U.S. patent application number 09/978061 was filed with the patent office on 2002-02-07 for activation control apparatus of occupant safety system.
This patent application is currently assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA. Invention is credited to Imai, Katsuji, Iyoda, Motomi.
Application Number | 20020016658 09/978061 |
Document ID | / |
Family ID | 26370312 |
Filed Date | 2002-02-07 |
United States Patent
Application |
20020016658 |
Kind Code |
A1 |
Imai, Katsuji ; et
al. |
February 7, 2002 |
Activation control apparatus of occupant safety system
Abstract
An activation control apparatus of an occupant safety system is
an activation control apparatus 2 for controlling activation of
airbag system 36 mounted on a vehicle in the event of the vehicle
colliding with an obstacle, which has a front sensor 30B mounted in
the left part of the vehicle, a front sensor 30A mounted in the
right part of the vehicle, a collision type identifying part 42 for
identifying a type of collision of the vehicle, based on values
detected by the front sensor 30B and the front sensor 30A, and an
activation control 40 for controlling the activation of the airbag
system 36, based on the type of the collision identified by the
collision type identifying part 42.
Inventors: |
Imai, Katsuji; (Nagoya-shi,
JP) ; Iyoda, Motomi; (Seto-shi, JP) |
Correspondence
Address: |
KENYON & KENYON
Suite 700
1500 K Street, N.W.
Washington
DC
20005
US
|
Assignee: |
TOYOTA JIDOSHA KABUSHIKI
KAISHA
|
Family ID: |
26370312 |
Appl. No.: |
09/978061 |
Filed: |
October 17, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09978061 |
Oct 17, 2001 |
|
|
|
09499309 |
Feb 7, 2000 |
|
|
|
Current U.S.
Class: |
701/45 ;
280/735 |
Current CPC
Class: |
B60R 21/0132 20130101;
B60R 2021/0009 20130101; B60R 21/013 20130101; B60R 2021/01006
20130101 |
Class at
Publication: |
701/45 ;
280/735 |
International
Class: |
B60R 021/32 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 9, 1999 |
JP |
031799/1999 |
May 17, 1999 |
JP |
136096/1999 |
Claims
What is claimed is:
1. An activation control apparatus of an occupant safety system for
controlling activation of the occupant safety system mounted on a
vehicle in the event of the vehicle colliding with an obstacle,
said activation control apparatus comprising: a plurality of impact
detecting means placed at mutually different positions in a front
part of the vehicle; collision type identifying means for
identifying a type of collision of said vehicle, based on values
detected by said plurality of impact detecting means; and
activation control means for controlling the activation of the
occupant safety system, based on the type of collision identified
by said collision type identifying means.
2. The activation control apparatus according to claim 1, wherein
said plurality of impact detecting means comprise first impact
detecting means mounted in a left part of said vehicle and second
impact detecting means mounted in a right part of said vehicle and
wherein said collision type identifying means identifies the type
of collision as an oblique crash if after the collision of the
vehicle there is a time difference between rises of the values
detected by the first impact detecting means and by the second
impact detecting means.
3. The activation control apparatus according to claim 1, wherein
said plurality of impact detecting means comprise first impact
detecting means mounted in a left part of said vehicle and second
impact detecting means mounted in a right part of said vehicle and
wherein said collision type identifying means identifies the type
of collision as an offset crash if after the collision of the
vehicle there is a time difference between rises of the values
detected by the first impact detecting means and by the second
impact detecting means and if a difference is large between
magnitudes of the values detected by said first impact detecting
means and by said second impact detecting means.
4. The activation control apparatus according to claim 1, wherein
each of said first impact detecting means and said second impact
detecting means is an electronic deceleration sensor.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an activation control
apparatus of an occupant safety system for controlling activation
of the occupant safety system which provides protection for vehicle
occupants in the event of a vehicle collision.
[0003] 2. Related Background Art
[0004] The vehicles now available are often equipped with an airbag
system for providing the protection for vehicle occupants in the
event of a vehicle collision. This airbag system has a sensor for
detecting impact upon collision of the vehicle and is activated
based on the impact detected by this sensor.
[0005] Incidentally, types of vehicle collision include a variety
of crash types such as a frontal crash, an offset crash, and so on.
In order to be able to detect the collision of the vehicle in the
event of any type of crash, there exist the airbag systems
constructed in such structure that sensors are located at plural
positions in the vehicle and that the airbag system is activated
based on detection of the collision of the vehicle by the plurality
of sensors. (Reference is made to Japanese Patent Application
Laid-Open No. 5-38998.)
SUMMARY OF THE INVENTION
[0006] In the airbag systems described above, the vehicle collision
was able to be detected in the event of any type of collision, but
it was difficult to activate the airbag system with accuracy in
accordance with either of the crash types, because the crash types
were not discriminated from each other.
[0007] An object of the present invention is to provide an
activation control apparatus of an occupant safety system that can
discriminate the crash types of the vehicle from each other with
accuracy and that can activate the occupant safety system with
accuracy in accordance with either of the crash types.
[0008] An activation control apparatus of an occupant safety system
according to the present invention is an apparatus for controlling
activation of the occupant safety system mounted on a vehicle in
the event of the vehicle colliding with an obstacle, the apparatus
comprising a plurality of impact detecting means mounted at
mutually different positions in a front part of the vehicle,
collision type identifying means for identifying a type of
collision of the vehicle, based on values detected by the plurality
of impact detecting means, and activation control means for
controlling the activation of the vehicle safety system, based on a
type of collision identified by the collision type identifying
means. The front part of the vehicle herein means the vicinity of
the bumper at the front end of the vehicle, the vicinity of the
front ends of the front side members, the areas on the front side
members, the area on the dash panel, and so on.
[0009] Since the activation control apparatus of the occupant
safety system can identify the type of collision of the vehicle by
the collision type identifying means, the activation control means
can activate the occupant safety system more accurately.
[0010] The activation control apparatus of the occupant safety
system is also characterized in that the plurality of impact
detecting means comprise first impact detecting means mounted in a
left part of the vehicle and second impact detecting means mounted
in a right part of the vehicle and in that if after the collision
of the vehicle there is a time difference between rises of values
detected by the first impact detecting means and by the second
impact detecting means the collision type identifying means
identifies the collision as an oblique crash. Here the left part of
the vehicle and the right part of the vehicle mean the vicinity of
the left and right ends of the bumper, the vicinity of the left and
right front side members, the areas on the left and right front
side members, the vicinity of the left and right ends of the dash
panel, and so on.
[0011] The activation control apparatus of the occupant safety
system can identify the collision of the vehicle as an oblique
crash by the collision type identifying means. Namely, since in the
event of the oblique crash relatively small impact acts on the
bumper at the front end of the vehicle to cause a time difference
between rises of the values detected by the first impact detecting
means and by the second impact detecting means, the collision can
be identified as an oblique crash.
