JP3145886B2 - Optical in-vehicle communication device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-vehicle communication device, and more particularly to an on-vehicle optical communication device for performing two-way communication with an optical vehicle detector installed on a road.

[0002]

2. Description of the Related Art In recent years, individual movements of vehicles traveling on a road are accurately grasped, and traffic information such as detours and guidance is provided to a driver of the vehicle in real time. A new traffic control system that actively manages the flow of traffic by promoting the efficiency of transportation such as transportation has been proposed. In order to construct this new traffic control system, an optical vehicle detector is being put into practical use. For example, JP-A-5-31
Japanese Patent Application Laid-Open No. 2949 and JP-A-6-96387, an optical vehicle sensor having a function of detecting the presence of a traveling vehicle, collecting an ID of the traveling vehicle, and transmitting traffic information and the like to the traveling vehicle. Has been proposed.

FIG. 5 is a diagram showing a configuration example of a two-way communication system using such an optical vehicle sensor. In FIG. 5, an optical vehicle sensor including an optical vehicle sensor control unit 210 and an optical vehicle sensor light emitting / receiving unit 240 is installed on a road A. Optical vehicle sensor control unit 210
Is attached to a column 220 installed on the road A. The optical vehicle sensor light emitting / receiving unit 240 is supported by an upper part of the support 220 (for example, at a height of 5.5 m above the ground) and extends from the support 220 to the center of the lane.
30 is attached to the middle part.

[0004] The optical vehicle sensor light emitting / receiving section 240 is connected to a road A.
An optical signal composed of downlink data is projected thereon. The emitted light signal forms a vehicle sensing area X for measuring the number of passing vehicles and a communication area (light emitting area) Y for communicating with the optical in-vehicle communication device 110. In the communication area (light emitting area) Y, this area Y
There is a transmission area Z in which the optical in-vehicle communication device 110 mounted on the vehicle 100 that has entered the inside transmits an optical signal including uplink data to the optical vehicle sensor light emitting / receiving unit 240. As shown in FIG. 5, when the vehicle 100 equipped with the optical in-vehicle communication device 110 enters the communication area (light projecting area) Y, the optical in-vehicle communication device 110 acquires information of the vehicle 100, for example, the vehicle type. And tens to hundreds of bytes of data including information such as a vehicle ID such as a car number and a destination are transmitted as uplink data at a transmission speed of 64 kbps.

On the other hand, the optical vehicle sensor light emitting / receiving section 240
Upon receiving this uplink data, it transmits this data to the optical vehicle sensor controller 210. When the optical vehicle sensor control unit 210 receives the uplink data, it transmits several kilobytes of data corresponding to the uplink data, for example, including information such as road traffic information, regulation information, and route guidance information at a transmission rate of 1024 kbps. Optical vehicle sensor emitter / receiver 24 as downlink data
0 to the in-vehicle optical communication device 110.

[0006] The optical in-vehicle communication device 110 determines whether or not the received downlink data is information corresponding to the previously transmitted uplink data. When the corresponding information is received, the received downlink data is transmitted to the navigation device mounted on the vehicle 100, and the two-way communication is completed. In the case of an abnormality, that is, when information corresponding to the uplink data cannot be received,
The uplink data is transmitted again, and the above communication is repeated.

Here, as shown in FIGS. 5 and 6, the communication area (light emitting area) Y is about 3.5 in the lane width direction.
m, has a range of about 3.7 m in the traveling direction of the vehicle 100, and an R ₁ point located 5 m from a point P directly below the optical vehicle sensor light emitting / receiving unit 240 is a start point of the communication area Y,
The R ₂ point is the end point. The transmission area Z is about 3.5m in the lane width direction, has a range of about 1.6m in the traveling direction of the vehicle 100, R ₁ point is the start point of the transmission area Z, and the point S is the end point Become.

[0008] For example, now, the vehicle 100 has a speed of 70 km / h.
h, it takes about 190 ms for the vehicle 100 to pass the 3.7 m distance from the start point R ₁ to the end point R _{2 of the} communication area Y, and the start point R of the transmission area Z is required. _It takes about 82 ms to pass a distance of 1.6 m from _one point to the end point S.

