JP3902866B2 - Vehicle collision determination device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle collision determination device that performs a collision determination based on an acceleration signal obtained by an acceleration sensor, and more particularly to a vehicle collision determination device that can properly activate an occupant protection device regardless of the collision mode. About.
[0002]
[Prior art]
In recent years, occupant protection devices such as an air bag system and a seat belt pretensioner have become widespread in order to protect the occupant from an impact caused by a vehicle collision. In this type of occupant protection device, a collision determination is made based on an acceleration signal obtained by an acceleration sensor. When the collision determination is made, an ignition device for an airbag or a seat belt pretensioner is activated to inflate the airbag. At the same time, seat belts are used to protect passengers.
[0003]
[Problems to be solved by the invention]
The occupant protection device described above is basically activated on the condition that the acceleration detected by the acceleration sensor exceeds a predetermined reference acceleration. However, if the collision determination is performed using only the magnitude of the acceleration as a parameter, it is not always accurate. The collision cannot be determined. For this reason, generally, together with the magnitude of acceleration, the frequency component of the acceleration signal is also used as a parameter for collision determination.
[0004]
For example, it is desirable to prevent the occupant protection device from being activated at the time of a low-speed collision with very little impact on the occupant. On the other hand, when the vehicle collides obliquely with an obstacle, even if it is desirable that the acceleration applied to the occupant is larger than that at the time of the collision at the low speed and it is desirable to start the occupant protection device, the acceleration sensor detects In some cases, the generated acceleration is smaller than that at the time of the collision at the low speed.
[0005]
In this way, the relative relationship between the acceleration detected by the acceleration sensor and the acceleration actually applied to the occupant can be reversed depending on the collision mode, so that the occupant protection device is not used in the conventional technology to prevent unnecessary operation. On the other hand, fast Fourier transform processing is executed, and collision determination is performed based on the absolute value and frequency of the acceleration signal.
[0006]
However, in the fast Fourier transform processing, trigonometric function operations and multiplications must be executed many times. Therefore, in order to perform accurate collision determination in a short time, a microprocessor capable of high-speed arithmetic processing must be used, and there is a problem that the collision determination apparatus becomes expensive.
[0007]
An object of the present invention is to provide a vehicle collision determination apparatus that solves the above-described problems of the prior art and that can perform accurate collision determination in a short time with a simple and inexpensive configuration.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, in a vehicle collision determination device that performs a collision determination based on an acceleration signal output in response to acceleration by an acceleration sensor, the acceleration signal output from the acceleration sensor is Amplification control means for amplifying at a higher amplification factor as the level is smaller, filter means for attenuating a predetermined frequency band of the amplified acceleration signal, and controlling the operation of the filter means according to the amplification factor by the amplification control means And a collision determination unit that performs a collision determination based on an output signal of the filter unit, and the filter control unit attenuates the filter unit when the amplification rate by the amplification control unit is low. The operation was restricted.
[0009]
According to the configuration described above, the acceleration signal is sufficiently amplified by the amplification control means, while a predetermined frequency band is selectively attenuated by the filter means from the amplified acceleration signal. Therefore, the frequency band to be attenuated by the filter means is specific to a collision mode (for example, a frontal collision at a low speed) that does not require the occupant protection device to be activated even though the acceleration detected at the time of the collision is not small. Thus, it is possible to prevent the collision determination in the collision mode.
[0010]
At this time, contrary to the above, in the collision mode (for example, oblique collision) in which it is desirable to activate the occupant protection device even though the acceleration detected at the time of the collision is not large, the frequency band of the acceleration signal at that time is Since it is different from the above, the filter means does not substantially function. For this reason, the amplified acceleration signal is inputted as it is to the collision determination means, so that the collision determination can be made reliably.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram of a vehicle collision determination apparatus according to an embodiment of the present invention.
[0012]
The acceleration sensor 10 is fixed at a predetermined position for each vehicle, and outputs an acceleration signal S1 having a voltage level corresponding to the magnitude of acceleration. The A / D conversion function unit 20 converts the acceleration signal S1 output from the acceleration sensor 10 into a digital signal D1 and outputs it.
[0013]
The amplification controller 30 amplifies the acceleration signal D1 at a higher amplification factor as the level is smaller so that the peak value of the acceleration signal D1 is amplified to a predetermined voltage level. The amplification control unit 30 includes an amplification factor determination unit 31 that determines an amplification factor based on the peak value of the digital signal D1, and an amplification unit 32 that amplifies (magnifies) the digital signal D1 at the determined amplification factor. Consists of.
[0014]
The filter 40 attenuates and outputs only the planned band (100 to 200 Hz in this embodiment) of the digital signal D2 output from the amplification control unit 30. The filter control unit 50 receives the amplification factor determined by the amplification factor determination unit 31 of the amplification control unit 30 and limits the attenuation operation of the filter 40 when the amplification factor is small. The collision determination unit 60 performs a collision determination based on the output signal D3 of the filter 40. When the collision determination is made, the ignition device of the airbag 70 or the seat belt pretensioner 80 is activated to protect the occupant.
[0015]
FIG. 2 is a diagram showing a list of the characteristics of the acceleration signal S1 output from the acceleration sensor 10 in three typical collision modes of the vehicle and whether or not the collision is determined in each collision mode.
[0016]
In general, in a frontal collision at a high speed where the peak value of the acceleration signal S1 reaches a collision determination level (for example, 40G) near the maximum rating (for example, 50G) of the acceleration sensor 10, the frequency band of the acceleration signal S1 is 50. It is in the range of ~ 200 Hz.
[0017]
In addition, it is not necessary to activate the occupant protection device (<40G). For example, in a frontal collision at a low speed such that the peak value of the acceleration signal indicates 30G, the frequency band of the acceleration signal S1 is in the range of 100 to 200 Hz. .
[0018]
Further, in an oblique collision in which the vehicle collides obliquely with an obstacle, the peak value of the acceleration signal S1 has a small level (for example, 15G) even when an impact is applied to the occupant so that it is desirable to activate the occupant protection device. The frequency band is in the range of 100 Hz or less and 200 Hz or more.
[0019]
As described above, when comparing a frontal collision at a low speed with an oblique collision, it is desirable that a frontal collision at a low speed that does not require the occupant protection device to be activated activates the occupant protection device. A reverse phenomenon occurs in which the peak value of the acceleration signal S1 becomes larger than the case. Further, the frequency band of the acceleration signal S1 differs for each collision mode and does not overlap each other.
[0020]
For this reason, in this embodiment, when the detected acceleration is sufficiently large (for example, a frontal collision at a high speed), the collision determination is made substantially unconditionally, and the detected acceleration is If it is not large enough, each acceleration signal is amplified enough to make a collision determination in the subsequent collision determination unit, and specific to a frontal collision at low speed for the amplified acceleration signal. By selectively attenuating only the frequency band of 100 to 200 Hz, the reverse phenomenon of the acceleration signal level between the frontal collision and the oblique collision at the low speed is eliminated.
[0021]
FIG. 3 is a diagram showing the waveform of the acceleration signal in each part of FIG. 1 in the three typical collision modes described above, and the same reference numerals as those described above represent the same or equivalent parts. In addition, here, a 50G acceleration sensor (absolute value of the maximum acceleration that can be detected is 50G) is used as the acceleration sensor 10, and the collision determination level at which the collision determination unit 60 activates each of the occupant protection devices 70 and 80 is 40G. Assume that
[0022]
(1) When a frontal collision vehicle at high speed collides with an obstacle at high speed and the peak value of the acceleration signal exceeds 40G which is a collision determination level, the amplification factor determination unit 31 of the amplification control unit 30 The amplification factor is determined to be “1”. Thus, in this embodiment, when the peak value of the acceleration detected by the acceleration sensor 10 exceeds the collision determination level, the amplification factor by the amplification controller 30 is set to “1” (not amplified).
[0023]
The filter control unit 50 controls the operation of the filter 40 based on the amplification factor determined by the amplification factor determination unit 31. When the amplification factor is “1” as described above, Prohibit processing. Therefore, the acceleration signal output from the amplification control unit 30 is input to the collision determination unit 60 without being attenuated in any frequency band. The collision determination unit 60 determines the level of the acceleration signal. Since the collision determination level exceeds 40G, which is the collision determination level, each ignition device of the airbag 70 and the seat belt pretensioner 80 is activated.
[0024]
(2) If the frontal collision vehicle at low speed collides with an obstacle at low speed, and the peak value of the acceleration signal is 30G below 40G which is the collision determination level, the amplification factor determination unit of the amplification control unit 30 31 determines the amplification factor to be “1.33” (= 40G / 30G). Thus, in the present embodiment, when the peak value of the acceleration signal falls below the collision determination level, the amplification factor in the amplification control unit 30 is determined so that the peak value reaches at least the collision determination level (40G).
[0025]
When the amplification factor determined by the amplification factor determination unit 31 is greater than “1”, that is, when the acceleration signal is amplified, the filter control unit 50 instructs the filter 40 to perform a filtering process for the frequency band 100 to 200 Hz. To do. Therefore, the acceleration signal output from the amplification control unit 30 is attenuated in the frequency band of 100 to 200 Hz by the filter 40.
[0026]
As described above, since the frequency band of the acceleration signal detected in the frontal collision at a low speed is 100 to 200 Hz, the level of the acceleration signal output from the filter 40 becomes very small. For this reason, the collision determination unit 60 determines that there is no collision, and the airbag 70 and the seat belt pretensioner 80 are not activated.
[0027]
(3) When the obliquely colliding vehicle collides obliquely with the obstacle and the peak value of the acceleration signal is 15 G below the collision determination level, the amplification factor determining unit 31 of the amplification control unit 30 sets the amplification factor “ 2.67 "(= 40G / 15G). Since the amplification factor determined by the amplification factor determination unit 31 is greater than “1”, the filter control unit 50 instructs the filter 40 to perform the filtering process for the frequency band 100 to 200 Hz. Therefore, the acceleration signal output from the amplification control unit 30 is attenuated in the frequency band of 100 to 200 Hz by the filter 40.
[0028]
However, as described above, in the oblique collision, since the frequency band of the acceleration signal is 100 Hz or less and 200 Hz or more, the filter 40 does not substantially function, and the acceleration signal level maintains the high level after the amplification (collision determination level). It is input to the collision determination unit 60 as it is. Accordingly, the collision determination unit 60 makes a collision determination and activates the airbag 70 and the seat belt pretensioner 80.
[0029]
【The invention's effect】
As described above, according to the present invention, the acceleration signal in the first collision mode (oblique collision), which is desirable to activate the occupant protection device even though the acceleration detected at the time of the collision is not large, The detected acceleration signal is set so as to exceed the level of the acceleration signal in the second collision mode (front collision at low speed) that does not require activation of the occupant protection device even though the detected acceleration is not small. Since it amplifies uniformly and selectively attenuates only the frequency band specific to the second collision form, the acceleration signal level in the first collision form becomes larger than the acceleration signal level in the second collision form. .
[0030]
Therefore, the collision determination unit can accurately determine the collision based only on the magnitude of the input acceleration signal, and provides a vehicle collision determination device that can perform accurate collision determination in a short time with a simple and inexpensive configuration. It becomes possible.
[Brief description of the drawings]
FIG. 1 is a block diagram of a vehicle collision determination apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram showing a list of characteristics of acceleration signals output from an acceleration sensor in three typical collision modes of a vehicle and whether or not a collision is determined in each collision mode.
FIG. 3 is a diagram showing signal waveforms at various parts in FIG. 1 for each of three typical collision modes.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Acceleration sensor, 20 ... A / D conversion part, 30 ... Amplification control part, 40 ... Filter, 50 ... Filter control part, 60 ... Collision determination part, 70 ... Air bag, 80 ... Seat belt pretensioner

Claims (1)

In a vehicle collision determination apparatus that performs a collision determination based on an acceleration signal output by an acceleration sensor in response to acceleration,
Amplification control means for amplifying the acceleration signal output from the acceleration sensor with a higher amplification factor as its peak value is smaller,
Filter means for attenuating a predetermined frequency band of the amplified acceleration signal;
Filter control means for controlling the operation of the filter means in accordance with the amplification factor by the amplification control means;
A collision determination unit that performs a collision determination based on an output signal of the filter unit;
The vehicle collision determination device, wherein the filter control means limits the attenuation operation of the filter means when the amplification factor by the amplification control means is low.

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