JP2003109181A - On-vehicle antenna for communications between road and vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an on-vehicle antenna for communications between road and vehicle in which communications between a road and a vehicle can be performed without being interrupted even when a communication disable area exists in the boundary of mutually adjacent blocks. SOLUTION: An on-vehicle antenna 12 is composed of a pair of loop antennas (coils) 12a and 12b having the same form (cylindrical form), the same size and the same number of winding wires while being serially connected to generate the magnetic fields of the same strength and the same direction when currents flow and a tuning capacitor 12c constituting a resonance circuit together with a pair of loop antennas 12a and 12b. When the radius of a loop part is defined as (d) and a distance between the antenna terminals of road side antennas is defined as (y), the loop antennas 12a and 12b are fixed on the lower surface of a vehicle M with the location so that an interval (x) between the central points of both the loop antennas 12a and 12b can satisfy the condition of y<=x-2d, namely, the entire loop part of any one of loop antennas 12a and 12b is surely positioned within the loop of road side antennas 2 at all the time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle-mounted antenna for road-to-vehicle communication mounted on a vehicle for spot-like road-to-vehicle communication performed within a limited communication area.

[0002]

2. Description of the Related Art Conventionally, there has been proposed a traffic system for improving safety during traveling and eliminating traffic congestion by controlling the traveling state of a vehicle by making full use of road-vehicle communication and vehicle-vehicle communication. .

As one of such transportation systems, an IMTS (Intelligent) which causes a bus vehicle traveling on a predetermined traveling route to perform automatic traveling or platooning, and performs blockage control for preventing collision between vehicles. Multi-mode Trans
it System) is known. The blockage control is to prevent a collision between vehicles by dividing the traveling route into a number of sections and prohibiting a plurality of vehicles (platoons) from entering the same section at the same time.

When performing the blockage control, in order to specify in which section each vehicle exists, road-to-vehicle communication is performed individually for each section only with vehicles located in that section.
It is necessary to enable so-called spot communication,
As a communication device suitable for such spot communication, an electromagnetic coupling system and an electromagnetic induction system are known.

In these communication devices, loop antennas are used both on the roadside and on the vehicle side, and there are a roadside loop antenna buried in a dedicated road which is a traveling route and a vehicle-mounted loop antenna installed on the lower surface of the vehicle body. Communicate using mutual guidance. That is, when the loop portions of both loop antennas overlap each other, electromagnetic coupling between both loop antennas increases and communication becomes possible. Therefore, normally, by forming the loop antenna on the road side in a shape that substantially matches the communication area, road-to-vehicle communication can be performed over the entire communication area.

[0006]

By the way, when the sections where road-to-vehicle communication is possible are continuously set for blockage control or the like, as shown in FIG. In some cases, the road-side loop antennas are installed separately, and in some cases, as shown in FIG. 3B, the road-side loop antennas are installed so as to cross each other.

However, at this boundary, in the former case,
The vehicle-mounted antenna ANTc is a roadside antenna ANT.
Since there is no sufficient overlap between the loop portions of r and r, there is an incommunicable area in which communication with any of the roadside antennas ANTr is impossible. Signal is obtained, and the two interfere with each other, so that there is an incommunicable area in which neither of them can communicate.

When the vehicle-mounted antenna ANTc is located in these areas where communication is impossible, road-to-vehicle communication is interrupted. In other words, in the control center that executes various controls based on communication with the vehicle via the roadside communication device,
It is not possible to specify whether the vehicle M, which has lost the road-to-vehicle communication, has stopped in the incommunicable area or is deviating from the traveling route and traveling on a road other than the dedicated road A. There was a problem that safety could not be secured.

In order to solve the above problems, the present invention provides
It is an object of the present invention to provide a vehicle-mounted antenna for road-to-vehicle communication that can perform road-to-vehicle communication without interruption even if a communication-disabled area exists at the boundary between adjacent sections.

[0010]

The on-vehicle antenna for road-to-vehicle communication according to claim 1, which is an invention for achieving the above object, has a plurality of transmission output peaks, and the peaks are present in the traveling direction of the vehicle. It has a transmission characteristic arranged along it.

