JP2008292347A - On-vehicle optical beacon device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an on-vehicle optical beacon device, surely acquiring down link data. <P>SOLUTION: Since a first frame 62a cannot be received normally, uplink is inhibited in a time zone when the next first frame 62e is being transmitted. Since a second frame 62b is received normally, uplink 63a is performed in a time zone when the next second frame 62f is being transmitted. Since a third frame 62c cannot be received normally, uplink is inhibited in a time zone when the next third frame 62g is being transmitted. Since a fourth frame 62d is received normally, uplink 63b is performed in a time zone when the next fourth frame 62h is being transmitted. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an in-vehicle optical beacon device that performs bidirectional communication using an optical signal with an optical beacon device installed on a road.

An optical beacon that performs two-way communication using a near infrared ray with a wavelength of 850 nm between a road device installed on the road and an on-vehicle device installed in an automobile is known as a conventional technique (for example, Patent Document 1).
Japanese Patent Laid-Open No. 10-332803

  In a conventional optical beacon such as Patent Document 1, the near-infrared wavelength when performing uplink and the near-infrared wavelength when performing downlink are both 850 nm and are the same. For this reason, when the downlink and the uplink overlap each other, near-infrared mutual interference occurs, and the in-vehicle device may not be able to acquire a part of the downlink data.

(1) The in-vehicle optical beacon device according to the first aspect of the present invention includes a receiving unit that receives downlink data repeatedly transmitted from the road optical beacon device, and a determination unit that determines normal reception of the downlink data by the receiving unit. Characterized in that it comprises a calculating means for calculating a transmission timing of downlink data for which the normal reception is determined by the determining means, and a transmitting means for transmitting the uplink data to the roadside optical beacon device at the transmission timing. To do.
(2) The invention according to claim 2 is the in-vehicle optical beacon device according to claim 1, wherein the determining means determines normal reception of the downlink data by the receiving means for each frame constituting the downlink data, and calculates The means is characterized in that a transmission timing at which a frame determined to have been normally received by the determination means is transmitted from the next time by the road optical beacon device is calculated.
(3) A third aspect of the present invention is the in-vehicle optical beacon device according to the second aspect, in which the calculation means determines that the determination means normally receives the frame based on the information of the header part constituting the frame. Is characterized in that the transmission timing transmitted next time or later by the road light beacon device is calculated.
(4) The invention of claim 4 is the vehicle-mounted optical beacon device according to claim 2, wherein the calculating means is normal by the determining means based on the reception time of a predetermined frame among the frames constituting the downlink data. It is characterized in that a transmission timing at which a frame determined to be received at a later time is transmitted from the next time by the road optical beacon device is calculated.
(5) The invention according to claim 5 is the in-vehicle optical beacon device according to claim 4, wherein the predetermined frame is a head frame among frames constituting downlink data.

  According to the present invention, the uplink is performed at the transmission timing of the next and subsequent downlink data that can be normally received, so that the downlink data can be acquired with certainty.

  An outline of the configuration of the in-vehicle optical beacon device 1 according to the embodiment of the present invention will be described with reference to FIG. The in-vehicle beacon device 1 transmits information such as a vehicle ID to an optical beacon device (hereinafter referred to as an on-road optical beacon device) provided on a road by near-infrared bidirectional communication. Receive traffic information. As shown in FIG. 1, the in-vehicle optical beacon device 1 includes a microcomputer 11, a ROM 12, a RAM 13, an infrared light receiver 14, a receiver circuit 15, an infrared light emitter 16, and a transmitter circuit 17. The in-vehicle optical beacon device 1 is connected to a navigation device (not shown).

  The microcomputer 11 includes a microprocessor and its peripheral circuits, and performs various controls by executing a control program stored in the ROM 12 using the RAM 13 as a work area. Further, the microcomputer 11 converts the electrical signal output from the receiving circuit 15 into information such as traffic information, and outputs the converted information to a navigation device (not shown). Moreover, information, such as vehicle ID for transmitting to a road light beacon apparatus, is converted into an electric signal, or the light emission timing of the infrared light emission part 16 is instruct | indicated.

