JPH0252229B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a roadside beacon system, and more specifically, for exchanging data between a roadside beacon and a vehicle device, for example, After entering the point information, at least the vehicle speed data,
The present invention also relates to a roadside beacon method used to calibrate a vehicle position in a navigation system that displays the current position of the vehicle by inputting azimuth data.

[Conventional technology]

Conventionally, vehicles are equipped with a small computer and a display device, and road map data stored in a storage device such as a compact disk is read out and displayed on the display device, and vehicle speed data from a vehicle speed sensor, The position of the vehicle at each point in time is calculated and the direction of travel is determined using the direction data from the direction sensor and the direction sensor as input, and based on these calculation results and judgment results, the corresponding road map displayed on the display device is So-called navigation systems, in which a display indicating the vehicle is added to a portion of the vehicle, are becoming available.

If such a navigation system is used, the current location and traveling direction of the vehicle can be easily identified visually, and the vehicle can be reliably reached the destination without getting lost.

However, in the navigation system with the above configuration, errors that the vehicle speed sensor and direction sensor inevitably have accumulate as the traveling distance increases, and when the traveling distance exceeds a predetermined distance (however,
This predetermined distance is determined by the degree of error of the vehicle speed sensor and direction sensor in each vehicle, and changes in atmospheric conditions at the location of each sensor.
(not necessarily a fixed distance), the vehicle display position on the display device will deviate significantly from the actual vehicle position, making it impossible to perform its original functions and causing a situation where the vehicle gets lost. .

In order to solve such problems, roadside antennas are installed in the road transportation network at predetermined distances shorter than the distance at which the cumulative error exceeds a predetermined value, and the roadside antennas transmit position data and road direction. A signal containing data is radiated only in a relatively narrow range, and the signal is received by an antenna installed on the vehicle and input into a computer, which calibrates the correct data for the vehicle's position and driving direction based on the received signal. It has been proposed to adopt a so-called roadside beacon method.

If such a roadside beacon method is adopted, it is possible to display information based on accurate position data and direction data while the cumulative error is always below a predetermined value, thereby maximizing the original performance of the navigation system. In particular, by installing roadside antennas near railway lines, at railroad crossings, etc., where large errors are likely to occur in the direction sensor, errors caused by external factors can be effectively suppressed. It has the advantage that it can be calibrated to

[Problem that the invention seeks to solve]

In the roadside beacon system with the above configuration, a roadside antenna with highly directional properties constantly radiates signals containing position data and road direction data, and a vehicle passes through an area covered by the radiated signals. Therefore, by increasing the area covered by the transmitted signal, the signal reception position relative to the roadside antenna can be adjusted. There is a problem that the deviation becomes large and a sufficient calibration effect cannot be achieved.

To explain in more detail, the basic function of the roadside beacon system is to provide signals containing position data and road direction data to vehicles equipped with a navigation system, but the following functions can also be added: This is required for effective use of the roadside beacon system. In other words, by providing the navigation system with additional traffic information such as road congestion, construction, and other road usage conditions around the location where the roadside antenna is installed, it assists the smooth operation of vehicles. , Adding detailed map information including residential locations and personal names around the locations where roadside antennas are installed to make it easier to reach the final destination; include,
By adding road map information covering a fairly wide range and providing it to the navigation system, we can provide additional services such as updating the road map displayed on the display device and allowing smooth operation to remote areas. If such additional services are to be provided, it will be necessary to expand the transmission band using signals radiated from roadside antennas and to expand the area covered by transmitted signals.

When the transmission area is expanded and the area covered by the transmitted signal is expanded as described above, the deviation of the signal reception position from the installation position of the roadside antenna increases, and the original purpose of A problem arises in that position calibration cannot be performed accurately due to the influence of the above-mentioned deviation.