Therefore, even if there is an incommunicable area at the boundary between adjacent sections, at least one of the plurality of peaks is always located in the communicable area.
By setting the arrangement of the peaks of the transmission output, it is possible to reliably perform communication with the roadside communication device without interruption.

The arrangement of the peaks of the transmission output may be set as appropriate according to the size of the incommunicable area. It is desirable to set it to be long. Specifically, when the antenna of the roadside communication device is a loop antenna, the distance between the centers of the peaks of the transmission output may be set larger than the distance between the closest parts of the loop antenna.

Further, the characteristics of the transmission output as described above may be realized by a single antenna, but as described in claim 3, a plurality of units each having one peak of the transmission output. If the antenna is used, desired transmission output characteristics can be easily realized. When a vehicle-mounted antenna is composed of a plurality of unit antennas as described above, all the unit antennas are connected in series to each other and form a resonance circuit together with a separately provided tuning capacitor. A coil may be used, and the wireless signal may be transmitted / received to / from the roadside communication device by an electromagnetic coupling method or an electromagnetic induction method using mutual induction of the coils.

In this case, the above-mentioned transmission characteristics can be realized with an extremely simple structure.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is an explanatory diagram showing a schematic configuration of a traffic system to which the vehicle-mounted antenna for road-to-vehicle communication of the embodiment is applied.

As shown in FIG. 2, the transportation system is composed of a single track and has a dedicated road A on which only a vehicle M adapted to the system travels. On this dedicated road A, magnetic markers (not shown) are installed at equal intervals along the road, and roadside antennas 2 for roadside-vehicle communication are installed in each of the sections set for blockage control. Has been done.

The roadside antenna 2 is composed of a rectangular loop antenna arranged so that its long side is located along the dedicated road A, and the range delimited by this loop antenna substantially coincides with the communication area. Further, from a central portion of one long side of the roadside antenna 2, a power supply line 4 reaching a roadside communication device 6 provided on the roadside is connected, and the roadside antenna 2 and the power supply line 4 are formed of asphalt or concrete. It is buried at a depth of about 3 cm from the paved road A. Here, the distance between the antenna ends of the roadside antenna 2 is y.

Each roadside communication device 6 transmits information about the vehicle M obtained via the roadside antenna 2 to a control center (not shown), and receives various commands for performing blockage control and the like from the control center. The vehicle M is notified via the roadside antenna 2.

On the other hand, the vehicle M has an on-vehicle antenna 12 installed on the lower surface of the vehicle body and an on-vehicle communication of an electromagnetic coupling system or an electromagnetic induction system for wireless communication utilizing mutual induction between the on-vehicle antenna 12 and the roadside antenna 2. In addition to the road-vehicle communication device 10 including the machine 14, a vehicle-vehicle communication device that communicates with other vehicles, a magnetic sensor that detects a magnetic marker installed on the road surface, various sensors that detect the running state of the vehicle, and the like are provided. There is. Then, the vehicle M performs steering control and vehicle speed control based on various information and commands from the control center and other vehicles obtained by the road-to-vehicle communication and the inter-vehicle communication by the road-to-vehicle communication device 10 and the inter-vehicle communication device. It is configured to automatically travel on a dedicated road by following a magnetic marker detected by a magnetic sensor.

As shown in FIG. 1, the vehicle-mounted antenna 12 has the same shape (circular shape), the same size, and the same number of windings, and when a current is applied, magnetic fields of the same strength and in the same direction are generated. Pair of loop antennas (coils) 12a and 12b connected in series as described above, and the pair of loop antennas 1
2a and 12b, and a tuning capacitor 12c forming a resonance circuit.

Then, the loop antennas 12a and 12b
Is the radius of the loop part, and both loop antennas 1
The distance between the center points of 2a and 12b (hereinafter "antenna distance")
X) satisfies the formula (1), and the vehicle M
Is fixed to the lower surface of the (see FIG. 2).

