JP2014042154A - Vehicle-to-vehicle optical communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle-to-vehicle optical communication device that can improve communication quality by obtaining an optimal irradiation characteristic while restraining wasteful power consumption.SOLUTION: A vehicle-to-vehicle optical communication device performs optical communication between a preceding vehicle and a subsequent vehicle in such a way that a light-emitting element 7 provided in a light-emitting unit 6 of an optical communication transmitter/receiver 1 mounted on a vehicle 20 irradiates light and an optical communication transmitter/receiver 1 mounted on another vehicle 20 receives the light. The light-emitting unit 6 of the optical communication transmitter/receiver 1 is built up with components including a plurality of light-emitting elements 7 arranged in an array shape and a lens 8 controlling their light distribution, and the vehicle-to-vehicle optical communication device is provided with a control unit 11 for controlling driving of the light-emitting elements 7 on the basis of at least information on distance between vehicles and information on disturbance light.

Description

  The present invention relates to an inter-vehicle optical communication device for transmitting and receiving various information between a preceding vehicle and a succeeding vehicle by optical communication.

  Conventionally, an inter-vehicle optical communication device that transmits and receives various kinds of information to and from the same type of optical communication device mounted on another vehicle by optical communication has been proposed (for example, see Patent Documents 1 and 2). This inter-vehicle optical communication device includes a light emitter that transmits communication light used for optical communication, and a receiver that receives communication light transmitted from the light emitter, and blinks the light emitter, for example. In this way, a predetermined message is sent to the preceding vehicle and the following vehicle that run forward and backward, and the preceding vehicle and the following vehicle can receive the message by the receiver.

By the way, the inter-vehicle optical communication technology was developed at the Aichi Expo held in 2005 in the next generation transportation system IMTS (Intelligent
Multimode Transit System) (see Non-Patent Documents 1 and 2).

  Thus, such an inter-vehicle optical communication device is mounted on a vehicle traveling on the road, and is assumed to be used outdoors. For this reason, optical communication by the inter-vehicle optical communication device is easily affected by disturbance light such as sunlight, and communication quality may be deteriorated. As a method of mitigating the influence of such disturbance light, an optical filter or a method of applying frequency modulation to communication data is used, but it is impossible to completely eliminate the influence of strong disturbance light such as sunlight. Impossible.

  Therefore, Patent Document 3 discloses the position of the sun, the position of the sun, and the illuminance due to sunlight calculated based on the vehicle position information such as the traveling direction, gradient, and altitude of the vehicle, the current time data, the coordinate data at the current position of the vehicle, etc. Based on the above, it is determined whether or not sunlight is in a state of affecting optical communication, and if it is determined that there is an influence of sunlight, the reception sensitivity of communication light used for optical communication is reduced, There has been proposed an optical communication apparatus that increases the light emission output at a light receiving unit for communication light.

  Patent Documents 4 and 5 describe optical communication in which the intensity of disturbance light around a communication device is measured, and the light emitting element is controlled to convert communication data into an optical communication signal having emission intensity corresponding to the intensity of disturbance light. A device has been proposed.

Patent Document 6 proposes an arrangement structure of light emitting diode units of a light transmitter. According to this, good horizontal directivity characteristics can be obtained by optimally setting the bonding direction of the light emitting diode.
Proposed.

JP-A-11-053689 Japanese Patent No. 40322253 JP 2007-304696 A JP 2001-0777759 A JP 2002-300113 A JP-A-9-246600 TOYOTA Technical Review Vol.51 No.2 Railway Research Review February 2008 “Current Status of Development of Automated Driving Bus IMTS” published by Railway Technology Research Institute

  However, in the optical communication device proposed in Patent Document 3, vehicle position information is acquired using a GPS device and a map DB (database), but there is a problem that the position information lacks accuracy. That is, it is impossible to obtain vehicle position information in places where a necessary number of GPS satellites cannot be seen, such as tunnels and mountainous areas. In addition, when the disturbance light is removed based on the sun position information, the S / N ratio is deteriorated in the absence of disturbance light such as sunlight, such as when it is cloudy or running in the shade. is there. And since the position information acquisition apparatus, direction acquisition apparatus, solar position calculation apparatus, etc. which comprise parts other than an optical communication apparatus are needed as a structure of the whole system, an apparatus enlarges and costs up.

