Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
2001-05-10
2003-08-19
Arthur, Gertrude (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C180S271000, C180S273000, C280S728100, C280S735000
Reexamination Certificate
active
06609054
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to systems and methods for detecting the occupants of an automobile. More specifically, this invention relates to weight-based and pattern-based automobile occupant detection systems and to methods and systems for making airbag deployment decisions based on information received from an occupant detection system.
In the United States, airbag deployment forces and speeds have been optimized to save 180 lb. males. Unfortunately, the force and speed requirements to save 180 lb. males are tremendous, and present a potentially fatal hazard to young children (especially when seated in rear-facing infant seats) and to small females. There is also a significant danger of physical injury or death from airbag deployment for anyone who is situated too close to the dashboard/steering column or who is otherwise in a vulnerable position during deployment. The National Highway Traffic Safety Administration (NHTSA) has proposed a set of requirements for automobile manufacturers to develop and install “smart” airbag systems that will detect an automobile occupant and disable the airbag when the occupant is at risk. It is also desirable to have systems which are able to adjust the deployment force/speed of airbags, as occupant classification becomes more accurate.
Several key terms are used by the NHTSA and most automotive manufacturers for occupant classification. A Rear Facing Infant Seat (RFIS) is a rear facing fixture designed to protect infants up to 30 lbs. An Infant Bed is a flat bed that straps into an automobile seat and allows infant to lie horizontally and sleep. Infant beds and RFISs are designed for infants only (typically up to 30 lbs.). A Forward Facing Child Seat (FFCS) is a forward facing seating fixture designed for children up to 40 lbs. A Booster Seat is also a forward facing seating fixture, but is designed for children heavier than 40 lbs. There are two types of booster seats: namely, booster seats that use the automobile's safety belt system to protect the child and simply augment the child's position in the seat and guide the shoulder belt into a proper position; and booster seats that are held by the automobile's belt system and have folding arms or other methods of restraining the child.
The broad goal of occupant detection/airbag suppression systems is to distinguish between adults, for whom the airbags should deploy, and children, for whom they shouldn't. Accordingly, occupant classification requirements are based on categories of occupants. Children weighing between 29.5-39.5 lbs. are generally termed “3-Year Olds” (although GM includes children up to 45 lbs.), while those weighing between 46.5-56.5 lbs. are defined as “6-Year Olds” (GM includes children up to 66 lbs.). Female adults weighing between 103-113 lbs. are referred to as “5
th
Percentile Females” or “5
th
Females”. And adult males weighing approximately 140-150 lbs. are “50th Percentile Males”. It should be noted that despite these generally accepted occupant categories, different automobile manufacturers interpret and endorse variations in the specific occupant detection requirements for their automobiles according to the development status and level of confidence they have in the occupant detection technologies they have evaluated.
FIG. 1
is a graph illustrating the industry deployment and suppression categories for airbag suppression systems. As shown, 5
th
Percentile Females and 50
th
Percentile Males are in the deploy section of the graph. In other words, airbags should typically be deployed when occupants within either of those two categories are sensed. The suppression category, on the other hand, encompasses 6-Year Olds, 3-Year Olds, and all types of child seats. When an occupant of any of these types is sensed, airbag deployment should typically be suppressed. A gray zone appears between the suppress and deploy zones. This gray zone represents a zone of uncertainty for occupants who do not clearly register within either the deployment zone or the suppression zone. A gray zone exists because the difference between actual weight/pattern characteristics in an automobile seat for 6-Year Olds and 5
th
Percentile Females is quite small. In other words, it is very hard to distinguish between 5
th
Percentile Females and 6-Year Olds based on their in-seat weight or pattern characteristics. Accordingly, there is very little room for error in occupant detection systems.
There are two common approaches to vehicle occupant detection, namely, weight-based detection and proximity detection. As its name implies, the weight-based detection approach uses the weight of the occupant in the seat for occupant classification. As will be discussed below, some conventional weight-based detection systems are strictly weight-based while others employ pattern-based occupant recognition of various types as well.
Because of the obvious physical differences between 5
th
Percentile Females, 6-Year Olds, and car seats, it might be fairly easy to distinguish between them in some applications. On the surface, therefore, it might appear that distinction between them as vehicle occupants should not be terribly difficult. Unfortunately, however, as the following table, Table 1, illustrates, distinguishing between these occupant categories is a very challenging undertaking.
TABLE 1
Typical In-Seat Weights of Vehicle Occupants
Occupant-Type
Typical Weight in Automobile Seat
5
th
Percentile Female
75 lbs.
6-Year Old
65 lbs.
3-Year Old in FFCS
73 lbs.
Table 1 compares typical weights exerted in an automobile seat by an average 5
th
Percentile Female, 6-Year Old, and 3-Year Old in a forward facing child seat (FFCS). The similarity between these occupant-types in their typical in-seat weights makes it extremely difficult to classify them based solely on this characteristic. As the table indicates, only 2 lbs. separates the average 5
th
Percentile Female's typical in-seat weight (75 lbs.) from that of the average 3-Year Old in a FFCS (73 lbs). Only 10 lbs. separates the average 5
th
Percentile Female's typical in-seat weight from that of the average 6-Year Old (65 lbs.).
There are several reasons for the similarity of typical in-seat weights between these occupant-types. One reason is that small children will have most of their weight in the seat itself while 5
th
Percentile Females tend to place more of their leg weight out of the seat. Another reason for the similarity is that the weight of the child seat contributes to the weight measured for a 3-Year Old in a FFCS.
The problem of accurately classifying an occupant based on his or her in-seat weight is compounded as the occupant moves in the seat. This is due to the fact that as the occupant moves in the seat, large variations in in-seat weight might be detected. Simply using the armrest or leaning against the door can reduce the occupant's weight in the seat. Clothing friction against the seat back and the angle of inclination of the seat back can also affect the amount of weight exerted in the seat. All of these factors make the in-seat weight of an occupant insufficient as a sole source of information for occupant detection.
Accordingly, several variations in the conventional weight-based approach exist. A first variation is based on “A-surface” technologies. A-surface technologies typically use film-type sensors which are placed on the “A” surface (i.e., the top surface) of the seat foam, just beneath the trim. A first of these A-surface systems uses the Institution of Electrical Engineers (IEE) Force Sensing Resistor (FSR). The FSR is a force sensor sandwiched between two layers of polyester. The IEE FSR was originally developed by Interlink Electronics, but has been licensed by IEE for automotive use. IEE had the first occupant detection system in production for such companies as Mercedes. Unfortunately, the IEE FSR is notoriously difficult to use and suffers from a high degree of variation in production. Accordingly, these early systems are very simple single sensor designs
Arthur Gertrude
Marger & Johnson & McCollom, P.C.
Wallace Michael W.
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