JP2874083B2 - Car travel control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a travel control device for a motor vehicle, and more particularly to a vehicle drive control device which is useful when running while following a preceding vehicle while keeping a target inter-vehicle distance according to the speed of the vehicle. is there.

[0002]

2. Description of the Related Art In order to reduce the driving operation of an automobile, a constant-speed traveling device has been put to practical use, and an inter-vehicle distance control device has been developed.

[0003] The "constant speed traveling device"
It is also called "speed control" or "cruise control." In vehicles equipped with this device,
When the set switch is pressed, the vehicle keeps running at the set vehicle speed even when the accelerator pedal is released. The set vehicle speed can be changed by operating the control switch. This function is canceled when the driver steps on the brake, depresses the clutch, shifts the gear, or the like.

[0004] In order to ensure safety when the above-mentioned constant-speed traveling device is used, some devices have the following additional functions. That is, the distance from the preceding vehicle is detected by a laser radar or the like, and when the vehicle approaches the preceding vehicle abnormally, an alarm is issued to alert the driver or the gear shift stage is shifted from the fourth speed (overdrive) to the third speed. The engine decelerates due to overdrive off, which causes the engine to brake down and activate the engine brake.

On the other hand, in an automobile equipped with an "inter-vehicle distance control device", when a set switch is pressed, a target inter-vehicle distance is calculated from the vehicle speed of the own vehicle at that time, and the inter-vehicle distance with the preceding vehicle is detected. The vehicle is controlled by controlling the engine output and the brake so that the inter-vehicle distance between the vehicle and the vehicle becomes the target inter-vehicle distance. In this case, the inter-vehicle distance to the preceding vehicle is detected by performing image processing on an image captured by a camera, or by using a laser radar or the like.

[0006]

In the conventional "constant-speed traveling apparatus", when the driver catches up with the preceding vehicle having a low vehicle speed, the driver must decelerate to release the constant-speed traveling control. . Therefore, the operation is frequent on a congested road, which is rather troublesome and increases the risk.

On the other hand, in the conventional "inter-vehicle distance control device",
Control cannot be performed when there is no preceding vehicle.

The inventor of the present application has developed a "vehicle travel control device" having both the functions of a constant speed travel device and an inter-vehicle distance control device. In the case of a vehicle equipped with this “vehicle travel control device”, details will be described later, but when there is no preceding vehicle, the vehicle travels at a constant speed at the set vehicle speed, and when there is a preceding vehicle, the vehicle runs ahead while maintaining the target inter-vehicle distance. The vehicle is tracked, and deceleration control is performed when there is further interruption or when the high-speed own vehicle catches up with the low-speed preceding vehicle. If this "vehicle travel control device" is used when traveling on the main road of a highway, the driver can travel by simply operating the steering wheel, so-called easy drive can be realized, and improvement in safety can be expected.

The present invention is directed to the "vehicle control device".
Is realized on the basis of information on a preceding vehicle traveling in the same lane as the own vehicle is traveling, so that the detection of the lane can be performed rationally.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an image capturing means for capturing an image in front of a lane in which a vehicle is traveling, and a vehicle based on image information as an output signal of the image capturing means. Vehicle recognition means for recognizing, lane recognizing means for recognizing a white line indicating a lane in which the vehicle is traveling based on the image information, and vehicle traveling based on processing information of the vehicle recognizing means and lane recognizing means. If there is a preceding vehicle in the lane, a target tracking vehicle recognizing unit that recognizes the preceding vehicle as a target tracking vehicle, and an inter-vehicle distance detecting unit that detects an inter-vehicle distance between the preceding vehicle in the lane in which the own vehicle is traveling The lane recognizing unit, based on the inter-vehicle distance information detected by the inter-vehicle distance detection means, excludes image information of a preceding vehicle. With processing the image information, characterized by being configured to process image information to expand the processing area in accordance with an increase of the inter-vehicle distance.

