JP2728174B2 - Forward car recognition device for mobile vehicles - Google Patents

Description

The present invention relates to an apparatus for recognizing a forward vehicle of a moving vehicle, and more particularly to, for example, recognizing a posture angle of a forward vehicle traveling ahead of the own vehicle with respect to a traveling direction of the own vehicle. Related to a recognition device.

(Prior Art) As a prior art for recognizing the outside world by image processing, there is, for example, JP-A-61-240307. The technique disclosed in Japanese Unexamined Patent Application, First Publication No. Sho-Hei is for estimating the position and direction of a moving body from images of feature points (plurality) of the moving body and infinity lines. The direction of the moving body in this case is an azimuth from the position of the vehicle to the moving body.

On the other hand, parameters necessary for recognizing the vehicle in front using an imaging device such as a CCD camera and performing the following movement with respect to the vehicle in front are: the inter-vehicle distance to the vehicle in front, and the own vehicle and the vehicle in front. And the deviation angle in the lateral direction with respect to: and the traveling direction angle (ie, attitude angle) of the preceding vehicle with respect to the traveling direction of the own vehicle.

(Problems to be Solved by the Invention) The deviation distance of the inter-vehicle distance has conventionally been easily obtained by various methods. However, this attitude angle has conventionally relied on advanced image analysis. Also,
Although the image analysis used in the prior art is simple, at best, the azimuth from the vehicle position to the moving object can be obtained at best, and it is very difficult to detect the posture angle. I haven't.

Therefore, an object of the present invention is to propose a forward vehicle recognition device for a moving vehicle that recognizes a forward vehicle by simply detecting the attitude angle.

(Means and Actions for Achieving the Object) FIG. 1 shows the principle of the present invention. In the figure, reference numerals 1 and 2 denote left and right symmetrical portions of the vehicle, for example, left and right tail lamps. Vertical length of the left 3 and right 4 of each of the tail lamp 2 is _{T L, T R (T L} = T R). The distance between the left and right of the tail lamp is 2 · l. FIG. 1 shows an optical image when a left-right symmetrical object such as a tail lamp is captured by image input means such as a camera when viewed from the Z-axis direction. It is assumed that the optical axis of the camera 5 as the input means is set to pass through the center of the symmetric object. In addition, camera 5
(That is, the position of the own vehicle) to the tail lamp of the preceding vehicle is detected by a conventional method.

It is assumed that the tail lamps 1 and 2 are rotating by θ around the Z axis in the XY plane, that is, the attitude angle of the preceding vehicle is θ. Note that θ is positive in the counterclockwise direction from the Y axis, and 0 ≦ θ
<90 degrees. The distance in the X direction from the camera 5 to the left side 3 is D−l · sin θ The distance in the X direction from the camera 5 to the right side 4 is D + 1 · sin θ. Tail lamp 1, the left side 3, shows an image of the right side 4 to 6, the length of the image of each, and T _L ', T _R'. Assuming that the paraxial condition is satisfied for the lens of the camera 5, Holds, Is obtained. Here, γ ^* is a line segment ratio, And Although the actual length l between the symmetric objects is used in the equation (2), it is equivalent to use the distance l 'measured in the image 6 instead.

However, according to the configuration of the present invention, in a forward vehicle recognizing device for a moving vehicle provided with image input means for external world recognition, first detecting means for detecting an inter-vehicle distance between the own vehicle and a preceding vehicle; From the image input from the means, based on a partial image extracted for a predetermined left-right symmetric part of the vehicle ahead,
Second detecting means for detecting the size of the symmetrical portion in the left and right images and the distance between the symmetrical portions; the inter-vehicle distance detected by these detecting means and the size of the symmetrical portion in the left and right images; And a calculating means for calculating a relative attitude angle of the preceding vehicle with respect to the own vehicle based on the distance between the symmetric portions.

(Embodiment) An embodiment in which the posture angle detection of the present invention is applied to follow-up running control of a preceding vehicle will be described below with reference to the accompanying drawings. This embodiment is a further extension of the principle shown in FIG.
This is to detect the attitude angle θ even when the preceding vehicle is laterally deviated from the own vehicle. In addition, in the present invention, the length of the image of the symmetrical object may be essentially considered, but in an actual vehicle, in consideration of the fact that the number of linearly shaped symmetrical objects is less and the number of arc-shaped objects is more, In the embodiment to be described, the area of the symmetric object, not the length, is considered. This is because there is less error in calculating the line segment ratio γ ^* from the area ratio than when the curve shape is approximated by a rectangle or the like and the line segment ratio γ ^{* of the} rectangle is obtained according to the equation (3). is there. This point will become clear from the following description.

