JPH1044827A - Preceding-vehicle follow-up device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a preceding-vehicle follow-up device capable of effecting appropriate running in response to the running speed of the vehicle when getting out of the main track of an expressway. SOLUTION: A camera 3 takes road images ahead of the vehicle and an image processor 5 detects the white lines on the road from the road images to thereby detect the width of the white lines on the road. On the basis of the width of the white lines detected by the image processor 5, it is determined whether the road on which the vehicle is running is near a junction or fork. A lane-change determination part 9 determines whether the vehicle has changed its running lane to a branch lane near a junction or fork. If the vehicle is determined to have changed its running lane to a branch lane, a running-speed setting part 15 set the speed at that time to a speed set by a throttle-angle calculation part 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a preceding-vehicle follow-up device applicable to a constant-speed traveling device that drives a vehicle at a constant set speed. The present invention relates to a preceding vehicle following device capable of controlling a vehicle speed according to a distance from a vehicle.

[0002]

2. Description of the Related Art Conventionally, as a preceding vehicle following device, for example, a vehicle running control device described in Japanese Patent Application Laid-Open No. 60-261736, a vehicle running control device described in Japanese Patent Application Laid-Open No. 60-154921, A vehicle travel control device described in JP-A-60-169333 and a vehicle travel control device described in JP-A-4-238743 are known.

[0003]

SUMMARY OF THE INVENTION Japanese Patent Application Laid-Open No. 60-2617
In the vehicle travel control device described in Japanese Patent Publication No. 36-36, a method of changing acceleration when changing lanes is disclosed. If you change lanes to a highway exit lane using this method,
When there is no preceding vehicle, the vehicle can accelerate to the set speed. On the other hand, in the case of a lane that branches off from the main lane of the highway, such as an exit lane, the shape and the like of the lane often change, and the target value of the speed control that has been set is appropriate for that lane. Despite whether it is unknown, in the conventional preceding vehicle following device, when the own vehicle changes lanes to the expressway exit lane during inter-vehicle distance control, when there is no vehicle on the front lane, Since acceleration control is performed up to the set speed, there is a problem that inappropriate acceleration is applied to the road.

Further, in the vehicle travel control device described in Japanese Patent Application Laid-Open No. 60-154921 and the vehicle travel control device described in Japanese Patent Application Laid-Open No. 60-169333, the traveling speed is kept constant during curve traveling. The method of traveling is shown. However, when the lane is changed to the exit lane of the highway using such a method, if there is no preceding vehicle, the acceleration is controlled to the set speed. There was a problem.

Japanese Patent Laid-Open Publication No. 4-238743 discloses a method for changing a set speed at the time of operation by a driver in a vehicle traveling control device. However,
No method for changing the set speed from the state of the traveling road at the time of traveling is disclosed, and the above-described problem similarly occurs.
The present invention has been made in view of the above, and an object of the present invention is to provide a preceding vehicle following device that can perform appropriate traveling according to the current traveling speed when the vehicle departs from the main highway. is there.

[0006]

According to the first aspect of the present invention,
In order to solve the above-mentioned problems, an inter-vehicle distance measuring unit that measures an inter-vehicle distance from a host vehicle to a preceding vehicle, a traveling speed detection unit that detects a traveling speed of the vehicle, and a vehicle that is based on a current traveling speed and an inter-vehicle distance. A preceding-vehicle-following device including: a throttle-opening-degree calculating means for calculating a target throttle-opening value to be driven; and a throttle-opening-degree changing means for changing the throttle opening in accordance with the calculated throttle-opening target value. Image input means for capturing a front road image of the vehicle,
Thick line detection means for detecting the thickness of the white road line based on the image of the road ahead of the vehicle, and merging / branching judgment for judging whether or not the connection state of the traveling road is near the merging branch based on the detected thickness of the white line. Means, a lane change judging means for judging whether or not the lane has been changed to the merging branch side near the merging branch, and when the lane has been changed to the merging branch side, the current traveling speed is set by the throttle opening calculating means. And a running speed setting means for setting a speed.