Y ≦ x−2d (1) The vehicle-mounted antenna 12 of the present embodiment configured as described above
Has a characteristic that the peak of the transmission output appears at two points facing both loop antennas 12a and 12b, and either one of the loop antennas 12a and 12b can communicate with the roadside communication device 6. That is, if the vehicle is located within the loop of the roadside antenna 2, road-to-vehicle communication becomes possible.

According to the vehicle-mounted antenna 12 of this embodiment, the antenna distance x between the loop antennas 12a and 12b is set so as to satisfy the equation (1). Even when passing through, the loop portion of either one of the loop antennas 12a and 12b is reliably positioned within the loop of the roadside antenna 2, and road-vehicle communication can be performed without interruption.

As a result, the vehicle-mounted antenna 12 of this embodiment is
In the traffic system applying the, the control center can reliably grasp the position of the vehicle M on the traveling route,
The safety of the system can be improved. In the present embodiment, the antenna distance x between the loop antennas 12a and 12b is set so that one of the loop antennas 12a and 12b is surely positioned so that the entire loop portion is located inside the loop of the roadside antenna 2. Although set, the antenna interval x may be narrowed within a range in which road-to-vehicle communication can be secured.

For example, if more than half of the loop portions of the loop antennas 12a and 12b are located within the loop of the roadside antenna 2, if the vehicle-to-vehicle communication can be secured, the antenna distance x is the distance between the antenna ends of the roadside antenna 2. It may be set to be larger than y (y ≦ x).

Further, in the present embodiment, the distance between the ends of the antenna is set to y, but when the roadside antenna 2 is laid crosswise, the length of the incommunicable area at the boundary portion may be set to y. .

[Brief description of drawings]

FIG. 1 is a configuration diagram of an in-vehicle antenna according to an embodiment.

FIG. 2 is an explanatory diagram showing a schematic configuration of a traffic system to which the vehicle-mounted antenna of the embodiment is applied.

FIG. 3 is an explanatory diagram showing a problem of the conventional device.

[Explanation of symbols]

2 ... Roadside antenna 4 ... Feed line 6 ... Roadside communication device 10 ... Roadside-to-vehicle communication device 12 ... In-vehicle antennas 12a, 12b ... Loop antenna 12c ... Tuning capacitor 14 ... In-vehicle communication device A ... Private road M ... Vehicle

Continued front page    (72) Inventor Hiroyuki Sakakibara             14 Iwatani Shimohakaku-cho, Nishio-shi, Aichi Stock Association             Company Japan Auto Parts Research Institute (72) Inventor Kyofumi Yamada             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO F-term (reference) 5H161 AA01 AA02 BB03 CC13 DD12                       DD16 DD21 DD43                 5H180 AA06 AA16 BB04 CC17 CC24                       LL09                 5J046 AA12 AB02 AB10 AB11 MA08

Claims (4)

[Claims] 1. A vehicle for transmitting and receiving a wireless signal to and from a roadside communication device that provides spot communication in each of a plurality of sections set on a travel route, the spot communication having only the section as a communication area. An in-vehicle antenna for road-to-vehicle communication mounted on a vehicle, having a plurality of transmission output peaks and having transmission characteristics in which the peaks are arranged along the traveling direction of the vehicle. In-vehicle antenna. 2. The on-vehicle vehicle-to-vehicle communication system according to claim 1, wherein the distance between the centers of the peaks of the transmission outputs is set longer than the incommunicable area existing at the boundary between adjacent sections. antenna. 3. The vehicle-mounted antenna for road-to-vehicle communication according to claim 1 or 2, comprising a plurality of unit antennas each having one transmission output peak. 4. The unit antennas are each composed of a coil that is connected in series with each other and constitutes a resonance circuit together with a separately provided tuning capacitor, and the unit transmits and receives radio signals to and from the roadside communication device. The on-vehicle antenna for road-to-vehicle communication according to claim 3, wherein the on-vehicle antenna is performed by an electromagnetic coupling method or an electromagnetic induction method using induction.