[0009] The maximum number of downlink data is 80.
Of frames, and about 90 to transmit all frames
It takes ms (the time varies because the HDLC format has a variable length). Therefore, when the vehicle 100 is traveling at a speed of 70 km / h or less, it is possible to receive the same frame twice or more. If no easy communication abnormality occurs, no problem will occur.

[0010]

However, in the optical in-vehicle communication device 110 and the optical vehicle sensor light emitting / receiving unit 240 configured as described above, the optical signal composed of the uplink data is also the optical signal composed of the downlink data. Since the signal is also a full-duplex communication system using the same near-infrared light, when the optical in-vehicle communication device 110 is installed in the vehicle cabin, or the light receiving element of the receiving unit and the transmitting unit of the optical in-vehicle communication device 110 When the light emitting element and the light emitting element are housed in one case, reflection occurs in this case or a windshield of a vehicle,
Since the uplink data transmitted from the light emitting element of the transmitting unit goes around to the light receiving element of the receiving unit, a phenomenon occurs that the uplink data interferes with the downlink data.

When the uplink data and the downlink data interfere with each other, the uplink data, which is the transmission signal, is a stronger signal than the downlink data. Becomes Here, an example of a frame structure of a format conforming to the HDLC of the uplink data and the downlink data is shown in FIG. 7, in which a frame of this format has one byte at the beginning and the end of the frame. Are provided, and between each of these flag areas F, the downlink data is 12 bits.
The 8-byte data area and the uplink data are provided with a 27-byte data area, a 1-byte synchronization area, and a 2-byte error check area (CRC).

As described above, since the error check area (CRC) is provided in each data frame, the CR
By inspecting the C error check code and the received data, a reception error can be detected. The reception and transmission will be described with reference to FIG. In FIG. 8, FIG.
FIG. 8B shows a state of reception of downlink data, and FIG.
Indicates transmission of uplink data. The uplink data is composed of one frame shown in FIG.
The same transmission data (transmission 1, transmission 2,...) Such as the first transmission (transmission 1), the second transmission (transmission 2), the third transmission (transmission 3). To send. on the other hand,
The downlink data is composed of a plurality of frames (up to 80 frames) in FIG. 7, and includes first basic data (base 1), second basic data (base 2), and third basic data (base 2). 3) First additional data (Appendix 1), fourth basic data (base 4), second additional data (Appendix 2)
.. the same basic data (base 1, base 2, ...)
.) And the same additional data (Appendix 1, Appendices 2,...) Are continuously received.

Here, in the downlink data of FIG. 8, there is no additional data after the first basic data (base 1) and the second basic data (base 2) because the second uplink data After the transmission of (Send 2), the optical vehicle sensor light emitting / receiving section 240 receives the uplink data (Send 2) for the first time, and based on this reception, the optical vehicle sensor light emitting / receiving section 240 performs the third downlink. This is because the first additional data (Appendix 1) corresponding to the uplink data is transmitted after the basic data (base 3) at the time of data transmission.

Then, reception starts when the vehicle 100 enters the communication area Y, and stops when the vehicle 100 goes out of the communication area Y. The vehicle 100 is located in the transmission area Z.
The transmission is started by entering, and the transmission is stopped by leaving the communication area Y. As is apparent from FIG. 8, the transmission time of each of the uplink data of transmission 3, transmission 4, transmission 5 and transmission 6 in the uplink data is determined by appendix 1, appendix 2, appendix 3 of the downlink data. Since the reception time overlaps with each downlink data of Appendix 4 and Appendix 4, it becomes impossible to receive additional data.

As described above, when the transmission interval of the uplink data is transmitted at a fixed time interval of T1, there is a problem that the downlink data overlapping with the transmission of the uplink data cannot be received at all. Therefore, the present invention has been made in view of the above problems, and has as its object to make it possible to change the transmission cycle of uplink data every transmission.