According to a second aspect of the present invention, there is provided an inter-vehicle distance measuring means for measuring an inter-vehicle distance from a host vehicle to a preceding vehicle, a traveling speed detecting means for detecting a traveling speed of the vehicle, Throttle opening calculating means for calculating a throttle opening target value for driving the vehicle based on the running speed and the following distance, and a throttle opening changing means for changing the throttle opening in accordance with the calculated throttle opening target value A preceding vehicle following device comprising: an image input unit that captures an image of the road ahead of the vehicle; a white line detection unit that detects a road white line based on the image of the road ahead of the vehicle; Adjacent white line detection means for detecting another adjacent road white line, and branch road determination means for determining whether or not the current traveling road is near a branch road based on the shape of the detected another road white line, A lane change determining means for determining whether or not the lane has changed to the branch side near the fork; and a running speed for setting the current running speed to the speed set by the throttle opening degree calculating means when the lane has been changed to the branch side. The gist is to provide setting means.

According to a third aspect of the present invention, there is provided an input device for inputting operation information to solve the above-mentioned problem, and when there is an input from the input device, the setting set by the traveling speed setting device. The point is to change the speed to the set speed before this setting.

[0009]

According to the first aspect of the present invention, the thickness of a road white line is detected based on a captured image of a running road ahead of a vehicle, and the thickness of a traveling road is detected based on the detected thickness of the road white line. It is determined whether the connection state is near the junction. Here, it is determined whether or not the lane has changed to the merging branch side near the merging branch, and if the lane has changed to the merging branch side, the current traveling speed is set to the speed set by the throttle opening degree calculating means. However, when traveling on the merging branch side, the throttle opening target value is calculated based on the current traveling speed, and the throttle opening is changed according to the calculated throttle opening target value. When the vehicle departs from the highway main line, it is possible to perform appropriate traveling according to the current traveling speed.

According to the second aspect of the present invention, a road white line is detected based on a captured image of a road ahead of a vehicle, and another road white line adjacent to the detected road white line is detected. Next, it is determined whether or not the current traveling road is near the forked road based on the detected shape of another road white line, and it is determined whether or not the lane has been changed to the branch side near the forked road. here,
When the lane is changed to the branch side, by setting the current running speed to the speed set by the throttle opening calculating means,
When traveling on the branch side, the throttle opening target value is calculated based on the current traveling speed, and the throttle opening is changed according to the calculated throttle opening target value. When the vehicle departs from the main line, it is possible to perform appropriate traveling according to the current traveling speed.

According to the third aspect of the present invention, when the operation information is input, the set speed is changed to the set speed before the setting, so that the release operation and the return operation can be performed. Can be done simultaneously.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a diagram showing a system configuration of a preceding vehicle following device 1 according to a first embodiment of the present invention. In FIG. 1, a camera 3 forms an image input unit, captures an image of a front running road of the own vehicle, and outputs the image to an image processing device 5. The image processing device 5 constitutes a thick line detection unit, and outputs the position and shape of the road white line obtained by detecting the road white line on the front road from the captured image to the traveling speed setting unit 15 and the lane change determination unit 9. The lane change judging unit 9 constitutes a merging / branching judging unit and a lane changing judging unit, and judges whether or not the connection state of the traveling road is near the merging / branch based on the position and shape of the road white line output from the image processing device 5. Next, it is determined whether or not the vehicle has changed lanes, and in the case of a lane change,
A lane change flag indicating lane change is set and output to the traveling speed setting unit 15.

The input switch 11 is operated by the driver at the time of setting and resetting the traveling speed, and outputs to the traveling speed setting section 15. The wheel speed sensor 13 constitutes a traveling speed detecting means, detects the traveling speed of the own vehicle, and outputs the detected traveling speed to the traveling speed setting unit 15 and the throttle opening calculating unit 19. The traveling speed setting unit 15 constitutes traveling speed setting means, and includes an image processing device 5, a lane change determination unit 9, an input switch 11, and a wheel speed sensor 13.
The target value of the traveling speed in the preceding vehicle follow-up device 1 is determined from the output of the preceding vehicle 1 and input to the throttle opening calculating unit 19.