[0011]

According to the present invention having the above-described structure, depending on the inter-vehicle distance to a preceding vehicle traveling in the same lane as the lane in which the own vehicle is traveling, a narrow area if the inter-vehicle distance is short, or If it is long, the lane information of a wide area is processed only for a necessary area which is not disturbed by the information of the preceding vehicle.

[0012]

【Example】

<Overall Description of "Vehicle Travel Control Device"> First, a description will be given of a vehicle travel control device currently under development.
The traveling control device for an automobile is used when traveling on an expressway and an automobile exclusive road (hereinafter, both are represented as “expressways”).

FIG. 1 shows an automobile provided with an automobile traveling control device. In the figure, 1 is a stereoscopic camera, 2 is a laser radar, 3 is a throttle actuator, 4 is a brake actuator, 5 is an operation switch / information display section, 6 is a controller, 7 is a vehicle speed sensor, 7a is a steering wheel angle sensor, and 7b. Is a brake switch, 7c is a brake pedal switch, and 7d is an accelerator pedal switch.

FIG. 2 is a front view of the stereo camera 1.
As shown in the figure, two C
The CD cameras 11 and 12 are arranged horizontally, and electronic components such as an image board and an aperture board are mounted in a body 13. The stereoscopic camera 1 is mounted near a room mirror in a vehicle cabin. Each camera 11, 1
The viewing angle in the horizontal plane of No. 2 is 23 degrees. Then, a video signal indicating an image captured by the cameras 11 and 12 is sent to the controller 6.

The images captured by the two cameras 11 and 12 are subjected to image processing by the image processing unit of the controller 6 to perform the following recognition. Recognition of the preceding car (preceding car). Recognition of a white line that indicates the lane on which the vehicle is traveling, among a plurality of lanes (lanes) on a highway. Recognition of the inter-vehicle distance between the preceding vehicle and the own vehicle.

The recognition of the preceding vehicle is performed, for example, as follows. That is, an area surrounded by a straight line in the vertical direction is extracted from the image, and an image which is symmetrical in the extracted area and whose position does not move much in the image to be captured one after another is recognized as a preceding vehicle. .

The recognition of the white line indicating the traveling lane of the own vehicle is performed, for example, as follows. That is, as shown in FIG. 3A, the front road screen is fetched from the stereoscopic camera 1, and then, as shown in FIG. 3B, the pixels are arranged along four horizontal lines W1 to W4. Then, a bright point is selected as a white line candidate, and as shown in FIG. 3C, a line segment obtained by interpolating the upper candidate point and the lower candidate point is extracted as a white line.

The above-described recognition of the inter-vehicle distance between the preceding vehicle and the host vehicle is performed as follows. That is, from the two cameras 11 and 12 of the stereoscopic camera 1, FIG.
Two images are obtained as shown in FIG. The same image as the car image surrounded by the window on the right image is slightly shifted in the left image. Therefore, the position of the most matching image is determined while shifting the right-side car image surrounded by the window by one pixel within the search area of the left-side image. At this time, as shown in FIG.
The focal length of the lenses 1 and 12 is f, and the left and right cameras 11 and 1
2, the distance between the optical axes is L, the pixel pitch of the CCD is P,
In FIGS. 4A and 4B, assuming that the number of pixels obtained by shifting the right image until the left and right vehicle images match is n, the distance R to the preceding vehicle (inter-vehicle distance) R is calculated according to the principle of triangulation. Can be calculated by the following equation. R = (fL) / (nP)

On the other hand, the laser radars 2 are arranged one by one at the right front end and at the left front end of the vehicle. The spread angle of the laser beam emitted from the laser radar 2 is 2 degrees. By measuring the time from when the laser beam is emitted from the laser radar 2 to when the laser beam reflected by the object returns to the laser radar 2 again, the distance to the object can be measured. it can.

