JP2014119956A - Road-vehicle optical communication device for vehicle and car navigation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a road-vehicle optical communication device for a vehicle and a car navigation device which can enhance reliability for determining that the vehicle is in a communication area.SOLUTION: When a road-vehicle optical communication device 11 for a vehicle successively receives a downlink signal twice within a predetermined time, the device 11 determines that the vehicle is in a communication area and transmits an uplink signal. Thus, as the device can enhance reliability for determining that the vehicle is in a communication area, it is possible to prevent such inconvenience that the device transmits an unnecessary uplink signal.

Description

  The present invention relates to a vehicular road-to-vehicle optical communication device and a car navigation device that transmit an uplink signal in response to receiving a downlink signal from an optical communication roadside device.

  In communication using conventional radio waves (for example, ETC (registered trademark), DSRC (registered trademark)), the strength of a received signal (carrier wave) from a roadside communication device is detected by an RSSI (Received Signal Strength Indicator) circuit. Generally, control for starting communication is performed when a certain level or more is secured.

Japanese Patent No. 3009360

By the way, in road-to-vehicle optical communication systems such as road traffic information communication systems (VICS: Vehicle Information And Communication Systems (registered trademark)) and safe driving support systems (DSSS: Driving Safety Support Systems), vehicles and optical communication roadside devices are used. Infrared rays are used as a communication medium with (hereinafter referred to as an optical beacon). Since infrared rays are transmitted and received as pulse signals, the RSSI circuit cannot be used, and it has been impossible to determine a stable communication area based on a received signal from an optical beacon. As a countermeasure against such a problem, for example, a method has been proposed in which, for example, a correct downlink signal can be received and one frame is determined to be a stable communication area and communication is started (see Patent Document 1).
However, in such a method, even if one frame of a downlink signal can be instantaneously received in an unstable communication area, it is determined as the communication area, and the uplink signal including ID information of the own vehicle is included. May be sent. For this reason, there was a problem that an unnecessary uplink signal was transmitted.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vehicular road-to-vehicle optical communication device and a car navigation device that can improve the reliability of determining that it is a communication area.

According to the first aspect of the present invention, the communication area is determined when the downlink signal is received a predetermined number of times within a predetermined time, so that the communication area is determined by receiving the downlink signal of one frame. Compared with the structure to perform, the reliability which determines that it is a communication area can be improved, and the malfunction of transmitting an unnecessary uplink signal can be prevented.
According to the invention of claim 2, since it is added as a condition that the downlink signal is continuously received in order to determine the communication area, the reliability for determining the communication area is further increased. be able to.
According to the third aspect of the present invention, the means for determining whether or not the downlink signal has been continuously received is configured by the software timer, so that it can be easily implemented.
According to the fourth aspect of the present invention, the vehicle road-to-vehicle optical communication device provides the user with various information received from the optical communication roadside device using the notification function of the car navigation device. Compared with a configuration in which the communication device is provided independently from the car navigation device, the overall configuration can be simplified.

The block diagram which shows the whole structure of the car navigation apparatus in one Embodiment. Diagram showing optical beacon communication area Diagram showing unstable communication area and stable communication area of optical beacon Figure showing optical beacon location information The figure which shows the downlink signal of 1 frame The figure which shows the communication sequence of the road-vehicle optical communication apparatus and the optical beacon of VICS The figure which shows the communication sequence of the road-vehicle optical communication apparatus and the optical beacon of DSSS Flow chart showing operation of road-to-vehicle optical communication device

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, the vehicle road-to-vehicle optical communication device (hereinafter referred to as the road-to-vehicle optical communication device) will be described as being built in the car navigation device, but it may be externally attached separately from the car navigation device, You may make it incorporate in vehicle equipment other than a car navigation apparatus.
In FIG. 1, the car navigation device 10 includes a road-to-vehicle optical communication device 11, a map data storage unit 12, a vehicle position detection unit 13, an operation switch 14, a display device 15, a sound output device 16, and a control unit 17. It communicates with various optical beacons 100 (corresponding to an optical communication roadside device) via the road-to-vehicle optical communication device 11. Examples of the various optical beacons 100 include a VICS optical beacon and a DSSS optical beacon.