  The infrared light receiving unit 14 is composed of a photodiode, and receives the infrared light emitted from the road light beacon device. The received infrared light is converted into an electrical signal and output to the receiving circuit 15. The receiving circuit 15 amplifies the electrical signal output from the infrared light receiving unit 14 and outputs the amplified signal to the microcomputer 11.

  The infrared light emitting unit 16 includes a near-infrared LED as a light-emitting element, and transmits an optical signal modulated from the near-infrared LED to a road light beacon device. The transmission circuit 17 controls driving of the near infrared LED.

  Next, the uplink region and the downlink region will be described with reference to FIG. The projector / receiver 21 of the road light beacon device will be described as being provided at a height of 8.0 m. When the vehicle 22 approaches a distance of 6.9 m from the position on the road surface of the projector / receiver 21, the vehicle 22 enters the uplink region and the downlink region. In this region, uplink and downlink are performed between the road light beacon device and the vehicle-mounted light beacon device 1. After the vehicle 22 enters the uplink area and passes 1.6 m, the uplink area ends. When the vehicle 22 passes through the uplink region, the uplink is not performed in principle, but the uplink is performed when the road light beacon device has not received the uplink data. When the vehicle 22 approaches a distance of 3.2 m from the position on the road surface of the light emitter / receiver 21, the vehicle 22 passes through the downlink region and is performed between the road light beacon device and the vehicle-mounted light beacon device 1. Uplink and downlink are terminated.

  Next, with reference to FIG. 3, the downlink data structure transmitted by the downlink of a road optical beacon apparatus is demonstrated. The downlink data is composed of a plurality of information types, and each information type is composed of one or a plurality of frames 40 configured as shown in FIG. For example, as shown in FIG. 3, the downlink data 30 includes lane notification information, current location information, connection network information, emergency message information, caution warning information, message information, simple graphic 1 information, simple graphic 2 information, parking information. The parking lot information, event regulation link information, center network failure notification information, failure information, and traffic jam link information are included.

  The downlink data 30 is repeatedly transmitted from the road optical beacon device 21. When the road optical beacon device receives the uplink of the in-vehicle optical beacon device 1, from the start of uplink reception to 250 milliseconds after the last uplink reception. The downlink data 30 includes traffic jam / travel time link information instead of traffic jam link information.

  When one information type is composed of a plurality of frames, all the information type data is obtained by continuously connecting the actual data portions of frames ordered by a header portion described later. The total number of frames of the downlink data 30 is 80 at maximum.

  The configuration of the frame 40 will be described with reference to FIG. The frame 40 includes a transmission control unit (synchronization), a header unit, an actual data unit, and a transmission control unit (CRC or the like). The transmission control unit (synchronization) stores a bit synchronization code. The header portion stores data representing the contents of the frame. Information type data of each information type is stored in the actual data part. The number of data in the actual data part is fixed at 123 bytes. Therefore, when the information type data exceeds 123 bytes, the information type is composed of a plurality of frames. The transmission control unit (CRC or the like) stores an idle fixed code, an error test code up to idle, and a bit synchronization code.

  The configuration of the header part will be described with reference to FIG. The header unit 50 includes a standard flag, an information flag, an information type, provision time information, a last frame flag, a frame number within the same information type, a frame data valid data length, a one frame time, and a total number of downlink frames. Yes.

  As the standard flag, a flag indicating whether the frame information standard is the UTMS (Universal Traffic Management System) standard or outside the UTMS standard is used. As the information flag, a flag indicating whether the data of the frame is operation data or test data is stored. The information type is an ID indicating the information type. As the provision time information, the time when the data is edited at the information center is used. As the final frame flag, a flag indicating whether or not it is the final frame among a plurality of frames constituting the information type is used. The frame number within the same information type is a sequence number among a plurality of frames constituting the information type. The frame data valid data length represents the number of valid data bytes in the actual data portion of 123 bytes. One frame time is the time required to transmit one frame. The total number of downlink frames is the total number of frames constituting the downlink data.

