Data processing: measuring – calibrating – or testing – Measurement system – Orientation or position
Reexamination Certificate
1999-03-01
2001-10-02
Assouad, Patrick (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system
Orientation or position
C702S159000, C280S735000, C356S622000
Reexamination Certificate
active
06298311
ABSTRACT:
TECHNICAL FIELD
This invention relates to a motor vehicle control system, and more particularly to a system and method for detecting the position of an occupant of the vehicle.
BACKGROUND OF THE INVENTION
Vehicle occupant position detection systems are useful in connection with air bags and other pyrotechnically deployed restraints as a means of judging whether, and/or how forcefully, to deploy the restraint. Ideally, the system should be capable of classifying the type of occupant (i.e., large adult, small adult, child, etc.) and the position of the occupant relative to the point of deployment of the air bag. Various systems incorporating one or more infrared and/or acoustical ranging sensors have been proposed for this purpose; see, for example, the U.S. Pat. Nos. 5,330,226 and 5,785,347. In general, such systems emit one or more beams of infrared energy to define a corresponding number of viewing fields, and receive the reflected energy to detect the presence of an occupant within the viewing fields. However, the information obtained by such techniques is sometimes corrupted by other light sources (such as reflected sunlight, or pulsed incandescent light), and even under best conditions is typically insufficient to accurately classify the occupant type and position. For example, it may be desired to deploy an air bag even though the occupant's hand or arm is near the point of deployment, but undesirable to deploy if the occupant's head or torso is near the point of deployment. For this reason, other position sensors or weight sensors are typically used in combination with a ranging sensor to provide a more comprehensive understanding of occupant classification and position. Unfortunately, such systems tend to be quite costly, and are difficult to package in the automotive environment. Moreover, a relatively high speed of response is required so that deployment can be properly inhibited or allowed when the occupant position quickly changes, possibly in anticipation of an impending collision. Accordingly, what is needed is a low-cost system that can accurately and quickly recognize an occupant for purposes of classification and position.
SUMMARY OF THE INVENTION
The present invention is directed to an improved infrared (IR) occupant recognition system that is low in cost, and provides accurate and reliable classification and position information at a speed sufficient to timely inhibit or otherwise control deployment of occupant restraints. A two-dimensional array of IR emitters is selectively activated to periodically illuminate two or more predetermined viewing planes in the vicinity of a passenger seating area, and the reflected IR energy is detected by a photo-sensitive receiver and analyzed to detect the presence of an occupant, to classify the occupant, and to determine the position of the occupant relative to predefined zones of the passenger compartment.
One aspect of the invention concerns a technique for reliably distinguishing the reflected IR energy from other signals picked up by the IR receiver. This involves modulating the intensity of the emitted IR beams with a known carrier frequency, band-pass filtering the received signal, and synchronously detecting the filtered signal.
Another aspect of the invention concerns a two stage adaptive control mechanism that compensates for the variation in intensity of the reflected energy. A first stage adaptively adjusts the gain of the receiver circuit, while a second stage adaptively adjusts the intensity of the emitted signal.
A further aspect of the invention concerns a novel mechanization of the two-dimensional emitter array which reduces manufacturing cost and package size, while retaining the flexibility of tailoring the dimensions of the array to suit a particular application. This is achieved through the use of orthogonal anode and cathode power rails with individual IR LED elements placed at each anode-cathode intersection. One of the anode and cathode terminals of each LED is mounted on its respective power rail, and the other is wire-bonded to its respective power rail. This eliminates interference between wire-bonds, reduces the number of driver circuits, and significantly shrinks the package size. Optical dispersion within the package is minimized by an opaque cover layer that effectively forms a deep cavity around each LED element.
A further aspect of the invention concerns a methodology for using the two-dimensional emitter array to recognize an occupant and quickly track any motion of the recognized occupant. This is achieved by identifying the emitter array positions corresponding to the torso of a recognized occupant, and scanning at least those positions at a rate much faster than the other positions.
REFERENCES:
patent: 5330226 (1994-07-01), Gentry et al.
patent: 5384716 (1995-01-01), Araki et al.
patent: 5737083 (1998-04-01), Owechko et al.
patent: 5785347 (1998-07-01), Adolph et al.
patent: 6113137 (2000-09-01), Mizutani et al.
U.S. application No. 09/237,309, filed Jan. 26, 1999.
Fultz William W.
Griffin Dennis Palmer
Perisho, Jr. Robert Allan
Thayer Peter Alan
Wu Cunkai
Assouad Patrick
Bui Bryan
Delphi Technologies Inc.
Funke Jimmy L.
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