Furthermore, in order to understand the congestion situation, accident situation, etc. in the road transportation network, for example, data from each vehicle is received by a roadside antenna, the received data is aggregated, and the data obtained by analysis is used again as road information. There is a growing trend that it is necessary to radiate data from roadside antennas or to exchange specific data between vehicles and roadside devices. There is a problem in that the error rate of transmitted data increases due to the influence of multipath fading caused by other vehicles running in parallel.

Furthermore, the road transportation network includes grade-separated intersections, and it may be necessary to install roadside antennas at these grade-separated intersections (see FIG. 7).

In this case, the roadside antenna can be installed by, for example, holding the antenna 22 diagonally downward with the support 21 and erecting the support 21 close to the road 8 over a predetermined area of the road. It is designed to emit radio waves with an intensity higher than that level.

Therefore, the upper road 8u which is overpassed
The radio waves from the roadside antenna 22 installed close to the road will leak to the road 8d below, and will be received by the on-vehicle antenna (not shown) of a vehicle traveling on the road 8d below. However, there is a problem in that the calibration of the vehicle position etc. may be performed incorrectly. That is, even though the directions of the upper road 8u and the lower road 8d are completely different, and the various information accompanying each road is also different, a vehicle traveling on the lower road 8d is traveling on the upper road 8u.
There is a problem in that the navigation data is updated by receiving 22 radiated signals from the roadside antenna installed close to u, and the navigation data is completely lost.

In order to solve this problem, it is sufficient to significantly reduce the strength of the leakage radio waves toward the road 8d below by increasing the directivity of the roadside antenna 22. However, in order to increase the directivity, teeth,
As shown in FIG. 10, the antennas must be stacked in an array in the width direction of the road, which increases the size of the roadside antenna 22 as a whole and increases costs. Furthermore, even when stacking antennas in an array as described above, there is a limit to practical dimensions, so directivity cannot be sufficiently increased, and it is not possible to completely prevent leakage radio waves. The problem is that it cannot happen.

[Purpose of the invention]

This invention was made in view of the above-mentioned problems, and provides a roadside beacon that can easily cope with the expansion of various functions in the roadside beacon system and that can calibrate the original vehicle position with high accuracy. The purpose is to provide a method.

[Means to solve the problem]

In the roadside beacon system of the first invention to achieve the above object, the roadside antenna emits a vertically polarized signal, and the on-vehicle antenna radiates the vertically polarized signal in the lateral direction of the vehicle. It has high directivity and also has high directivity in the longitudinal direction of the vehicle for horizontally polarized signals.

Further, in the roadside beacon system of the second invention, the roadside antenna emits a horizontally polarized signal,
The vehicle-mounted antenna has high directivity in the lateral direction of the vehicle for horizontally polarized signals, and has high directivity in the longitudinal direction of the vehicle for vertically polarized signals.

However, in any of the above inventions, the vehicle-mounted antenna has a pair of roadside antenna plates attached to the ground plate via a common shorting plate, and a power supply to each antenna plate. The point may be connected to a pair of conjugate terminals of a hybrid circuit, and the terminal on the opposite phase side of the other pair of conjugate terminals may be connected to a navigator mounted on a vehicle, or an antenna base 1 in place
1 formed by forming a pair of slits
It has a pair of antenna plates, and the feeding point for each antenna plate is connected to a pair of conjugate terminals of the hybrid circuit, and among the other pair of conjugate terminals,
The reverse phase side terminal may be connected to a navigator mounted on the vehicle.

Further, in the above case, the shape of the pair of antenna plates may be rectangular or semicircular.

[Effect]

In the roadside beacon system of the first invention, a modulated wave signal modulated based on transmission data is fed to a roadside antenna, and a roadside beacon installed at a predetermined position on a road transportation network is transmitted. The antenna radiates vertically polarized radio waves to the vehicle.

These radio waves are received by an on-vehicle antenna that has high directivity for vertically polarized radio waves in a direction almost perpendicular to the vehicle's driving direction, and a received signal is output when the vehicle passes in front of the roadside antenna. Ru.

Therefore, by supplying this received signal to the navigator as a navigation signal,
Data necessary for navigation can be updated based only on vertically polarized signals emitted in a direction substantially perpendicular to the traveling direction of the vehicle.