  According to the optical communication device proposed in Patent Document 4, it is necessary to separately provide an optical sensor that measures the intensity of ambient disturbance light, which increases the size and cost of the device. In a communication device, it is necessary to provide background light intensity detection means and feed back the information obtained from the background light intensity detection means to the optical communication device, which increases the number of communication paths and increases the size and complexity of the device. In addition, there is a problem of increasing the cost.

  According to the configuration proposed in Patent Document 6, the light distribution characteristic in the horizontal direction becomes symmetrical by optimizing the direction of the light emitting diode, but since the same amount of light is irradiated in the vertical direction, A large amount of light is radiated to a place where it is not necessary, and power is wasted. This waste of power results in a decrease in the life of the light emitting diode.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and the object of the present invention is an inter-vehicle optical communication apparatus capable of improving communication quality by obtaining optimum irradiation characteristics while suppressing wasteful power consumption. Is to provide.

  In order to achieve the above object, an invention according to claim 1 is an optical communication transceiver in which light emitted from a light emitting element provided in a light emitting section of an optical communication transceiver mounted on a vehicle is mounted on another vehicle. In the inter-vehicle optical communication apparatus that performs optical communication between the preceding vehicle and the following vehicle by receiving light by the plurality of light emitting elements arranged in an array of light emitting units of the optical communication transceiver and the light distribution thereof A control unit that includes a lens to be controlled and that controls driving of the light-emitting element based on at least inter-vehicle distance information and ambient light information is provided.

  According to a second aspect of the present invention, in the first aspect of the invention, the light emitting unit is divided into a plurality of parts, and the control unit independently controls driving of the divided light emitting units.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the control unit increases the light emission amount of the light emitting element when the inter-vehicle distance is long, and decreases when the disturbance light is large. The light emission amount of the light emitting element is increased more than the case.

  According to the first aspect of the present invention, since the light distribution of each light emitting element is controlled by the lens, the width in the left-right direction is wide and the width in the vertical direction is necessary for a vehicle traveling on a horizontal road. A narrow optical communication area can be secured. Further, by controlling the driving of the light emitting element based on at least the inter-vehicle distance information and the ambient light information, it is possible to obtain optimal irradiation characteristics and improve communication quality while suppressing wasteful power consumption.

  According to the invention of claim 2, since the driving of each of the divided light emitting units is controlled independently, it is possible to easily obtain the optimum irradiation characteristics according to the inter-vehicle distance information and the disturbance light information, It is possible to improve communication quality while suppressing wasteful power consumption.

  According to the invention described in claim 3, when the inter-vehicle distance is long, the light emission amount of the light emitting element is increased as compared with the short case, and when the disturbance light is large, the light emission amount of the light emitting element is increased as compared with the small case. Optimal irradiation characteristics according to the length of the inter-vehicle distance and the magnitude of ambient light can be obtained, and communication quality can be improved while suppressing wasteful power consumption.

It is a side view which shows the vehicle carrying the inter-vehicle optical communication apparatus which concerns on this invention. It is a figure which shows the structure of the light emission part of the inter-vehicle optical communication apparatus which concerns on this invention, Comprising: (a) is a top view, (b) is a side view. 1 is a system configuration diagram of an inter-vehicle optical communication apparatus according to the present invention. It is a figure which shows the irradiation characteristic of the light emission part of the inter-vehicle optical communication apparatus which concerns on this invention. It is a figure which shows another structure of the light emission part of the inter-vehicle optical communication apparatus which concerns on this invention, Comprising: (a) is a top view, (b) is a side view. It is a figure which shows another structure of the light emission part of the inter-vehicle optical communication apparatus which concerns on this invention, Comprising: (a) is a top view, (b) is a side view.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a side view showing a vehicle equipped with an inter-vehicle optical communication device according to the present invention, FIG. 2 is a diagram showing a configuration of a light emitting unit of the inter-vehicle optical communication device, and FIG. FIG. 3 is a side view, FIG. 3 is a system configuration diagram of the inter-vehicle optical communication device, and FIG. 4 is a diagram illustrating irradiation characteristics of a light emitting unit of the inter-vehicle optical communication device.

  The inter-vehicle optical communication apparatus according to the present invention is for transmitting and receiving various information between a preceding vehicle and a succeeding vehicle by optical communication, and a plurality of vehicles traveling in a row as shown in FIG. The optical communication transmitter / receiver 1 installed in each front part and each rear part of 20 is provided. Each vehicle 20 includes a wireless communication device that obtains communication information other than light, an inter-vehicle distance measuring device 4 such as a millimeter wave radar, a laser radar, and a stereo camera, an ambient light measuring device 5 that measures the illuminance and position of the sun, and the like. Is installed.

