Method and device for determining the position of an object within a given area
First Claim
Patent Images
1. A method for determining the position of a moveable object within a given area, which comprises:
- taking a sequence of frames of a given area with a video camera and calculating a current position of an object in the given area by electronically evaluating the frames of the sequence;
comparing a currently taken one of the frames with a previously stored one of the frames to produce a differential image in which a contour of the object appears only when the object moves; and
calculating the position of the object based on the differential image; and
when the object is located within a predetermined region;
a1) calculating a current differential image;
b1) extracting a current contour of the object form the current differential image;
c1) after initiation, defining a first contour and using the first contour as a template, and for all further contours, incorporating the current contour into the template in a weighted manner; and
d1) repetitively performing steps a1 through c1 in order.
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Abstract
Within a given area, the position of the head of the front seat passenger in a vehicle is determined by producing a differential image, in which only the contour of the moving object appears, from two frames that are recorded one after the other by a video camera. The contours of the differential images are used to calculate the position.
20 Citations
10 Claims
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1. A method for determining the position of a moveable object within a given area, which comprises:
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taking a sequence of frames of a given area with a video camera and calculating a current position of an object in the given area by electronically evaluating the frames of the sequence;
comparing a currently taken one of the frames with a previously stored one of the frames to produce a differential image in which a contour of the object appears only when the object moves; and
calculating the position of the object based on the differential image; and
when the object is located within a predetermined region;
a1) calculating a current differential image;
b1) extracting a current contour of the object form the current differential image;
c1) after initiation, defining a first contour and using the first contour as a template, and for all further contours, incorporating the current contour into the template in a weighted manner; and
d1) repetitively performing steps a1 through c1 in order. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
a2) calculating a current differential image;
b2) extracting a current contour from the current differential image;
c2) calculating the position of the object using a cross-correlation of the current contour with the template;
d2) if a magnitude of the correlation exceeds a predefined amount, centering a measuring window on the current contour, replacing the template with the current contour, and going to step e2);
in an absence of a differential image, jumping to step a2);
otherwise jumping to step a1);
e2) if the contour is again within the predetermined region;
jumping to step a1);
f2) if the contour moves in a predetermined warning region, issuing an alarm signal; and
h2) jumping to step a2).
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4. A device for determined the position of a moveable object within a given area, comprising:
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a video camera with a defined frame sequence time;
a control unit with a computer unit;
a frame storage device; and
evaluation software configured to perform the method according to claim 1.
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5. The device according to claim 4, wherein said frame storage device has a capacity for storing at least five frames.
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6. The device according to claim 4, wherein said video camera is a camera selected from the group consisting of a CCD camera and a CMOS camera.
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7. The device for determining the position of a moveable object according to claim 4, wherein:
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the object is a head of a passenger in a front seat of a vehicle having a dashboard;
said video camera has an optical axis and is configured such that the optical axis is aligned approximately perpendicularly with respect to a plane in which movements of the passenger normally take place between the front seat and the dashboard; and
said camera captures images a region between the passenger and the dashboard.
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8. The device according to claim 7, comprising:
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an airbag control device activated dependent on a prediction of when the head of the passenger will penetrate into a hazard range;
said prediction based on a trajectory of the head and a speed of the head.
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9. The device according to claim 4, comprising an infrared light source, said video camera provided with a filter that cuts out wavelengths below a near infrared spectrum range.
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10. The device according to claim 4, wherein said control device receives an emergency braking signal when an emergency braking occurs.
Specification