In addition, if the above-mentioned received signal is a data transmission signal other than navigation, only vertically polarized signals radiated in a direction approximately perpendicular to the direction of travel of the vehicle are received, so the data has a low error rate. transmission can be carried out.

The above has only explained the case where radio waves are radiated from a roadside antenna, but since the directivity is the same when the antenna is used for transmission and when it is used for reception,
The vertically polarized radio waves emitted from the vehicle antenna are
The signal can be received by the roadside antenna when a vehicle passes in front of the roadside antenna.

In addition, in the roadside beacon method of the second invention, by feeding a modulated wave signal modulated based on transmission data to a roadside antenna, the beacon system is installed at a predetermined position on the road transportation network. A roadside antenna emits horizontally polarized radio waves to vehicles.

These radio waves are received by an on-vehicle antenna that has high directivity for horizontally polarized radio waves in a direction almost perpendicular to the direction of travel of the vehicle, and a received signal is output when the car passes in front of the roadside antenna. Ru.

Therefore, by supplying this received signal to the navigator as a navigation signal,
Data necessary for navigation can be updated based only on horizontally polarized signals radiated in a direction substantially perpendicular to the traveling direction of the vehicle.

Furthermore, if the above-mentioned received signal is a data transmission signal other than navigation, only horizontally polarized signals radiated in a direction approximately perpendicular to the direction of travel of the vehicle are received, so the data has a low error rate. transmission can be carried out.

The above has only explained the case where radio waves are radiated from a roadside antenna, but since the directivity is the same when the antenna is used for transmission and when it is used for reception,
The horizontally polarized radio waves emitted from the in-vehicle antenna are
The signal can be received by the roadside antenna when a vehicle passes in front of the roadside antenna.

The in-vehicle antenna has a pair of antenna plates attached to the ground plate via a common shorting plate, and a feeding point for each antenna plate is connected to a pair of conjugate terminals of the hybrid circuit. If the opposite-phase terminal of the other pair of conjugate terminals is connected to the navigator mounted on the vehicle, both feed points should be in a substantially horizontal plane relative to the vertically polarized radio waves. It has high directivity in the direction that connects the two feed points, and also has high directivity in the direction perpendicular to the direction that connects the two feed points in a substantially horizontal plane for horizontally polarized radio waves. By mounting the antenna so that it is located in the width direction, the vehicle-mounted antenna applied to the first invention can be obtained, and conversely, by mounting the antenna so that both feeding points are located in the front-rear direction of the vehicle, the antenna applied to the second invention can be obtained. An applicable in-vehicle antenna can be obtained.

Further, the above-mentioned in-vehicle antenna has a pair of antenna plates formed by forming a pair of slits at predetermined positions on the antenna base, and a feeding point for each antenna plate is connected to a pair of slits of the hybrid circuit. The same directivity as in the case of the above configuration can be achieved even when the terminal is connected to a conjugate terminal, and the reverse phase terminal of the other pair of conjugate terminals is connected to the navigator mounted on the vehicle. can,
In-vehicle antennas applicable to the first invention and the second invention can be obtained depending on the mounting state.

Furthermore, the same effect as described above can be achieved even when the shape of each of the antenna plates is rectangular or semicircular.

〔Example〕

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings showing examples.

FIG. 9 is a diagram schematically showing an example of a road map displayed on a display device, in which arrow A indicates the current position of the vehicle and the direction of travel. The roadside antennas P1, P2, . . . Pn are displayed corresponding to their actual setting positions (however, there is no problem even if the roadside antennas P1, P2, . . . Pn are not displayed). and,
Although not shown in the diagram, landmarks such as buildings are displayed.

FIG. 8 is a schematic diagram illustrating the roadside beacon system, in which a roadside antenna 9 is placed close to the road 8 at a preset point and emits a signal containing position data, road direction data, etc. At the same time, an on-vehicle antenna 7 for receiving the signal is mounted at a predetermined position of the vehicle 10 traveling on the road 8, and the received signal is fed to a navigation device (not shown).