  Here, the light receiving unit 6 of the optical communication transmitter / receiver 1 installed before and after each vehicle 20 has a plurality of light emitting elements 7 such as LEDs (light emitting diodes) arranged vertically and horizontally as shown in FIG. And a lens 8 for covering each light emitting element 7 and controlling its light distribution. The plurality of light emitting elements 7 are mounted in an array on a rectangular plate 9 as shown in FIG.

  By the way, in the vehicle-to-vehicle optical communication apparatus according to the present invention, as shown in FIG. 3, the light emitting unit 6 includes a first light emitting unit 6 (1), a second light emitting unit 6 (2), ... n (n is an integer). Each of the divided first light emitting section 6 (1) to nth light emitting section 6 (n) includes a plurality of light emitting elements 7 and a lens 8 for controlling the light distribution. Contains.

  The divided first light emitting unit 6 (1) to nth light emitting unit 6 (n) are independently driven by the light emitting element driving unit 10 to emit light, and the light emitting element driving unit 10 is controlled. In response to a control signal from the unit 11, the currents i1, i2,... In are supplied to the first light emitting unit 6 (1) to the nth light emitting unit 6 (n), respectively, and the first light emitting unit 6 (1) to nth light emission are supplied. The units 6 (n) are driven independently.

  By the way, in the control unit 11, the inter-vehicle distance information measured by the inter-vehicle distance measuring device 4 shown in FIG. 1 installed in each vehicle 20, the inter-vehicle communication information obtained by inter-vehicle wireless communication or inter-vehicle optical communication, An optimum irradiation pattern is calculated based on the disturbance light information and various vehicle information measured by the disturbance light measuring device 5, and a control signal corresponding thereto is output to the light emitting element driving unit 10. Then, the light emitting element driving unit 10 supplies the driving currents i1, i2,... In according to the control signal transmitted from the control unit 11 to the light emitting elements 7 of the first light emitting unit 6 (1) to the nth light emitting unit 6 (n). , And the light emitting elements 7 of the first light emitting unit 6 (1) to the nth light emitting unit 6 (n) respectively emit light having a light amount corresponding to the magnitudes of the drive currents i1, i2,. . The various vehicle information includes yaw rate, vehicle speed, acceleration, information detected by a magnetic sensor or direction sensor, information obtained from GPS or a map, and various operation information such as steering, throttle, and brake.

  Thus, the control unit 11 uses the first light emitting unit 6 (1) to the nth light emitting unit 6 (n) using all or part of the inter-vehicle distance information, the inter-vehicle communication information, the disturbance light information, and the various vehicle information. ) Of the light-emitting element 7 and the drive currents i1, i2,... In are controlled to obtain optimum irradiation characteristics.

  For example, when the inter-vehicle distance measured by the inter-vehicle distance measuring device 4 is long and the communication distance is long, the control unit 11 controls the light emitting unit 6 so that the light amount of the light-emitting element 7 is larger than when the communication distance is short. To do. Specifically, all of the light emitting elements 7 of the first light emitting unit 6 (1) to the nth light emitting unit 6 (n) are driven, or the first light emitting unit 6 (1) to the nth light emitting unit 6 (n ) Of the drive currents i1, i2,. Then, when the preceding vehicle of the vehicle 20 turns to the left, the control unit 11 of the succeeding vehicle determines the first light emitting unit 6 (1) to the nth light emitting unit 6 based on the inter-vehicle distance information, the inter-vehicle communication information, and the like. (N) is driven and controlled so that the irradiation pattern is directed to the left side. Conversely, when the preceding vehicle turns to the right, the control unit 11 of the succeeding vehicle drives the first light emitting unit 6 (1) to the nth light emitting unit 6 (n) based on the inter-vehicle distance information, the inter-vehicle communication information, and the like. Control so that the irradiation pattern faces to the right.