[0016]

SUMMARY OF THE INVENTION The present invention is directed to a receiving means for receiving an optical signal containing downlink data emitted from an optical vehicle sensor installed on a road; An optical in-vehicle communication device including a transmission unit that transmits an optical signal including uplink data,
Level detection means for receiving a light signal of a predetermined level or more of a light signal including downlink data emitted from the optical vehicle sensor and transmitting a level detection signal for determining a communication area, switching select from the time table set in advance a plurality of transmission interval for each transmission the transmission interval time of the uplink data to which the transmitting means transmits
And a transmission interval time adjusting means for changing the transmission interval time .

[0017]

According to the present invention constructed as described above, the transmission of the uplink data transmitted by the transmitting means is performed.
Transmission interval time to switch selected from the time table set in advance a plurality of transmission intervals time interval for each transmission
Since the adjusting means is provided, every time uplink data is transmitted by the transmission interval time adjusting means, the transmission interval time of the uplink data changes. Thereby, the transmission time of the uplink data and the same data (for example, additional data) included in the downlink data
Will no longer overlap with the
All downlink data can be received.

[0018]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an overall configuration of an embodiment of a two-way communication system using an optical vehicle sensor according to the present invention. In FIG. 1, a two-way communication system using an optical vehicle sensor according to the present invention includes an optical vehicle sensor controller 2.
10, an optical vehicle sensor that transmits downlink data and receives uplink data, and an optical vehicle sensor that receives downlink data and transmits uplink data. It comprises a vehicle-mounted communication device 110 and a navigation device 140 that combines downlink data received by the optical vehicle-mounted communication device 110 with a navigation screen and displays the combined data.

The optical vehicle sensor comprises an optical vehicle sensor control section 210 and an optical vehicle sensor light emitting / receiving section 240. The optical vehicle sensor light emitting / receiving unit 240 includes, based on a control command from the optical vehicle sensor control unit 210, a light emitting element 241 including an LED that emits an optical signal of downlink data corresponding to the uplink data. , A light receiving element 24 comprising a photodiode for receiving the uplink data transmitted from the optical in-vehicle communication device 110
And 2. In addition, the optical vehicle sensor control unit 210 transmits several kilobytes of data including information such as road traffic information, regulation information, and route guidance information, corresponding to the uplink data received by the light receiving element 242. The downlink data is transmitted to the light emitting element 241 at 1024 kbps.

On the other hand, the optical in-vehicle communication device 110 receives the optical signal of the downlink data emitted from the light emitting element 241 of the optical vehicle sensor light emitting / receiving unit 240, and converts the received optical signal into an electric signal. A light receiving element 111 composed of a photodiode for converting the data into downlink data converted by the light receiving element 111 into an electric signal.
, A transmission unit 110 that sends a transmission command to the transmission unit 110b based on downlink data, and a processing unit 120 that performs various arithmetic processes, and sends uplink data based on a transmission command from the processing unit 120. Transmission unit 1
10b, and converts the uplink data into an optical signal, and converts the converted optical signal into an optical vehicle sensor light emitting / receiving unit 240
And a light emitting element 118 composed of an LED for transmission toward Note that the light emitting element 118 made of an LED
Uses an LED element that emits near-infrared light having a wavelength of 850 nm or 950 nm.

FIG. 2 is a block diagram showing the overall configuration of one embodiment of the receiving section of FIG. In FIG. 2, the receiving unit 11
Reference numeral 0a denotes an amplifying unit 112 that amplifies an electric signal obtained by converting an optical signal composed of downlink data received by the light receiving element 111 into an electric signal, and converts the amplified electric signal into a split phase code (or Manchester code, A data demodulation unit 113 that demodulates the data into a bi-phase code), reproduces a stable clock signal (CK) from the demodulated split-phase code, and outputs the reproduced clock signal (CK) to the processing unit 120. And a clock reproducing unit 115.

The receiving section 110a is provided with the data demodulating section 1
13 is converted to a clock signal (C) reproduced by the clock reproducing unit 115.
K), a code conversion unit 114 that converts the data into an NRZ code and outputs the data to the processing unit 120 as a received data signal (RD).

The receiving section 110a compares the signal amplified by the amplifying section 112 with a carrier detection level (for example, 3 μW / cm ² ) set to a predetermined detection level to set a light receiving signal. And a level detection unit 116 that sends a carrier detection signal (LD) (see FIG. 6) to the processing unit 120 when the carrier detection level (for example, 3 μW / cm ² ) or more is reached.

