JP3580094B2 - Forward recognition device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a forward recognition device that measures the distance to a vehicle in front using a scanning laser radar, and particularly, even when another vehicle provided with a reflector at a high position interrupts immediately before its own vehicle. The present invention relates to a forward recognition device that can reliably recognize another vehicle.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a forward recognition device that measures a distance to a vehicle ahead using a scanning laser radar has been known.
[0003]
The laser beam scanned in the left-right direction is sent forward from a scanning laser radar provided on the front of the vehicle, and the laser beam reflected by a reflector provided on the rear surface of the vehicle in front is again reflected. The distance to the vehicle in front is measured by receiving the data with a scanning laser radar provided on the front of the vehicle. On the other hand, the image camera recognizes the presence of the preceding vehicle and also recognizes the lane, and provides information for determining whether the preceding vehicle received by the scanning laser radar is traveling on its own lane. It is.
[0004]
[Problems to be solved by the invention]
However, when another vehicle interrupts immediately before the own vehicle, particularly when a vehicle provided with a reflector at a high position interrupts, the reflector of the preceding vehicle is not irradiated with the laser beam, and the immediately preceding vehicle cannot be recognized. There was a problem that it became possible.
[0005]
The present invention has been made in view of the above, and an object of the present invention is to reliably recognize another vehicle even when another vehicle provided with a reflector at a high position interrupts immediately before the own vehicle. It is another object of the present invention to provide a forward recognition device capable of reliably recognizing a preceding vehicle over a wide range from a distance to a short distance.
[0006]
[Means for Solving the Problems]
According to an aspect of the present invention, there is provided a scanning laser radar for detecting an inter-vehicle distance between a host vehicle and a preceding vehicle, and a lane determining device for recognizing a lane change of the preceding vehicle. A recognizing device, wherein, despite the fact that the preceding vehicle has entered the own lane by the lane determining device, it is impossible to detect the preceding vehicle by the scanning laser radar, The gist of the present invention is to include a beam width switching unit that changes a laser beam emitted from a laser radar to a wide angle state in an upward direction.
[0007]
According to a second aspect of the present invention, in order to solve the above-mentioned problem, the beam width switching means causes the lane judging device to move the preceding vehicle to another lane when the laser beam is changed to the wide angle state in the upward direction. When it is recognized that the vehicle has left and the detection of the preceding vehicle by the scanning laser radar becomes impossible, or the inter-vehicle distance between the preceding vehicle and the own vehicle that is continuously being recognized by the scanning laser radar. It is essential that the irradiation range of the laser beam in the upward direction is returned to the normal state when the distance is a predetermined distance.
[0008]
【The invention's effect】
According to the first aspect of the present invention, in spite of recognizing that the preceding vehicle has entered the own lane by the lane determination device, if the scanning type laser radar cannot detect the preceding vehicle, By changing the laser beam emitted from the scanning laser radar to a wide-angle state in the upward direction, for example, even if another vehicle with a reflector installed at a high position interrupts immediately before the host vehicle, it can recognize other vehicles. Can be performed reliably.
[0009]
According to the second aspect of the present invention, when the laser beam is changed to the wide angle state in the upward direction, the lane judging device recognizes that the preceding vehicle has departed to another lane, and performs the scan. When it is no longer possible to detect a vehicle ahead using the laser radar, or when the inter-vehicle distance between the vehicle ahead and the vehicle being continuously recognized by the scanning laser radar is separated to a certain distance, the laser beam By returning the upper irradiation range of the vehicle to the normal state, it is possible to prevent the distant vehicle ahead from becoming unrecognizable due to insufficient light density due to the laser beam wide-angle state, and satisfy the normal ranging performance. The vehicle in front can be reliably recognized over a wide range from a distance to a short distance.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a system configuration of a forward recognition device 1 according to one embodiment of the present invention.
In FIG. 1, an arithmetic unit 11 transmits a signal from a scanning laser radar 3, a signal from an image camera 5, a signal from a vehicle speed sensor 7, and a signal from a brake SW9 to a vehicle ahead or an obstacle. , Calculation of the relative speed, determination of the preceding vehicle or obstacle in the own lane, determination of the risk of sudden approach to the preceding vehicle or obstacle, and the like.
[0011]
The inter-vehicle distance adjustment device 13 performs accelerator control and brake control of the own vehicle in accordance with the distance to the preceding vehicle or an obstacle calculated by the arithmetic device 11 and the relative speed.
The warning device 15 gives a warning to the driver when there is a sudden approach to a vehicle ahead or an obstacle as a result of the calculation by the calculation device 11 and there is a danger of a rear-end collision.
Based on the signal from the scanning laser radar 3 and the signal from the image camera 5, the beam width switching device 17 interrupts the other vehicle immediately before, particularly, the vehicle in which the reflector provided at a high position is interrupted. Is determined by the arithmetic unit 11, the laser beam is changed to the wide-angle state.
[0012]
Next, the operation of the forward recognition device 1 will be described.