The laser radar 17 constitutes an inter-vehicle distance detecting means, measures the inter-vehicle distance from the own vehicle to the preceding vehicle, and outputs it to the throttle opening calculating section 19. The throttle opening calculator 19 constitutes a throttle opening calculator, and calculates the throttle opening of the vehicle from the outputs of the wheel speed sensor 13, the traveling speed setting unit 15 and the laser radar 17 and outputs the calculated throttle opening to the throttle actuator 21. The throttle actuator 21 controls the throttle opening of the vehicle based on the output of the throttle opening calculating section 19 so as to be a target value. In addition,
The CPU 7 has a ROM, a RAM, an input / output port, and operates with a control program and control data for controlling the apparatus. The CPU 7 includes the lane change determination unit 9, the traveling speed setting unit 15, the throttle opening, and the like. The calculation unit 19 is realized by software processing.

Next, the operation of the preceding vehicle following device 1 will be described with reference to the flowcharts shown in FIGS. 2, 3 and 5. FIG. 4 used in the process of this description shows the position of the white line detection window, FIG. 6 shows the variables of the white line detection window, and FIG. 7 shows an example of the edge image. FIG. 8 shows an example of a detected straight line. The broken lines on the left side shown in FIGS. 4, 6, 7, and 8 exist only when the vehicle is near the merging branch of the expressway, and the thickness of the broken line is in a lane that is not near the merging branch. It is thicker than a certain white line.

In FIG. 2, at step S10, the traveling speed setting unit 15 determines that the target speed is the current internal RA of the CPU 7.
It is determined whether M is set. If the target speed has been set, the process proceeds to step S40. If the target speed has not been set, the process proceeds to step S20. Step S
At 20, the traveling speed setting unit 15 determines whether the input switch 11 has been operated to set the target speed. If no switch operation has been performed, step S
On the other hand, when the switch operation has been performed, the process proceeds to step S30.

In step S30, the traveling speed setting unit 15
Is the internal running speed R of the CPU 7 using the current running speed v detected by the wheel speed sensor 13 as the target running speed during the constant speed running control.
Save to AM. In step S <b> 40, the camera 3 captures an image of the traveling road ahead of the host vehicle and inputs the captured image to the image processing device 5. In step S50, the image processing device 5 detects the shape and position of the road white line from the input road image to perform left white line detection.

Here, the image processing device 5 creates an edge image from the input road image and searches for a portion where the arrangement of edge points is linear. The edge points include a positive edge that changes from black to white and a negative edge that changes from white to black, and it is assumed that straight lines are detected separately for both edges. This processing will be described using the white line detection processing flow shown in FIG. The following processing is performed by the CPU in the image processing apparatus 5 or processing dedicated hardware.

Referring to FIG. 3, in step S210, the image processing apparatus 5 applies a SOBEL operator for extracting a vertical edge component to the entire input front road image, and as shown in FIG. Create Step S220
Then, as shown in FIG. 4, a detection window area is set at a position where a road white line appears on the screen, and a search for a road white line is performed in the detection window area. As the position of the window, a position W1 (x1, y1) near the road that appears on the screen when the vehicle is running straight on the highway is stored in the internal RAM in advance as an initial position.
The window position is WP (xwp, ywp).

In step S230, step S220
The straight line is detected with reference to the window position WP (xwp, ywp) set in the step (1). Here, a straight line detection method will be described with reference to the processing flow of FIG. Moving on to FIG. 5, in step S310, the tip of the straight line is determined by the window position WP and the width WL of the preset search area (FIG. 6).
Is calculated from The tip initial position S (xs, y) shown in FIG.
s) becomes xs = xwp + WL / 2 ys = ywp.

Next, in step S320, the rear end initial position E of the straight line is set in advance with the inclination of the detectable white line from the state of attachment of the camera 3. As shown in FIG.
Assuming that the inclination of the white line that can be detected is θ ± aα, the straight line rear end initial position E (xe, y) shown in FIG.
e) is xe = xs-h * tan (θ-α) and ye = ys-h. In step S330, the tip initial position S (x
s, ys) and a straight line f passing through the rear end initial position E (xe, ye). The straight line f is

(Equation 1) Becomes

In step S340, the number of edge points on the edge image through which the straight line f passes is measured. At this time, the number of both the positive edge and the negative edge is separately measured, and the measurement result is stored in the internal RAM of the image processing apparatus 5 with the tip position xs and the number of each edge. In step S350, the x coordinate of the rear end of the straight line is moved. That is, this movement is set as xe = xe-1.

