JPH04248489A - Preceding car detector for vehicle - Google Patents

Abstract

PURPOSE:To detect a preceding car without fail even in case of a curved running way, and to improve reliability of an automatic tracking system and the like. CONSTITUTION:Detection signal from a scanning laser radar device 10 is fed to an ECU 12. The ECU 12 detects a preceding car which runs on the same running lane, based on the detection signal from each sensor and the laser radar device 10. However, in the case that the preceding car can not be detected and also steering thereof is out of control, the ECU 12 judges that the preceding car is running on a curved way and the vehicle on which the ECU 12 is loaded, is running just before the curved way. Subsequently, an image obtained by a detection camera 24 of running way is processed by a computer 26 to calculate radius of the curved way, and, by changing a laser beam direction, the preceding car is re-detected.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a preceding vehicle detection device for a vehicle;
In particular, the present invention relates to a preceding vehicle detection device for a vehicle that reliably detects a preceding vehicle even on a curved road.

0002

2. Description of the Related Art Conventionally, a preceding vehicle detection device for a vehicle is well known, which detects the inter-vehicle distance, relative speed, etc. to a preceding vehicle for the purpose of automatically following the vehicle. Laser radar devices have conventionally been used as such preceding vehicle detection devices, but when the preceding vehicle and the own vehicle are not on the same straight road, for example on a curved road, the laser radar device is used. If the direction of the laser beam emitted from the radar device is fixed, the vehicle in front cannot be detected. Therefore, conventionally, scan-type laser radar devices that scan a laser beam within a predetermined range, or steer-type laser radar devices that detect a curved path by some means and change the beam according to the direction of the curve have been proposed. There is. For example, in the vehicle radar sensor disclosed in Japanese Patent Application Laid-Open No. 51-30490, the radiator of the radar sensor is linked with the steering wheel of the vehicle, and the radar beam emitted from the radiator is adjusted according to the steering angle of the steering wheel. It changes direction.

0003

[Problems to be Solved by the Invention] However, in this configuration in which the direction of the laser beam of the laser radar device is changed in conjunction with the steering wheel, even though the preceding vehicle is traveling on a curved road, the own vehicle is still This will not be possible if you are driving on a straight road before a curve. In other words, in such a case, the driver of the own vehicle has not yet operated the steering wheel to match the curved road, and therefore the radiator of the laser radar device linked to the steering wheel still detects the front of the vehicle, so it is difficult to detect the vehicle in front. The problem was that it could not be detected.

[0004] In particular, when such a laser radar device is incorporated into a system that detects a preceding vehicle and automatically follows the preceding vehicle according to the inter-vehicle distance and relative speed, such a lost target is There was a problem that had a huge impact on the reliability of the system.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to reliably detect a preceding vehicle even when there is a curved road, etc., and to improve the reliability of an automatic following system, etc. An object of the present invention is to provide a preceding vehicle detection device for a vehicle that is capable of detecting a preceding vehicle.

[0006]

[Means for Solving the Problems] In order to achieve the above object, a preceding vehicle detection device for a vehicle according to the present invention includes a radar device that detects a predetermined range in front of the vehicle, and a camera that photographs the shape of the road in front of the vehicle. a steering angle detection means for detecting a steering angle of the vehicle; and a steering angle detection means for detecting a steering angle of the vehicle; The present invention is characterized by comprising a control means for correcting the detection range of the radar device according to the road shape obtained by the means.

[0007]

[Operation] The preceding vehicle detection device for a vehicle of the present invention has such a configuration, and instead of changing the detection range of the laser radar device in conjunction with the steering wheel as in the conventional case, the steering angle detection device When the vehicle is traveling in a straight line and almost no steering is detected, and the vehicle in front is traveling on a curved road and has left the detection range of the laser radar device, the image is taken. The vehicle in front is tracked by correcting the detection range of the radar device based on road shape information from the vehicle.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the preceding vehicle detection device for a vehicle according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram of the configuration of this embodiment, in which a scanning laser radar device 10 is installed at the front of a vehicle. As is well known, a scanning laser radar device scans a narrowly focused laser beam in a horizontal plane at regular angles, and calculates the distance to an object from the time it takes for the laser beam to be reflected from the object and warped. It is a measuring device, and the distance L to the object is calculated for each scan angle θ.

