Radiant energy – Photocells; circuits and apparatus – With circuit for evaluating a web – strand – strip – or sheet
Reexamination Certificate
1998-04-24
2001-06-26
Le, Que T. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
With circuit for evaluating a web, strand, strip, or sheet
C280S735000, C307S010100, C701S045000, C250S221000
Reexamination Certificate
active
06252240
ABSTRACT:
TECHNICAL ART
The instant invention generally relates to systems and methods for discriminating the seat occupancy configuration in a vehicle for purposes of controlling the activation of a safety restraint system.
BACKGROUND OF THE INVENTION
Recently, the automotive industry has been faced with the challenge of designing a vehicle airbag deployment system which can inhibit deployment of the airbag in situations where allowing deployment increases the likelihood of causing harm to an occupant, such as where a rear-facing infant seat is located in the front passenger seat. Examples of such attempts or proposals include: (1) manually actuated switches for enabling/disabling air bags; (2) magnetic or inductive “tags” that must be affixed to a rear-facing infant seat; and (3) capacitance sensors to distinguish humans from inanimate objects, or weight threshold sensors that disable the air bag below a predetermined threshold weight (such as 25 pounds).
However, none of these arrangements has proven entirely satisfactory. More specifically, manually actuated switches are subject to human forgetfulness or inattention. Tag systems have to be retroactively affixed to all existing rear-facing infant seats. Capacitive and weight sensing systems have not achieved acceptable levels of reliability.
SUMMARY OF THE INVENTION
The instant invention overcomes the above-noted problems by providing a vehicle occupant discrimination system and method which is capable of differentiating rear-facing infant seats from people so that deployment of passenger-side air bags can be controlled depending on whether a rear-facing infant seat or larger human is present.
The system and method of the instant invention reliably distinguishes humans from infant seats without any action on the part of the driver or other person. The instant invention examines a variety of information, such as from separate optical, weight, speed, and door switch sensors, to determine factors such as distance between the airbag and the object located in the seat, small amplitude motions such as breathing, large scale motions, and weight. The instant invention tracks current and past information concerning these factors to accurately discriminate between people and infant seats.
In accordance with the instant invention, a vehicle occupant discrimination system and method comprises an algorithm programmed into processor that processes information produced by an optical sensor, such as a sensor utilizing a collimated and modulated optical beam produced by an LED, which is reflected from a surface and imaged by a lens onto a position sensitive detector (PSD). A range limit detector can also be utilized to provide an indication when the reflecting surface is too close to the PSD to produce a reading. The position of the imaged light on the PSD is used to compute distance to the reflecting surface from a fixed structure within the interior of the vehicle. As discussed more fully hereinbelow, the instant invention also preferably processes information from other inputs such as a seat weight sensor, a speed sensor, and a door switch.
The system and method of the instant invention tracks distance, patterns of motion, and weight over time and processes to determine the likelihood of various predefined seat occupancy scenarios. As a particular scenario becomes “older,” the discrimination thereof becomes more reliable. Examples of particular seat occupancy scenarios include an empty seat, a seat with a rear facing infant seat (RFIS), a normally seated occupant, and a normally seated occupant holding a newspaper or map.
The signals from the optical sensor are identified as follows:
1. Inside channel signal (I): this is the signal from the inside end of the PSD chip. The signal level gets higher as the distance to the target gets higher;
2. Outside channel signal (O): this is the signal form the outside end of the PSD chip. The signal level gets lower as the distance to the target gets higher;
3. LED signal: this is the value of the driving voltage of the LED; and
4. Limit detector signal: this switch signal becomes high when the target is closer than a threshold.
In addition, processor receives weight information from the weight sensor and speed information from the speed sensor. The door switch is used for instantaneous recognition of new scenarios.
In accordance with a first and preferred embodiment of the instant invention, the following four measures are calculated from the input signals:
(M
0
) Mean distance (avgda);
(M
1
) Variance of the distance (&sgr;
2
);
(M
2
) Mean weight (w); and
(M
3
) Slant measure (&dgr;).
These measures are reset at the onset of a new scenario and therefore the recognition of a new scenario is a key factor.
An associated scenario sample space {S
i
} is divided into the following three categories:
(S
0
) Rear Facing Infant Seat (RFIS);
(S
1
) Empty Seat;
(S
2
) Person Seated Normally (PSN);
In accordance with a second embodiment of the instant invention, the following five measures are calculated from the input signals:
(M
0
) Mean distance (avgda);
(M
1
) Maximum distance (Xmax);
(M
2
) Variance of the distance (&sgr;
2
);
(M
3
) Mean weight (w); and
(M
4
) Slant measure (&dgr;).
The associated scenario sample space {S
i
} is divided into the following eight categories:
(S
0
) Rear Facing Infant Seat (RFIS);
(S
1
) Front Facing Infant Seat (FFIS);
(S
2
) Object;
(S
3
) Empty Seat;
(S
4
) Rear Facing Infant Seat with Blanket (RFIS/b);
(S
5
) Person Seated Normally (PSN);
(S
6
) Person Reading Newspaper (PRN); and
(S
7
) Person Holding Object (PHO);
All of these scenarios are assigned a priori probabilities Pr(S
i
). In the case of the second embodiment, the probability distributions defined for the above five measures given these eight scenario, i.e., f
x
(M
j
) S
i
, thus making a total of 40 distributions. As the processor calculates the five measures, the probability of a particular measure given a particular scenario (i.e., Pr(M
j
S
i
)) is calculated using the available distributions. The probability of the five measures, given a particular scenario, is calculated as follows:
Pr
(
M
0
,
M
1
,
M
2
,
M
3
,
M
4
❘
S
i
)
=
∏
j
=
0
4
Pr
(
M
j
❘
S
i
)
W
ji
+
∑
j
=
0
3
∑
k
=
1
4
Pr
(
M
j
❘
S
i
)
Pr
(
M
k
❘
S
i
)
Pr
(
S
i
)
{
C
jkK
i
}
j
≠
k
,
k
>
j
where, W
ji
and C
jkK
i
are the autocorrelation and crosscorrelation terms respectively. The correlation matrix (I
i
) for each scenario for the five measures is:
I
i
=
[
W
0
i
C
01
K
i
C
02
K
i
C
03
K
i
C
04
K
i
C
10
K
i
W
1
i
C
12
K
i
C
13
K
i
C
14
K
i
C
20
K
i
C
21
K
i
W
2
i
C
23
K
i
C
24
K
i
C
30
K
i
C
31
K
i
C
32
K
i
W
3
i
C
34
K
i
C
40
K
i
C
41
K
i
C
42
K
i
C
43
K
i
W
4
i
]
(
i
=
0
…
7
)
If is assumed that there is very little correlation between the measures, therefore the crosscorrelation terms are taken to be zero. The autocorrelation terms being one, the above equation then simplifies down to:
Pr
(
M
0
,
M
1
,
M
2
,
M
3
,
M
4
❘
S
i
)
=
∏
j
=
0
4
Pr
(
M
j
❘
S
i
)
Then, probability of a scenario can be calculated using the five measures and Baye's rule as follows:
Pr
(
S
i
❘
M
0
,
M
1
,
M
2
,
M
3
,
M
4
)
=
Pr
(
M
0
,
M
1
,
M
2
,
M
3
,
M
4
❘
S
i
)
Pr
(
S
i
)
∑
k
=
0
7
Pr
(
M
0
,
M
1
,
M
2
,
M
3
,
M
4
❘
S
k
)
Pr
(
S
k
)
This provides eight probabilities, i.e. probabilities of the eight scenarios, given the five measures, Pr(S
i
|M
0
,M
1
,M
2
,M
3
,M
4
,M
5
) e. The airbag inflator is then enabled, controlled, or disabled depending on what the most probable scenario warrants.
Accordingly, one object of the instant invention
Campbell James A.
Farmer Michael E.
Gillis Edward J.
Mahbub Naveed
Stanley J. Gregory
Le Que T.
Luu Thanh X.
Lyon PC
LandOfFree
Vehicle occupant discrimination system and method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Vehicle occupant discrimination system and method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Vehicle occupant discrimination system and method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2470725