JPH09243750A - Laser radar for vehicles - Google Patents

Abstract

(57) Abstract: A laser radar for a vehicle that accurately measures an inter-vehicle distance is provided. SOLUTION: A light emitting unit 10a and a light receiving unit 14a are arranged in a rear vehicle 2a, a light emitting unit 10b and a light receiving unit 14b are arranged in a front vehicle 2b, and a transmission and reception controller for emitting a laser pulse from the light emitting unit 10a to the front vehicle 2b. 16a and a transmission / reception controller 16b that causes the light emitting unit 10b to emit a laser pulse after a predetermined time has elapsed since the light receiving unit 14b received the laser pulse emitted from the light emitting unit 10a.
And a distance calculation unit 32a that measures the distance between the vehicles based on the time when the light emitting unit 10a emits the laser pulse to the front vehicle 2b and the time when the light receiving unit 14a receives the laser pulse emitted from the light emitting unit 10b. With.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle laser radar, and more particularly to a vehicle laser radar capable of communicating between vehicles and accurately measuring an inter-vehicle distance.

[0002]

2. Description of the Related Art Generally, a laser radar generates laser pulse light (hereinafter referred to as pulse light) from a laser diode on a transmitting side, and emits the pulse light via a translucent lens. When there is a target such as an obstacle or a vehicle in the emitting direction of the emitted pulsed light, the emitted pulsed light is reflected by the target and becomes reflected pulsed light. The reflected pulsed light is detected by the photodiode via the optical filter on the receiving side.

The laser radar obtains the time difference between the reference signal and the received light signal associated with the emission of the laser pulse, obtains the inter-vehicle distance based on the time difference and displays it on the display, or when the distance is very close. For example, an alarm is generated.

In recent years, a laser radar for a vehicle has been proposed which can measure a distance using a laser radar and communicate with vehicles in front of and behind it.

For example, as shown in FIG. 6 (a), there is a one-way laser radar that sends information from its own vehicle to a vehicle ahead.
Both front and rear vehicles are equipped with unidirectional laser radar.
In this case, the emission pulse light emitted from the transmission unit of the own vehicle hits the front vehicle, is reflected, and is received by the reception unit to obtain the inter-vehicle distance to the front vehicle. At this time, the emitted pulsed light is received by the receiving unit at the rear of the front vehicle, and the front vehicle obtains the distance from the rear vehicle.

However, for the own vehicle, it is very useful for avoiding a collision if the behavior of the vehicle ahead, such as right turn or left turn, deceleration and stop, is known. Therefore, as shown in FIG.
The transmitter and receiver are located in front of and behind the vehicle, and the receiver attached to the front of the vehicle receives the information emitted from the transmitter of the vehicle in front, and the transmitter at the rear of the vehicle transmits the behavior information of the vehicle to the rear. I try to send it to the car.

Further, in the laser radar having a communication function in addition to the distance measurement, different types of light emitting devices are combined to perform various vehicle communication and separate the distance measurement and the communication use so that signals are not mixed. There is something.

However, this is not preferable because it requires a plurality of devices. Further, in the control cycle of the distance measurement mode to the communication mode, there is a problem that the distance measurement is interrupted while the distance measurement mode is switched to the communication mode.

[0009]

Therefore, as a solution to the above problem, the present applicant has filed an application for a vehicle laser radar in Japanese Patent Application No. 7-85334 (not yet published). This vehicle laser radar includes a transmitter / receiver including a light emitting unit having a laser diode and a light receiving unit for receiving reflected light, and emission data control means.

The emission data control means activates the laser diode in a predetermined cycle, alternately selects the data for distance measurement or the data for communication during operation, and emits a light emission pulse based on the selected data. Fire from.

For example, as shown in FIG. 7, when data for distance measurement is selected, a pulse signal for distance measurement of 1 KHz synchronized with the first pulse P1 of the laser drive signal of 2 KHz is emitted from the light emitting unit. Is fired.

Further, when the data for communication is selected, a pulse signal for communication of 1 KHz synchronized with the second pulse P2 of the laser drive signal of 2 KHz is emitted from the light emitting section.

As a result, since the emitted pulsed light is allocated for distance and for communication, lasers for distance and measurement are not required. Therefore, one set of transmitting / receiving unit performs distance measurement and communication. Therefore, the structure of the device is simplified. Further, since distance and communication are alternately used continuously by one laser, distance measurement is not interrupted.