Distance data and angle data from this scan type laser radar device 10 are input to an ECU 12 which is a control computer.

On the other hand, a vehicle speed sensor 1 detects the vehicle speed of the own vehicle.
4. A steering sensor 16 that detects the steering angle of the own vehicle and a system operation switch 18 that turns on and off the operation of this device are provided at predetermined positions on the vehicle, respectively.
Detection signals from each sensor are also input to this ECU 12. Note that as the vehicle speed sensor 14, a sensor that detects the rotation speed of the gears of the transmission, etc. can be used.
Further, as the steering sensor 16, a sensor can be used which combines a slit plate provided on the steering shaft and a photo interrupter and detects the light blocking state of the photo interrupter as the slit plate rotates.

The ECU 12 includes an input port 12a for inputting detection signals from each sensor, and a vehicle obstacle recognition section 12b for extracting obstacles existing in front of the vehicle from the input detection signals.
, a target vehicle identification unit 12c that further extracts the preceding vehicle as a target from the extracted obstacles, a calculation unit 12d that calculates the inter-vehicle distance and relative speed with respect to the identified preceding vehicle, and an output port that outputs the processed signal to the outside. 12e and a memory 12f for storing data, and outputs a control signal from the output port 12e according to the inter-vehicle distance and relative speed to the preceding vehicle, operates the throttle actuator 20 and the brake actuator 22, and controls the vehicle. It is configured to perform acceleration and deceleration.

What is characteristic about this embodiment is that in addition to the scanning laser radar device 10, a camera 24 for detecting the road ahead is installed at the front of the vehicle, and the image data from this camera 24 is The image processing computer 26 detects the shape of the road ahead (for example, the curve radius R on a curved road) and outputs it to the ECU 12, and the ECU 12 adjusts the laser beam of the scanning laser radar device 10 according to this road shape information. The purpose is to correct the radiation direction.

The processing performed by this ECU 12 will be explained in detail below with reference to FIG.

FIG. 2 shows a processing flowchart of the ECU 12. First, in S101, it is determined whether the system operation switch 18 is turned on. This S
If it is determined as YES in step 101, the next step S102
, and input the set vehicle speed V0 set by the driver. This set vehicle speed is input via the system activation switch 18. This set vehicle speed V0 gives the maximum speed during follow-up travel, and follow-up travel will be performed at a vehicle speed below this V0.

After the set vehicle speed V0 is input, distance data L and angle data θ from the scan type laser radar device 10 are input via the input port 12a. Furthermore,
At S104, the vehicle speed V from the vehicle speed sensor 14 is input. Then, in the next step S105, the vehicle obstacle recognition unit 12b recognizes an obstacle existing in front of the vehicle.

That is, the scan type laser radar device 1
When 0 detects an obstacle at a distance L and an angle θn to θn+m, the size of the obstacle is calculated as L(θn+m −θn)=Lmθ, as shown in FIG.

After the vehicle or obstacle is recognized in S105, the process moves to the next S106, and the steering sensor 16
The steering angle θs inputted at S107 is used to identify whether or not the recognized vehicle is the own lane target traveling on the same lane as the own vehicle. Whether or not the recognized vehicle is a target in the own lane is determined by the curve radius R, and this curve R is determined by the steering angle θs. Of course, the relationship between this curve radius R and θs changes depending on the vehicle speed, and generally R=P・θs・V(P
is a constant). Then, based on this curve radius R, it is determined whether the vehicles detected by the laser radar device 10 are on the same lane. (S108).