Now, it is assumed that the preceding vehicle on the other lane running ahead of the own vehicle has changed lanes and cut into the own lane as shown in FIG. Here, the arithmetic unit 11 recognizes that the vehicle traveling in the adjacent lane has entered the own lane by using the image camera 5, and obtains the preceding vehicle information on the own lane from the scanning laser radar 3. If not, an interrupted vehicle occurs immediately before the vehicle 19, and it is determined that the interrupted vehicle is a vehicle provided with a high reflector.
[0013]
Next, the beam switching device 17 can irradiate the vertical width of the scanning radar set at the time of normal traveling from ± 1.5 degrees to, for example, 15 degrees in the upward direction as shown in FIG. By changing the radar beam 21 to the wide-angle state, the reflector 25 of the preceding vehicle 23 that has been out of the field of view can be recognized, and the presence of the vehicle immediately before can be reliably recognized.
[0014]
Next, the switching state of the laser beam in the scanning laser radar will be described with reference to the flowchart shown in FIG.
First, in step S10, it is determined using the image camera 5 whether or not it has been recognized that the preceding vehicle has entered the own lane. When it is recognized that the preceding vehicle has entered the own lane, the process proceeds to step S20. On the other hand, if it is not recognized that the preceding vehicle has entered the own lane, the process returns to step S10.
[0015]
In step S20, it is determined whether or not the preceding vehicle has been detected on the own lane using the scanning laser radar 3. If a preceding vehicle is detected on the own lane, the process returns to step S10. On the other hand, if no preceding vehicle is detected on the own lane, the process proceeds to step S30.
In step S30, the laser beam emitted from the scanning laser radar 3 is changed to an upward wide angle state.
[0016]
Next, in step S40, it is determined whether or not the preceding vehicle continuously recognized by the scanning laser radar 3 is separated by a certain distance or more. When the preceding vehicle is separated by a certain distance or more, the process proceeds to step S80. On the other hand, if the preceding vehicle is not separated by a certain distance or more, the process proceeds to step S50.
In step S50, it is determined whether or not it has been recognized that the preceding vehicle has left the other lane using the image camera. When it is recognized that the preceding vehicle has left the other lane, the process proceeds to step S60. On the other hand, if it is not recognized that the preceding vehicle has left the other lane, the process returns to step S40.
[0017]
In step S60, it is determined whether or not a preceding vehicle has been detected on the own lane by the scanning laser radar 3. When a preceding vehicle is detected on the own lane, the process proceeds to step S70. On the other hand, if it is not impossible to detect the preceding vehicle on the own lane, the process proceeds to step S80.
[0018]
In step S70, it is determined whether the detected preceding vehicle is separated from the own vehicle by a certain distance or more. If the preceding vehicle is at least a certain distance from the host vehicle, the process proceeds to step S80. If the preceding vehicle is not separated from the own vehicle by a certain distance or more, the process returns to step S40.
Next, in step S80, the laser beam emitted from the scanning laser radar 3 is changed to return to the normal state, and the process returns to step S10.
Next, in the present embodiment, how to recognize a preceding vehicle that has become unrecognizable as in the related art will be specifically described using numerical examples.
[0019]
FIG. 5 is a diagram showing the vertical spread of the laser beam emitted from the scanning laser radar 3.
In the figure, the upper limit height Z of laser beam irradiation of the laser beam 21 transmitted from the scanning laser radar 3 at a distance Y from the scanning laser radar 3 is:
Z (m) = Y (m) × tan θ + h (m) (1)
It can be expressed as.
[0020]
Next, a description will be given using specific numerical examples.
FIG. 6 is a diagram showing the vertical spread of the laser beam 21 emitted from the scanning laser radar 3 in the normal state.
[0021]
As an example of a conventional forward recognition device, when the irradiation angle in the upward direction of the scanning laser radar is θ = 1.5 degrees and the ground clearance at which the scanning laser radar is mounted is h = 0.3 m, the highest of the vehicle ahead is highest. Considering the state in which the reflector is provided at the position of 1.5 m, the area where the reflector can be detected by using the scanning laser radar has an inter-vehicle distance of 46 m or more as shown in FIG.
[0022]
In other words, at an inter-vehicle distance of 46 m or less, a vehicle provided with a reflector at a position of 1.5 m could not be detected using a scanning laser radar.
[0023]
FIG. 7 is a diagram showing the vertical spread of the laser beam emitted from the scanning laser radar 3.
As an example of the present embodiment, it is assumed that the upward irradiation angle of the scanning laser radar 3 is θ = 15 degrees, and the height above the scanning laser radar 3 is h = 0.3 m. In consideration of the fact that the reflector is provided at the highest position 1.5 m of the preceding vehicle, the detectable area is the inter-vehicle distance of 4.5 m or more, and the preceding vehicle can be detected in most areas.
