Image analysis – Applications – Vehicle or traffic control
Reexamination Certificate
1995-06-06
2001-09-04
Patel, Jay (Department: 2623)
Image analysis
Applications
Vehicle or traffic control
C180S167000, C318S587000, C340S443000
Reexamination Certificate
active
06285778
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
This invention relates to a vehicle surroundings monitor and, more specifically, to a vehicle surroundings monitor which monitors the surroundings of a vehicle such as an automobile to support a driver in checking safety during vehicle driving.
A vehicle surroundings monitor for automobiles has been available, in which the distance to an obstacle is detected by measuring the time it takes for an ultrasonic wave, which is emitted from an ultrasonic wave transmitter and reflected by the obstacle, to return to a wave receiver.
There is also a method in which a television camera is mounted on the rear part of the roof of a vehicle so that the driver is given a rearward view on a TV monitor of an interested area when the vehicle is moving backward.
Of the above-mentioned conventional apparatuses, the one which uses the ultrasonic wave transmitter and receiver cannot detect the positions and sizes of obstacles and ditches and the depths of the ditches. Hence, it cannot fully support the driver in confirming safety in the near surroundings of the vehicle during driving.
In the method that uses a TV monitor, on the other hand, it may be difficult to distinguish the obstacles or ditches from the level ground depending on their shapes. Especially during nighttime, there may be cases where obstacles cannot be identified unless sufficiently illuminated.
SUMMARY OF THE INVENTION
This invention has been accomplished to overcome the above drawbacks and its object is to provide a vehicle surroundings monitor which can detect the sizes, positions and depths of obstacles, ditches or humans and thereby give adequate aid for the driver to confirm the safety in the near surroundings of the vehicle while driving.
To solve the above problems, the vehicle surroundings monitor according to this invention comprises: a pattern light projector which receives a laser beam and projects a light spot pattern onto the monitored area; a camera for photographing the light spot pattern; and a data processor which processes images supplied from the camera to detect the presence of obstacles, grooves or humans.
The data processor consists of: a reference data generating means which extracts a light spot pattern from pixel data, the pixel data being produced from the image signals supplied by the camera that photographed the light spot pattern thrown upon a flat road surface, and which generates reference data of the light spot pattern including the coordinates of each light spot; a detecting means which compares the light spots of the reference data with light spots which are extracted from pixel data, the pixel data being produced from the image signals supplied by the camera that photographed the light spot pattern thrown upon a road surface being examined, in order to detect the presence of obstacles, ditches or humans; a height correction means which corrects the reference data according to changes in the height of the pattern light projector and the camera from the road surface; and a brightness correction means which corrects the brightness of pixel data—which is produced from image signals supplied by the camera that photographed the light spot pattern thrown upon the road surface being examined—according to a difference between the brightness of a background other than the light spots and the background brightness of the reference data.
The vehicle surroundings monitor also has a vehicle path prediction means to calculate the path the vehicle will take and thereby predict a possible contact or collision of the car with obstacles.
The vehicle surroundings monitor also has at least one of a buzzer, voice synthesizer and display device to inform the driver of the presence of obstacles and the location where the automobile is predicted to contact the obstacles.
In the above configuration, the pattern light projector receives an incoming laser beam and projects a light spot matrix in the form of a regular grating onto the monitored area (in the embodiment the monitored area is the ground surface being examined). When there is any obstacle, ditch or human within the monitored area, the three-dimensional positions of the light spots thrown onto these objects change resulting in local disturbances of the light spot projection image obtained from the camera. By processing the image disturbances it is possible to detect the sizes and positions of the obstacles.
When the height of the pattern light projector and the camera from the road surface changes, the reference data is corrected accordingly. Therefore, when the car is weighed down by heavy goods or passengers, the vehicle surroundings monitor can detect obstacles, ditches or persons correctly. When the brightness of the background other than the light spots changes, the brightness of the pixel data on the monitored road surface can be corrected according to the amount of brightness change. This prevents erroneous detection of light spots, which would otherwise result from an increased brightness by brake lamp illumination. At the same time, the display device shows the size and position of the obstacle with or without an alarm buzzer sound. Further, the apparatus predicts the path the car will follow and shows on the display device the location where the car will contact or collide with the obstacle to alert the driver.
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Akita Hiroya
Ishikawa Naoto
Nakajima Masato
Sasaki Kazuyuki
Tsuji Yoshihiro
Armstrong Westerman Hattori McLeland & Naughton LLP
Patel Jay
Yazaki -Corporation
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