If it is determined in S108 that there is a target in the vehicle's own lane, the process moves to S109, where inter-vehicle distance control calculations are performed to perform follow-up travel. In this embodiment, this inter-vehicle distance control calculation for follow-up travel is performed as follows. That is, first, the safe inter-vehicle distance RS is calculated from the relative speed VR calculated in S105 and the vehicle speed V input in S104. This safe inter-vehicle distance RS is defined as the inter-vehicle distance that allows the vehicle to safely stop without colliding with the preceding vehicle, and is generally expressed as a function of the own vehicle speed V, the relative speed VR, the own vehicle's acceleration α, and the preceding vehicle's acceleration β. =f1
It is expressed as (V, VR, α, β). For example, RS=V・t+V2/2α−(V+VR)2/2β
becomes. Here, t is the idle running time, α is the time differential of the vehicle speed V, and β is the time differential of V+VR. The safe inter-vehicle distance RS obtained in this way is a safe inter-vehicle distance within the range where only the throttle is controlled. In contrast,
If the distance between the vehicle and the preceding vehicle suddenly decreases due to an interruption from another lane or an interruption such as overtaking, such throttle control alone will not be enough and there will be a distance between the vehicle and the vehicle that requires brake control as well. The dangerous inter-vehicle distance Rd that requires this brake control is Rd=f2 (
V, VR, α', β). Here, α' is the maximum acceleration when the throttle is fully closed and the engine brake is activated.

In this way, the safe inter-vehicle distance RS and the dangerous inter-vehicle distance Rd are calculated in S109, and the throttle and brake are controlled so that the inter-vehicle distance is equal to or greater than these RS and Rd, and the vehicle follows the preceding vehicle (S110). ).

As described above, if it is determined in S108 that there is a target in the vehicle's own lane, the vehicle can follow the target, but if there is no target in the vehicle's lane, the process moves to S111. In S111, it is determined whether or not the own lane target existed in the previous process. If the own lane target did not exist last time, there is no need to perform follow-up driving, and the set vehicle speed V input in S102
A speed control calculation is performed so that (S112), and throttle or brake control is performed (S110). On the other hand, if it is determined in this S111 that the own lane target existed in the previous control, the preceding vehicle that is the own lane target has changed lanes, or even though it is traveling in the same lane. It is possible that only the preceding vehicle entered the curved road and could not be recognized as the target in the vehicle's own lane.

Therefore, in the next step S113, it is determined whether the steering angle θs is approximately 0 degrees or not.
If YES is determined in step 3, it is determined that only the preceding vehicle is traveling on the curved road and the own vehicle is still traveling on the road in front of the curved road, and the process proceeds to the next step S114 and subsequent steps. If the determination in S113 is NO, it is determined that the preceding vehicle has changed lanes, and the process proceeds to S112 described above, where vehicle speed control is performed such that the set vehicle speed is set to V0.

As mentioned above, the steps after S114 are the flow corresponding to the processing when the preceding vehicle is traveling on a curved road and the own vehicle is traveling on a straight road just before the curved road. In the flow, the curve radius R of the curved travel route is detected based on image data from the travel route detection camera 24 shown in FIG. 1, and the scanning direction of the laser beam of the laser radar device 10 is changed according to this curve radius R. This is the flow to do this.

That is, first, in S114, the image processing computer 26 calculates the curve radius R based on the input image data.
Calculate. The image processing computer 26 includes an input port 26a, a CPU 26b, an output port 26c, and a memory 2.
6d, the image data taken in through the input port 26a is processed by the CPU 26b and sent to the output port 26.
The curve radius R is supplied from c to the input port of the ECU 12. Here, there are several possible methods for detecting the curve radius R from the image data, but in this example, two white line portions indicating lanes are extracted from the obtained image, and the white line portions 2 Calculate the tangent at the location,
The curve radius R is calculated by finding the difference in these inclinations. In other words, the tangents at the two white line parts are
When y=a1 x+b1 y=a2 x+b2, the slope difference Δa is given by the following equation.

