕

Hereinafter, an embodiment of a vehicle-mounted navigation device according to the present invention will be described with reference to the accompanying drawings.

The in-vehicle navigation device of the present embodiment is applied to a navigation system that displays a map near the current position of an automobile, and is configured as shown in FIG. This first
In the figure, (1) is a vehicle coordinate detector for calculating and detecting the current position of the vehicle from supplied data, and a coordinate setting switch (2) is connected to the vehicle coordinate output device (1). The operation of the coordinate setting switch (2) enables the setting of the starting point of the automobile and the like.

In the figure, reference numeral (3) denotes a vehicle speed sensor for detecting the traveling speed of the vehicle. The speed data detected by the vehicle speed sensor (3) is supplied to a distance integrator (4).
Performs the integration of the traveling distance based on the speed data. Then, the integrated traveling distance data is supplied to the automatic coordinate detector (1). In the figure, reference numeral (5) denotes an azimuth sensor for detecting the azimuth. The azimuth data detected by the azimuth sensor (5) is supplied to the own vehicle direction detector (6). The traveling direction of the vehicle is detected based on the direction data. Then, the detected traveling direction data is supplied to the automatic coordinate detector (1). Then, the own vehicle coordinate detector (1)
Calculates the current position by moving the current coordinate position from the coordinate position set as the starting point by an amount indicated by the traveling distance data and the azimuth data.

In the figure, (7) indicates an antenna, and this antenna (7) transmits a radio signal for position evaluation from a coordinate information signal transmitter called a sign post or a beacon installed at a predetermined interval on a road. The signal received by the antenna (7) is supplied to the receiver (8) and demodulated from the modulated wave. Then, the demodulated received signal is supplied to the decoder (9), and the coordinate information in the received signal is demodulated. In this case, in this example, the coordinate information contained in the radio wave from the coordinate information signal transmitter is converted into digital data, and the decoder (9) demodulates the coordinate information as digital data. The decoder (9) supplies the coordinate information to the coordinate error determining circuit (10) only once when the coordinate information can be demodulated.

The coordinate information of the current position calculated by the vehicle coordinate detector (1) is supplied to a coordinate error determination circuit (10).

When the coordinate information is supplied from the decoder (9), the coordinate error determination circuit (10) determines the position indicated by the coordinate information and the position indicated by the coordinate information calculated by the own vehicle coordinate detector (1). Are compared to determine whether or not both coordinate positions are separated by a linear distance of, for example, 20 m or more. The setting of this linear distance is performed based on the service area where the radio signal from one coordinate information signal transmitter reaches,
Hereinafter, description will be made assuming that the distance is set to 20 m. And
When the difference between the two coordinate positions is 20 m or more, the coordinate information from the decoder (9) is supplied to the host vehicle coordinate detector (1), and the host vehicle coordinate detector (1) receives the coordinate information from the decoder (9). The coordinate position indicated by the coordinate information is set as the current position. When the difference between the two coordinate positions is within 20 m, the current position calculated by the own vehicle coordinate detector (1) is not corrected.

In the figure, (11) indicates a CD ROM device.
The device (11) is equipped with a CD ROM that stores road map information of the whole country as vector data and the speed limit of each road, etc., and receives a CD according to an instruction from the own vehicle coordinate detector (1).
Predetermined information stored in the ROM is read by the CD ROM device (11), and the read information is supplied to the display device (12).

The display device (12) includes a cathode ray tube for displaying a map, and is disposed, for example, in the vicinity of a driver's seat in a car, and has a CD.
A map indicated by map information supplied from the ROM device (11) is displayed. In this case, since map information is stored as vector data in the CD ROM, the vector data is converted into raster data for display by the arithmetic means provided in the display device (12).

In this example, the map information read from the CD ROM device (11) is supplied from the display device (12) to the vehicle coordinate detector (1), and the calculated vehicle coordinates are included in the map information. Is performed to match on the road.

Next, an operation of displaying the position of the own vehicle by the navigation device of the present embodiment will be described.