However, the laser radar for vehicles shown in FIGS. 6 (a) and 6 (b) and Japanese Patent Application No. 7-85334 shown in FIG.
In the above-mentioned vehicle laser radar, the inter-vehicle distance is measured by measuring the arrival time of the reflected light of the laser pulse reflected from the vehicle ahead. Therefore, when the laser pulse emitted from the rear vehicle hits the front vehicle,
Depending on the hit portion, the reflectance of the reflected light may be low.

Further, since distance measurement is performed using weak reflected light per unit time, there is a possibility that the accuracy of distance measurement may vary. Further, since the reflectance is low, it is necessary to increase the laser output and perform distance measurement.

Therefore, an object of the present invention is to provide a vehicle laser radar capable of accurately measuring an inter-vehicle distance and reducing a laser output.

[0017]

The present invention adopts the following means in order to solve the above problems. Claim 1 of the present invention
In a laser radar for a vehicle, in which a transceiver unit including a light emitting unit and a light receiving unit is arranged in a front vehicle and a rear vehicle, and a distance between the vehicles is measured, a light emitting unit in one of the front vehicle and the rear vehicle From the first pulse emission control means for emitting a laser pulse from the other vehicle to the other vehicle, and after a predetermined time has elapsed from the time when the light receiving section of the other vehicle receives the laser pulse emitted from the light emitting section in the one vehicle. Second pulse emission control means for emitting a laser pulse from the light emitting portion of the other vehicle, the time when the light emitting portion of the one vehicle emits a laser pulse to the other vehicle, and the light receiving portion of the one vehicle is the other. The distance measuring means for measuring the distance between the vehicles based on the time when the laser pulse emitted from the light emitting section in the vehicle is received.

According to the present invention, when the laser pulse is emitted from the light emitting section in one vehicle to the other vehicle by the first pulse emission control means, the light receiving section of the other vehicle is in the one vehicle. The laser pulse emitted from the light emitting unit is received.

Then, the second pulse emission control means causes the light emitting portion of the other vehicle to emit a laser pulse after a predetermined time has elapsed from the time when the laser pulse was received.

Further, when the light receiving section of one vehicle receives the laser pulse emitted from the light emitting section in the other vehicle,
The distance measuring means is based on the time when the light emitting unit of one vehicle emits the laser pulse to the other vehicle and the time when the light receiving unit of one vehicle receives the laser pulse emitted from the light emitting unit in the other vehicle. Measure the distance between vehicles.

That is, since the reflected light is not used as in the conventional case, the laser pulse can be received more reliably than the reflected light, and the inter-vehicle distance can be accurately measured. Further, since the light reception output is large, the laser emission output can be reduced.

According to a second aspect of the present invention, the time when the light emitting section of the one vehicle emits a laser pulse to the other vehicle and the laser pulse emitted from the light emitting section of the other vehicle to the light receiving section of the one vehicle. The gist of the present invention is to include a storage unit that stores the time when the light was received and that outputs the time when the light was emitted and the time when the light was received to the distance measuring unit.

The inter-vehicle distance can be measured using the laser pulse emission time and the light reception time stored in the storage means.

The invention according to claim 3 is characterized in that the distance between the vehicles is measured after the light emitting section of the one vehicle sends a series of communication data to the light receiving section of the other vehicle. The gist of the present invention is to provide distance measurement operating means for operating the first pulse emission control means, the second pulse emission control means, and the distance measurement means.

In the case of performing data communication, after transmitting a series of communication data, the distance measurement operating means operates the first pulse emission control means, the second pulse emission control means and the distance measurement means. Since it is operated, the inter-vehicle distance can be measured.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a vehicle laser radar according to the present invention will be described in detail below. FIG. 1 shows a configuration diagram of a vehicle laser radar according to a first embodiment of the present invention. FIG. 2 shows the appearance of the front vehicle and the rear vehicle.

<Embodiment 1> In FIG. 2, a transmitter / receiver including a light emitting portion 10a and a light receiving portion 14a is attached to a front portion of a rear vehicle 2a, and a light emitting portion 10b and a light receiving portion are attached to a rear portion of a front vehicle 2b. A transmission / reception unit composed of 14b is attached so that vehicles can communicate with each other.

Although not shown, the transmitter / receiver may be attached to the rear portion of the rear vehicle 2a so that the vehicle following the rear vehicle 2a and the rear vehicle 2a can communicate with each other. Further, the transmitter / receiver may be attached to the front part of the front vehicle 2b in order to communicate with the front vehicle of the front vehicle 2b.

Next, referring to FIG. 1, the rear vehicle 2a includes a light emitting section 10a, a laser oscillation controller 12a, and a light receiving section 1.
4a, transmission / reception controller 16a, communication data processing unit 1
8a, a distance measurement data section 20a, and a switching section 22a.