[0012] The activation control apparatus of the occupant safety
system is also characterized in that the plurality of impact
detecting means comprise first impact detecting means mounted in a
left part of the vehicle and second impact detecting means mounted
in a right part of the vehicle and in that if after the collision
of the vehicle there is a time difference between rises of values
detected by the first impact detecting means and by the second
impact detecting means and if a difference is large between
magnitudes of the values detected by the first impact detecting
means and by the second impact detecting means the collision type
identifying means identifies the collision as an offset crash.
[0013] The activation control apparatus of the occupant safety
system can identify the collision of the vehicle as an offset crash
by the collision type identifying means. Namely, since in the event
of the offset crash either one of the first impact detecting means
and the second impact detecting means detects greater impact, the
collision can be identified as an offset crash.
[0014] Another activation control apparatus of an occupant safety
system is an apparatus for controlling activation of the occupant
safety system mounted on a vehicle in the event of the vehicle
colliding with an obstacle, the apparatus comprising first impact
detecting means mounted in a left front part of the vehicle, second
impact detecting means mounted in a right front part of the
vehicle, likelihood computing means for classifying collision of
the vehicle under a frontal crash, an offset crash, and an oblique
crash, based on values detected by the first impact detecting means
and by the second impact detecting means, and computing a
likelihood of the collision classified, and activation control
means for controlling the activation of the occupant safety system,
based on the likelihood computed by the likelihood computing
means.
[0015] In the activation control apparatus of the occupant safety
system the likelihood computing means classifies the collision of
the vehicle under the frontal crash, the offset crash, and the
oblique crash, based on the values detected by the first impact
detecting means and by the second impact detecting means, and
computes the likelihood of the collision classified. Therefore, the
activation control apparatus can determine the type of collision of
the vehicle accurately and activate the occupant safety system with
accuracy.
[0016] The activation control apparatus of the occupant safety
system is also characterized in that when the likelihood computing
means classifies the collision as an oblique crash and computes the
likelihood of the oblique crash, the activation control means
controls the activation of the occupant safety system with
reference to an oblique crash threshold corresponding to the
likelihood of the oblique crash.
[0017] The activation control apparatus of the occupant safety
system is also characterized in that when the likelihood computing
means classifies the collision as an offset crash and computes the
likelihood of the offset crash, the activation control means
controls the activation of the occupant safety system with
reference to an offset crash threshold corresponding to the
likelihood of the offset crash.
[0018] The activation control apparatus of the occupant safety
system is also characterized in that when the likelihood computing
means classifies the collision as an ODB crash and computes the
likelihood of the ODB crash, the activation control means controls
the activation of the occupant safety system with reference to an
ODB crash threshold corresponding to the likelihood of the ODB
crash.
[0019] The activation control apparatus of the occupant safety
system is also characterized in that the ODB crash threshold is set
as follows; in a small deceleration range from occurrence of the
collision a threshold corresponding to a strong-likelihood ODB
crash is lower than a threshold corresponding to a small-likelihood
ODB crash and in a large deceleration range from occurrence of the
collision a threshold corresponding to the strong-likelihood ODB
crash is higher than a threshold corresponding to the
small-likelihood ODB crash.
[0020] The activation control apparatus of the occupant safety
system is also characterized in that when the likelihood computing
means classifies the collision as a soft crash and computes the
likelihood of the soft crash, the activation control means controls
the activation of the occupant safety system with reference to a
soft crash threshold corresponding to the likelihood of the soft
crash.
[0021] The activation control apparatus of the occupant safety
system is also characterized in that in a small deceleration range
from occurrence of the collision a soft crash threshold
corresponding to a strong-likelihood soft crash is lower than a
soft crash threshold corresponding to a small-likelihood soft crash
and in a large deceleration range from occurrence of the collision
a soft crash threshold corresponding to the strong-likelihood soft
crash is higher than a soft crash threshold corresponding to the
small-likelihood soft crash.
[0022] In the activation control apparatus of the occupant safety
system the likelihood computing means classifies the collision
under the oblique crash, the offset crash, the ODB crash, and the
soft crash and computes the likelihood of the collision classified.
The activation control means controls the activation of the
occupant safety system with reference to the threshold
corresponding to the likelihood of the collision classified. The
apparatus can activate the occupant safety system at accurate
timing accordingly.
[0023] The activation control apparatus of the occupant safety
system is also characterized in that the likelihood computing means
classifies the collision of the vehicle under a frontal crash, an
offset crash, and an oblique crash, based on a ratio of the values
detected by the first impact detecting means and by the second
impact detecting means, and computes a likelihood of the collision
classified.
[0024] The activation control apparatus of the occupant safety
system is also characterized in that the likelihood computing means
classifies the collision of the vehicle as a frontal crash when the
ratio of the values is large, classifies the collision as an
oblique collision when the ratio of the values is small, or
classifies the collision of the vehicle as an offset crash when the
ratio of the values is intermediate.
[0025] In the activation control apparatus of the occupant safety
system the likelihood computing means classifies the collision of
the vehicle under the frontal crash, the offset crash, and the
oblique crash, based on the ratio of the values detected by the
first impact detecting means and by the second impact detecting
means and, therefore, the collision can be classified under the
crash types with accuracy.
[0026] The activation control apparatus of the occupant safety
system is also characterized in that the likelihood computing means
classifies the collision of the vehicle under an ODB crash and an
ORB crash, based on an initial deviation between the values
detected by the first impact detecting means and by the second
impact detecting means, and computes a likelihood of the ODB crash,
based on the initial deviation, when the collision of the vehicle
is classified as an ODB crash.
[0027] The activation control apparatus of the occupant safety
system is also characterized in that the likelihood computing means
determines that the likelihood of the ODB crash is strong when the
initial deviation is large, or the likelihood computing means
determines that the likelihood of the ODB crash is small when the
initial deviation is small.
[0028] In the activation control apparatus of the occupant safety
system the likelihood computing means classifies the collision of
the vehicle under the ODB crash and the ORB crash and computes the
likelihood of the ODB crash, based on the initial deviation between
the values detected by the first impact detecting means and by the
second impact detecting means, and, therefore, it can classify the
collision under the crash types with accuracy and compute the
accurate likelihood thereof.
[0029] The activation control apparatus of the occupant safety
system is also characterized in that the likelihood computing means
determines whether the collision of the vehicle is the ODB crash,
based on the magnitude of the difference between the values
detected by the first impact detecting means and by the second
impact detecting means, and computes a likelihood of the ODB crash,
based on the magnitude of the difference between the values
detected, when it is determined that the collision of the vehicle
is the ODB crash.
[0030] The activation control apparatus of the occupant safety
system is also characterized in that the likelihood computing means
determines that the likelihood of the ODB crash is strong if the
magnitude of the difference between the values detected is large,
or determines that the likelihood of the ODB crash is small if the
initial deviation is small.
[0031] In the activation control apparatus of the occupant safety
system the likelihood computing means determines whether the
collision of the vehicle is the ODB crash, based on the magnitude
of the difference between the values detected by the first impact
detecting means and by the second impact detecting means, and
computes the likelihood of the ODB crash and, therefore, it can
classify the collision under the crash types with accuracy and
compute the accurate likelihood thereof.