Although the laser radar 2 can detect the presence or absence of an object at a long distance (100 m to several hundred m) in a short time, it cannot judge whether the object is an automobile.
On the other hand, in image processing using a camera, it is possible to accurately determine whether or not a target is an automobile, but it takes a long processing time until the determination is made. Therefore, the presence or absence of the object is detected by the laser radar 2, and when the presence of the object is confirmed, the roles are divided so as to detect the presence or absence of the car by performing image processing of the camera image by focusing on the detection area. Is also good. In this way, the preceding vehicle can be quickly and accurately detected.

As shown in FIG. 6 which shows an automobile running on a highway as viewed from above, a laser beam 2a emitted from a laser radar 2 travels in a straight line while a camera 1
Since the field of view 1a is 23 degrees, when another vehicle suddenly breaks in front of the own vehicle, the laser beam 2a first strikes and reflects on the other vehicle (the other vehicle interrupted at this time is the camera 1). Not in the field of view 1a). Therefore, the detection of the interrupted vehicle is handled by the laser radar 2 which can detect the interrupted vehicle first and has a quick response. In FIG. 6, 8, 8a and 8b are white lines. The continuous white line 8 is at the end of the highway, and the dotted white lines 8a and 8b are at the positions separating the lanes.

When the throttle actuator 3 is actuated by a command from the controller 6 to increase the throttle opening, the engine speed increases and the vehicle speed increases. Conversely, as the opening of the throttle is reduced, the engine brake is activated and decelerates. Tracking running control and constant speed running control described later are executed by adjusting the throttle opening. When the brake actuator 4 is actuated by the command of the controller 6 to apply a brake, the vehicle decelerates rapidly. This rapid deceleration occurs when another vehicle interrupts immediately before the own vehicle, or when performing a brake control described later, that is, when the own vehicle traveling at a high speed approaches the preceding vehicle traveling at a low speed, and This is performed when the distance becomes shorter than the safe inter-vehicle distance. In the present system, the vehicle is suddenly decelerated by the command of the controller 6, but does not stop suddenly, but is stopped only when the driver depresses the brake pedal.

Next, an outline of traveling control performed mainly by the controller 6 will be described with reference to FIG. The image processing unit 61 of the controller 6 performs image processing on the image captured by the stereoscopic camera 1, the vehicle recognition unit 61a recognizes the image of the car from the scene in front, and the lane recognition unit 61b runs the vehicle. The inter-vehicle distance recognizing unit 61c recognizes the inter-vehicle distance between the preceding vehicle and the host vehicle by recognizing a white line indicating the lane in which the vehicle is traveling. The target tracking vehicle recognizing unit 62 recognizes the vehicle as the target tracking vehicle when there is a vehicle ahead of the lane in which the own vehicle is traveling.

The target tracked vehicle is recognized by the target tracked vehicle recognition unit 62.
When both are recognized, the setting command unit 63 performs the tracking drive control.
do. In other words, the setting command unit 63 is the inter-vehicle distance recognition unit 61c.
Or the car to the target tracking vehicle using the laser radar 2
The distance D is obtained, and the vehicle speed obtained from the vehicle speed sensor 7 is
Vehicle speed V_aMultiplied by the set time (for example, 2 seconds)
Distance D₀Ask for. And the actual inter-vehicle distance D is the target inter-vehicle distance.
Distance D₀Throttle actuator to equal
Engine 3 to operate the engine (∽ throttle opening)
Control. In this way, depending on the vehicle speed
Target inter-vehicle distance D ₀Tracking the target tracking vehicle
While the vehicle is running. Therefore, the target tracking vehicle
Is traveling at high speed (for example, 120 km / h)
Target inter-vehicle distance D₀Becomes longer (for example, 66.7 m)
The car travels at high speed while tracking the target tracking vehicle (for example, 120
km / h). Also, the target tracking vehicle runs at low speed (for example, 6
0 km / h), the target following distance D₀Is short
(For example, 33.3m), the vehicle tracks the target tracking vehicle
While traveling at a low speed (for example, 60 km / h).