FIG. 1 is a schematic perspective view showing an embodiment of an in-vehicle antenna 7 and a hybrid circuit 11. Attach antenna plates 3 and 4 of the same shape extending in the direction, and connect the antenna plates 3 and 4 and the ground plate 1 at symmetrical positions with the shorting plate 2 as the center.
A pair of conjugate terminals 12, 6 of the hybrid circuit 11 are provided between the two feed points 5, 6 via feed cables 16, 17.
It is connected to 13. Of the other pair of conjugate terminals of the hybrid circuit 11, the in-phase terminal 1
4 is connected to a data transmission system (not shown), and the opposite phase side terminal 15 is connected to a position determination system (not shown).

The shape of each antenna plate is a square with one side approximately equal to 1/4 wavelength, and the distance between the antenna plate and the ground plate 1 is set to a value smaller than the wavelength. The hybrid circuit 11 is a combination of 90° phase delay circuits, and when signals with amplitudes A and B are supplied to a pair of conjugate terminals 12 and 13, respectively, the in-phase terminal 1
4 outputs a signal with an amplitude of A/√2+B/√2, and a signal with an amplitude of A/√2−B/√2 is output from the negative phase side terminal 15.

FIG. 2 is a diagram showing the directivity obtained by the in-vehicle antenna 7 having the above configuration. When the reverse phase side terminal 15 of the hybrid circuit 11 is used as the reception signal extraction terminal, teeth,
As shown in FIG. 2A, the receiving sensitivity increases in a direction close to the direction perpendicular to the shorting plate 2,
It is possible to obtain reception directivity in which the reception sensitivity is lower in the direction parallel to the direction. Conversely, for horizontally polarized radio waves, as shown in Figure 2B, the receiving sensitivity is high in a direction close to parallel to the shorting plate 2, and the receiving sensitivity is low in a direction perpendicular to the shorting plate 2. It is possible to obtain lower reception directivity.

Furthermore, the above measurement results were obtained while the device was placed on a 1 mφ metal disk modeled after the roof of an automobile.

Therefore, vertically polarized radio waves are radiated from the roadside antenna 9, the on-vehicle antenna 7 having the above configuration and the hybrid circuit 11 are used, and the on-vehicle antenna 7 is connected so that both feeding points are relative to the traveling direction of the vehicle 10. When installed at right angles (3rd
When installed on the roof of the vehicle 10 as shown in Figure A, or on the dash board of the vehicle 10 as shown in Figure B), the received signal is extracted through the negative phase side terminal 15 of the hybrid circuit 11. By doing so, it is possible to achieve the high receiving directivity shown in FIG. vertically polarized radio waves (lower road 8d shown in Figure 7).
The upper road 8u with respect to the vehicle 10 traveling on
The reception sensitivity is extremely low for radio waves radiated from the roadside antenna 9 installed in the area.

As a result, navigation data can be calibrated by using only vertically polarized radio waves radiated to the vehicle 10 from a direction perpendicular to the traveling direction as navigation data.

In addition, horizontally polarized radio waves are radiated from the roadside antenna 9, the vehicle-mounted antenna 7 having the above configuration and the hybrid circuit 11 are used, and the vehicle-mounted antenna 7
is installed so that both feed points are located in the running direction of the vehicle 10 (when installed on the roof of the vehicle 10 as shown in FIG. 3C, or when installed on the roof of the vehicle 10 as shown in FIG. 3D). (when mounted on a dash board, etc.), by extracting the received signal through the negative phase side terminal 15 of the hybrid circuit 11, horizontally polarized radio waves radiated from a direction perpendicular to the traveling direction of the vehicle 10 are detected. A horizontally polarized radio wave radiated from the direction in which the vehicle 10 is traveling (the vehicle 10 traveling on the lower road 8d shown in FIG. 7) can achieve the high receiving directivity shown in FIG. On the other hand, the reception sensitivity is extremely low for radio waves radiated from the roadside antenna 9 installed on the road 8u above.