In step S360, the rear end position xe is set to x
When xe> xs−h × tan (θ + α) is satisfied with respect to sh × tan (θ + α), the process returns to step S330. On the other hand, if xe> xs−h × tan (θ + α), the process proceeds to step S370. Move the position E to the lower limit.

In step S370, xs-1 is substituted for the x coordinate xs of the used linear tip S, xs = xs-1, and the linear tip S is moved. In step S380,
When xs indicating the straight-line tip S is xwp-WL / 2 and xs ≦ xwp-WL / 2, the process proceeds to step S390. On the other hand, when xs> xwp-WL / 2, the process proceeds to step S330. Then, the processing moves to the lower limit of the tip.

In step S390, a tip position having the maximum number of positive edges is searched from a certain tip position and the number of positive edges stored in the internal RAM. In step S400,
If the number of found positive edges is equal to or greater than the threshold value set in the internal RAM in advance, it is determined that there is a white line, and the process proceeds to step S410. I do. In step S410, by substituting the x-coordinate of the searched straight line tip into the white line position LP,
Determine the straight line position of the positive edge. In step S420, a tip position having the maximum number of negative edges is searched from a certain tip position S and the number of negative edges stored in the internal RAM.

In step S430, when the number of searched edges is equal to or larger than a threshold value set in the internal RAM in advance, it is determined that there is a white line, and the process proceeds to step S440. The line detection processing ends. In step S440, the x coordinate of the searched straight line tip is substituted for the white line position LN, and 1 is set to the left white line flag.
To determine the straight line position of the negative edge. In the above processing, the presence or absence of a white line in the detection area is determined, and if there is a white line, the position of the white line on the image is calculated.

Next, returning to the white line detection processing flow shown in FIG. 3, the white line detection processing will be described. Step S240
Then, if the white line flag is 1, it is determined that there is a white line, and the routine goes to Step S250. Otherwise, the process ends. In step S250, the distance between the two straight lines with respect to the detected both edges is calculated, and the thickness LLW of the white line is calculated.
Is calculated. In addition, as shown in FIG.
W is represented by the interval between the tip coordinates of each straight line, and LLW = (LN−LP).

In step S260, the detected left white line position LLINEP is represented by calculating LLINEP = (LN + LP) / 2 using the coordinates of the tip of the searched straight line. In step S270, the x coordinate x of the window position WP (xwp, ywp) where the white line is to be detected
The left white line position LLINEP is substituted for wp. As a result, even when the position of the white line moves, the white line can be detected. This completes the white line detection process.

Next, returning to FIG. 2, in step S60, the shape and position of the road white line are detected from the road image input from the camera 3 to the image processing device 5 to detect the right white line. The method for detecting the right white line is the same as the above-described method for detecting the left white line. As a detection result, the position of the right white line is RLINEP, the thickness of the left white line is LLW.
And In step S70, it is determined based on the calculated thickness of the left and right white lines whether or not a thick line indicating that the connection state of the traveling road is located near the junction is detected. This determination is made by using the thickness threshold value stored in the internal ROM in advance, and if the thickness LLW of the left white line is larger than the thickness threshold value, substitute L for the thickness flag and go to step S80. Move on.

On the other hand, if the thickness RLW of the right white line is larger than the thickness threshold, R is substituted for the thickness flag, and the routine goes to Step S80. Otherwise, the process moves to step S120. By the determination in step S70, it can be determined that the vehicle is traveling near the junction. Step S
At 80, it is determined whether or not the lane has been changed at the position of the detected white line. More specifically, if the thickness flag is L and the left white line position LLINEP is greater than the threshold value THL and LLINEP> THL, it is determined that a lane change has occurred, and the routine goes to step S90. On the other hand, if the thickness flag is R and the right white line position RL
If RINEP <THR with respect to INEP with respect to threshold value THR, it is determined that there is a lane change, and the process proceeds to step S90. By the determination in step S80, it is possible to determine that the lane has been changed to the merge branch side when the vehicle is traveling near the merge branch.