  Next, uplink processing of the in-vehicle optical beacon device 1 according to the embodiment of the present invention will be described with reference to FIG. FIG. 6 is a diagram for explaining the transmission timing of the frames constituting the downlink data transmitted from the roadside optical beacon device and the transmission timing of the frames constituting the uplink data transmitted from the in-vehicle optical beacon device 1. It is.

  In this example, the first downlink data composed of four frames 62a to 62d and the second downlink data composed of four frames 62e to 62h are continuously transmitted from the road beacon device. Sent. That is, eight frames 62 a to 62 h are sequentially transmitted according to the arrow 61.

  Then, the in-vehicle optical beacon device 1 cannot normally receive the first frame 62a and the third frame 62c indicated by white characters in the first downlink data reception process, and the black-out characters are black. The second frame 62b and the fourth frame 62d indicated by characters are normally received. Whether or not the frame has been successfully received is determined, for example, based on whether or not the number of bytes of the received frame is the original number of bytes.

  On the other hand, from the in-vehicle optical beacon device 1, the first uplink data composed of one frame 63a and the second uplink data composed of one frame 63b are predetermined as described in detail below. It is transmitted at the timing. As described above, there is a mutual interference between the downlink and uplink performed between the road light beacon device and the in-vehicle optical beacon device 1, and a problem of poor reception of downlink data occurs. Therefore, the present inventors have conceived that the reception failure due to mutual interference is resolved if uplink data is not transmitted at the timing of transmitting downlink data.

  In the example illustrated in FIG. 6, the first frame 62 a and the third frame 62 c that are not received by the in-vehicle optical beacon device 1 in the first downlink data reception process are the first frame of the second downlink data. 62e and the third frame 62g. Therefore, it is possible to solve reception failure due to mutual interference without transmitting uplink data at the timing of transmitting the first frame 62e and the third frame 62g of the second downlink data.

  That is, at the timing when the first frame 62e of the second downlink data is transmitted from the road light beacon device, the in-vehicle light beacon device 1 is prevented from performing uplink. As a result, the infrared rays that transmit the first frame 62e from the roadside optical beacon device and the infrared rays that transmit uplink data do not cause mutual interference, and the in-vehicle optical beacon device 1 can normally receive the first frame 62e. it can.

  When the in-vehicle optical beacon device 1 uplinks the first frame 63a at the timing of transmitting the second frame 62f of the second downlink data from the road light beacon device, the second frame 62f of the downlink data is transmitted. There is a possibility that the infrared ray to be transmitted and the infrared ray to transmit the first frame 63a of the uplink data cause mutual interference, and the second frame 62f of the downlink data may not be normally received. However, the second frame 62b is already normal. Therefore, there is no problem even if the second frame 62f cannot be normally received.

  As described above, the frame of the first downlink data that could not be received by the in-vehicle optical beacon device 1 is received by the corresponding frame of the second downlink data. Therefore, the transmission timing of the first frame 62e and the third frame 62g of the second downlink data is calculated in the following step S702, and uplink data is not transmitted at that timing.

  The uplink process of the in-vehicle optical beacon device 1 in one embodiment will be described with reference to the flowchart of FIG. The processing in FIG. 7 is performed by the microcomputer 11 executing a program that starts when the vehicle approaches the road light beacon device and starts receiving downlink data.

  In step S701, it is determined whether a downlink data frame has been normally received. Whether or not the frame has been normally received is determined from the number of bytes of the received data. For example, for a frame that is 135-byte data, if the number of bytes of received data is 135 bytes, it is determined that the frame has been normally received. However, if the received data is 134 bytes or less, it is determined that the reception was not successful. When the downlink data frame is normally received, an affirmative determination is made in step S701, and the process proceeds to step S702. If the downlink data frame is not normally received, a negative determination is made in step S701, and the process proceeds to step S703.