The light emitting section 10a includes a laser diode, a lens and the like, and emits a laser pulse from the laser diode. The laser oscillation controller 12a includes the light emitting unit 10
The light emitting unit 1 outputs a drive signal for driving the laser diode of a.
0a.

The light receiving section 14a receives the reflected light of the pulsed light emitted by the light emitting section 10a, converts the reflected light into an electric signal, and outputs it as a received signal. In addition, the light receiving unit 14a
Receives the pulsed light emitted by the light emitting unit 10b in the front vehicle 2b, converts the reflected light into an electric signal, and outputs the electric signal as a reception signal.

The transmission / reception controller 16a as the first pulse emission control means controls the transmission / reception timing of the light emitting section 10a and the light receiving section 14a, and the light emitting section 1 in the rear vehicle 2a.
A laser pulse is emitted from 0a to the front vehicle 2b. The communication data processing unit 18a converts the data from the communication requirement input into communication data.

The switching unit 22a is a communication data processing unit 18a.
The communication data processed in step S1 and the distance measurement data for distance measurement between vehicles stored in the distance measurement data unit 20a are selectively output to the light emitting unit 10a.

Further, the rear vehicle 2a includes a storage unit 24a,
Switching unit 26a, communication data processing unit 28a, display unit 30
a, a distance calculation unit 32a. The storage unit 24a stores the emission time of the laser pulse emitted by the light emitting unit 10a and the light reception time at which the light receiving unit 14a receives the laser pulse emitted from the light emitting unit 10b in the front vehicle 2b.

The switching unit 26a includes a communication data processing unit 28a.
And the distance calculation unit 32a are selectively switched. The communication data processing unit 28a processes the communication data received by the light receiving unit 14a and outputs it to the display unit 30a.

The distance calculation unit 32a obtains a time difference between the emission time of the laser pulse stored in the storage unit and the light reception time of the laser pulse received by the light receiving unit 14a, and based on the time obtained by subtracting a predetermined time from this time difference. The inter-vehicle distance is obtained and output to the display unit 30a for display.

Next, the structure of the front vehicle 2b will be described. The forward vehicle 2b includes a light emitting unit 10b, a laser oscillation controller 12b, a light receiving unit 14b, a transmission / reception controller 16b, a communication data processing unit 18b, a distance measurement data unit 20b, and a switching unit 2.
2b. Further, the front vehicle 2b has a storage unit 24.
b, switching unit 26b, communication data processing unit 28b, display unit 3
0b, the distance calculation unit 32b.

The light receiving portion 14b is the light emitting portion 1 of the front vehicle 2a.
The laser pulse emitted at 0a is received. The transmission / reception controller 16b as the second pulse emission control means,
The transmission / reception timing between the light emitting unit 10b and the light receiving unit 14b is controlled so that the light emitting unit 10b emits a laser pulse after a predetermined time has elapsed from the time when the light receiving unit 14b received the laser pulse emitted from the light emitting unit 10a.

The other constituent parts of the front vehicle have the same structure as the corresponding parts of the rear vehicle, and the details thereof will be omitted.

Next, the operation of the first embodiment of the present invention thus configured will be described with reference to the drawings. FIG. 3 shows a timing chart for explaining the distance measurement between the front vehicle and the rear vehicle.

FIG. 4 shows the first embodiment of the vehicle laser radar.
3 shows a flowchart of the operation. Here, the rear vehicle 2
A case will be described in which a laser pulse is emitted from a to the vehicle 2b in front of the vehicle and the inter-vehicle distance is measured.

First, it is assumed that data communication is normally performed between the front vehicle 2b and the rear vehicle 2a.
Next, a laser pulse is emitted from the light emitting unit 10a to the front vehicle 2b using the measured distance data stored in the distance measurement data unit 20a of the rear vehicle 2a (step S11).

Then, the emitted laser pulse hits a certain portion of the front vehicle 2b, and the reflected light returns to the rear vehicle 2a. The light receiving unit 14a of the rear vehicle 2a determines whether there is reflected light (step S13), and if there is reflected light, the received signal is sent to the transmission / reception controller 16a.

The light emitting section 10a of the rear vehicle 2a emits a laser pulse including distance measuring data to the front vehicle 2b at time t1 by the timing control from the transmission / reception controller 16a (step S15). At the same time, information on the laser pulse emission time t1 is written in the storage unit 24a (step S17).

On the other hand, the light receiving portion 14b of the front vehicle 2b determines whether or not the laser pulse emitted from the light emitting portion 10a is received (step S19), and when the light receiving portion 14b receives the laser pulse at the time t2. The received signal is sent to the transmission / reception controller 16b. The transmission / reception controller 16b gives the light emitting unit 10b an instruction for emitting a laser pulse.

