Communications: electrical – Condition responsive indicating system – With particular system function
Reexamination Certificate
2000-07-12
2001-10-30
Lefkowitz, Edward (Department: 2632)
Communications: electrical
Condition responsive indicating system
With particular system function
C340S937000, C382S104000, C348S148000
Reexamination Certificate
active
06310546
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a stereo type vehicle monitoring apparatus that executes a fail-safe function when an anomaly occurs with a pair of images taken by stereoscopic cameras.
2. Description of the Related Art
In recent years, attention has been focused on a stereo type vehicle monitoring apparatus using on-board cameras. Each camera has a built-in solid-state image sensing device, such as CCD. The monitoring apparatus determines a positional deviation of an object, that is a parallax, from a pair of images taken by left and right cameras (stereoscopic cameras) and calculates a distance to the object (distance information) by using a principle of triangulation. Then, based on the calculated distance, the monitoring apparatus recognizes the running surrounding (e.g., the distance between an outside object and the self vehicle) and alerts the vehicle driver or performs a vehicle control such as shiftdown, as required.
In a practical application of the stereo type vehicle monitoring apparatus, a fail-safe function needs to be provided to guarantee the safe operation of the apparatus. One of failures to be detected in such a vehicle monitoring apparatus is a brightness unbalance in the pair of images (stereoscopic images) taken by stereoscopic cameras. The brightness unbalance is caused by external causes. In order to secure a precision for calculating the distance to the object or recognizing a three-dimensional object in front of the vehicle, by a stereo method based on the principle of triangulation, the brightnesses of the left and right images are set to be balanced. That is, the brightnesses thereof are set so that overall luminance of the pair of images is substantially same. The unbalance in the brightnesses of the pair of images due to external causes will hinder normal monitoring of the outside of the vehicle. The external causes for such anomaly, for example, include an accidental situation where a view scope of one of the stereoscopic cameras is blindfolded. The anomaly also occurs when the optical system (particularly lens) of one of the cameras is smeared or fogged. Further, when a scene in front is taken through the windshield, partially smeared or fogged windshield or irregular reflection due to raindrops may also cause the brightness unbalance. In order to secure a high level of safety of the stereo type vehicle monitoring apparatus, when there is a brightness unbalance between the left and right images, the fail-safe function needs to be activated, so as to temporarily stop the monitor control.
Since the fail-safe function, which is essential in the practical application of the stereo type vehicle monitoring apparatus, has not been established, however, there is a problem for securing a high level of safety of the apparatus.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a stereo type vehicle monitoring apparatus that can precisely detect a brightness unbalance, which occurs in stereoscopic images and make an appropriate stereo processing impossible, and thereby can execute a secure fail-safe function.
The object can be achieved by a stereo type vehicle monitoring apparatus with a fail-safe function, which executes the fail-safe function when the vehicle monitoring apparatus is determined as a failure. The apparatus comprises a pair of cameras, a stereo image producer, a calculator and a fail decision unit. The pair of cameras take pictures of scenes outside of a vehicle. The stereo image producer produces a first image and a second image respectively based on pictures taken by the cameras. The calculator calculates a level of brightness of a first monitor area in the first image produced by the stereo image producer and a level of brightness of a second monitor area in the second image produced by the stereo image producer. The fail decision unit determines a failure of the vehicle monitoring apparatus when a difference between the brightness level of the first monitor area and the brightness level of the second monitor area exceeds a predetermined value. The second monitor area positionally corresponds to the first monitor area.
According to the above-mentioned stereo type vehicle monitoring apparatus, by monitoring the brightness balance, for example, when a normal image cannot be obtained as when one of the cameras is blindfolded, it is possible to accurately detect it. The same also applies when a normal image cannot be obtained due to partial smear or fogging of the lens of one of the cameras, of windshield or the like, or due to diffused reflections from raindrops.
The above-mentioned stereo type vehicle monitoring apparatus may further comprise a processor. The processor executes the fail-safe function on the basis of the failure decision by the failure decision unit.
Accordingly, even when an abnormal image is generated due to theses external causes, the fail-safe function can be executed, securing a high level of safety of the stereo type vehicle monitoring apparatus.
In the stereo type vehicle monitoring apparatus, it is preferable that a position of the second monitor area in the second image is offset in a stereo matching direction from a position of the first monitor area in the first image. This makes the views shown in the first and second monitor areas substantially same. Accordingly, the overall brightness of the two monitor areas under the normal condition results approximately in the same levels.
Further, in the stereo type vehicle monitoring apparatus, it is also preferable that the calculator calculates the level of the brightness of the first monitor area based on image data of a part of the first monitoring area, and the level of brightness of the second monitor area based on image data of a part of the second monitor area. This prevents an amount of calculations from increasing.
Furthermore, in the stereo type vehicle monitoring apparatus, it is also preferable that the first monitor area comprises a plurality of monitor portions set in different positions in the first image, the second monitor area comprises a plurality of monitor portions set in different positions in the second image and positionally corresponding to the respective monitor portions in the first monitor area. A position of each monitor portion of the second monitor area may preferably offset in a stereo matching direction from a position of the monitor portion of the first monitor area, the monitor portion of the first monitor area positionally corresponding to the monitor portion of the second monitor area. Further, the amounts of offsets of the monitor portions of the second monitor area to the respective monitor portions of the first monitor area may preferably differ from one another.
This allows the offset of each monitor area to be determined according to the parallax of a three-dimensional object that is highly likely to be shown in that monitor area. This in turn makes the levels of overall brightness of the first and second monitor areas more closely equal to each other.
The above-mentioned object can be also achieved by a stereo type vehicle monitoring method, the method comprising:
taking pictures of scenes outside of a vehicle by a pair of cameras;
producing a first image and a second image based on the thus taken pictures;
calculating a level of brightness of a first monitor area in the first image thus produced and a level of brightness of a second monitor area in the second image thus produced, the second monitor area positionally corresponding to the first monitor area; and
determining a failure of the vehicle monitoring apparatus when a difference between the brightness level of the first monitor area and the brightness level of the second monitor area exceeds a predetermined value.
According to the above-mentioned stereo type vehicle monitoring method, by monitoring the brightness balance, for example, when a normal image cannot be obtained as when one of the cameras is blindfolded, it is possible to accurately detect it. The same also applies when a normal ima
Fuji Jukogyo Kabushiki Kaisha
Lefkowitz Edward
Smith , Gambrell & Russell, LLP
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