  In step S702, a time zone during which the in-vehicle optical beacon device 1 performs uplink (hereinafter referred to as an uplink time zone) is calculated. The uplink time zone is calculated as follows. The one frame time of the header part 50 of the frame 40 and the total number of downlink frames (see FIG. 4) are read out. Then, n times (n = 1, 2, 3,...) That is a time obtained by multiplying the time of one frame time by the total number of downlink frames is added to the reception start time of a normally received frame. The time calculated in this way becomes the start time of the uplink time zone. Furthermore, the time obtained by adding the time of one frame time to the start time becomes the end time of the uplink time zone. The road light beacon device repeatedly transmits a total frame every time information is transmitted. Therefore, the time zone calculated as described above is a time zone in which a normally received frame is transmitted from the road optical beacon device.

  In step S703, it is determined whether or not the current time is an uplink time zone. If the current time is the uplink time zone, an affirmative determination is made in step S703 and the process proceeds to step S704. If the current time is not an uplink time zone, a negative determination is made in step S703, and the process returns to step S701. In step S704, uplink is performed. In step S705, it is determined whether or not the current time is an uplink time zone. If the current time is the uplink time zone, an affirmative determination is made in step S703 and the process returns to step S704. If the current time is not an uplink time zone, a negative determination is made in step S705, and the process proceeds to step S706. In step S706, the uplink is terminated.

  In step S707, it is determined whether or not traffic jam / travel time link information has been received for the information type constituting the downlink data. When the road light beacon device receives the uplink, the traffic light / travel time link information is transmitted instead of the traffic congestion link information. Therefore, it is possible to determine whether or not the road light beacon device has received the uplink by the above determination. When the traffic jam / travel time link information is received, an affirmative determination is made in step S707, and the uplink processing ends. If the traffic jam / travel time link information is not received, a negative determination is made in step S707, and the process returns to step S701.

The vehicle-mounted optical beacon device 1 according to the embodiment described above has the following operational effects.
(1) With respect to downlink data that can be normally received, uplink is performed in a time zone (transmission timing) transmitted next from the road optical beacon device. Thereby, it is possible to prevent the downlink data that could not be normally received due to the mutual interference between the downlink and the uplink from being normally received again. Therefore, downlink data can be acquired with certainty.

(2) Uplink is performed in the next transmission time zone of a frame that can be normally received. In the downlink, since the total frames constituting the downlink data are repeatedly transmitted, it is possible to calculate a time zone in which a frame that can be normally received is transmitted next time. Therefore, uplink can be reliably performed in a time zone in which a frame in which downlink data can be normally received is transmitted from the roadside optical beacon device.

(3) Since the time zone for transmitting the uplink data is calculated based on the information of the header part 50 constituting the frame 40, the time zone for performing the uplink immediately after the frame 40 is normally received. Can be calculated.

The above embodiment can be modified as follows.
(1) Although the next transmission time zone of a frame that can be normally received is calculated, the transmission timing after the next time may be calculated. Further, the calculating means may be configured to calculate the next transmission time zone of a frame that can be normally received based on, for example, the reception time of a predetermined frame among the frames constituting the downlink data 30. Good. It is assumed that reception is started normally after t1 seconds from the end of reception of the reference first frame, and reception is completed normally after t2 seconds from the end of reception of the first frame. In this case, a time period from t1 seconds after the completion of the first frame reception to t2 seconds after the completion of the first frame reception is a time period for performing uplink. Therefore, when the first frame is received again, the uplink is started after t1 seconds from the end of reception of the first frame, and the uplink is ended after t2 seconds from the end of reception of the first frame. In particular, by using the reception time of the first frame of downlink data (the frame of lane notification information) as a reference, even if the cycle for repeatedly transmitting the total frame changes slightly, the frame that could be received normally Uplinks can be performed during the time period of transmission.

