Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
1999-10-05
2001-06-12
Camby, Richard M. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C280S735000, C280S801100
Reexamination Certificate
active
06246936
ABSTRACT:
TECHNICAL FIELD
This invention relates to a method of characterizing the occupant of a motor vehicle for purposes of enabling or disabling air bag deployment based on sensed occupant weight, and more particularly to a method of distinguishing a cinched child seat from an occupant of similar apparent weight.
BACKGROUND OF THE INVENTION
Vehicle occupant weight detection systems are useful in connection with air bags and other pyrotechnically deployed restraints as a means of characterizing the occupant for purposes of determining whether to enable or disable deployment of the restraints. For example, it is generally desired to enable deployment for adult-weight occupants, and to disable deployment (or reduce deployment force) for child-weight occupants. In the case of infant or child seats (referred to herein collectively as child seats) that are placed on the vehicle seat and cinched down with a seat belt, it is generally believed that deployment should be disabled entirely. Unfortunately, there can be some ambiguity in the case of a child seat, particularly if the seat belt restraining the child seat is cinched very tightly, as a tightly cinched child seat can produce a weight reading similar to that of a small adult.
Accordingly, various attempts have been made to distinguish a child seat from other occupants producing a similar weight reading. In certain systems, for example, a special tag is affixed to the child seat for detection by a sensor located in the seat back or instrument panel. It has also been proposed to measure the seat belt restraining force to determine if a significant portion of the sensed weight is due to a cinched seat belt. However, both of these approaches are difficult to implement in an inexpensive and reliable manner.
SUMMARY OF THE INVENTION
The present invention is directed to an improved weight-based occupant characterization method that can inexpensively and reliably distinguish between a child or small adult and a tightly cinched child seat. When the sensed weight is in a specified range that could be produced by a tightly cinched child seat, the system characterizes the occupant based on a detected variation in sensed weight during movement of the vehicle. If the variance of the sensed weight is below a threshold for a predetermined interval, the occupant is characterized as a child seat, since a tightly cinched seat belt severely restricts variance. If the variance exceeds the threshold for a predetermined interval, the occupant is characterized as a child or small adult. A correlative factor that can be used in distinguishing between a child seat and a child or small adult is determined by computing a slope reversal rate, or frequency, of the measured weight. In this case, a child seat is indicated by the combination of low variance and a high frequency, whereas a child or small adult is indicated by the combination of high variance and a low frequency. Additionally, movement of the vehicle can be detected when the variance of the sensed weight is within a predetermined range for at least a predetermined interval.
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Fortune Duane Donald
Gray Charles A.
Kaltenbacher II Phillip E
Lee Chiutsun Albert
Little David R.
Camby Richard M.
Delphi Technologies Inc.
Funke Jimmy L.
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