FIG. 2A and FIG. 2B are block diagrams of the forward vehicle recognizing device and the forward vehicle following travel control device of the embodiment, respectively. In FIG. 2A, reference numeral 10 denotes a camera for obtaining an image of the outside world. The image obtained by the camera 10 is subjected to, for example, extraction of an image signal of a predetermined color by an image processing unit 12, and further, binarization processing and the like. The predetermined color is, for example, a color of a tail lamp. The image signal subjected to these processes is sent to the preceding vehicle recognition device 18. On the other hand, 11 is the inter-vehicle distance D with the preceding vehicle.
The reflected laser light is received by a head 11, and the received signal is subjected to processing such as removal of noise components by a distance measuring signal processing unit 13 to recognize a preceding vehicle. It is sent to the device 18.

The recognition device 18 comprises four calculation modules. The area ratio / symmetric body length calculation module 18a is a module that calculates the area ratio γ and the length 1 of the images of the left and right tail lamps, which are symmetric objects. The lateral deviation calculation module 18b calculates the lateral deviation y of the preceding vehicle with respect to the own vehicle from the image captured by the image processing unit 12 and the inter-vehicle distance D. The inter-vehicle distance calculation module 18c calculates the inter-vehicle distance D from the preceding vehicle from the distance measurement signal.

The attitude angle calculation module 18d calculates the attitude angle θ of the preceding vehicle from γ, l, y, D, and calculates the attitude angle θ in addition to γ, l, y, D,
This is sent to the following travel control device 30 shown in the figure.

In FIG. 2B, reference numeral 40 denotes an acceleration / deceleration control unit, and reference numeral 41 denotes a steering control unit. The control units 40 and 41 control the throttle actuator 43, the steering actuator 44, and the brake actuator 42 based on the recognition result of the distance D to the preceding vehicle, the lateral deviation y, the posture angle θ, and the like by the recognition device 18 to travel. Perform control. That is, the acceleration / deceleration control unit 40 determines the vehicle speed of the own vehicle based on the distance D to the preceding vehicle, the vehicle speed, and the like, and controls the throttle actuator 43 or the brake actuator 42 to correspond to the vehicle speed. Similarly, the steering control unit 41 calculates the lateral deviation y,
The steering actuator 30 is controlled based on the attitude angle θ of the vehicle ahead. In this way, the following running control for the preceding vehicle is performed.

FIG. 3A is a rear view of a general vehicle, which is assumed to be a front vehicle. In this figure, the brake lights
50L, 50R, turn signals 51L, 51R, etc. are symmetrical. FIG. 4 shows a forward vehicle 61 in front of the own vehicle 60, that is, the forward vehicle 61 is shifted from the own vehicle 60 by D in the X-axis direction and by y in the Y-axis direction, and the posture angle at that time is θ. I do. FIG. 3B shows an image obtained from the image input means described later in the state of FIG.

The principle of calculating the area ratio γ will be described with reference to FIG. Fifth
The figure shows the tail lamp portion extracted from the rear image of the front vehicle shown in FIG. 3A. If the area ratio of the brake lamp 50 is determined as a symmetric object, the image processing unit 12 extracts the brake lamp image and performs a binarization process by setting the above-described predetermined color to red. This binarized image should be as shown in FIG. In FIG. 5, G 'is the center between the images of the left and right brake lamps, and l' is the distance on the image from G 'to each end of the left and right tail lamp images. Calculation module 18a is counted the number of pixels of each of the fifth left tail lamp image 50L shown in FIG. And right tail lamp image 50R N _L, the N _R, , The area ratio γ is calculated.

Next, a method of calculating the lateral deviation y and the actual length l between the left and right brake lamps will be described with reference to FIGS. In the figure, A in FIG. 6 is the camera position of the own vehicle, and P, Q
Indicates an edge portion when the both end portions on the rear surface of the front vehicle are modeled, and has a length 2l of a straight line PQ. F is the focal length of the camera lens, α is the viewing angle, and the straight line EF is the imaging plane. The point G 'in FIG. 5 corresponds to the middle point of the straight line EF in FIG.

The inter-vehicle distance D is calculated by the calculation module 18c based on the distance measurement signal. As can be seen from FIG. 5, l 'is given by (the number of pixels from G to the end) × the length of one pixel. In FIG. 6, since EG '= G'F = l' and PG = l ≒ P'G, It is. As for the lateral deviation y, if the number of pixels from the point G 'on the image to the X axis is Ny in FIG. It is. The above is the method of calculating γ, l, y, and D in the calculation modules 18a, 18b, and 18c.

