JP2957058B2 - VICS beacon position detection and correction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a VICS beacon receiver used in a navigation system mounted on a vehicle, and more particularly to correcting an error in road distance data based on a beacon position.

[0002]

2. Description of the Related Art Conventionally, as a technology in such a field, a navigation system mounted on a vehicle basically calculates a current position by integrating a moving distance from a starting point and a change in a traveling direction, and calculates a current position on a map. It is provided with a function of displaying the position, the direction, and, in some cases, the running history on a vehicle-mounted LCD or the like. In order to display a map, an on-vehicle map database stored in a CD-ROM or the like is provided. As means for transmitting information outside the vehicle to the vehicle, a vehicle information communication system (V
ICS; Vehicle Information Communication System
In this, a spot communication road device called a “beacon” is installed every 2 to 5 km on the road, and communication is performed between the device and the vehicle-mounted device. The beacon is used to transmit the position of a communication point, shape guidance of an intersection, or changing road traffic information to a navigation system.

FIG. 5 is a diagram for explaining a transmission signal from a beacon. As shown in the figure, the antenna of the beacon emits radio waves in the direction in which the vehicle is coming from one side and in the direction coming from the opposite direction. Then, a VICS receiver mounted on a vehicle running on the road receives the above radio wave. The radio wave from the beacon antenna contains different information (for example, destination guidance) depending on the running direction of the vehicle, but the radio wave transmitted to one side is received by the vehicle coming from the opposite direction so that the information is not processed. is there. That is, in the beacon, for example, FM modulation is performed on a vehicle coming from one direction with AM1 data, and FM modulation is performed on a vehicle coming from the opposite direction with AM2 data.
M1 data and AM2 data are amplitude-modulated by a square wave whose phase is opposite to that of FM modulation. The AM1 data and the AM2 data have, for example, a data cycle of 47.
The frame is composed of 128 bytes, one frame is composed of 128 bytes, one frame is 16 ms, the blank period is 2 ms, the data is transmitted at a data rate of about 64 kbps, and the frequency of the square wave amplitude modulation component is 1 kHz. In the in-phase region in one direction, the AM1 data frame is synchronized with the rise of the amplitude modulation component, and in the opposite phase region in the opposite direction, the AM2 data frame is synchronized with the fall of the amplitude modulation signal. Thus, the driving direction is identified and VIC
The S receiver is receiving road information. Furthermore, when the vehicle passes directly below the beacon antenna, the phase of the amplitude modulation component is inverted, and this is detected to detect the position of the beacon.

FIG. 6 is a diagram for explaining the relationship between the received direction data and the beacon detection position. As shown in this figure,
The contents of the AM1 data and the AM2 data include, for example, information on the distance L0 (m) from this position to the intersection with reference to the time of detecting the position of the beacon, necessary information on the intersection, the name of the intersection, and the destination in each direction. Etc. When the information passes through the beacon, the intersection information is displayed in synchronization with the beacon position detection.

[0005]

However, in the conventional beacon position detecting device of the vehicle information communication system, the level of the AM modulation component is reduced immediately below the beacon, and an area where the phase cannot be detected occurs. An error occurs in the beacon position detection due to the vehicle running for the time required for the change detection. However, since the intersection information is displayed in synchronization with the beacon position detection,
During this time, the beacon position is detected after the vehicle has traveled a certain distance ΔL, but this means that the beacon position has shifted in the traveling direction by the distance ΔL, so that the intersection information is also displayed in the traveling direction by the distance ΔL. Therefore, an error occurs in the distance to the intersection, and when the vehicle travels for the displayed distance, it passes through the actual intersection,
There is a problem that it cannot be used as appropriate information, and rather gives a misunderstanding.

Accordingly, the present invention has been made in view of the above-mentioned problems, and a beacon position detection and correction device for a VICS which can correct a beacon position error caused by a decrease in the level of an AM modulation component immediately below a beacon in road distance data obtained from a beacon. The purpose is to provide.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a beacon that performs frequency modulation or phase modulation with road information data, and synchronizes with the modulated data and performs amplitude modulation with square waves having mutually opposite phases. In a device that receives a radio wave transmitted from and detects a beacon position based on the change in the phase, a correction value for a beacon position detection error caused by a decrease in a reception level immediately below the beacon or the like is provided in a vehicle equipped with the device. The beacon position detection error is corrected according to the vehicle speed.

In addition, a correction value for a detection error of a beacon position generated due to a decrease in a reception level immediately below a beacon or the like is stored so as to correspond to an antenna position of a vehicle equipped with the device, and is stored in accordance with antenna position information. Correct the detection error of the beacon position.

[0009]

According to the VICS beacon position detection and correction device of the present invention, a correction value for a beacon position detection error caused by a decrease in the reception level immediately below the beacon or the like is obtained by a running experiment. It is confirmed that it corresponds to the speed, and this is stored. By correcting the detection error of the beacon position according to the speed of the vehicle, the display of the road distance data obtained from the beacon can be performed without error, and can be used as appropriate information. It became so. In addition, it was confirmed by a driving experiment that the correction value for the detection error of the beacon position caused by a decrease in the reception level immediately below the beacon, etc., corresponded to the antenna position of the vehicle equipped with the device, and this was stored. By correcting the detection error of the beacon position according to, the display of the road distance data obtained from the beacon can be performed without error, and can be used as appropriate information.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram schematically illustrating a VICS receiver and a navigation system according to an embodiment of the present invention. As shown in the figure, a VICS beacon receiver 1 mounted on a vehicle receives a radio wave from the above-described beacon,
The navigation system 2 is configured as described above,
Input data of intersections and other information from the VICS beacon receiver 1 and a beacon position detection signal, and further input vehicle speed information (speed information) such as running pulses of the vehicle and antenna mounting position information of the vehicle to extract distance data. The beacon position is to be corrected when performing the operation.