During the tracking travel control, the target tracking vehicle travels at a high speed to advance ahead of the own vehicle, and the stereo tracking camera 1 or the laser radar 2 cannot capture the target tracking vehicle, or When the tracked vehicle moves to another lane, the setting command unit 63 sets the throttle opening (throttle opening degree) of the throttle actuator 3 so as to maintain the speed of the own vehicle at that time for a preset holding time (for example, 2 seconds). ∽Control the engine speed). That is, the control shifts from the tracking drive control to the vehicle speed holding control (see FIG. 8).

If another preceding vehicle is recognized as the target pursuit vehicle before the above-mentioned holding time elapses, that is, if the preceding vehicle can be captured on the traveling lane of the own vehicle, the above-mentioned pursuit traveling again is performed. Take control. After the elapse of the above-described holding time, the process proceeds to the constant speed traveling control described below (see FIG. 8).

When the control is shifted to the cruise control, the setting command section 63
As the vehicle travels at the preceding vehicle was speed or preset at the time that can no longer capture set speed V _s,
Throttle opening by throttle actuator 3 (∽
Engine speed). When the target tracking vehicle is captured during the constant-speed running control, the process proceeds to the tracking running control (FIG. 8).
reference).

If the laser radar 2 detects the presence of an interrupted vehicle during the tracking running control, the vehicle speed holding control, or the constant speed running control, the process shifts to the interrupt control.
The setting command section 63 controls the throttle actuator 3 so that the throttle is fully closed for a certain time. After a lapse of a fixed time period when the vehicle is fully closed, the process shifts to tracking running control when the target tracking vehicle can be captured, and shifts to constant speed running control when the target tracking vehicle cannot be captured (see FIG. 8).

During the tracking travel control, the vehicle speed holding control, the constant speed travel control, and the interrupt control, the vehicle is located at a position closer than the safe inter-vehicle distance determined by the relative speed between the own vehicle and the traveling vehicle and the own vehicle speed. When it detects that a preceding vehicle is present,
Shift to deceleration running control. That is, the setting command unit 63 operates the throttle actuator 3 to fully close the throttle, and also operates the brake actuator 4 to operate the brake to decelerate. This deceleration traveling control is performed when the own vehicle traveling at a high speed catches up with the preceding vehicle traveling at a low speed, or when the preceding vehicle suddenly decelerates. The deceleration control is performed until the inter-vehicle distance with the preceding vehicle returns to the safe inter-vehicle distance. When the deceleration running control ends, the process shifts to tracking running control if the target tracking vehicle can be captured, and shifts to vehicle speed holding control if the target tracking vehicle cannot be captured (see FIG. 8).

When the driver operates the accelerator pedal, the brake pedal, and the turn signal during the tracking travel control, the vehicle speed holding control, the constant speed travel control, the interrupt control, and the deceleration travel control, the operation is shifted to the manual operation. At this time, the control commands from the setting command unit 63 to the throttle actuator 3 and the brake actuator 4 are released, and the operation of the driver is prioritized. When a set switch (described later) is turned on during manual operation, the mode shifts to tracking travel control or constant-speed travel control.

The lane recognition unit 61b described with reference to FIG.
In the process of recognizing the white line indicating the traveling lane of the own vehicle in (see FIG. 7), if all the image information from the stereoscopic camera 1 is processed, the possibility of erroneous recognition increases due to unnecessary information. In addition, extra processing time is required. That is, since the image information from the stereoscopic camera 1 also includes the image information of the preceding vehicle, if the entire image information including the image information of the preceding vehicle is processed, the image information of the preceding vehicle will be a white line. May cause misrecognition.

On the other hand, when attention is paid to the positional relationship between the own vehicle and the preceding vehicle in the output image information of the stereoscopic camera 1, the image information of the white line W almost changes on the screen 64 as shown in FIG. In contrast, the image information of the preceding vehicle C changes up and down on the screen 64 with respect to the image information of the white line W. That is, when the inter-vehicle distance D is short, it is at the bottom of the screen 64 and moves upward with an increase in the inter-vehicle distance D.