  The road-to-vehicle optical communication device 11 (corresponding to the communication area determining means) is a surface mounting type infrared light emitting LED (infrared light emitting diode) (not shown), for example, as a transmission means for transmitting an uplink signal composed of an optical signal, As a receiving means for receiving a downlink signal consisting of the above, a transmission / reception unit having a surface mount type PD (photodiode) (not shown) is also provided, and infrared rays are used as a communication medium to transmit / receive via various optical beacons 100 and the transmission / reception unit. . The transmission / reception light unit is attached to the dashboard of the vehicle so as to facilitate optical communication with the optical beacon 100. As a downlink signal transmitted from the optical beacon 100, a downlink signal intermittently transmitted for all vehicles existing in the communication area of the optical beacon 100 and the communication area of the optical beacon 100 exist. There is a downlink signal that identifies a vehicle and is transmitted for that identified vehicle.

  As shown in FIG. 2, the communication area of the various optical beacons 100 is a range on the road about 6 meters before and after, but as shown in FIG. 3, along the vehicle traveling direction, on the front side of the stable communication area. An unstable communication area is formed. In the unstable communication area, although the downlink signal from the optical beacon 100 is transmitted, the light intensity is weak and the area becomes unstable to receive. For this reason, the reception success rate in the stable communication region is high, whereas the reception success rate in the unstable communication region is low. As a result of the unstable communication area being formed in front of the stable communication area in this way, the vehicle enters the stable communication area after passing through the unstable communication area.

  The road-to-vehicle optical communication device 11 includes a data conversion unit 111. The data conversion unit 111 converts an electrical signal including various types of information into an infrared pulse signal for transmission to the optical beacon 100, while inversely converting the received infrared pulse signal into an electrical signal. Is. An electrical signal including various information inversely converted by the data conversion unit 111 is input to the control unit 17 and is notified to the user via the display device 15 and the audio output device 16.

  The road-to-vehicle optical communication device 11 determines whether or not the communication with the optical beacon 100 has ended based on whether or not a predetermined time has elapsed since the end of reception of the last information transmitted from the optical beacon 100. For example, when a downlink signal or various downlink signals transmitted from the optical beacon 100 are received within 3 seconds after the last information is received, it is determined that the information from the same beacon is being received. .

  The road-to-vehicle optical communication device 11 determines whether or not the transmitted uplink signal is received by the optical beacon 100. Whether the uplink signal is received by the optical beacon 100 is determined by whether the vehicle ID is included in the downlink signal transmitted from the optical beacon 100 after transmitting the uplink signal. When the own vehicle ID is included in the downlink signal, it is determined that the uplink signal is received by the optical beacon 100. When the own vehicle ID is not included in the downlink signal, the uplink signal is the optical beacon. 100 is determined not to be received. The road-to-vehicle optical communication device 11 does not transmit the uplink signal until it is determined that the communication with the optical beacon 100 is completed after it is determined that the uplink beacon 100 is received. This is because various downlink signals are intermittently transmitted from the various optical beacons 100, and accordingly uplink signals are prevented from being transmitted more than necessary.

  In the map data storage unit 12, route data 121 necessary for searching for a route to the destination, drawing data 122 necessary for drawing a map on the display device 15, and positions of various optical beacons 100 are stored in latitude. -Optical beacon position information 123 stored as longitude information, and although not shown, guidance images, audio data, and the like are stored. As the storage medium, a ROM (Read Only Memoly), a readable / writable hard disk, a memory, or the like can be used.

  In the route data 121, road map information is stored as network information including a node indicating a connection point and a link connecting the nodes in order to search for a route to the destination. For example, information such as an identification number assigned to each link or node, a road type, and the number of lanes is assigned to the link and node corresponding to each road and intersection. A cost based on these pieces of information is set for each link and node. Based on the network information and the cost stored in the route data 121, the control unit 17 performs an optimum route calculation to the destination using a known Dijkstra method or the like so that the product sum value of the cost is minimized.

The drawing data 122 includes polygon data of facilities such as roads, railways, buildings, private land, etc., background data for drawing terrain such as seas and rivers, and position information for various facilities existing on the map. The facility data which memorize | store etc. are memorize | stored.
The optical beacon position information 123 is information as shown in FIG. 4. For each optical beacon 100, the type of the optical beacon 100, the installation position of the optical beacon 100, the link number of the road where the optical beacon 100 is installed, etc. Contains information.