As a result, navigation data can be accurately calibrated by using only horizontally polarized radio waves emitted from a direction perpendicular to the traveling direction of the vehicle 10 as navigation data.

FIG. 4 is a perspective view showing another configuration of the in-vehicle antenna 7. The difference from the above embodiment is that each antenna plate has a semicircular shape, and both antenna plates are connected to the shorting plate 2. It is only the points that are made to be circular as a whole. Note that the length of the arcuate outer peripheral surface of each antenna plate is set to approximately one wavelength.

In the case of this embodiment as well, when the negative phase side terminal 15 of the hybrid circuit 11 is used as the reception signal extraction terminal, FIGS. 2A and B are used for vertically polarized radio waves and horizontally polarized radio waves, respectively. The reception directivity shown in can be obtained.

Next, the operation of the roadside beacon system having the above configuration will be explained.

From a roadside antenna 9 installed close to the upper road 8u at an elevated intersection in the road transportation network,
A vehicle 10 traveling on an upper road 8u while emitting radio waves for data transmission (vertically polarized radio waves or horizontally polarized radio waves) in a considerably downward direction.
When the vehicle approaches the roadside antenna 9, the navigation data can be calibrated by receiving radio waves radiated from the roadside antenna 9 with high reception sensitivity.

Furthermore, the vehicle 10 traveling on the lower road 8d will also receive the leakage radio waves from the roadside antenna 9 at the grade-separated intersection, but the reception sensitivity is very low in the direction in which the vehicle 10 is traveling. Since it is in a low state, the navigation data is not calibrated at all based on the received signal, and navigation can be performed based on the previous navigation data.

Figure 5 shows the in-vehicle antenna 7 and the hybrid circuit 1.
1 is a schematic perspective view showing still another embodiment of the present invention, which differs from the embodiment of FIG. 2', a pair of antenna plates 3' and 4' connected to the antenna base 1' at the center is formed.

In this embodiment as well, when the negative phase side terminal 15 of the hybrid circuit 11 is used as the reception signal extraction terminal, the antenna is used for vertically polarized radio waves as shown in FIG. 6A. base 1'
It is possible to obtain reception directivity in which the reception sensitivity is high in a direction close to the direction perpendicular to the connection to the antenna base 1', and the reception sensitivity is low in a direction parallel to the connection to the antenna base 1'. Conversely, for horizontally polarized radio waves, as shown in Figure 6B, the reception sensitivity is high in the direction close to parallel to the connection to the antenna base 1'; It is possible to obtain reception directivity in which the reception sensitivity is lower in the direction perpendicular to the direction.

Therefore, in the case of this embodiment as well, among the vehicles 10 traveling at the grade-separated intersection of the road transportation network, only the vehicles 10 traveling on the upper road 8u are installed close to the upper road 8u. The radio waves radiated from the roadside antenna 9 are received with high reception sensitivity, and navigation data is calibrated.

Note that the present invention is not limited to the above-described embodiments; for example, it is possible to simply transmit data without configuring navigation data at all, and it is also possible to transmit data from an in-vehicle antenna to a roadside antenna. It is possible to perform data transmission according to the present invention, and various other design changes can be made without changing the gist of the present invention.