(2) When a plurality of downlink data are repeatedly transmitted from the optical beacon device on the road, the timing for performing the uplink may be determined not in units of frames but in units of downlink data. As shown in FIG. 8, a case will be described in which downlink data A composed of frames A1 to A4 and downlink B composed of frames B1 to B4 are repeatedly transmitted according to an arrow 81. Similar to the above-described embodiment, it is assumed that a frame of white characters can be normally received and a frame of black characters cannot be normally received. As shown in FIG. 8, in the transmission 82a of the first downlink data A, all the frames A1 to A4 could be normally received. Next, in the transmission 82b of the first downlink data B, the frame B1 and the frame B3 could not be received normally. Therefore, the uplink C1 is repeatedly performed at the timing of the second downlink data A transmission 82c, and the uplink is not performed at the timing of the second downlink data A transmission 82d. When a plurality of downlink data is repeatedly transmitted from the optical beacon device on the road, if uplink is performed in units of downlink data, the uplink can be repeatedly performed continuously, which may be efficient.

  The above description is merely an example, and the present invention is not limited to the above embodiment.

The correspondence between the elements of the claims and the embodiments will be described.
The receiving means of the present invention corresponds to the infrared light receiving unit 14 and the receiving circuit 15, and the determining means and calculating means correspond to the microcomputer 11. The transmission means corresponds to the infrared light emitting unit 16 and the transmission circuit 17. In addition, the above description is an example to the last, and when interpreting invention, it is not limited to the correspondence of the component of said embodiment and the component of this invention at all.

It is a block diagram which shows the structure of the vehicle-mounted optical beacon apparatus by one Embodiment of this invention. It is a figure for demonstrating an uplink area | region and a downlink area | region. It is a figure for demonstrating the data structure of downlink data. It is a figure for demonstrating the structure of a flame | frame. It is a figure for demonstrating the structure of a header part. It is a figure for demonstrating the uplink process of the vehicle-mounted optical beacon apparatus in embodiment of this invention. It is a flowchart for demonstrating the uplink process of the vehicle-mounted optical beacon apparatus in embodiment of this invention. It is a figure for demonstrating the modification of the uplink process of a vehicle-mounted optical beacon apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle-mounted optical beacon apparatus 11 Microcomputer 14 Infrared light-receiving part 16 Infrared light-emitting part 21 The light transmitter / receiver 22 of a road light beacon apparatus Vehicle 30, 82a-82d Downlink data 40, 62a-62h, 63a, 63b Frame 50 Header part

Claims (5)

Receiving means for receiving downlink data repeatedly transmitted from the road optical beacon device;
Determining means for determining normal reception of downlink data by the receiving means;
A calculating means for calculating a transmission timing for the next and subsequent downlink data for which normal reception is determined by the determining means;
An in-vehicle optical beacon device comprising: a transmission unit that transmits uplink data to the road optical beacon device at the transmission timing. The in-vehicle optical beacon device according to claim 1,
The determining means determines normal reception of downlink data by the receiving means for each frame constituting the downlink data,
The on-vehicle optical beacon device characterized in that the calculating means calculates a transmission timing at which a frame determined to have been normally received by the determining means is transmitted by the road optical beacon device from the next time onward. The in-vehicle optical beacon device according to claim 2,
The calculation means calculates a transmission timing at which a frame determined to have been normally received by the determination means is transmitted next time or later by the road optical beacon device based on information of a header part constituting the frame. An in-vehicle optical beacon device. The in-vehicle optical beacon device according to claim 2,
The calculation means transmits a frame determined to have been normally received by the determination means based on a reception time of a predetermined frame among frames constituting the downlink data, from the next time onward by the road optical beacon device. A vehicle-mounted optical beacon device that calculates a transmission timing to be transmitted. The in-vehicle optical beacon device according to claim 4,
The in-vehicle optical beacon device, wherein the predetermined frame is a head frame among frames constituting the downlink data.

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