Further, the transmitting unit 110b (see FIG. 1)
A driving circuit (not shown) for driving the light emitting element 118 composed of an LED which receives the uplink data signal (SD) from the processing unit 120 and converts the uplink data signal (SD) into an optical signal is provided.

The processing unit 120 (see FIG. 1)
It is constituted by a known microcomputer including U, ROM, RAM, etc., and includes a downlink data signal (RD) output from the code conversion unit 114, a clock signal (CK) output from the clock recovery unit 115, The carrier detection signal (L
D) is input to perform various data processing, and the vehicle 10
0, for example, an uplink data signal (SD) of several tens to several hundreds of bytes consisting of information such as a vehicle ID such as a vehicle type and a vehicle number, and a destination, etc.
Output at speed. The data processing program is stored in the ROM of the processing unit 120 in advance.

FIG. 3 is a flowchart for executing a data processing program of the processing section 120. In step 300 of FIG. 3, execution of this processing program is started. Then, the process proceeds to step 302, where step 30 is executed.
In 2, it is determined whether or not a carrier detection signal (LD) (see FIG. 6) is output from the level detection section 116,
If “YES” is determined, that is, the light receiving element 111
If it is determined that the level of the received light signal has become equal to or higher than the set carrier detection level (for example, 3 μW / cm ² ) and communication with the optical vehicle sensor light emitting / receiving unit 240 is enabled, The reception of the link data signal (RD) is started, and the process proceeds to the next step 304. Step 3
In 02, when the determination is “NO”, that is, when the level of the light receiving signal received by the light receiving element 111 is lower than the set carrier detection level (for example, 3 μW / cm ² ), the vehicle 100 performs communication. since (in the case of FIG. 5 R ₁ point) area Y does not reach the repeats the above process.

In step 304, the vehicle 100
Is (in the case of FIG. 5 R ₁ point) transmission area Z so has been reached, starts transmission of uplink data. After the transmission of the uplink data signal (SD), the process proceeds to step 306. In this step 306, the uplink data signal (SD) including the own vehicle ID transmitted in step 304 in the received downlink data signal (RD). It is determined whether or not data corresponding to is included. That is,
In step 306, the ID code included in the additional data of the received downlink data signal (RD) (see appendix 1 and appendix 2 in FIG. 4) is checked, and step 304
It is determined whether or not the own vehicle ID included in the transmitted uplink data signal (SD) is included.

If "YES" is determined in the step 306, that is, if the received downlink data signal (RD) includes the own vehicle ID, the process proceeds to the next step 308, where the step 308 is executed. In, the transmission operation is determined to be completed and the transmission operation is stopped. Then, the process proceeds to step 310, where it is determined whether or not all the received uplink data signals (SD) have been received. If “YES” is determined in the step 310, the process proceeds to the next step 318. If "NO" is determined in the step 310, that is, the received uplink data signal (SD)
Are not completed, and this process is repeated.

If "NO" is determined in this step 306, that is, if the received downlink data signal (RD) does not include the own vehicle ID, the process proceeds to the next step 312. In this step 312, the transmission interval time T1 set in the time table in advance,
One transmission interval time Tn is selected from T2, T3, and so on. Then, proceed to step 314,
It is determined whether the transmission interval time Tn selected at 12 has elapsed. If “YES” is determined in step 312, that is, if the transmission interval time Tn selected in step 312 has elapsed, the next step 31
Proceed to 6. If "NO" is determined in the step 314, that is, since the transmission interval time Tn selected in the step 312 has not elapsed, this process is repeated.

Here, as shown in FIG. 4, the transmission interval time Tn in step 312 is selected in the order of transmission interval times T1, T2, T3... The selection of the transmission interval time Tn is as follows.
The transmission interval time such as T1, T2, T3, etc. may be randomly selected. Alternatively, the transmission interval time may be fixed to two of T1 and T2, and T1 and T2 may be alternately selected. Note that T1, T2, T
A specific example of the transmission interval time such as 3... Is longer than the transmission time of the uplink data, for example, 30 ms, 35 m
s, 40 ms, 45 ms, etc.