Therefore, the lane recognizing section 61 according to the present embodiment.
In b, the processing area E on the screen 64 can be appropriately cut out using the information on the inter-vehicle distance D detected by the setting command section 63 as a parameter. That is, the lane recognition unit 61b performs processing based on the flowchart shown in FIG.

As shown in FIG. 10, first, an image is captured from the stereoscopic camera 1 (step S ₁ ). Next, the processing area E is determined based on the information on the inter-vehicle distance D from the setting command section 63 (steps S ₂ and S ₃ ). The processing area E at this time is set in advance according to the following distance D as shown in FIG. When the inter-vehicle distance D is, for example, 30 m, it is a portion indicated by oblique lines.

Thereafter, a processing area E is instructed to an image processing section (not shown), and lane position information is acquired after waiting for a time during lane recognition processing (steps S ₄ , S ₅ , S ₅₎ .
S _6).

[0036]

As described above in detail with the embodiment, according to the present invention, the recognition of the white line indicating the driving lane required for the driving control of the vehicle is based on the inter-vehicle distance from the preceding vehicle.
This can be performed accurately without being disturbed by the image information of the preceding vehicle. Also, at this time, unnecessary image information is not processed, so that the processing time is shortened accordingly.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an automobile including an automobile travel control device according to an embodiment of the present invention.

FIG. 2 is a front view showing the stereoscopic camera in the embodiment.

FIG. 3 is an explanatory diagram showing a method for detecting a white line by image processing in the embodiment.

FIG. 4 is an explanatory diagram showing a method for detecting an inter-vehicle distance by image processing in the embodiment.

FIG. 5 is an explanatory diagram showing the principle of triangulation by a stereoscopic camera in the embodiment.

FIG. 6 is a plan view showing an automobile running on a highway and equipped with the embodiment.

FIG. 7 is a block diagram showing a controller according to the embodiment.

FIG. 8 is a state diagram showing a transition state of traveling control according to the embodiment.

FIG. 9 is an explanatory view conceptually showing an image processing mode of a lane recognition unit according to the embodiment.

FIG. 10 is a flowchart showing a processing procedure in the lane recognition unit.

[Explanation of symbols]

 1 Stereo Vision Camera 61a Vehicle Recognition Unit 61b Lane Recognition Unit 61c Inter-Vehicle Distance Recognition Unit 62 Target Tracking Vehicle Recognition Unit 63 Setting Command Unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FIG08G1 / 16 G08G1 / 16E (56) References JP-A-64-66712 (JP, A) JP-A-5-166098 ( JP, A) JP-A-4-262207 (JP, A) JP-A-3-282708 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B60K 31/00 B60R 21/00 620 F02D 29/02 301 G05D 1/02 G08G 1/16

Claims (1)

(57) [Claims] 1. An image capturing means for capturing an image in front of a lane in which a vehicle is traveling, a vehicle recognizing means for recognizing a vehicle based on image information which is an output signal of the image capturing means, and a vehicle recognizing means based on the image information. If there is a lane recognizing unit that recognizes a white line indicating the lane in which the car is traveling, and if there is a vehicle that precedes the lane in which the vehicle is traveling based on the processing information of the vehicle recognizing unit and the lane recognizing unit, A vehicle travel control device comprising: a target tracked vehicle recognition unit that recognizes a target tracked vehicle; and an inter-vehicle distance detection unit that detects an inter-vehicle distance between a preceding vehicle in a lane in which the own vehicle is traveling. The unit processes the image information of the narrow processing area when the inter-vehicle distance is small so as to exclude the image information of the preceding vehicle based on the inter-vehicle distance information detected by the inter-vehicle distance detection means, and increases the inter-vehicle distance. Correspondingly vehicle running controller characterized by being configured to process image information to expand the processing area.