First, the coordinates of the departure place (current point) are set in the own vehicle coordinate detector (1) by the coordinate setting switch (2). When the vehicle starts running, the coordinate position being detected by the own vehicle coordinate detector (1) is moved based on the data from the vehicle speed sensor (3) and the direction sensor (5), and the current position is determined by an independent navigation method. Is calculated. At this time, map information near the current coordinate position detected from the CD ROM device (11) is read, and a map is displayed on the display device (12).
The current traveling position is displayed on the map by blinking or the like.

Then, when the vehicle approaches the intersection where the coordinate information signal transmitter is set by traveling, when the vehicle enters a service area where a radio signal for position evaluation can be received from the transmitter, the antenna (7) and the receiver The received coordinate information is supplied to the decoder (9) via (8), and when this coordinate information can be demodulated for the first time by this decoder (9), 1
The coordinate information is supplied to the coordinate error determination circuit (10) only once.

At this time, for example, when the vehicle travels from the departure point to the intersection in a relatively stable state with few curves, accelerations and decelerations, etc., the position detection accuracy by the independent navigation is kept high, and the error is small. Therefore, the coordinate error determination circuit (1
In (0), it is detected that the difference between the coordinate information included in the radio signal for position estimation and the coordinates detected by the independent navigation is a small value of 20 m or less. Therefore, the own vehicle coordinate detector (1)
It is determined that the coordinate position detected by the self-contained navigation is accurate, and the coordinate position detected by the self-contained navigation is set as the current position, and the coordinate position is detected from this current position by subsequent traveling.

Also, when traveling from the starting point to the intersection where the coordinate information signal transmitter is set is relatively variable, and when the position detected by independent navigation is relatively far away from the actual traveling point, When the vehicle approaches and receives a radio signal for position estimation, it detects the coordinate position indicated by the coordinate information supplied from the decoder (9) to the coordinate error determination circuit (10) and the own vehicle coordinate detector (1) by independent navigation. It is determined that the coordinate position is separated from the coordinate position by a straight line distance of, for example, 20 m or more, and the coordinates detected by the independent navigation have a large error. Therefore, it is determined that the coordinate position indicated by the information supplied from the decoder (9) is more accurate, and the received coordinate position is set as the current position in the own vehicle coordinate detector (1). From the newly set current position, a coordinate position is detected by the subsequent traveling.

As described above, according to the navigation device of the present example, considering the error that occurs due to the wide service area where the radio signal for position estimation from a transmitter called a beacon, a sign post, or the like arrives, the coordinates detected by the independent navigation are calculated based on the error. The coordinates are corrected by determining whether the coordinates are within the range of the error. For this reason, it is possible to more accurately detect the coordinate position using a receiver having a simple configuration that does not need to determine the electric field strength of the position evaluation signal, and to display the current position of the own vehicle accurately on a map. There is.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION According to the vehicle-mounted navigation device of this invention, there exists an advantage that the receiver for receiving the position evaluation signal from the transmitter installed on the ground can display the present position of the own vehicle more accurately with a simple structure.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an in-vehicle navigation device according to the present invention, and FIG. 2 is a schematic diagram showing a receiving state of an external signal. (1) is a vehicle coordinate detector, (8) is a receiver, (9) is a decoder, (10) is a coordinate error determination circuit, and (11) is a CD ROM.
The device, (12) is a display device.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takahiko Watanabe 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Osamu Hamada 6-35-35 Kita-Shinagawa, Shinagawa-ku, Tokyo (56) References JP-A-63-157012 (JP, A) JP-A-63-247612 (JP, A) JP-A-58-16283 (JP, A)

Claims (1)

(57) [Claims] A distance calculating means for calculating a traveling distance of the own vehicle; an azimuth calculating means for calculating a traveling direction of the own vehicle; and a self calculating means for calculating coordinates of a position of the own vehicle by the distance calculating means and the azimuth calculating means. Vehicle coordinate calculating means, receiving means for receiving a position evaluation signal transmitted from a transmitter installed on the ground and indicating the position of the transmitter, comparing the output of the own vehicle coordinate calculating means and the receiving means, When the distance between the coordinate points of the absolute positions indicated by the two is equal to or greater than a predetermined value, the output of the receiving means is adopted as position information. When the distance is equal to or less than the predetermined value, the output of the vehicle coordinate calculating means is used as position information. An on-vehicle navigation device having a comparison control means that is adopted and the output level of the receiving means is not used for the determination of the adoption.