Based on the instruction, the light emitting section 10b emits a laser pulse to the rear vehicle 2a at time t3 when a predetermined time T has elapsed from the time t2 when the light receiving section 14b received the laser pulse (step S21).

Next, the light receiving portion 14a of the rear vehicle 2a determines whether or not the laser pulse emitted from the light emitting portion 10b is received (step S23), and when the light receiving portion 14a receives the laser pulse at time t4. The received signal is stored in the storage unit 24a together with the information on the light reception time t4 (step S25).

Further, the distance calculation unit 32a includes a storage unit 24.
The laser pulse emission time stored in a and the light receiving unit 14
The time difference from the light reception time of the laser pulse received in a is obtained, and the inter-vehicle distance is obtained based on the time obtained by subtracting a predetermined time from this time difference, and is output to the display unit 30a and displayed (step S27).

In this case, as can be seen from FIG. 3, the time DT from time t1 to time t4 is the time from the emission of the laser pulse from the rear vehicle 2a to the reception of the laser pulse from the front vehicle 2b. .

The times Δt1 and Δt2 are the arrival times of the laser pulses, and the time T is the time from the reception of the laser pulses to the emission of the laser pulses in the vehicle ahead. The inter-vehicle distance is calculated by the following formula using these pieces of information.

(DT−T) · C / 2 = 2Δt · C / 2 = Δt · C Here, C is the speed of light, and Δt1 and Δt2 are assumed to be substantially equal. Note that, for example, if the laser emission cycle is 1 KHz, the time T may be about 10 μsec.

As described above, according to the first embodiment, the pulse emitted by the rear vehicle 2a is used as a trigger to drive the front vehicle 2b.
Returns the pulse to the rear vehicle 2a after receiving the pulse.
Since the inter-vehicle distance is obtained by the operation as described above, the pulse can be received more reliably and the inter-vehicle distance can be measured more accurately than in the conventional case where the reflected light is used.

Further, since the reflected light is not used, it is possible to measure an inter-vehicle distance farther than before, for example, up to about 100 m. Furthermore, since the pulse output when receiving light is large, the emission output of the laser diode can be set to a small value, thereby extending the life of the laser diode,
Furthermore, safety can be improved.

In the first embodiment, a laser pulse is emitted from the rear vehicle 2a to the front vehicle 2b, and the front vehicle 2b
The rear vehicle 2a received the pulse emitted from the light emitting section 10b of the vehicle and measured the distance. For example, a laser pulse was emitted from the front vehicle 2b to the rear vehicle 2a and emitted from the light emitting section 10a of the rear vehicle 2a. The front vehicle 2b may receive the pulse and measure the distance.

In this case, the transmission / reception controller 16b of the front vehicle 2b emits a laser pulse at the time t1.
Fire from b. The light receiving unit 14a receives the laser pulse at time t2, and the transmission / reception controller 16 of the rear vehicle 2a
a causes a laser pulse to be emitted from the light emitting unit 10a at time t3. The light receiving unit 14b may receive the laser pulse at time t4.

<Second Embodiment> Next, a second embodiment of the vehicle laser radar of the present invention will be described. FIG. 5 shows a configuration diagram of a second embodiment of a vehicle laser radar according to the present invention. The feature of the second embodiment with respect to the first embodiment is that the distance measuring operation parts 34a and 34b are provided.

The distance measuring operation unit 34a is provided in the rear vehicle 2c, and the series of communication data processed by the communication data processing unit 18a by the light emitting unit 10a of the rear vehicle 2c is sent to the light receiving unit 14b of the front vehicle 2d. After that, in order to measure the distance between the vehicles, the transmission / reception controller 16a, the distance calculation unit 32a, the switching units 22a and 26a.
Activate

The distance measuring operation unit 34b is provided in the rear vehicle 2d, and measures the distance between the vehicles after receiving a series of communication data transmitted from the light emitting unit 10a of the rear vehicle 2c. , The transmission / reception controller 1
6b is activated.

The other structure is the same as that of the first embodiment, and the same parts are designated by the same reference numerals and the detailed description thereof will be omitted.

According to this structure, first, communication is performed between the front and rear vehicles. In this case, when a communication requirement is input from an input unit (not shown), the communication data processing unit 18a converts the communication requirement, and the processed communication data is processed by the laser of the light emitting unit 10a via the switching unit 22a. It is sent to the forward vehicle 2d by a pulse.