In step 316, it is determined whether or not the carrier detection signal (LD) (see FIG. 6) is still output from the level detection section 116. This step 316
Is "YES", ie, the light receiving element 1
11, the level of the received light signal is equal to or higher than a set carrier detection level (for example, 3 μW / cm ² );
If the vehicle 100 is still present in the communication area Y (in the case of FIG. 5 does not reach the _two-point R), the process returns to step 304, the above-mentioned step 304 to step 31
The processing up to 6 is repeated. “NO” in step 316
If it is determined that, i.e., if the vehicle 100 has passed the communication area Y (if in the case of FIG. 5 beyond the _two-point R), the processing proceeds to the next step 318.

As described above, when the process proceeds to step 318, the receiving operation is stopped in this step 318, and the received downlink data signal (RD) is transmitted to the navigation device 140. Then, the process proceeds to step 320, where the two-way communication is terminated.

In the present embodiment configured as described above, the transmission interval time T1 set in the time table in advance,
One transmission interval time Tn is selected from T2, T3, etc., and the uplink data signal (SD) is transmitted after the selected transmission interval time Tn has elapsed. Transmission time of the uplink data signal (SD) (see transmission 1, transmission 2, and transmission 3 in FIG. 4).
Does not overlap with the reception timing of the additional data of the downlink data signal (RD) (refer to Appendix 1 and Appendix 2 in FIG. 4), and all downlink data signals (RD)
Can be received.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of an embodiment of a two-way communication system using an optical vehicle sensor according to the present invention.

FIG. 2 is a block diagram illustrating an overall configuration of an embodiment of a receiving unit in FIG. 1;

FIG. 3 is a flowchart showing an operation of the optical in-vehicle communication device in FIG. 1;

4A and 4B are diagrams illustrating a configuration of transmission / reception data according to the present invention, FIG. 4A is a diagram illustrating a configuration of downlink data, and FIG. 4B is a diagram illustrating a configuration of uplink data.

FIG. 5 is a diagram illustrating a configuration example of a two-way communication system using an optical vehicle sensor.

6 is a diagram showing a relationship between a reception position and a light reception level, and a relationship between a reception position and a carrier detection level of the optical on-vehicle communication device in FIG.

FIG. 7 is a diagram showing a configuration of a format of downlink data.

FIG. 8 is a diagram showing a configuration of conventional transmission / reception data;
(A) is a diagram showing a configuration of downlink data,
(B) is a figure which shows the structure of uplink data.

[Explanation of symbols]

110: Optical in-vehicle communication device, 110a: Receiver, 11
0b: transmission unit, 120: processing unit (data processing means), 1
40 navigation device, 210 optical vehicle sensor control unit, 240 optical vehicle sensor light emitting / receiving unit

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-5-312949 (JP, A) JP-A 8-180293 (JP, A) JP-A-6-112902 (JP, A) JP-A 8- 195716 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G08G 1/09 G01S 17/93 H04B 10/10 H04B 10/105 H04B 10/22

Claims (2)

(57) [Claims] 1. A receiving means for receiving an optical signal including downlink data emitted from an optical vehicle sensor installed on a road, and a light including uplink data toward the optical vehicle sensor. An optical in-vehicle communication device provided with a transmitting unit for transmitting a signal, the optical vehicle receiving device receiving an optical signal of a predetermined level or more of an optical signal including downlink data emitted from the optical vehicle sensor. Level detection means for transmitting a level detection signal for determining a communication area, and a transmission interval of uplink data transmitted by the transmission means
Optical-vehicle communication apparatus characterized by comprising a transmission interval time adjusting means for switching to select a time from the time table set in advance a plurality of transmission interval for each transmission. As claimed in claim 2, wherein the transmission interval time adjusting means, feeding at least two transmission interval time from the time table
2. The optical in-vehicle communication according to claim 1, further comprising means for selecting and fixing each transmission signal, and alternately switching the two transmission intervals to determine the transmission interval of the uplink data. apparatus.