〔Effect of the invention〕

As described above, the first invention emits vertically polarized radio waves using a roadside antenna, and receives vertically polarized radio waves with high sensitivity only in a direction substantially perpendicular to the direction of travel in the vehicle antenna. The second invention is
The roadside antenna emits horizontally polarized radio waves, and the in-vehicle antenna receives horizontally polarized radio waves with high sensitivity only in the direction approximately perpendicular to the direction of travel, making it possible to avoid overpasses in road transportation networks. When driving on the lower road, the vehicle is not affected by radio waves from the roadside antenna installed close to the upper road.
It is possible to calibrate navigation data, receive data, etc. by receiving radio waves from the roadside antenna only when driving on the road above, and the navigation data is calibrated based on erroneous data. The present invention has the unique effect of reliably preventing inconveniences such as aggregation, analysis, etc. being performed based on erroneously received data.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing an example of the relationship between the vehicle-mounted antenna and the hybrid circuit used in the roadside beacon system of the present invention, FIG. 2 is a diagram showing reception directivity, and FIG. 3 is a diagram showing the relationship between the vehicle-mounted antenna and the hybrid circuit. 4 is a schematic perspective view showing another embodiment. FIG. 5 is a schematic perspective view showing another embodiment. FIG. 6 is a reception directivity of the embodiment shown in FIG. 5. 7 is a schematic diagram showing an elevated intersection in a road transportation network, FIG. 8 is a schematic diagram explaining the roadside beacon method, and FIG. 9 is a schematic diagram showing an example of a road map displayed on a display device. FIG. 10 is a diagram showing the configuration of a roadside antenna in a conventional example. 1...Grounding plate, 1'...Antenna base, 2...Shorting plate, 2'...Slit, 3, 4, 3', 4'...Antenna plate, 5, 6...Feeding point, 11...Hybrid circuit, 15...Reverse phase side terminal.

Claims (1)

[Scope of Claims] 1. A roadside antenna installed at a predetermined position on a road transportation network transmits various data to a vehicle, and data is exchanged between a roadside device and an in-vehicle device. In the roadside beacon system, the roadside antenna emits vertically polarized signals, and the on-vehicle antenna has high directivity in the lateral direction of the vehicle for vertically polarized signals, and has high directivity in the lateral direction of the vehicle for vertically polarized signals. The roadside beacon system is characterized by having high directivity in the front and rear directions of the vehicle. 2. An on-vehicle antenna has a pair of antenna plates attached to a ground plate via a common shorting plate, and the feeding point for each antenna plate is connected to a pair of conjugate terminals of a hybrid circuit. The roadside beacon system according to claim 1, wherein the opposite-phase terminal of the other pair of conjugate terminals is connected to a navigator mounted on a vehicle. 3 The on-vehicle antenna has a pair of antenna plates formed by forming a pair of slits at predetermined positions on the antenna base, and the feeding point for each antenna plate is connected to one of the hybrid circuits.
The roadside beacon system according to claim 1, wherein the opposite-phase terminal of the other pair of conjugate terminals is connected to a navigator mounted on a vehicle. 4. The roadside beacon system according to claim 2 or 3, wherein each antenna plate is square. 5. The roadside beacon system according to claim 2 or 3, wherein each antenna is semicircular. 6. In the roadside beacon system, which transmits various data to the vehicle from a roadside antenna installed at a predetermined position on the road transportation network, and exchanges data between the roadside device and the in-vehicle device, The roadside antenna emits horizontally polarized signals, and the vehicle-mounted antenna has high directivity in the lateral direction of the vehicle for horizontally polarized signals, and in the longitudinal direction of the vehicle for vertically polarized signals. A roadside beacon system characterized by having high directivity. 7. An on-vehicle antenna has a pair of antenna plates attached to a ground plate via a common shorting plate, and the feed point for each antenna plate is connected to a pair of conjugate terminals of a hybrid circuit. 7. The roadside beacon system according to claim 6, wherein the opposite-phase terminal of the other pair of conjugate terminals is connected to a navigator mounted on a vehicle. 8 The on-vehicle antenna has a pair of antenna plates formed by forming a pair of slits at predetermined positions on the antenna base, and the feeding point for each antenna plate is connected to one of the hybrid circuits.
The roadside beacon system according to claim 6, wherein the other pair of conjugate terminals is connected to a pair of conjugate terminals, and the opposite-phase terminal of the other pair of conjugate terminals is connected to a navigator mounted on a vehicle. 9. The roadside beacon system according to claim 7 or 8, wherein each antenna plate is square. 10. The roadside beacon system according to claim 7 or 8, wherein each antenna is semicircular.