FIG. 2 is a diagram showing a configuration of a beacon position detection correction device in the navigation system 2 of FIG. 1, and FIG. 3 is a diagram for explaining a beacon position detection error.
As shown in FIG. 3, when the vehicle advances from the in-phase region to the out-of-phase region, the reception level of the VICS beacon receiver 1 is immediately below the beacon antenna, and in the range of A below the level necessary for phase detection, the phase is undetermined. Even if the vehicle passes through this area, the area of the area B where the vehicle has traveled at the time required for the reverse phase detection is required. That is, it is predicted that the error ΔL1 of the beacon position is correlated with the traveling speed of the vehicle, and the inventor of the present application obtains the correlation as follows by a traveling experiment, and furthermore, has a correlation with the mounting state of the antenna of the vehicle through the experiment. Was clarified as follows.

In a running test of the vehicle speed, as an example, when the vehicle speed is 20 km / h, the beacon position error ΔL1 = 0 m, and when the vehicle speed is 40 km / h, ΔL1 = + 1 m. , Vehicle speed is 60km / h
Is ΔL1 = + 2 m, and the speed of the vehicle is 80 k
In the case of m / h, ΔL1 = + 5 m. Furthermore, if the antenna is located on the roof at the position of the antenna of the vehicle, the antenna error Δ
L2 = 0 m, and ΔL2 = −3 m when it is before, and ΔL2 = −2 m when it is behind. The correction data obtained in advance for the vehicle in this manner is stored in the storage unit 3 of FIG. 2 in the form of a table using the speed of the vehicle as a parameter. This storage unit 3 has a ROM (Read only m
emory). When the speed correction unit 4 in FIG. 2 detects the beacon position, the speed correction unit 4 reads the beacon position error from the storage unit 3 based on speed information (vehicle speed) such as a running pulse and performs an extrapolation process to perform the beacon position error ΔL1.
Ask for. Distance from this beacon position to the intersection (L
0) is corrected as follows.

L = L0−ΔL1 Antenna position corrector 5 provided at the subsequent stage of speed corrector 4
The antenna error .DELTA.L2 is read from the storage unit 3 by a switch for providing antenna mounting position information, and the distance (L0) from the beacon position to the intersection is corrected as follows. L = L0 + ΔL2 Further, the result obtained by the speed correcting section 4 may be corrected by adding the result as follows.

L = L0−ΔL1 + ΔL2 The distance to the intersection corrected in this way is displayed on the display unit 6. Note that the speed correction unit 4 and the antenna position correction unit 5
Is formed on the computer. FIG. 4 is a diagram illustrating a series of operations of the beacon position detection and correction device according to the embodiment of the present invention. In step 1 of the figure, when the VICS beacon receiver 1 receives the data of the beacon, it transmits the received data of the distance (L0) to the intersection to the speed correction unit 4 (computer).

In step 2, when the beacon position is detected as in step 1, the beacon position is transmitted to the speed correction unit 4 (computer). In step 3, the error of the beacon position corresponding to the vehicle speed at the time of detecting the beacon position (Δ
L1) corrects the received data (L0). Further, the antenna error (Δ
L2) further corrects the received data.

[0016]

As described above, according to the present invention, it has been confirmed by a running experiment that the detection error of the beacon position caused by the decrease in the reception level immediately below the beacon corresponds to the speed of the vehicle. Since the road distance data is corrected based on the detection error, the display of the road distance data obtained from the beacon can be reduced without error.Also, in a driving experiment, the detection error of the beacon position can also correspond to the antenna position attached to the vehicle. Since the road distance data is corrected using the detection error, the display of the road distance data obtained from the beacon can be reduced without error.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating a VICS beacon receiver and a navigation system according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a beacon position detection correction device in the navigation system 2 of FIG.

FIG. 3 is a diagram illustrating a beacon position detection error.

FIG. 4 is a flowchart illustrating a series of operations of the beacon position detection and correction device according to the embodiment of the present invention.

FIG. 5 is a diagram illustrating a transmission signal from a beacon.

FIG. 6 is a diagram illustrating a relationship between received direction data and a beacon detection position.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... VICS beacon receiver 2 ... Navigation system 3 ... Storage part 4 ... Speed correction part 5 ... Antenna position correction part 6 ... Display part

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁶ , DB name) G08G 1/00-1/16 G01C 21/00 H04B 7/26 G01S 1/68

Claims (2)

(57) [Claims] 1. A radio wave transmitted from a beacon, which is frequency-modulated or phase-modulated with road information data, and is synchronized with the modulated data and amplitude-modulated with a square wave having mutually opposite phases, receives a beacon position based on a change in the phase. In the device for detecting the, the correction value for the detection error of the beacon position generated due to a decrease in the reception level immediately below the beacon and the like is stored so as to correspond to the speed of the vehicle equipped with the device, according to the speed of the vehicle V to correct the detection error of this beacon position
ICS beacon position detection correction device. 2. A correction value for a detection error of a beacon position generated due to a decrease in a reception level immediately below a beacon or the like is stored so as to correspond to an antenna position of a vehicle equipped with the device, and according to the antenna position information. A VICS beacon position detection correction device for correcting a beacon position detection error.