  On the other hand, when the inter-vehicle distance measured by the inter-vehicle distance measuring device 4 is short and the communication distance is short, the control unit 11 controls the light emitting unit 6 so that the light amount of the light-emitting element 7 is smaller than when the communication distance is long. To do. Specifically, one of the first light emitting unit 6 (1) to the nth light emitting unit 6 (n) is driven, or each of the first light emitting unit 6 (1) to the nth light emitting unit 6 (n). Drive currents i1, i2,. When the communication distance is short, the influence of the saturation of the light receiving element due to the reflection of the vehicle on the communication partner side is reduced. For example, in the case of running in a row such as a truck, light is likely to be reflected because the cargo compartment at the rear of the truck is covered with metal. In such a case, when the emitted light power is large, the reflected light tends to cause a reduction in communication quality. In such a case, it is possible to prevent a reduction in communication quality by reducing the light emission power.

  Further, when disturbance light such as sunlight measured by the disturbance light measuring device 5 is large, the control unit 11 of the succeeding vehicle causes the light emitting unit 6 to increase the light amount of the light emitting element 7 compared to when the disturbance light is small. To control.

  By the way, when a plurality of vehicles 20 that transmit and receive various information to each other by optical communication by the inter-vehicle optical communication apparatus according to the present invention are traveling on a horizontal road as shown in FIG. A wide optical communication area in the (horizontal) direction is required.

  Thus, in the inter-vehicle optical communication apparatus according to the present invention, the light distribution of each light emitting element 7 is controlled by the lens 8 respectively, so that the width is wide in the left-right direction as shown in FIG. Irradiation characteristics that can ensure a narrow optical communication area can be obtained. In FIG. 4, the horizontal axis indicates the directivity angle (°), the vertical axis indicates the relative irradiation intensity (%), the solid line indicates the horizontal irradiation characteristic, and the broken line indicates the vertical irradiation characteristic.

  By the way, in order to obtain an optimum irradiation pattern, among the plurality of light emitting elements 7 arranged in an array as shown in FIG. 5, the light emitting elements 7 arranged at both ends are inclined or as shown in FIG. Alternatively, the lens 6 at both ends may be inclined to add independent light distribution characteristics to each lens 6.

  Further, in the present embodiment, the driving of the light emitting element 7 is controlled based on the inter-vehicle distance information and the disturbance light information. When the inter-vehicle distance is long, the light emission amount of the light emitting element 7 is increased as compared with the case where the inter-vehicle distance is short. When the light is large, the light emitting element 7 emits more light than when it is small. Therefore, it is possible to obtain the optimum irradiation characteristics according to the distance between the vehicles and the magnitude of the disturbance light, and to reduce wasteful power consumption. Thus, the communication quality can be improved while extending the life of the light emitting element 7.

  And in this Embodiment, the light emission part 6 is divided | segmented into several 1st light emission part 6 (1)-nth light emission part 6 (n), and the control part 11 is 1st light emission part 6 (1)-nth. Since the driving of the light emitting unit 6 (n) is controlled independently, the optimum irradiation characteristics according to the inter-vehicle distance information and the disturbance light information can be easily obtained.

  Further, in optical communication by the inter-vehicle optical communication device, the influence of disturbance light such as sunlight and the influence of reflected light are large, and it is difficult to ensure safety and reliability. The effect of light can be greatly suppressed, and high communication quality can be ensured with a simple configuration.

DESCRIPTION OF SYMBOLS 1 Optical communication transmitter / receiver 3 Wireless communication device 4 Distance measuring device 5 Disturbance light measuring device 6 Light emission part 6 (1) 1st light emission part 6 (2) 2nd light emission part 6 (n) n light emission part 7 Light emitting element 8 Lens 9 Substrate 10 Light emitting element driving unit 11 Control unit 20 Vehicle

Claims (3)

Light is emitted between a preceding vehicle and a succeeding vehicle by receiving light emitted from a light emitting element provided in a light emitting unit of an optical communication transceiver mounted on a vehicle by an optical communication transmitter / receiver mounted on another vehicle. In the inter-vehicle optical communication device that performs communication,
The light emitting unit of the optical communication transceiver includes a plurality of light emitting elements arranged in an array and a lens for controlling the light distribution, and drives the light emitting elements based on at least inter-vehicle distance information and disturbance light information A vehicle-to-vehicle optical communication device characterized by comprising a control unit for controlling the vehicle.   The inter-vehicle optical communication device according to claim 1, wherein the light emitting unit is divided into a plurality of parts, and the control unit independently controls driving of the divided light emitting units. The controller is configured to increase the light emission amount of the light emitting element when the inter-vehicle distance is long, and to increase the light emission amount of the light emitting element when the disturbance light is large than when the disturbance light is small. Item 3. The vehicle-to-vehicle optical communication device according to Item 1 or 2.

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