  The own vehicle position detection unit 13 receives a transmission radio wave from a GPS (Global Positioning System) via a GPS antenna to detect the own vehicle position and the current time, and a rotational motion applied to the vehicle. Is provided with a gyro sensor 132 for detecting the size of the vehicle and a vehicle speed sensor 133 for detecting the speed of the vehicle. The own vehicle position detection unit 13 calculates the current own vehicle position of the vehicle as a set of the position coordinates and the traveling direction based on each detection signal. And since these sensors 131-133 have the error from which a property differs, it is comprised so that the own vehicle position may be detected, mutually complementing. In addition, you may comprise the own vehicle position detection part 13 by the one part sensor mentioned above. Further, a geomagnetic sensor for detecting a traveling direction from geomagnetism, a steering rotation angle sensor, or the like may be added.

As the operation switch 14, a plurality of button switches provided around the display device 15 are used. The user can make various settings via the operation switch 14 and output the settings to the control unit 17.
The display device 15 is a liquid crystal display capable of color display. Various information such as information input by the user via the operation switch 14 and information received via the road-to-vehicle optical communication device 11 is displayed.

The voice output device 16 includes a speaker, and outputs various guidance voices based on guidance voice data stored in the map data storage unit 12.
The control unit 17 is mainly configured by a known microcomputer including a CPU, a ROM, a RAM, an I / O, a bus line connecting these components, and the like. And based on the program memorize | stored in ROM etc., the information display process which displays the information input by the user, the information received via the road-to-vehicle optical communication apparatus 11, etc. on the display apparatus 15, road-to-vehicle optical communication The apparatus 11 performs communication processing for executing transmission / reception of information with each optical beacon 100.

Next, the operation of the above configuration will be described.
When the road-to-vehicle optical communication device 11 is traveling outside the communication area of the optical beacon 100, is the reception standby state for receiving the downlink signal as shown in FIG. 8 (S1), and receives one frame of the downlink signal? Is monitored (S2: NO).
As shown in FIG. 5, the downlink signal has 133 bytes per frame, 1 byte synchronization code, 5 bytes header, 123 bytes data, 1 byte idle, 2 bytes CRC, 1 byte synchronization. It consists of a code.
The VICS optical beacon 100 intermittently transmits a VICS information signal (downlink signal) as shown in FIG.

  Now, when a vehicle approaches the optical beacon 100, first, the vehicle enters an unstable communication area. In this unstable communication area, the road-to-vehicle optical communication device 11 receives the VICS information signal from the optical beacon 100 in an unstable state. Here, when the VICS information signal is received, the road-to-vehicle optical communication device 11 normally transmits an uplink signal including ID information of the own vehicle, but happens to be VICS momentarily in an unstable communication region. Since an information signal may be received, the stable communication area is determined as follows.

  That is, when the road-to-vehicle optical communication device 11 receives the VICS information signal as shown in FIG. 8 (S2: YES), it starts a timer (several tens of milliseconds) (S3), and the next VICS information signal Reception is monitored (S4: NO, S5: NO). This timer is set to a time longer than the transmission interval of the VICS information signal from the optical beacon 100. If a vehicle happens to momentarily receive a VICS information signal while passing through an unstable communication area, it will time out without receiving the next VICS information signal because it will not receive the VICS information signal continuously. (S4: YES). In such a case, the road-to-vehicle optical communication device 11 shifts to a reception standby state for the VICS information signal (S1). Therefore, in a state where the vehicle passes through the unstable communication area, the reception standby state continues. Note that the flowchart shown in FIG. 8 shows only operations related to reception of downlink signals and transmission of uplink signals, and other operations are omitted.

  When the vehicle exits the unstable communication area and enters the stable communication area, the VICS information signal is continuously received, so the next VICS information signal is received before the time-out occurs after receiving the VICS information signal. (S5: YES). When the next VICS information signal is received before the time-out in this way, it is determined that the communication area (stable communication area) is reached (S6). That is, since the VICS information signal is received twice in succession (see FIG. 6), it is determined that the communication area is set, and the uplink signal is sent to the optical beacon 100 in response to the determination of the communication area. Is transmitted (S7) (see FIG. 6). The uplink signal includes an ID number for determining each vehicle individually, travel time measurement information indicating how long it took to travel a certain section, and the like. The travel time measurement information included in the uplink signal is used in VICS to grasp the road traffic situation such as which point is currently congested. In communication with the VICS, even when no uplink signal is transmitted, the main VICS information signal can be received and used on the vehicle side.