Next, in step S90, since there is a lane change, the current traveling speed v detected by the wheel speed sensor 13 is set in the traveling speed setting section 15 as the target traveling speed during the constant speed traveling control. Next, in step S100, the target speed change flag is changed to 1. Next, step S11
At 0, the window position for white line detection used in steps S40 and S50 is replaced with an initial value and initialized. In step S120, the wheel speed sensor 13
By controlling the throttle valve with the throttle actuator 21 so that the current traveling speed v detected by the above becomes the set target speed, the inter-vehicle distance controlled traveling is performed.
However, when a preceding vehicle that is lower than the target speed is detected, the throttle valve is controlled so that the following distance becomes the safe following distance.

Here, to control the throttle valve so that the inter-vehicle distance becomes the safe inter-vehicle distance, the safe inter-vehicle distance L
In general, s is determined by using an inter-vehicle time. Assuming that the current traveling speed is v (m / s) and the inter-vehicle time is t (s), Ls = vt. Next, the throttle opening θ is calculated using the safe inter-vehicle distance Ls and the current inter-vehicle distance L.

(Equation 2) Note that Lo is the previous measured value of the following distance, dt is the measuring interval of the following distance, Gp is a proportional gain, and Gd is a differential gain.

Next, in step S130, it is determined whether or not the input switch 11 has been operated to set the target speed. If the switch operation has not been performed, the process proceeds to step S10, whereas if the switch operation has been performed, the process proceeds to step S140. In step S140, it is determined whether or not the target speed has been changed due to the lane change. If the target speed change flag is 1, step S1
Move to 50. Otherwise, the process moves to step S160. In step S150, the traveling speed setting unit 15 returns the target speed set before changing the target speed by changing lanes to the internal RAM as the current target speed.

On the other hand, in step S160, the current traveling speed v is set as the target traveling speed during the constant speed traveling control. Next, in step S170, the target speed change flag is initialized to 0.

As described above, the image of the road ahead of the vehicle is captured by the camera 3, and the image processing device 5 detects the white line of the road from the image of the road ahead of the vehicle to detect the thickness of the white line. next,
Based on the thickness of the road white line detected by the image processing device 5, it is determined whether or not the connection state of the traveling road is near the junction.
Here, the lane change determination unit 9 determines whether or not the lane has been changed to the merging branch side near the merging branch. If the lane has been changed to the merging branch side, the traveling speed setting unit 15 determines the current traveling speed. By setting to the set speed of the throttle opening calculating section 19, when traveling on the merging branch side, a throttle opening target value is calculated based on the current running speed, and the calculated throttle opening target value is calculated. Since the throttle opening is changed accordingly, when the vehicle departs from the main road of the expressway, it is possible to perform appropriate traveling according to the current traveling speed.

As a result, when the vehicle is following the preceding vehicle, if the lane is changed and there is no preceding vehicle on the road to which the vehicle is to be changed, the acceleration operation is conventionally performed up to the set speed. In this case, the vehicle travels in accordance with the traveling speed of the vehicle. In addition, the limitation of the acceleration operation can be released by a switch input from the driver, and the driver can return to the acceleration operation when it thinks it is necessary, so that the trouble of setting the speed again is eliminated. Can be.

(Second Embodiment) FIG. 9 is a diagram showing a system configuration of a preceding vehicle following device 1 according to a second embodiment of the present invention. In FIG. 1, a camera 3 forms an image input unit, captures an image of a front running road of the own vehicle, and outputs the image to an image processing device 5. White line detection unit 3 in image processing device 5
Reference numeral 1 denotes a white line detection unit, which detects a road white line on the front running road from an image captured by the camera 3 and outputs the position and shape of the road white line to the traveling speed setting unit 37 and the branch detection unit 35. The lane change judging unit 33 constitutes a lane change judging unit, judges whether or not the own vehicle has changed lanes based on the output of the white line detecting unit 31, and in the case of lane change, sets a flag indicating lane change and runs. Output to the speed setting unit 37.