The light receiving unit 14b of the front vehicle 2d receives the communication data, and the communication data is processed by the communication data processing unit 28b via the storage unit 24b and the switching unit 26b and displayed on the display unit 30b.

Next, when a series of communication data, for example, one group data is sent from the communication data processing section 18a,
The distance measurement operation unit 34a operates the transmission / reception controller 16a, the distance calculation unit 32a, and the switching units 22a and 26a in order to measure the distance between the vehicles. The distance measurement operating unit 34b receives the series of communication data,
The transmission / reception controller 16b is operated to measure the distance between the vehicles.

After such an operation is performed, an operation for measuring the inter-vehicle distance is performed according to the flowchart shown in FIG. That is, the front vehicle 2d and the rear vehicle 2
Even when communication is performed with c, the inter-vehicle distance can be measured after sending out certain communication data.

[0064]

According to the present invention, the light emitting section in one vehicle emits a laser pulse to the other vehicle, and the light receiving section of the other vehicle emits a laser pulse from the light emitting section in one vehicle. When light is received and the laser pulse is emitted from the light emitting unit of the other vehicle after a predetermined time has elapsed from the time of receiving the laser pulse, and the light receiving unit of one vehicle receives the laser pulse emitted from the light emitting unit in the other vehicle. , The distance measuring means,
The distance between vehicles based on the time when the light emitting unit of one vehicle emits a laser pulse to the other vehicle and the time when the light receiving unit of one vehicle receives the laser pulse emitted from the light emitting unit in the other vehicle. To measure.

That is, since the reflected light is not used as in the conventional case, the laser pulse can be received more reliably than the reflected light, and the inter-vehicle distance can be accurately measured. Further, since the light reception output is large, the laser emission output can be reduced.

Further, the inter-vehicle distance can be measured by using the emission time and the light reception time of the laser pulse stored in the storage means. Furthermore, when performing data communication, the distance measurement operating means operates the first pulse emission control means, the second pulse emission control means, and the distance measurement means after transmitting a series of communication data. You can measure the distance between cars.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a vehicle laser radar of the present invention.

FIG. 2 is a diagram showing the exchange of pulses between a front vehicle and a rear vehicle.

FIG. 3 is a timing chart for explaining distance measurement between a front vehicle and a rear vehicle.

FIG. 4 is a flowchart showing the operation of the first embodiment of the vehicle laser radar.

FIG. 5 is a configuration diagram showing a second embodiment of a vehicle laser radar of the present invention.

FIG. 6 is a diagram showing an example of a conventional vehicle laser radar.

FIG. 7 is a timing chart for explaining a vehicle laser radar that has already been filed by the present applicant.

[Explanation of symbols]

 2a Rear vehicle 2b Front vehicle 10a, 10b Light emitting section 12a, 12b Laser oscillation controller 14a, 14b Light receiving section 16a, 16b Transmission / reception controller 18a, 18b Communication data processing section 20a, 20b Distance measurement data section 22a, 22b Switching section 24a, 24b Storage Section 26a, 26b switching section 28a, 28b communication data processing section 30a, 30b display section 32a, 32b distance calculation section 34a, 34b distance measurement operation section

Claims (3)

[Claims] 1. A laser radar for a vehicle, wherein a transmitter / receiver including a light emitting portion and a light receiving portion is arranged in a front vehicle and a rear vehicle, and a distance between the vehicles is measured, in a vehicle of one of the front vehicle and the rear vehicle. First pulse emission control means for emitting a laser pulse from the light emitting unit of the other vehicle to the other vehicle, and a predetermined time from the time when the light receiving unit of the other vehicle receives the laser pulse emitted from the light emitting unit in the one vehicle. Second pulse emission control means for emitting a laser pulse from the light emitting portion of the other vehicle after a lapse of time, the time when the light emitting portion of the one vehicle emits a laser pulse to the other vehicle, and the light reception of the one vehicle. And a distance measuring means for measuring the distance between the vehicles based on the time when the laser light emitted from the light emitting section in the other vehicle is received. Da. 2. The time when the light emitting unit of the one vehicle emits a laser pulse to the other vehicle and the light receiving unit of the one vehicle receives the laser pulse emitted from the light emitting unit in the other vehicle. The vehicle laser radar according to claim 1, further comprising: a storage unit that stores the time and outputs the emission time and the light reception time to the distance measuring unit. 3. The first pulse emission control means for measuring the distance between the vehicles after the light emitting section of the one vehicle sends a series of communication data to the light receiving section of the other vehicle. The vehicle laser radar according to claim 1 or 2, further comprising: a distance measuring operation unit that operates the second pulse emission control unit and the distance measuring unit.