  Next, the road-to-vehicle optical communication device 11 starts a timer (3 seconds) (S8) and determines whether a downlink signal has been received before the time-out (S9: NO, S10: NO). When the vehicle exits the communication area, the downlink signal is not received by the time-out (S10: YES), so the operation is terminated, and the downlink signal reception standby state is entered by the next operation start (S1).

In short, a frame error rate can be calculated in a pseudo manner by confirming that a predetermined number of frames (two times in the present embodiment) of downlink signals can be continuously received within a predetermined time. It is possible to determine the communication area.
Thereafter, the traffic direction traffic jam information, travel time information, various restriction information, and the like are received from the optical beacon 100 and output to the control unit 17 of the car navigation apparatus 10. Thereby, various information from the optical beacon 100 can be provided to the user by the car navigation device 10.

  On the other hand, when a vehicle enters the communication area of the DSSS optical beacon 100, the road-to-vehicle optical communication device 11 receives a downlink signal transmitted from the DSSS optical beacon 100 as shown in FIG. When the road-to-vehicle optical communication device 11 continuously receives the downlink signal twice, the road-vehicle optical communication device 11 transmits the uplink signal to the DSSS optical beacon 100 in response to the second downlink signal reception. When the DSSS optical beacon 100 receives the uplink signal, the DSSS optical beacon 100 transmits a DSSS information signal including the ID number included in the uplink signal to the road-to-vehicle optical communication apparatus 11. When the received DSSS information signal includes an ID number indicating the own vehicle, the road-to-vehicle optical communication device 11 determines that the information is for the own vehicle and receives the information. In DSSS, unless an uplink signal is transmitted from the vehicle side, a main DSSS information signal cannot be received and used.

According to such an embodiment, the following effects can be produced.
The roadside-to-vehicle optical communication device 11 on the vehicle side determines that it is a communication area when it receives a downlink signal twice within a predetermined time and transmits an uplink signal. Reliability can be improved, and a problem that an unnecessary uplink signal is transmitted can be prevented.
Since the communication area is determined on the condition that the downlink signal is continuously received, the reliability of determining the communication area can be further improved.
Since the means for determining whether or not the downlink signal is continuously received is constituted by a software timer, it can be easily implemented.
Since the road-to-vehicle optical communication device 11 is built in the car navigation device 10 and the various information received by the road-to-vehicle optical communication device 11 from the optical beacon 100 is provided to the user using the notification function of the car navigation device 10. Compared to a configuration in which the road-to-vehicle optical communication device 11 is provided independently from the car navigation device 10, the overall configuration can be simplified.

(Other embodiments)
The present invention is not limited to the above embodiment, and can be modified or expanded as follows.
In the above-described embodiment, the communication area is determined when the downlink signal of one frame is continuously received twice. However, when the downlink signal of three or more predetermined times is continuously received. The communication area may be confirmed.
In the above embodiment, the communication area is determined when the downlink signal of one frame is received twice in succession. However, it is not necessary to be continuous, and a predetermined number of downlink signals are transmitted at a predetermined time. When it is received, it may be determined that it is a communication area.
The optical beacon 100 may be other than the VICS optical beacon and the DSSS optical beacon.

  In the drawings, 10 is a car navigation device, 11 is a road-to-vehicle optical communication device (vehicle road-to-vehicle optical communication device, transmitting means, receiving means, communication area determining means), and 100 is an optical beacon (optical communication roadside device).

Claims (4)

A receiving means (11) for receiving a downlink signal from the optical communication roadside device (100), and a communication area confirmation means for confirming that a communication area with the optical communication roadside equipment has been entered based on a reception state of the receiving means. (11) and a vehicular road-to-vehicle optical communication apparatus comprising: a transmission means (11) that transmits an uplink signal to the optical communication roadside device when the communication area determination means is determined to be a communication area; ,
The vehicular road-to-vehicle optical communication apparatus according to claim 1, wherein the communication area determination unit determines that the communication area is the communication area when a downlink signal from the optical communication roadside device is received a predetermined number of times within a predetermined time.   2. The vehicular road-to-vehicle optical communication apparatus according to claim 1, wherein the communication area determining means determines the communication area when a downlink signal is received a predetermined number of times continuously within a predetermined time. .   The communication area determining means starts a software timer when the first downlink signal is received, and continuously receives the downlink signal when the next downlink signal is received before the timer expires. The vehicular road-to-vehicle optical communication device according to claim 2, wherein:   A car navigation device comprising the vehicular road-to-vehicle optical communication device according to any one of claims 1 to 3.

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