Δa=|1/a1/a2 | This slope difference Δa is caused because the white line representing the lane is curved according to the curve radius R, and this slope difference Δa
By storing the relationship between a and the curve radius R in advance in the memory 26d, and comparing the detected inclination difference Δa with the stored data, the curve radius R of the curve road existing in front of the vehicle can be calculated. can.

After the curve radius R is calculated and input to the ECU 12, it is determined in S115 whether the calculated curve radius R is approximately infinite. Here, if it is determined that the curve radius R is almost infinite,
It is determined that the own vehicle will be traveling in a straight line from now on, and S11
Move to 2. On the other hand, if the curve radius R is a finite value, the laser beam direction of the laser radar device 10 is changed in accordance with the curve radius R in S116, and the own lane target is re-identified.

The identification process performed in S116 will be explained in detail below.

Let L be the inter-vehicle distance from the preceding vehicle before losing sight of the preceding vehicle, VR be the relative speed at that time, and Lc be the distance to the start of the curve.

When the vehicle traveling direction is x and the vehicle width direction is y, the relationship between x and y at the curve radius R is y=R−(R2
−x2 )0.5. Therefore, in FIG. 3, the amount of deviation of the preceding vehicle from the straight line after the calculation processing time of t seconds is calculated from this formula:
y=R-[R2-{(V+VR)t+(L-
Lc)}2 ]0.5. That is, it can be seen that the deviation amount y is a function of the curve radius R, the vehicle speed V, the relative speed VR, and the inter-vehicle distance L. Here, (V+VR)t
is the distance traveled by the preceding vehicle during the calculation processing time t.

[0030] Therefore, by correcting the center of the scan width of the laser radar device 10 in accordance with this amount of deviation, it becomes possible to capture the preceding vehicle again. Note that the scan width may be set to 3.5 m+w (0<w<1) considering that the normal lane width is 3.5 m.

[0031] Then, in S116, the target in the own lane is re-identified by changing the scanning direction of the laser radar device 10, and in the next S117, if it is determined that the target in the own lane has been captured again, the above-mentioned In S109, the vehicle distance control calculation for following driving is performed, and if the own lane target does not exist, the set vehicle speed V is determined in S112.
A speed calculation is performed so that the value becomes 0.

As described above, in this embodiment, when detecting a preceding vehicle using a laser radar device, even when only the preceding vehicle is traveling on a curved road, the laser radar device detects the vehicle according to the curve radius R of this curved road. It detects the vehicle in front by correcting the beam of the radar device, and can stably detect the vehicle in front even on various road shapes.
For example, even when the present preceding vehicle detection device is used in a following driving system, it is possible to reliably follow the preceding vehicle.

[0033]

[Effects of the Invention] As explained above, according to the preceding vehicle detection device for a vehicle according to the present invention, even when only the preceding vehicle is traveling on a curved road, it is possible to reliably detect the preceding vehicle. , it becomes possible to perform extremely reliable preceding vehicle detection.

[Brief explanation of the drawing]

FIG. 1 is a configuration block diagram of an embodiment of a preceding vehicle detection device for a vehicle according to the present invention.

FIG. 2 is a control flowchart in the same embodiment.

FIG. 3 is an explanatory diagram of a curve deviation amount on a curved running path in the same embodiment.

FIG. 4 is an explanatory diagram of detection by the laser radar device in the same embodiment.

[Explanation of symbols]

10 Laser radar device 12 ECU 16 Steering sensor 20 Throttle actuator 22 Brake actuator 24 Camera 26 Image processing computer

Claims (1)

[Claims] 1. A radar device for detecting a predetermined range in front of a vehicle, a photographing means for photographing a road shape in front of the vehicle, a steering angle detecting means for detecting a steering angle of the vehicle, and a radar device for detecting a preceding vehicle by the radar device. control means for correcting the detection range of the radar device according to the road shape obtained by the photographing means when the steering angle detecting means detects a nearly non-steering state when the detection is impossible; A preceding vehicle detection device for a vehicle, comprising: