Collision type decision device

Details Collision type decision device Collision type decision device

2002-04-11

2004-04-27

Nguyen, Tan Q. (Department: 3661)

Data processing: vehicles, navigation, and relative location

Vehicle control, guidance, operation, or indication

C701S046000, C701S047000, C280S735000, C340S436000

Reexamination Certificate

active

06728604

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a collision type decision device for deciding whether a vehicle has had a head-on (symmetric) collision or an asymmetric collision.
2. Description of the Background Art
A driver/passenger protection apparatus, e.g., air bag, on a vehicle is controlled to activate by a protection activation device. Conventionally, the human protection activation device detects an impact on the vehicle as a deceleration by means of an acceleration sensor, and controls the activation of the human protection apparatus on the basis of the measured deceleration.
There are various collision types including a symmetric (full-wrap) collision where the entire front face of a vehicle is impacted, an asymmetric (offset) collision where a part of the front face of a vehicle is impacted, and a bias collision where a vehicle is impacted by a skewed force having a certain angle. In order to activate a suitable human protection apparatus at more appropriate timing, the use of a collision type decision device has been contemplated.
JP-A-2000-255373 discloses collision type decision devices, each of which decides the collision type by means of acceleration sensors (satellite sensors) situated at the left and right front corners of a vehicle. One of the collision type decision devices disclosed in the publication calculates the respective velocity values of the left and right portions of the vehicle on the basis of the measured decelerations, recognizes the time moments when the respective velocity values exceed a threshold, and decides the collision type on the basis of the time difference between the time moments.
Another collision type decision device disclosed in the publication decides the collision type on the basis of the difference between the left and right velocity values of the vehicle. A still another collision type decision device identifies the time moments when the respective velocity values reach respective peaks and decides the collision type on the basis of the difference between the time moments. These devices utilize a theory that either of the left and right acceleration sensors produces a larger output when an asymmetric collision occurs.
FIG. 16
is a block diagram showing in a simplified form one of collision type decision devices disclosed in JP-A-2000-255373. In
FIG. 16
, numeral
520
designates a collision type decision device. The collision type decision device
520
includes a left front sensor
22
, a right front sensor
24
, an arithmetic unit
530
, and a comparison unit
540
. The sensors
22
and
24
that are disposed left and right front corners of a vehicle, respectively, detect the accelerations (more exactly, decelerations) at the respective positions. The arithmetic unit
530
makes calculations on the outputs of the sensors
22
and
24
to obtain respective arithmetic results with respect to the left and right portions of the vehicle and calculates the difference between the arithmetic results. For example, the arithmetic unit
530
integrates the respective outputs Gl and Gr of the left and right sensors
22
and
24
to obtain the left and right velocities f(Gl) and f(Gr) and calculates the velocity difference |f(Gl)−f(Gr)|. The comparison unit
540
compares the velocity difference |f(Gl)−f(Gr)| with a threshold Thr
0
and decides the collision type on the basis of the comparison result.
Conventionally, the left and right front acceleration sensors
22
and
24
are located near the engine room. Accordingly, the temperature change resulting from that in the engine room and other disturbances may affect the acceleration sensors
22
and
24
, thereby frequently disenabling the decision device to decide the collision type properly. For example, if either of the left and right acceleration sensors
22
and
24
is significantly affected by the temperature change in comparison with the other sensor although the vehicle has had a symmetric collision, the collision type decision device may improperly decides that an asymmetric collision has occurred.
This problem will be discussed in more detail with reference to
FIGS. 17A and 17B
.
FIG. 17A
depicts results at a symmetric collision while
FIG. 17B
depicts results at an asymmetric collision. In these graphs, dotted lines depict results when no disturbances were applied to the sensors while solid line depict results when some disturbances were applied to the sensors. As will be understood from the dotted lines in
FIG. 17A
, at the symmetric collision, the velocity difference |f(Gl)−f(Gr)| was always lower than the threshold Thr
0
. As in
FIG. 17B
, at the asymmetric collision, the velocity difference |f(Gl)−f(Gr)| exceeded the threshold Thr
0
at at least a certain period.
However, as will be understood from the solid lines in
FIG. 17A
, even at the symmetric collision, when some kind of disturbance was applied, the velocity difference |f(Gl)−f(Gr)| increased farther than that at no disturbance and exceeded the threshold Thr
0
for any while. Furthermore, although the same disturbance was applied while the asymmetric collision has occurred, the velocity difference |f(Gl)−f(Gr)| might decrease to be lower than that at no disturbance and be always lower than the threshold Thr
0
as will be understood from FIG.
17
B. These phenomena make appropriate decisions difficult, so that it is difficult for manufacturers of collision type decision devices to even set the threshold Thr
0
.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a collision type decision device for making appropriate decisions of collision type although there are measurement errors of sensors resulting from disturbances.
In accordance with an aspect of the present invention, a collision type decision device includes left and right deceleration detectors, an average calculating unit, and a decision unit. The left and right deceleration detectors are located at left and right front portions of a vehicle for detecting decelerations at the left and right front portions, respectively. The average calculating unit calculates an average of values based on the decelerations detected by the left and right deceleration detectors. The decision unit compares the average with a threshold and decides whether a collision type of the vehicle is a symmetric or asymmetric on the basis of the comparison.
With such a structure, it is possible to make appropriate decisions of collision type although there are measurement errors of deceleration detectors resulting from disturbances.
In an embodiment, the collision type decision device may further include an arithmetic unit for calculating the decelerations detected by the deceleration detectors to obtain arithmetic results with respect to the left and right portions of the vehicle. The average calculating unit may calculate an average of the arithmetic results.
With such a structure, the arithmetic unit may obtain left and right velocities, jerks, and other optional arithmetic results. The collision type decision device can make appropriate decisions of collision type on the basis of such optional arithmetic results.
In another embodiment, the average calculating unit may calculate an average of the decelerations themselves detected by the left and right deceleration detectors.
With such a structure, it is possible to make appropriate decisions of collision type in a more simplified manner.
The collision type decision device may further include a central deceleration detector located near the central portion of the vehicle for detecting deceleration at the central portion, and a collision beginning detector for detecting a collision beginning moment of the vehicle on the basis of the deceleration detected by the central deceleration detector or on the basis of the decelerations detected by the central deceleration detector and at least one of the left and right deceleration detector

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