The branch road judging section 35 in the image processing device 5 constitutes an adjacent white line detecting means and a branch detecting means, and detects another road white line adjacent to the road white line detected by the white line detecting section 31, It is determined whether or not the position where the vehicle is currently traveling is a branch of the expressway. If the current position is a branch, a branch road detection flag indicating the branch is set and output to the traveling speed setting unit 37. The input switch 11 is operated by the driver at the time of setting and resetting the traveling speed, and outputs to the traveling speed setting section 37. The wheel speed sensor 13 constitutes a traveling speed detecting means, detects a traveling speed of the own vehicle, and outputs a traveling speed setting unit 37.
It is output to the throttle opening calculator 19. The traveling speed setting unit 37 constitutes traveling speed setting means, and includes a white line detection unit 31, a branch road designation unit 35, the input switch 11, and the wheel speed sensor 1.
The target value of the traveling speed in the preceding vehicle follow-up device is determined from the output of 3 and input to the throttle opening calculating unit 19.

The laser radar 17 constitutes an inter-vehicle distance detecting means, measures the distance to the preceding vehicle, and outputs the measured distance to the throttle opening calculator 19. The throttle opening calculator 19 constitutes a throttle opening calculator, and calculates the throttle opening of the vehicle from the outputs of the wheel speed sensor 13, the traveling speed setting unit 37 and the laser radar 17 and outputs the calculated throttle opening to the throttle actuator 21. The throttle actuator 21 controls the throttle opening of the vehicle based on the output of the throttle opening calculating section 19 so as to be a target value. Note that the CPU 7
It has a ROM, a RAM, an input / output port, and operates with a control program and control data for controlling the apparatus.
7. The throttle opening calculator 19 is realized by software processing.

Next, the operation of the preceding vehicle following device 1 will be described with reference to the flowcharts shown in FIGS. In addition,
FIG. 12 used in the process of this description shows the position of the branch road detection window, and FIG. 13 shows the variables of the branch road detection window. The left broken line shown in each of FIGS. 12 and 13 exists only when it is near the merging branch of the expressway, and the thickness of the broken line is larger than that near the non-merging branch. It is. The lanes on the left side respectively shown in the figure are road lane markings that branch off from the expressway.

In FIG. 10, in step S510,
It is determined whether the target speed is currently set in the internal RAM. If it has been set, the process proceeds to step S540. If it has not been set, the process proceeds to step S520. In step S520, it is determined whether the input switch 11 has been operated to set the target speed. If the switch operation has not been performed, the process proceeds to step S510, whereas if the switch operation has been performed, the process proceeds to step S5.
Move to 30.

Next, in step S530, the current running speed v detected by the wheel speed sensor 13 is saved in the internal RAM as the target running speed during the constant speed running control. In step S 540, a road image ahead of the host vehicle is input to the image processing device 5 using the camera 3.

In step S550, the image processing device 5 detects the shape and position of the road white line from the input road image and detects the left white line in order to perform the road white line detection process.
More specifically, the image processing apparatus 5 creates an edge image from the input runway image and searches for a portion where the arrangement of edge points is linear. Edge points include a positive edge that changes from black to white and a negative edge that changes from white to black.
Straight line detection is performed separately for both edges. In addition, it is detected whether another white line exists beside the detected white line. If another white line is detected, it is determined that the input front image is on the fork, and the fork detection flag is set to 1. This processing will be described using the white line detection processing flow shown in FIG. The following processing is performed by the CPU in the image processing apparatus 5 or processing dedicated hardware.

Turning to FIG. 11, in step S700,
A vertical edge component is extracted from the entire front road image input to the image processing device 5. For details, S
By applying the OBEL operator, a vertical edge image is created as shown in FIG. Next, in step S710, a detection window area is set at a position where the road white line appears on the screen, and a search is made for a road white line in the detection window area. As a position of the window, a position W1 (x1, y1) near a road white line appearing on the screen when the vehicle is running straight on the highway is stored in advance as an initial position, and as shown in FIG.
wp, ywp).

Next, in step S720, step S
Straight line detection is performed based on the window position WP set in 710. Note that the method of detecting a straight line is the same as that shown in the first embodiment. Next, step S730
Then, it is determined whether or not there is a white line. If the white line flag is 1, the process moves to step S740. Otherwise, the process moves to step S790.

In step S740, the distance between the two straight lines with respect to the two detected edges is calculated. White line thickness LL
As shown in FIG. 8, W is represented by the interval between the coordinates of the tip of each straight line, and the thickness of the white line is calculated as LLW = (LN-LP) In step S750,
The detected white line position LLINEP is calculated by using the coordinates of the tip of the searched straight line as LLINEP = (LN + LP) / 2 to calculate the white line position.