[0024]
Also, when the interruption of the preceding vehicle in front is recognized and the laser beam is in the wide-angle state, the inter-vehicle distance to the preceding vehicle on the own lane continuously recognized by the scanning laser radar 3 is, for example, 45 m. When the vehicle is separated from the above, or when the image camera 5 recognizes that the preceding vehicle has changed lanes, and when the scanning laser radar 3 cannot recognize the preceding vehicle on the own lane, the laser beam is wide-angled. By returning from the state to the original normal state, it is possible to prevent the distant vehicle ahead from becoming unrecognizable due to insufficient light density due to the laser beam wide-angle state, thereby satisfying normal distance measurement performance.
[0025]
Next, the configuration of the scanning laser radar according to the present embodiment will be described with reference to FIG.
8, the light emitting element 31 emits light in response to a transmission signal from the control device 33, and the transmission signal transmitted from the light emitting element 31 is fixed to a motor 35 having a mechanism for changing the focal length with the light emitting element 31. After passing through the lens A and reflected by the mirrors A and B, the beam shade 37 blocks the spread in the lower left and right directions, changes the upper direction to a wide angle state, and transmits the transmission laser beam 21a forward. .
[0026]
Further, the reflected laser beam 21 b reflected by the front object is reflected by the mirror B, is received by the light receiving element 39 through the lens B, and is input to the control device 33.
[0027]
Next, an optical operation of the scanning laser radar 3 will be described with reference to FIG.
In FIG. 9A, a transmission signal transmitted from the light emitting element 31 passes through a lens A fixed to a motor 35 having a mechanism for changing the focal length with the light emitting element 31 and passes through a normal laser beam irradiation range. Is sent forward.
[0028]
Next, in FIG. 9B, the motor 35 is controlled by a transmission signal from the control device 33 shown in FIG. 8 to slide the lens A and change the focal length between the light emitting element 31 and the lens A. As a result, the laser beam sent forward is changed to a wide-angle state.
[0029]
However, the laser beam that has been changed to the wide-angle state in all directions is blocked by the beam shade 37 in FIG. 8 in the lower right and left directions. Sent to
[0030]
As described above, when the vehicle provided with the reflector at a high position interrupts immediately before the host vehicle, the scanning laser radar 3 recognizes the preceding vehicle, despite the fact that the image camera 5 recognizes the interruption of the preceding vehicle. When it is impossible, the laser beam 21 is changed to the wide angle state in the upward direction, and when the laser beam 21 is in the wide angle state, the inter-vehicle distance to the preceding vehicle continuously recognized by the scanning laser radar 3 is: The image camera 5 recognizes that the vehicle in front has changed lanes when the vehicle is sufficiently far enough to be detected by the normal laser beam 21, and recognizes the vehicle ahead in its own lane by the scanning laser radar 3. When it is not possible, by returning the laser beam 21 from the upward wide-angle state to the normal state, the vehicle ahead can be reliably recognized over a wide range from a long distance to a short distance. .
[Brief description of the drawings]
FIG. 1 is a diagram showing a system configuration of a forward recognition device 1 according to one embodiment of the present invention.
FIG. 2 is a diagram illustrating a state in which a preceding vehicle traveling on another lane has changed lanes and cut into its own lane.
FIG. 3 is a side view showing an image camera, a scanning laser radar, and the like attached to a vehicle.
FIG. 4 is a flowchart for changing an irradiation angle of a laser beam.
FIG. 5 is a diagram showing an optical vertical spread of a laser beam transmitted from a scanning laser radar.
FIG. 6 is a diagram showing an irradiation range in a vertical direction of a laser beam in a normal state transmitted from a scanning laser radar.
FIG. 7 is a diagram illustrating an irradiation range in a vertical direction of a laser beam in a wide-angle state transmitted from a scanning laser radar.
FIG. 8 is a diagram showing a detailed configuration of a scanning laser radar.
9A is a diagram illustrating a lens position in a normal state of a scanning laser radar, and FIG. 9B is a diagram illustrating a lens position in a wide-angle state.
[Explanation of symbols]
3 Scanning Laser Radar 5 Image Camera 11 Computing Device 13 Vehicle Distance Adjustment Device 15 Alarm Device 17 Beam Width Switching Device

Claims (2)

A forward-looking device including a scanning laser radar that detects an inter-vehicle distance between the host vehicle and a preceding vehicle, and a lane determining device that recognizes a lane change of the preceding vehicle,
In spite of recognizing that the preceding vehicle has entered the own lane by the lane judgment device, when the scanning type laser radar cannot detect the preceding vehicle, the scanning type laser radar emits light. A forward recognition device comprising a beam width switching means for changing a laser beam to a wide angle state in an upward direction. The beam width switching means,
When the laser beam has been changed to the wide angle state in the upward direction, the lane determination device recognizes that the preceding vehicle has left on another lane, and the scanning type laser radar makes it impossible to detect the preceding vehicle. When the distance between the host vehicle and the preceding vehicle, which is continuously recognized by the scanning laser radar, is increased to a certain distance, the irradiation range of the laser beam in the upward direction is returned to the normal state. The forward recognition device according to claim 1, wherein:

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