Next, an attitude angle calculation method in the calculation module 18d will be described with reference to FIG. In the figure, since the triangle AEF and the triangle AP'Q 'are similar, an equation for the attitude angle θ can be obtained. That is, θ
Can be obtained by solving the equation f (θ) = 0 for the function f (θ) of θ represented by the equation (8). Here, f (θ) is ^{f (θ) = (γ *} +1) · yD · sinθ- (γ * -1) · D 2 · cosθ - (γ * -1) · ylsin 2 θ + (γ * +1)・ Dl ・ cos
θ · sin θ (8) Here, γ ^* is given by γ ^* = γ ^1/2 from Expression (4). This is because the area ratio is the square of the line segment ratio.

Since equation (7) is a nonlinear equation, for example, Newton
-Can be solved numerically by applying the Raphson method. New
When the ton-Raphson method is applied, the attitude angle θ is approximately Is represented by n is 1, 2, 3,..., and the initial value θ ₀ of θ _n is obtained by solving the equations (7) and (8) for y = 0. Becomes Equation (11) has been described with reference to FIG.
Same as the formula.

The above is the method of calculating θ in the attitude angle calculation module 18d.

In general, in an image captured by a camera, an image having a lateral deviation y is distorted. Since this distortion is proportional to the viewing angle α,
Θ in equation (10) can be calculated more accurately. That is, if the proportionality constant is ε, then θ ^* = θ _{n + 1} + ε · α (13)

The present invention can be variously modified without departing from the gist thereof. For example, in the embodiment of FIG. 2, the lateral deviation y is considered, but when this y is small, the influence of y is smaller than the accuracy of calculating the area ratio γ, for example. In such a case, θ can be calculated by ignoring y, as in equation (2).

In the above embodiment, the tail lamp has been described as a symmetric object. However, the invention is applicable to any symmetrical object at the rear of the vehicle.

Further, the use of the attitude angle of the preceding vehicle obtained according to the present invention is as follows.
It is not limited to the forward vehicle following travel control.

(Effects of the Invention) As described above, according to the apparatus for recognizing a vehicle ahead of a moving vehicle of the present invention, the distance between the vehicles and the size of each of the predetermined left-right symmetrical parts of the preceding vehicle obtained from the image in the image In addition, since the relative attitude angle of the preceding vehicle with respect to the own vehicle can be calculated based on the distance between the symmetrical portions, the attitude angle can be obtained much more easily than in the past.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the principle of the present invention, FIGS. 2A and 2B are diagrams showing the configuration of an embodiment system to which the present invention is applied in a block diagram, and FIGS. 3A and 3B are front vehicles, respectively. FIG. 4 is a view for explaining the positional relationship between the own vehicle and the preceding vehicle, FIG. 5 is a diagram showing a state of the brake lamp of the preceding vehicle after image processing, and FIG. FIG. 9 is a diagram illustrating a principle of calculating a posture angle θ in an example. In the figure, 1,2 ... left-right symmetric part of the vehicle, 3,4 ... left and right sides of the left-right symmetric part, 5 ... image input means, 6 ... image, 10 ... camera, 11 ... laser radar head , 12 …… Image processing unit,
13 ... Distance measurement signal processing unit, 18 ... Front car recognition device, 18a ...
… Area ratio / symmetric body length calculation module, 18b …… Side deviation calculation module, 18c …… Inter-vehicle distance calculation module, 18d…
… Attitude angle calculation module, 30… tracking control device, 40…
Acceleration / deceleration control section, 41: steering control section, 42: brake actuator, 43: throttle actuator, 44:
Steering actuator, 50L, 50R …… Brake lamp, 51L, 51R …… Tail lamp, 60 …… Own car, 61 ……
Vehicle ahead, A: Camera position of own vehicle, G: Center of vehicle ahead,
l: symmetric object length, D: inter-vehicle distance, y: lateral deviation, θ:
... attitude angle, f ... focal length.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location G05D 1/02 G05D 1/02 K G08G 1/16 G08G 1/16 EA

Claims (1)

(57) [Claims] 1. An apparatus for recognizing a vehicle ahead of a moving vehicle having image input means for recognizing the outside world, wherein: first detection means for detecting an inter-vehicle distance between a host vehicle and a preceding vehicle; and input from the image input means. Second detecting means for detecting the size of the symmetrical portion in each of the left and right images and the distance between the symmetrical portions on the basis of the partial images extracted for the predetermined left-right symmetrical portion of the preceding vehicle from the obtained image. Calculating means for calculating the relative attitude angle of the preceding vehicle with respect to the own vehicle based on the inter-vehicle distance detected by these detecting means, the size of each of the symmetrical parts in the left and right images, and the distance between the symmetrical parts. A forward vehicle recognition device for a mobile vehicle comprising: