Communications: electrical – Land vehicle alarms or indicators – Of relative distance from an obstacle
Reexamination Certificate
2000-10-20
2002-11-19
Swarthout, Brent A. (Department: 2632)
Communications: electrical
Land vehicle alarms or indicators
Of relative distance from an obstacle
C340S903000, C340S932200, C348S118000, C348S148000
Reexamination Certificate
active
06483429
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to systems for assisting a driver of a vehicle to park via an image of around the vehicle and, more specifically, to a system for calculating a distance from the vehicle to a specific 3D object in the image picked up from the vehicle and advising the driver of what is located around the vehicle.
2. Description of the Background Art
Conventional technologies so far disclosed as relevant to vehicles, such as automobiles, include detecting any obstacle around a vehicle, for example. If any obstacle is detected, and if a collision with the obstacle is determined as being highly possible, a driver of the vehicle is warned by alarm, advised of a distance to the obstacle, or according to the distance, the vehicle is automatically braked to stop. As an example of such detection means, there is a distance detection system utilizing an image recognition technology, such as disclosed in Japanese Patent Laid-Open No. 5-114099 (93-114099). Utilized in this system is an image picked up by a camera mounted in a vehicle.
The distance detection system is now described with reference to
FIGS. 11 and 12
. Specifically,
FIG. 11
is a diagram showing the relationship between a camera and a 3D object, while
FIG. 12
a block diagram showing the distance detection system.
In the distance detection system, a vehicle, such as in an automobile, is equipped with a stereo optical system for picking up an image of the 3D object located outside of the vehicle within a given range. The stereo optical system is exemplarily implemented by several cameras utilizing a solid image-pickup device, such as a charge-coupled device (CCD), and each fixedly attached to a ceiling surface of the vehicle towards its front. Here, the number of cameras is presumably two, and the camera located on the right, as viewed from the front, is referred to as the right camera, and the other camera on the left is as the left camera.
In
FIG. 11
, the right and left cameras are placed so as to be away from each other by a distance s, and each of the cameras photograph a point P at a perpendicular distance D therefrom. Assuming a focal distance for both cameras being f, an image of the point P is picked up on each camera's projection surface, which is away from the camera by the focal distance f. In this case, the distance between these two images on the projection surfaces is s+t, where t denotes a displacement. Thus, the distance D is so calculated as follows:
D=s*f/t
That is, the displacement t leads to the distance D.
Described next is the process of calculating the displacement t. In
FIG. 12
, a stereo optical system
100
forwards data two of analog images picked up therein to an image processing part
201
. The two analog image data are then subjected to an A/D conversion for output to a hamming distance calculation part
202
. The two digital image data are then calculated, respectively, for a hamming distance H on a pixel basis. The hamming distances H are used to determine the displacement of the two images. A minimum/maximum value detection part
203
then searches the hamming distances H calculated by the hamming distance calculation part
202
for a minimum value Hmin and a maximum value Hmax. It is herein assumed that the minimum value Hmin is the displacement t.
As such, the distance detection system
200
processes two images picked up by a stereo camera mounted in a vehicle, and finds the displacement t. Thereby, the system can assist a driver with a 3D position of an obstacle, for example, and a warning alarm is possible to prevent against a collision or bump.
Such a distance detection system, however, requires considerable accuracy for fixedly attaching several cameras of the stereo optical system to a vehicle, especially with regard to angle, direction, interval, and the like. There also needs to be previously input, to a stereo image processing device, data indicating the satisfactory positions of those cameras. As a result, structuring such a stereo optical system is very difficult. Further, as described in the foregoing, in order to calculate the hamming distances H, object detection needs to be performed for one image with reference to the other image in their entirety. Also, the search on the pixel basis needs to be repeated, the amount of calculation is thus quite large, and the hardware structure is complicated. Still further, the distance to an obstacle advised by this distance detection system is often in numerical figures or by images being quite different in appearance from the actual obstacle. Therefore, the driver cannot quite perceive the actual distance.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a parking assistance system for assuredly advising a driver of a distance between his/her vehicle and an obstacle in a perceivable manner, while easing attachment of an image pick-up to the vehicle and reducing the number of calculations required for image processing.
The present invention has the following features to attain the above object.
An aspect of the present invention is directed to a parking assistance system for assisting a driver of a vehicle to park by picking up an image around the vehicle, and advising the driver of a 3D object located therearound. The system comprises an image pick-up for picking up, with a single camera during the vehicle's transition, first and second images around the vehicle picked up at a different location and first and second times, an object specification part for detecting and specifying the 3D object found in each of the first and second images, a vehicle position calculation part for calculating transition data of the vehicle from the first location to the second location, an object distance calculation part for calculating a distance from the vehicle to the 3D object by using the position of the 3D object in each of the first and second images, and the transition data of the vehicle, and an image creation part for creating a third image for display to the driver based on the images picked up by the image pick-up and data calculated by the object distance calculation part.
As described above, in the aspect of the present invention, as is provided with a single image pick-up, the parking assistance system picks up two images at different location and time, and calculates the transition data of the vehicle between the two locations. Therefore, with the principle of triangulation applied to the 3D objects in two images, the parking assistance system can correctly calculate the distance to the 3D object. Accordingly, one image pick-up will do, and the parking assistance system achieves easy attachment thereof as having no more need to fixedly attaching several image pick-ups with considerable accuracy, especially with regard to angle, direction, interval, and the like. Further, the data calculated by the object distance calculation part correctly indicates the distance from the vehicle, and thus the third image will not be askew and tell the correct distance. Still further, by displaying the image onto which the distance data is added, the actual distance from the vehicle to the 3D object is easier for the driver.
The object distance calculation part preferably detects edges of each of the 3D objects found in the first and second images. Also, the object distance calculation part uses the coordinate data of any edge identical in the first and second images and the transition data of the vehicle so that the distance from the vehicle to the edge of the 3D object is calculated. Therefore, even if the vehicle moves in a complex fashion, the distance to the 3D object can be easily calculated with only the coordinates data of any edge identical in the two images and the transition data of the vehicle. Further, in order to detect any identical edge, by using the transition data of the vehicle, the object distance calculation part may estimate the position of the edge identical in the first and second images, and then positiona
Iisaka Atsushi
Yasui Nobuhiko
Matsushita Electric - Industrial Co., Ltd.
Swarthout Brent A.
Wenderoth , Lind & Ponack, L.L.P.
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