[0032] The activation control apparatus of the occupant safety
system is also characterized in that the activation control
apparatus comprises impact measuring means placed in the vehicle,
the likelihood computing means determines whether the collision of
the vehicle is a soft crash, based on a state of unevenness of a
temporal change waveform of a measurement measured by the impact
measuring means, and the likelihood computing means computes a
likelihood of the soft crash, based on the unevenness of the
temporal change waveform of the measurement when it is determined
that the collision of the vehicle is the soft crash.
[0033] The activation control apparatus of the occupant safety
system is also characterized in that when the unevenness of the
temporal change waveform of the measurement is large, the
likelihood computing means determines that the likelihood of the
soft crash is strong and in that when the unevenness of the
temporal change waveform of the measurement is small, the
likelihood computing means determines that the likelihood of the
soft crash is small.
[0034] In the activation control apparatus of the occupant safety
system the likelihood computing means determines whether the
collision of the vehicle is the soft crash, based on the state of
unevenness of the temporal change waveform of the measurement
measured by the impact detecting means, and determines the
likelihood of the soft crash, also based thereon, and, therefore,
it can determine the type of the collision with accuracy and
compute the accurate likelihood thereof.
[0035] Another activation control apparatus of an occupant safety
system is an apparatus for controlling activation of the occupant
safety system mounted in a vehicle in the event of the vehicle
colliding with an obstacle, the apparatus comprising impact
measuring means placed in the vehicle, soft crash determining means
for determining whether the collision of the vehicle is a soft
crash, based on a state of unevenness of a temporal change waveform
of a measurement measured by the impact measuring means, and
activation control means for controlling the activation of the
occupant safety system, based on a soft crash activation
determination map, when the soft crash determining means determines
that the collision is the soft crash.
[0036] In the activation control apparatus of the occupant safety
system the soft crash determining means determines whether the
collision of the vehicle is the soft crash, based on the state of
unevenness of the temporal change waveform of the measurement
measured by the impact measuring means. Therefore, the apparatus
can accurately determine whether the collision is the soft crash
and can activate the occupant safety system with accuracy.
[0037] The present invention will be more fully understood from the
detailed description given hereinbelow and the accompanying
drawings, which are given by way of illustration only and are not
to be considered as limiting the present invention.
[0038] Further scope of applicability of the present invention will
become apparent from the detailed description given hereinafter.
However, it should be understood that the detailed description and
specific examples, while indicating preferred embodiments of the
invention, are given by way of illustration only, since various
changes and modifications within the spirit and scope of the
invention will be apparent to those skilled in the art from this
detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] FIG. 1 is a block structural diagram of the activation
control apparatus of the airbag system according to the first
embodiment;
[0040] FIG. 2 is a diagram for explaining an on-vehicle state of
front sensors etc. of the airbag system according to the first
embodiment;
[0041] FIG. 3 is a detailed block diagram of an activation control
etc. of the activation control apparatus of the airbag system
according to the first embodiment;
[0042] FIG. 4 is a flowchart to show an activation control process
in the activation control apparatus of the airbag system according
to the first embodiment;
[0043] FIG. 5 is a flowchart to show a collision type identifying
process in the activation control apparatus of the airbag system
according to the first embodiment;
[0044] FIG. 6 is graphs to show states of changes in right front G
and left front G in the case of an oblique crash in the first
embodiment;
[0045] FIG. 7 is graphs to show states of changes in right front G
and left front G in the case of an offset crash in the first
embodiment;
[0046] FIG. 8 is graphs to show states of changes in right front P
and left front P in the case of a middle-speed 0DB crash in the
first embodiment;
[0047] FIG. 9 is graphs to show states of changes in right front P
and left front P in the case of a low-speed ORB crash in the first
embodiment;
[0048] FIG. 10 is a graph to show states of changes in the
deceleration and a factor based on the deceleration in the case of
a soft crash in the first embodiment;
[0049] FIG. 11 is a graph to show states of changes in the
deceleration and a factor based on the deceleration in the case of
a frontal crash in the first embodiment;
[0050] FIG. 12A is a diagram to s how an activation determination
map (an oblique crash map) used in the activation control apparatus
of the airbag system according to the first embodiment;
[0051] FIG. 12B is a diagram to show an activation determination
map (a frontal crash map) used in the activation control apparatus
of the airbag system according to the first embodiment;
[0052] FIG. 13A is a diagram to show an activation determination
map (a pole/underride map) used in the activation control apparatus
of the airbag system according to the first embodiment;
[0053] FIG. 13B is a diagram to show an activation determination
map (an ODB map) used in the activation control apparatus of the
airbag system according to the first embodiment;
[0054] FIG. 13C is a diagram to show an activation determination
map (an ORB map) used in the activation control apparatus of the
airbag system according to the first embodiment;
[0055] FIG. 14 is a diagram to show a map for determining severity
of collision, used in the activation control apparatus of the
airbag system according to the first embodiment;
[0056] FIG. 15 is a flowchart to show an activation control process
in the activation control apparatus of the airbag system according
to the second embodiment;
[0057] FIG. 16 is a diagram to show an activation determination map
used in the activation control apparatus of the airbag system
according to the second embodiment;
[0058] FIG. 17 is a diagram to show an activation determination map
used in the activation control apparatus of the airbag system
according to the second embodiment;
[0059] FIG. 18 is a diagram to show an activation determination map
used in the activation control apparatus of the airbag system
according to the second embodiment;
[0060] FIG. 19 is a diagram to show an activation determination map
used in the activation control apparatus of the airbag system
according to the second embodiment;
[0061] FIG. 20 is a diagram to show determination procedures of
crash type carried out in the activation control apparatus of the
airbag system according to the second embodiment;
[0062] FIG. 21 is graphs to show output waveforms of the front
sensors used in the determination of crash type in the activation
control apparatus of the airbag system according to the second
embodiment;
[0063] FIG. 22 is a diagram for explaining the determination of
crash type carried out in the activation control apparatus of the
airbag system according to the second embodiment;
[0064] FIG. 23 is graphs to show output waveforms of the front
sensors used in the determination of crash type in the activation
control apparatus of the airbag system according to the second
embodiment;
[0065] FIG. 24 is a diagram for explaining the determination of
crash type carried out in the activation control apparatus of the
airbag system according to the second embodiment;
[0066] FIG. 25 is graphs to show output waveforms of the front
sensors used in the determination of crash type in the activation
control apparatus of the airbag system according to the second
embodiment;
[0067] FIG. 26 is a diagram for explaining the determination of
crash type carried out in the activation control apparatus of the
airbag system according to the second embodiment;
[0068] FIG. 27 is a graph to show an output waveform of the front
sensor used in the determination of crash type in the activation
control apparatus of the airbag system according to the second
embodiment;
[0069] FIG. 28 is a diagram for explaining the determination of
crash type carried out in the activation control apparatus of the
airbag system according to the second embodiment;
[0070] FIG. 29 is a table used in the determination of crash type
carried out in the activation control apparatus of the airbag
system according to the second embodiment;
[0071] FIG. 30 is a diagram for explaining the determination of
severity of impact carried out in the activation control apparatus
of the airbag system according to the second embodiment;
[0072] FIG. 31 is a diagram for explaining the determination of
severity of impact carried out in the activation control apparatus
of the airbag system according to the second embodiment;
[0073] FIG. 32 is a diagram for explaining the determination of
soft crash carried out in the activation control apparatus of the
airbag system according to the second embodiment;
[0074] FIG. 33 is a diagram for explaining the determination of
soft crash carried out in the activation control apparatus of the
airbag system according to the second embodiment; and
[0075] FIG. 34 is an activation determination map used in the case
of the soft crash in the activation control apparatus of the airbag
system according to the second embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0076] The activation control apparatus of the occupant safety
system according to the first embodiment of the present invention
will be described with reference to the drawings.
[0077] As illustrated in FIG. 1, the activation control apparatus 2
of the airbag system is an apparatus for controlling activation of
the airbag system 36 and is mainly composed of a control circuit
20, a front sensor (second impact detecting means) 30A, a front
sensor (first impact detecting means) 30B, a floor sensor 32, and a
driving circuit 34.
[0078] Among them, the front sensors 30A, 30B are electronic
sensors for detecting the magnitude of impact exerted on the
vehicle, which are mounted in the front part of the vehicle.
Specifically, they detect decelerations acting on the vehicle and
output deceleration signals G'(t) in time series corresponding to
the decelerations. The floor sensor 32 is a so-called acceleration
sensor for measuring the impact exerted on the vehicle and
transmitted through the vehicle body. Specifically, it measures
decelerations acting in the longitudinal direction on the vehicle
as occasion arises, and outputs deceleration signals G(t) in time
series corresponding to the measurements (decelerations).
[0079] The control circuit 20 is comprised of a central processing
unit (CPU) 22, an input/output circuit (I/O circuit) 24, a read
only memory (ROM) 26, a random access memory (RAM) 28, and so on,
and the components are connected through a bus. Among these
components, the CPU 22 executes control of the activation of the
airbag system 36 according to programs etc. stored in the ROM 26.
The RAM 28 is a memory for storing data obtained based on the
signals from the front sensors 30A, 30B and the floor sensor 32,
results computed based thereon by the CPU 22, and so on. Further,
the I/O circuit 24 is a circuit for input of the signals from the
front sensors 30A, 30B and the floor sensor 32, for output of an
activation signal to the driving circuit 34, and so on.
[0080] The CPU 22 functions as an activation control 40 for
comparing a value obtained based on the value detected by the floor
sensor 32, with a predetermined threshold and controlling the
activation of the airbag system 36, based on the result of the
comparison, and also as a collision type identifying section 42 for
identifying the type of collision of the vehicle 46, based on the
values detected by the front sensors 30A, 30B, and the like.
[0081] The driving circuit 34 is a circuit for energizing a squib
38 of an inflator in the airbag system 36 in response to the
activation signal from the control circuit 20 to fire a gas
generator. Further, the airbag system 36 includes the gas generator
(not illustrated) fired by the squib 38, a bag (not illustrated)
inflated by evolving gas, and so on, in addition to the squib 38 of
a firing device.
[0082] Among these components, the control circuit 20, the floor
sensor 32, and the driving circuit 34 are housed in an ECU
(electronic control unit) 44 illustrated in FIG. 2, which is
mounted on the floor tunnel located approximately in the center in
the vehicle 46. The front sensor 30A is mounted on the right front
side member of the vehicle 46 obliquely right ahead of the floor
sensor 32 housed in the ECU 44, while the front sensor 30B is
mounted on the left front side member of the vehicle 46 obliquely
left ahead of the floor sensor 32.
[0083] Next, the control of activation of the airbag system carried
out in the CPU 22 will be described referring to FIG. 3, FIG. 4,
and FIG. 5. As illustrated in FIG. 3, the activation control 40 in
the CPU 22 incorporates an operation part 58 and an activation
determination part 60. The floor sensor 32 measures the
deceleration exerted in the longitudinal direction on the vehicle
46 as occasion arises, and outputs the signal G(t) indicating the
deceleration. When the operation part 58 of the activation control
40 acquires the deceleration G(t) outputted from the floor sensor
32 (step S10 of FIG. 4), it executes predetermined operations with
the deceleration G(t), i.e., the operations according to Eq. 1 and
Eq. 2 to obtain operation results V.sub.10, V.sub.n (step S11 of
FIG. 4). Here V.sub.10 is an interval integral of the deceleration
G(t) every interval of 10 ms in a period from occurrence of
collision to the end of collision, and V.sub.n is an integral of
the deceleration G(t) over the time necessary from the occurrence
to the end of collision (n is the time of about 100 ms), i.e., the
speed change (deceleration) from occurrence of collision.
V.sub.10=.intg..sub.t-10msG(t)dt [Eq. 1]
[0084] G(t): output of floor sensor
V.sub.n=.intg.G(t)dt [Eq. 2]
[0085] G(t): output of floor sensor
[0086] Next, the collision type identifying part 42 shapes the
deceleration signal G'(t) outputted from each front sensor 30A,
30B, by a Kalman filter and executes identification of the
collision type according to the process shown in the flowchart of
FIG. 5, based on the deceleration signals thus shaped and the
deceleration signal G(t) outputted from the floor sensor 32 (step
S12 of FIG. 4).
[0087] First, the collision type identifying part 42 determines
whether a type of collision is an oblique crash (step S20). Namely,
the collision type identifying part 42 identifies the collision as
an oblique crash when a time difference is large between rises of
the deceleration signal G'(t) outputted from the front sensor 30A
(right front G) and the deceleration signal G'(t) outputted from
the front sensor 30B (left front G) (i.e., when the following
condition is met; (V.sub.s: an integral based on collision-side
front G).times.(T: a rise delay time of non-collision-side front
G)>(threshold)).
[0088] FIG. 6 is the graphs to show states of changes in left front
G and right front G appearing when an oblique crash occurs in the
left front part of the vehicle 46 during running at a middle speed.
As seen from these graphs, the rise of right front G lags behind
the rise of the left front G by the delay time T and the condition
of (V.sub.s).times.(T)>(- threshold) is met. Therefore, the type
of collision is identified as an oblique crash. When this condition
is not met, the collision is regarded as a crash except for the
oblique crash and further identification of crash type is carried
out.
[0089] Next, the collision type identifying part 42 determines
whether the type of collision is an offset crash (step S21).
Namely, the collision type identifying part 42 identifies the
collision as an offset crash when there is no time difference
between the rises of right front G and left front G and when a
difference is large between maximums thereof (i.e., when the
condition of rR V.sub.R1 (an integral of collision-side front
G)/V.sub.R2 (an integral of non-collision-side front G)>>1 is
met).
[0090] FIG. 7 is the graphs to show states of changes in left front
G and right front G appearing when an offset crash occurs in the
left front part of the vehicle 46 during running at a middle speed.
As seen from these graphs, the left front G and right front G start
rising at approximately identical timing, but the difference is
large enough between the maximums to satisfy the condition of rR
V.sub.R1/VR.sub.2>>1. Therefore, the collision is identified
as an offset crash.
[0091] Next, after identifying the type of collision as an offset
crash, the collision type identifying part 42 determines whether
the offset crash is an ORB crash (an irregular collision against a
hard obstacle) or an ODB crash (an irregular collision against a
soft obstacle) (step S22). Namely, the identifying part 42 computes
right front P and left front P from the right front G and left
front G, based on Eq. 3, and identifies the type of collision as an
ODB crash when the condition of (a peak value of collision-side
front P)/(a peak value of non-collision-side front P)>threshold
is met. The identifying part 42 identifies the collision as an ORB
crash when this condition is not met.
P(t)=.intg..sub.T.sup.tG'(t)dt [Eq. 3]
[0092] G(t): output of front sensor
[0093] FIG. 8 is the graphs to show states of changes in the right
front P and left front P appearing when an ODB crash occurs in the
right front part of the vehicle 46 during running at a middle
speed. In this case, as illustrated in the graphs, the difference
is large between the first peak values of left front P and right
front P and the condition of (the first peak value of
collision-side front P)/(the first peak value of non-collision-side
front P)>threshold is met. Therefore, the collision is
identified as an ODB crash.
[0094] FIG. 9 is the graphs to show states of changes in the right
front P and left front P appearing when an ORB crash occurs in the
right front part of the vehicle 46 during running at a low speed.
In this case, as illustrated in the graphs, the difference is small
between the first peak values of left front P and right front P and
the condition of (the peak value of collision-side front P)/(the
peak value of non-collision-side front P)>threshold is not met.
Therefore, the collision is identified as an ORB crash.
[0095] Next, after identifying the collision as a crash except for
the offset crashes, the collision type identifying part 42
determines whether the type of collision is a pole/underride crash
(step S23). Namely, P(t) is computed by Eq. 4 based on the
deceleration signal G(t) of the floor sensor 32 in the event of a
pole crash occurring in the vehicle 46, and whether the type of
collision is a pole/underride crash is determined based on the
waveform of G(t) before and after the first peak of P(t).
P(t)=.intg..sub.T.sup.tG(t)dt [Eq. 4]
[0096] G(t): output of floor sensor
[0097] FIG. 10 is a graph to show the waveform of P(t) and the
waveform of G(t) appearing when a pole crash occurs in the vehicle
46. As illustrated in this graph, when a time average G1 of G(t) in
the zone {circle over (1)} (the zone up to a maximum of P(t)) is
compared with a time average G2 of G(t) in the zone {circle over
(2)} (the zone from the maximum to a minimum of P(t)), there is the
relation of G1>G2. Therefore, the collision is identified as a
pole crash.
[0098] FIG. 11 shows the waveform of P(t) and the waveform of G(t)
appearing when a frontal crash occurs in the vehicle 46. As
illustrated in this graph, when the time average G1 of G(t) in the
zone {circle over (1)} (the zone up to a maximum of P(t)) is
compared with the time average G2 of G(t) in the zone {circle over
(2)} (the zone from the maximum to a minimum of P(t)), there is the
relation of G1<G2. Therefore, the type of collision is
identified as a frontal crash except for the pole/underride crash.
Namely, the type of collision is identified as a frontal crash when
it is neither of the oblique crash, the ORB crash, the ODB crash,
and the pole/underride crash.
[0099] The activation determination part 60 compares a value
defined by the operation results V.sub.10, V.sub.n with either one
of activation determination maps stored in the activation
determination part 60. Namely, the activation determination part 60
stores an oblique crash map selected when the type of collision is
identified as an oblique crash (step S24 of FIG. 5), a frontal
crash (high) map selected when the type of collision is identified
as a frontal crash except for the pole/underride crash (step S25 of
FIG. 5), a pole/underride map selected when the type of collision
is identified as a pole/underride crash (step S26 of FIG. 5), an
ODB map selected when the type of collision is identified as an ODB
crash (step S27 of FIG. 5), and an ORB map selected when the type
of collision is identified as an ORB crash (step S28 of FIG. 5),
and compares the value defined by the operation results V.sub.10,
V.sub.n with either one activation determination map selected
according to the type of collision identified by the collision type
identifying part 42.
[0100] In the oblique crash map (see FIG. 12A) a threshold 72 is
set so as not to activate the airbag system 36 even in the event of
a middle-speed oblique crash of the vehicle 46. In the frontal
crash (high) map (see FIG. 12B) a threshold 74 is set so as not to
activate the airbag system 36 even in the event of a low-speed
frontal crash occurring in the vehicle 46.
[0101] In the pole/underride map (see FIG. 13A) a threshold 76 is
set so as not to activate the airbag system 36 even in the event of
a low-speed pole crash occurring in the vehicle 46. In the ODB map
(see FIG. 13B) a threshold 78 is set so as not to activate the
airbag system 36 even in the event of a low-speed ODB crash
occurring in the vehicle 46. In the ORB map (see FIG. 13C) a
threshold 80 is set so as not to activate the airbag system 36 even
in the event of a low-speed ORB crash occurring in the vehicle 46.
Each of these determination maps is a plot of the operation result
V.sub.n on the axis of abscissas and the operation result V.sub.10
on the axis of ordinates.
[0102] Therefore, the activation determination part 60 compares the
value defined by the operation results V.sub.10, V.sub.n computed
in the operation part 58, with either one of the activation
determination maps (step S13 of FIG. 4). When the value defined by
the operation results V.sub.10, V.sub.n is over the threshold, the
activation determination part 60 outputs the activation signal A to
the driving circuit 34 (see FIG. 1) (step S14 of FIG. 4). The
driving circuit 34 energizes the squib 38 to fire the gas generator
(not illustrated) by the squib 38.
[0103] Since the activation control apparatus of the occupant
safety system according to the first embodiment is constructed to
determine the type of collision, based on the values detected by
the front sensors 30A, 30B, it can determine the type of collision
in the early stage and with accuracy and can activate the airbag
system 36 accurately according to the type of collision.
[0104] The first embodiment described above may also be arranged
further so as to determine the severity of impact and vary the
output of the inflator of the airbag system. Specifically, the
airbag system is provided with two inflators and the airbag system
is activated by one inflator (low output) or by two inflators (high
output) according to the severity of collision. In this case, the
severity of collision is judged depending upon whether a value
defined by V.sub.n computed according to Eq. 2 and V.sub.5 computed
according to Eq. 5 is over a threshold 82 of the map illustrated in
FIG. 14. When the value is over the threshold 82, it is determined
that the collision is severe and the airbag system is activated at
the high output of the inflators. When the value is not over the
threshold 82, it is determined that the collision is not severe and
the airbag system is activated at the low output of the inflator.
Here V.sub.5 is an interval integral of the deceleration G'(t)
detected by the front sensor every interval of 5 ms in the period
from occurrence of collision to the end of collision.
V.sub.5=.intg..sub.t-5ms.sup.tG'(t)dt [Eq. 5]
[0105] G'(t): output of front sensor
[0106] Therefore, the airbag system can be activated accurately
according to the type of collision and the airbag system can also
be activated at an appropriate output according to the severity of
collision.
[0107] In the first embodiment described above the apparatus is
provided with the two front sensors 30A, 30B, but the apparatus may
also provided with three front sensors, without having to be
limited to two. In this case, when the third front sensor is
mounted in the central part of the vehicle, the pole crash can be
detected accurately.
[0108] In the first embodiment described above the two front
sensors 30A, 30B are mounted on the right front side member and on
the left front side member, but they may also be located at
appropriate positions ahead of the floor sensor in the vehicle; for
example, near the left and right ends of the bumper in the front
part of the vehicle, near the front portions of the left and right
front side members, near the left and right ends of the dash panel,
and so on.
[0109] Next, the activation control apparatus of the occupant
safety system according to the second embodiment of the present
invention will be described. The activation control apparatus of
the airbag system according to the second embodiment has the same
structure as the activation control apparatus 2 of the airbag
system according to the first embodiment (see FIG. 1 to FIG.
3).
[0110] FIG. 15 is a flowchart for explaining the control of
activation of the airbag system. When the operation part 58 of the
activation control 40 acquires the deceleration G(t) outputted from
the floor sensor 32 (step S30), it executes the predetermined
operations with the deceleration G(t), i.e., the operations
according to Eq. 1 and Eq. 2 to obtain the operation results
V.sub.10, V.sub.n (step S31).
[0111] Next, the activation determination part 60 acquires
information concerning the type of collision from the collision
type identifying part 42 (step S32) and compares the value defined
by the operation results V.sub.10, V.sub.n with either one of the
activation determination maps stored in the activation
determination part 60 (step S33).
[0112] Namely, the activation determination part 60 stores a
frontal crash/oblique crash map (FIG. 16), a frontal crash/offset
crash map (FIG. 17), an offset crash/ODB crash map (FIG. 18), and a
frontal crash/soft crash map (FIG. 19) as the activation
determination maps and compares the value defined by the operation
results with either map selected according to the information
concerning the type of collision acquired from the collision type
identifying part 42. Here the soft crash means a type of collision
in which the impact exerted on the vehicle in the late stage of
collision is greater than that in the initial stage of collision,
in which in the initial stage of collision the left and right side
members are relatively unaffected by the impact due to the
collision while the impact is absorbed by deformation of the front
part of the vehicle, and in which in the late stage of collision
the crash reaches the rigid body including the engine etc. while
the impact on the vehicle becomes great.
[0113] The frontal crash map is selected before execution of the
determination of the collision type by the collision type
identifying part 42, i.e., immediately after the occurrence of
collision, and the value defined by the operation results V.sub.10,
V.sub.n is compared with this frontal crash map.
[0114] Therefore, the activation determination part 60 compares the
value defined by the operation results V.sub.10, V.sub.n computed
in the operation part 58, with either of the activation
determination maps and outputs the activation signal A to the
driving circuit 34 (see FIG. 1) when the value defined by the
operation results V.sub.10, V.sub.n is over the threshold (step
S34). This causes the driving circuit 34 to energize the squib 38,
whereupon the gas generator (not illustrated) is fired by the squib
38.
[0115] In the collision type identifying part 42 the Kalman filter
shapes the deceleration signal G'(t) outputted from each front
sensor 30A, 30B and the type of collision is identified based on
the deceleration signals thus shaped and the deceleration signal
G(t) outputted from the floor sensor (impact detecting means) 32.
This identification of the collision type is carried out in two
stages of an initial stage and a middle stage of collision. Namely,
FIG. 20 shows a graph of the waveform of the deceleration signal
G(t) outputted from the floor sensor 32. In this graph the period
from 0 to T.sub.1 is defined as an initial stage of collision and
the period from T.sub.1 to T.sub.2 as a middle stage of
collision.
[0116] First, in the initial stage of collision the collision of
the vehicle is classified under the frontal crash, the offset
crash, and the oblique crash, based on a ratio of the left and
right deceleration signals G'(t) outputted from the front sensors
30A, 30B. Namely, as illustrated in FIG. 21, the operation
according to Eq. 6 is started with the deceleration signals G'(t)
outputted from the respective front sensors 30A, 30B when the
deceleration signal G'(t) outputted from the collision-side front
sensor out of those G'(t) outputted from the front sensors 30A, 30B
becomes over a threshold. This operation is terminated when the
operation result V.sub.A based on the deceleration signal G'(t)
outputted from the collision-side front sensor reaches a constant
(a value set for each vehicle).
V=.intg..intg.G'(t)dtdt [Eq. 6]
[0117] G'(t): output of front sensor
[0118] Next, the identifying part 42 calculates a ratio of the
operation result V.sub.A based on the deceleration signal G'(t)
outputted from the collision-side front sensor to the operation
value V.sub.B based on the deceleration signal G'(t) outputted from
the non-collision-side front sensor, i.e., V.sub.A/V.sub.B and
classifies the collision under the frontal crash, the offset crash,
and the oblique crash, based on the value of V.sub.A/V.sub.B.
Namely, as illustrated in FIG. 22, when the value of
V.sub.A/V.sub.B is 0 to 0.3, the collision is classified into
either of likelihood 1, likelihood 2, and likelihood 3 of the
oblique crash, based on the value of V.sub.A/V.sub.B. When the
value of V.sub.A/V.sub.B is 0.3 to 0.6, the collision is classified
into either of likelihood 1, likelihood 2, and likelihood 3 of the
offset crash, based on the value of V.sub.A/V.sub.B. Further, when
the value of V.sub.A/V.sub.B is 0.6 to 1.0, the collision is
classified into either of likelihood 1, likelihood 2, and
likelihood 3 of the frontal crash, based on the value of
V.sub.A/V.sub.B.
[0119] The term "likelihood" herein is certainty; the likelihood 1
of the oblique crash means the highest certainty of the collision
being the oblique crash, while the likelihood 3 of the oblique
crash means the lowest certainty of the collision being the oblique
crash. Similarly, the likelihood 1 of the frontal crash means the
highest certainty of the collision being the frontal crash, while
the likelihood 3 of the frontal crash means the lowest certainty of
the collision being the frontal crash. In contrast with it, the
likelihood 1 of the offset crash represents an ambiguous situation
also including the possibility of the collision being the oblique
crash, while the likelihood 3 of the offset crash represents an
ambiguous situation also including the possibility of the collision
being the frontal crash.
[0120] When the collision is classified into either one of
likelihood 1, likelihood 2, and likelihood 3 of the oblique crash,
the collision type identifying part 42 outputs either of likelihood
1, likelihood 2, and likelihood 3 of the oblique crash as collision
information to the activation determination part 60. In this case,
therefore, the activation determination part 60 selects either one
of an oblique crash likelihood 1 map, an oblique crash likelihood 2
map, and an oblique crash likelihood 3 map corresponding to the
collision information (see FIG. 16). When the collision is
classified into either one of likelihood 1, likelihood 2, and
likelihood 3 of the offset crash, the collision type identifying
part 42 outputs either of likelihood 1, likelihood 2, and
likelihood 3 of the offset crash as collision information to the
activation determination part 60. In this case, therefore, the
activation determination part 60 selects either one of an offset
likelihood 1 map, an offset likelihood 2 map, and an offset
likelihood 3 map corresponding to the collision information (see
FIG. 17).
[0121] On the other hand, when the collision is classified into
either one of likelihood 1, likelihood 2, and likelihood 3 of the
frontal crash, the collision type identifying part 42 outputs no
collision information to the activation determination part 60 and
then the activation determination part 60 selects the frontal crash
map as an activation determination map (see FIG. 16 and FIG.
17).
[0122] In the initial stage of collision, when the above
classification of the collision type results in classifying the
collision into either of likelihood 1, likelihood 2, and likelihood
3 of the offset crash, and likelihood 3 of the frontal crash, the
identifying part determines whether the collision of the vehicle is
the ORB crash (the irregular collision against the hard obstacle)
or the ODB crash (the irregular collision against the soft
obstacle), based on the initial deviation between the deceleration
signals G'(t) outputted from the front sensors 30A, 30B.
[0123] Namely, as illustrated in FIG. 23, the operation according
to Eq. 6 is started with the collision-side deceleration signal
G'(t) when the deceleration signal G'(t) outputted from the
collision-side front sensor out of those G'(t) outputted from the
front sensors 30A, 30B becomes over the threshold. The operation
according to Eq. 6 is also started with the non-collision-side
deceleration signal G'(t) when the deceleration signal G'(t)
outputted from the non-collision-side front sensor out of those
G'(t) outputted from the front sensors 30A, 30B becomes over the
threshold.
[0124] The operation based on the deceleration signal G'(t)
outputted from the collision-side front sensor is terminated when
the operation result V.sub.A reaches a constant (a value set for
each vehicle). The operation based on the deceleration signal G'(t)
outputted from the non-collision-side front sensor is terminated
when the operation result V.sub.B reaches the constant (the value
set for each vehicle).
[0125] Next, average accelerations G.sub.Aa, G.sub.Ba are computed
according to Eq. 7, based on the operation result V.sub.A and the
operation result V.sub.B, and an operation value R is computed
according to Eq. 8.
G.sub.Aa=V.sub.A/(T.sub.A1-T.sub.A0) [Eq. 7]
G.sub.Ba=V.sub.B/(T.sub.B1-T.sub.B0)
R=(V.sub.A/V.sub.B)/(G.sub.Aa/G.sub.Ba) [Eq. 8]
[0126] Then the collision is classified under the ORB crash and the
ODB crash, based on the value of the operation result R. Namely,
when the value of the operation result R is 1 to 1.1, the collision
is classified as an ORB crash. When the value of the operation
result R is 1.1 to 1.5, the collision is classified into either of
likelihood 1, likelihood 2, and likelihood 3 of the ODB crash,
based on the value of the operation result R. Namely, the greater
the initial deviation between the collision-side operation result
V.sub.A and the non-collision-side operation result V.sub.B, the
higher the probability of the ODB crash to be classified into.
[0127] Here "likelihood 1 of the ODB crash" means the highest
certainty of the collision being the ODB crash, while "likelihood 3
of the ODB crash" means the lowest certainty of the collision being
the ODB crash. Since the classification herein is provisional
classification, the collision type identifying part 42 outputs no
collision information to the activation determination part 60 even
if the collision is classified here into either of likelihood 1,
likelihood 2, and likelihood 3 of the ODB crash. In this case,
therefore, the frontal crash map, the offset crash map, or the
oblique crash map is used as an activation determination map.
[0128] Next, in the middle stage of collision (see FIG. 20) the
collision of the vehicle is classified into either of likelihood 1,
likelihood 2, and likelihood 3 of the ODB crash, based on the
difference between the left and right deceleration signals G'(t)
outputted from the front sensors 30A, 30B, thereby determining the
type of collision. The classification here into likelihood 1,
likelihood 2, or likelihood 3 of the ODB A crash is carried out
only when the collision was classified into either likelihood 1,
likelihood 2, or likelihood 3 of the ODB crash in the initial stage
of collision, and it is not carried out when the collision is
classified as an ORB crash.
[0129] Namely, as illustrated in FIG. 25, the difference is
calculated between the deceleration signals G'(t) outputted from
the front sensors 30A, 30B, i.e., between the deceleration signal
G'(t) outputted from the collision-side front sensor and the
deceleration signal G'(t) outputted from the non-collision-side
front sensor, and a value G.sub.Gap is defined as an excess of this
difference G"(t) over a threshold.
[0130] Then the collision is classified into either of likelihood
1, likelihood 2, and likelihood 3 of the ODB crash, based on the
value of G.sub.Gap (see FIG. 26). When the collision is classified
here into either of likelihood 1, likelihood 2, and likelihood 3 of
the ODB crash, the collision type identifying part 42 outputs
either of likelihood 1, likelihood 2, and likelihood 3 of the ODB
crash as collision information to the activation determination part
60. In this case, therefore, the activation determination part 60
selects either one of an ODB likelihood 1 map, an ODB likelihood 2
map, and an ODB likelihood 3 map corresponding to the collision
information (see FIG. 18).
[0131] In the middle stage of collision, whether the collision of
the vehicle is a soft crash is determined based on the deceleration
signal G(t) outputted from the floor sensor 32. The determination
of whether a soft crash or not is carried out only when the
collision of the vehicle was classified into either likelihood 1,
likelihood 2, or likelihood 3 of the frontal crash, or likelihood 3
of the offset crash in the initial stage of collision.
[0132] Namely, as illustrated in FIG. 27, letting T.sub.0 be a time
when the deceleration signal G(t) outputted from the floor sensor
32 exceeds a threshold 1 and letting T.sub.1 be a time when the
deceleration signal G(t) exceeds a threshold 2, the range between
T.sub.0 and T.sub.1 is expanded onto a normalized GT plane having
the axis of abscissas (0 to 1) and the axis of ordinates (0 to 1).
When the deceleration signal G(t) or a peak hold waveform
G(t).sub.PH of the deceleration signal G(t) is over a threshold set
in the normalized GT plane, the identifying part does not carry out
the determination of certainty or likelihood of the soft crash as
to the collision of the vehicle. On the other hand, when the
deceleration signal G(t) and the peak hold waveform G(t).sub.PH of
the deceleration signal G(t) are not over the threshold set in the
normalized GT plane, the identifying part carries out the
determination of likelihood of the soft crash as to the collision
of the vehicle.
[0133] Namely, the identifying part computes V.sub.A and V.sub.B
according to Eq. 9 and also computes an unevenness ratio r
according to Eq. 10.
V.sub.A=.intg.G(t)dt [Eq. 9]
[0134] G(t): output of floor sensor
V.sub.B=.intg.G(t).sub.PHdt
[0135] G(t).sub.PH: peak hold value of floor sensor output
unevenness ratio r=V.sub.A/V.sub.B [Eq. 10]
[0136] Then, based on this unevenness ratio r, the identifying part
determines the likelihood of how the collision of the vehicle is
likely to be the soft crash. Namely, when the certainty of the
collision of vehicle being the soft crash is strong, the collision
is classified into likelihood 1, because the unevenness ratio r is
small (or unevenness is large). When the certainty of the collision
of the vehicle being the soft crash is small, the collision is
classified into likelihood 3, because the unevenness ratio r is
large (or unevenness is small) (see FIG. 28).
[0137] When the collision is classified here into either of
likelihood 1, likelihood 2, and likelihood 3 of the soft crash, the
collision type identifying part 42 outputs either of likelihood 1,
likelihood 2, and likelihood 3 of the soft crash as collision
information to the activation determination part 60. In this case,
therefore, the activation determination part 60 selects either one
of a soft crash likelihood 1 map, a soft crash likelihood 2 map,
and a soft crash likelihood 3 map corresponding to the collision
information (see FIG. 19).
[0138] In the late stage of collision (see FIG. 20), when the type
of collision is in an intermediate range, an activation
determination map is selected with reference to the table
illustrated in FIG. 29. For example, in the case wherein the
likelihood of the front crash is 1 and the likelihood of the soft
crash is 1, the soft crash map 1 is selected. In the case wherein
the likelihood of the frontal crash is 2 and the likelihood of the
soft crash is 2, the soft crash map 2 is selected. In the case
wherein the likelihood of the frontal crash is 3, the likelihood of
the soft crash is 3, and the likelihood of the ODB crash is 1, the
ODB crash map 2 is selected.
[0139] Therefore, the activation determination part 60 compares the
value defined by the operation results V.sub.10, V.sub.n computed
by the operation part 58, with the activation determination map
selected at each point. When the value defined by the operation
results V.sub.10, V.sub.n is over the threshold of the activation
determination map selected at each point, the activation
determination part 60 outputs the activation signal A to the
driving circuit 34 (see FIG. 1).
[0140] Since the activation control apparatus of the occupant
safety system according to the second embodiment is constructed to
obtain the likelihood of each collision type, select an activation
determination map based on the likelihood, and determine the
activation of the occupant safety system, the apparatus can
determine the type of collision with accuracy and can activate the
airbag system 36 accurately according to the type of collision.
[0141] In the second embodiment the apparatus may also be arranged
further so as to determine the severity of impact and vary the
output of the inflator of the airbag system according thereto.
Namely, the airbag system is provided with two inflators and the
airbag system is activated by one inflator (low output) or by two
inflators (high output), depending upon the severity of collision.
In this case, the severity of collision is determined as follows;
as illustrated in FIG. 30, an initial integral (from the start of
collision to t.sub.0) of the measurement G(t) of the floor sensor
32 is computed and a colliding speed is estimated from this initial
integral with reference to the graph illustrated in FIG. 31. This
colliding speed estimated can be regarded as severity of impact
(crash severity). When the colliding speed is over a threshold
defined for each collision type, the airbag system is activated at
the high output of the inflators, assuming that the collision is
severe. When the colliding speed is not over the threshold, the
airbag system is activated at the low output of the inflator,
assuming that the collision is not severe.
[0142] Further, a condition for determination discontinuation may
also be set in the determination of the soft crash in the second
embodiment. The determination of the soft crash is carried out when
the collision is finally determined as a symmetric collision, based
on the outputs from the front sensors 30A, 30B. Namely, when the
condition of T2>Tc2 is met in FIG. 32, the determination of the
soft crash is not carried out, whereby an ODB crash is prevented
from being identified as a soft crash. As illustrated in FIG. 33,
the values of Tc2 are values determined based on peak hold
values.
[0143] In the second embodiment the activation determination map
illustrated in FIG. 34 may also be employed as an activation
determination map in the case of the collision being identified as
a soft crash. This activation determination map has the nature of a
high output map in the portion indicated by the thick solid line
and also has the nature of a low output map in the portion
indicated by the dashed line. Namely, when the output waveform G(t)
of the floor sensor 32 in the case of the soft crash interferes
with the portion indicated by the thick solid line, the airbag
system is activated at the high output of the inflators. When it
interferes with the portion indicated by the dashed line, the
airbag system is activated at the low output of the inflator.
[0144] According to the present invention, the collision type
identifying means can identify the collision type of the vehicle as
either the oblique crash, the offset crash, or the like with
accuracy, and thus the activation control means can activate the
occupant safety system more accurately.
[0145] According to the present invention, the likelihood computing
means classifies the collision of the vehicle into either of the
frontal crash, the offset crash, and the oblique crash, based on
the values detected by the first impact detecting means and by the
second impact detecting means, and computes the likelihood of the
collision classified. Therefore, the apparatus can determine the
collision type of the vehicle accurately and can activate the
occupant safety system with accuracy.
[0146] According to the present invention, the likelihood computing
means classifies the collision into either of the oblique crash,
the offset crash, the ODB crash, and the soft crash and computes
the likelihood of the collision classified. The activation control
means controls the activation of the occupant safety system with
reference to the threshold corresponding to the likelihood of the
collision classified. Therefore, the apparatus can activate the
occupant safety system at accurate timing.
[0147] According to the present invention, the likelihood computing
means classifies the collision of the vehicle into either of the
frontal crash, the offset crash, and the oblique crash, based on
the ratio of the values detected by the first impact detecting
means and by the second impact detecting means, and thus the
collision can be classified with accuracy.
[0148] According to the present invention, the likelihood computing
means classifies the collision of the vehicle into either the ODB
crash or the ORB crash and computes the likelihood of the ODB
crash, based on the initial deviation between the values detected
by the first impact detecting means and by the second impact
detecting means, whereby the collision can be classified with
accuracy and whereby the accurate likelihood can be computed.
[0149] According to the present invention, the likelihood computing
means determines whether the collision of the vehicle is the ODB
crash and computes the likelihood of the ODB crash, based on the
magnitude of the difference between the values detected by the
first impact detecting means and by the second impact detecting
means, whereby the collision can be classified with accuracy and
whereby the accurate likelihood can be computed.
[0150] According to the present invention, the likelihood computing
means determines whether the collision of the vehicle is the soft
crash and computes the likelihood of the soft crash, based on the
state of unevenness of the temporal change waveform of the
measurement measured by the impact measuring means, whereby the
collision can be determined with accuracy and whereby the accurate
likelihood can be computed.
[0151] According to the present invention, the soft crash
determining means determines whether the collision of the vehicle
is the soft crash, based on the state of unevenness of the temporal
change waveform of the measurement measured by the impact measuring
means. Therefore, the apparatus can accurately determine whether
the collision is the soft crash and can activate the occupant
safety system with accuracy.
[0152] From the invention thus described, it will be obvious that
the invention may be varied in many ways. Such variations are not
to be regarded as a departure from the spirit and scope of the
invention, and all such modifications as would be obvious to one
skilled in the art are intended for inclusion within the scope of
the following claims.
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