In step S760, the x coordinate x of the window position WP (xwp, ywp) for performing white line detection
The window position is moved by substituting the left white line position LLINEP into wp. Thus, even if the position of the white line moves, it can be detected. Next, step S77
If the thickness of the detected white line is equal to or larger than a predetermined threshold value, it is determined that there is a thick line, and step S800
Move on to If it is equal to or smaller than the threshold, the process moves to step S790. Next, in step S790, the branch road detection flag is initialized to 0.

In step S800, a detection window area for detecting a white line in an adjacent lane is set based on the detected white line. In this setting method, as shown in FIG. 12, the initial position WP2 (xwp2, ywp2) of the detection window area is set at a position away from the detected left white line position LLINEP by a preset window setting width WIS.
Set 2). Next, in step S810, FIG.
As shown in (5), a straight line detection process similar to that in step S720 is performed using the search area width WL2, window height h, and detectable white line inclination θ2 ± α preset in the internal RAM.

Next, in step S820, it is determined whether there is a white line. If the white line flag is 1, the process moves to step S830. Otherwise, the process ends. In step S830, the left branch road detection flag is set to 1. Next, returning to FIG. 10, in step S560, the image processing device 5 detects the shape and position of the road white line from the road image captured by the camera 3, and detects the right white line. Note that the detection method of the right white line is the same as the detection method of the left white line.

Next, in step S570, the branch detector 35 determines whether or not a branch road has been detected. If either one of the left and right branch road detection flags is 1, step S
Move to 580. Otherwise, the process moves to step S590. By the determination in step S570, it can be determined that the vehicle is traveling near the branch. Step S5
At 80, it is determined whether or not the lane has been changed at the position of the detected white line. When the left white line branch road detection flag is 1 and the left white line position LLINEP is larger than the threshold value THL, it is determined that LLINEP> THL lane change has occurred, and the routine goes to step S590.

If the right white line branch road detection flag is 1 and the right white line position RLINEP is smaller than the threshold value THR, it is determined that RLINEP <THR lane change has occurred, and the routine goes to step S590. Otherwise, the process moves to step S630. When the vehicle is traveling near the branch according to the determination in step S580,
It can be determined that the lane has been changed to the branch side. In step S590, the current traveling speed v detected by the wheel speed sensor 13 is set as the target traveling speed during the constant speed traveling control.

In step S600, the target speed change flag is changed to 1. In Step S610, Step S
540, the window position for white line detection used in step S550 is replaced as an initial value to initialize the white line detection window. In step S620, the left and right branch road detection flags are initialized to zero. In step S630,
The throttle valve is controlled by the throttle actuator 21 so that the traveling speed becomes the set target speed.
However, when a preceding vehicle that is lower than the target speed is detected, the throttle valve is controlled so that the following distance becomes the safe following distance. The control of the throttle valve is performed in the same manner as in step S120 described in the first embodiment.

In step S640, it is determined whether an input switch operation has been performed from input switch 11 for setting the target speed. If the switch operation has not been performed, the process moves to step S510. If the switch operation has been performed, the process moves to step S650. Step S65
At 0, it is determined whether or not the target speed change flag is 1 due to a lane change. If the target speed change flag is 1, the process moves to step S660. Otherwise, step S670
Move on to In step S660, the previous target speed already set in the internal RAM before changing the target speed by changing lanes is returned to the internal RAM as the current target speed. In step S670, the current traveling speed is set as a target traveling speed at the time of constant-speed traveling control. In step S680,
The target speed change flag is initialized to 0.

As described above, the image of the road ahead of the vehicle is captured by the camera 3, the white line detector 31 detects the road white line from the image of the road ahead of the vehicle, and detects another road white line adjacent to the detected road white line. To detect. Next, in the branch detection unit 35,
Based on the detected shape of another road white line, it is determined whether or not the current traveling road is near a forked road, and the lane change determination unit 33 determines whether or not the lane has been changed to the branch side near the forked road. Here, when the lane is changed to the branch side, the traveling speed setting unit 37 determines the current traveling speed by using the throttle opening calculation unit 1.
When the vehicle travels on the branch side by setting the set speed of 9, the throttle opening target value is calculated based on the current running speed, and the throttle opening is set in accordance with the calculated throttle opening target value. Since the vehicle is changed, when the vehicle departs from the main road of the expressway, it is possible to perform appropriate traveling according to the current traveling speed.

As a result, when the vehicle is following the preceding vehicle, if the lane is changed and there is no preceding vehicle on the lane to be changed, the acceleration operation has been performed up to the set speed in the related art. In this case, the vehicle travels in accordance with the traveling speed of the vehicle. In addition, the limitation of the acceleration operation can be released by a switch input from the driver, and the driver can return to the acceleration operation when it thinks it is necessary, so that the trouble of setting the speed again is eliminated. Can be.

[Brief description of the drawings]

FIG. 1 is a diagram showing a system configuration of a preceding vehicle following device 1 according to a first embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the preceding vehicle following device 1.

FIG. 3 is a flowchart for explaining the operation of the preceding vehicle following device 1;

FIG. 4 is a diagram showing the position of a white line detection window.

FIG. 5 is a flowchart for explaining the operation of the preceding vehicle following device 1;

FIG. 6 is a diagram showing variables of a white line detection window.

FIG. 7 is a diagram illustrating an example of an edge image.

FIG. 8 is a diagram illustrating an example of a detected straight line.

FIG. 9 is a diagram showing a system configuration of a preceding vehicle following device 1 according to a second embodiment of the present invention.

FIG. 10 is a flowchart for explaining the operation of the preceding vehicle following device 1;

FIG. 11 is a flowchart illustrating the operation of the preceding vehicle following device 1;

FIG. 12 is a diagram showing the position of a branch road detection window.

FIG. 13 is a diagram showing variables of a branch road detection window.

[Explanation of symbols]

 Reference Signs List 3 camera 5 image processing device 7 CPU 9 lane change determination unit 11 input switch 13 wheel speed sensor 15 traveling speed setting unit 17 laser radar 19 throttle opening calculation unit 21 throttle actuator 31 white line detection unit 33 lane change determination unit 35 branch detection unit 37 Running speed setting section

Claims (3)

[Claims] 1. An inter-vehicle distance measuring means for measuring an inter-vehicle distance from a host vehicle to a preceding vehicle, a traveling speed detecting means for detecting a traveling speed of the vehicle, and driving the vehicle based on a current traveling speed and an inter-vehicle distance. A preceding vehicle following device comprising: throttle opening calculating means for calculating a throttle opening target value; and throttle opening changing means for changing a throttle opening in accordance with the calculated throttle opening target value. Image input means for capturing an image of the road ahead of the vehicle, thick line detection means for detecting the thickness of the road white line based on the image of the road ahead of the vehicle, and a connection state of the traveling road based on the thickness of the detected road white line. Merging / branching judging means for judging whether or not it is near the merging branch; lane change judging means for judging whether or not the lane has changed to the merging branch near the merging branch; , The adaptive cruise system is characterized in that a traveling speed setting means for setting a current running speed to the set speed of the throttle opening calculating means. 2. An inter-vehicle distance measuring means for measuring an inter-vehicle distance from a host vehicle to a preceding vehicle, a traveling speed detecting means for detecting a traveling speed of the vehicle, and driving the vehicle based on a current traveling speed and an inter-vehicle distance. A preceding vehicle following device comprising: throttle opening calculating means for calculating a throttle opening target value; and throttle opening changing means for changing a throttle opening according to the calculated throttle opening target value. Image input means for capturing an image of the road ahead of the vehicle, white line detecting means for detecting a road white line based on the image of the road ahead of the vehicle, and adjacent white line detecting means for detecting another road white line adjacent to the detected road white line Branch road determining means for determining whether or not the current traveling road is near a branch road based on the detected shape of another road white line, and determining whether or not the lane has been changed to the branch side near the branch A traveling speed setting means for setting a current traveling speed to a speed set by the throttle opening calculation means when the lane is changed to a branch side. apparatus. 3. An input means for inputting operation information, wherein when there is an input from the input means, the setting speed set by the traveling speed setting means is changed to a setting speed before the setting. The preceding vehicle following device according to claim 1 or 2, wherein: