JPH04146847A - Collision detector for vehicle - Google Patents

Abstract

PURPOSE:To make an accurate collision detection with a proper timing by performing several-order filtering by use of an acceleration signal obtained from an acceleration detector means and comparing the calculated value with a collition reference value. CONSTITUTION:There is provided an acceleration detector means 100 for detecting the acceleration of a traveling vehicle. The acceleration signal obtained by detection operation of this acceleration detector means 100 is inputted to a several-order linear filter 200 in which that signal is processed. This signal processing is, for example, a secondary linear low-pass filtering to calculate the changed amount from the acceleration. The value thus obtained by this calculation is compared with a collision decision reference value Vref in a collision decision means to make decision of whether or not any vehicle collision has taken place. This enables detecting the generation of any vehicle collision accurately and with a proper timing.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a collision detection device for a vehicle suitable for use in activating a protection device such as an air pack system or a bullet tensioner system installed in a vehicle such as an automobile, which accurately detects the occurrence of a collision. The purpose of the present invention is to provide a collision detection device capable of detecting a collision at an appropriate time, and includes an acceleration detection means for detecting the acceleration of a running vehicle, a multi-order linear filter for processing the detected acceleration signal, and an output of the filter. and a collision determination means +e1 stage (300) for comparing the collision determination value with a predetermined collision determination reference value (■).

[Industrial application field]

The present invention relates to a vehicle collision detection device suitable for use in activating a protection device such as an air pack system or a prevention system installed in a vehicle such as an automobile.

In order to more safely protect occupants from impact during a collision, recent automobiles are being equipped with air pack systems, britensioner systems, and the like as supplementary means to seat belt devices. When an air pack is inflated during a collision, it is done by igniting a pyrotechnic device attached to the air pack or seat belt. The ignition signal for this pyrotechnic device is provided by a collision detection device. A problem in the collision detection device is determining whether a collision has occurred and determining the output timing of the detection signal.

[Conventional technology]

BACKGROUND ART Conventionally, as a collision detection device for a vehicle, a system is known in which a collision is determined to occur when an acceleration of a predetermined value or more is applied. Structurally, there are devices that electrically detect acceleration and detect collisions through signal processing, or magnets.
There are various types such as mechanical ones that combine weights, contacts, etc.

However, since the above-mentioned collision detection device only makes judgments based on the acceleration at a single point, it does not detect instantaneous shocks, such as impact acceleration when the car runs onto a curb or crosses a ditch, or when repairs are needed. There was a problem in that erroneous detection or detection timing was caused by impact acceleration caused by a hammer or the like.

As another collision detector that compensates for the above-mentioned drawbacks of the conventional collision detector, there is one that integrates an acceleration detection signal of a predetermined level or higher, and determines that a true collision has occurred when the integrated value exceeds a predetermined value (for example, , Special Publication No. 63-503531). This method calculates velocity by first-order integration of acceleration, and evaluates collisions in terms of velocity.

[Invention or problem to be solved]

However, according to the above method, there are problems with a delay in the detection timing of collision detection and detection accuracy.

That is, when the predetermined value of the collision detector is set to match the appropriate timing for collision detection during high-speed driving, there is a problem in that the detection timing for medium-speed collisions is delayed. On the other hand, if it is adjusted to a medium-speed collision, there is a problem of erroneous detection, such as a collision detected at a low-speed collision, which is an unnecessary detection area. Further, since acceleration below a predetermined level is not detected, there are problems such as a delay in collision detection and a short judgment time.

An object of the present invention is to provide a collision detection device that can detect the occurrence of a collision accurately and at an appropriate timing.

[Means to solve the problem]

As shown in FIG. 1, the present invention comprises an acceleration detection means 100 for detecting the acceleration of a running vehicle, a multi-order linear filter 200 for processing the detected acceleration signal, and a predetermined filter for outputting the output of the filter. collision determination means +e1 300 for comparing with the collision determination reference value V.

[Effect]

According to the present invention, the acceleration detection means 100 detects the acceleration of a running vehicle. The detected acceleration signal is input to a multi-order linear filter 200. The multi-order linear filter 200 processes the acceleration signal. This signal processing is, for example, second-order linear low-pass filtering, and the amount of change is calculated from the acceleration. This calculated value is compared with the collision determination reference value (2) in the collision determination means, and is used to determine whether or not there is a collision.

〔Example〕

Next, embodiments of the present invention will be described based on the drawings.

First example FIG. 2 shows a first embodiment of the present invention.

The air pack system is a system that instantly inflates the air pack system to protect occupants from leaning forward and colliding with the steering wheel, windshield, etc. in the event of a collision.

Therefore, it is necessary for the air pack system to operate properly, and for this purpose, it is necessary to accurately and quickly detect the collision state of the vehicle, and to output a collision detection signal to the air pack system activation device at the appropriate timing. . In the case of an air pack system, the optimal timing for outputting a collision detection signal is when the occupant begins to lean forward at the time of a collision.

The challenge is how to know when to start leaning forward. In this embodiment, the obtained acceleration signal is converted into the dimension of displacement by second-order incomplete integration, and the collision determination output is output when the output corresponding to the displacement reaches a predetermined amount. We are working to optimize the

Bypass filters take advantage of the fact that acceleration changes are relatively slow in low-speed collisions, and perform processing such that the output is attenuated in low-speed collisions where the air pack system does not need to be activated, thereby achieving accurate detection. realized.

That is, in this embodiment, the collision detection device includes an acceleration sensor 1 that detects the acceleration of the vehicle, as shown in FIG.
have. The acceleration signal obtained from the acceleration sensor 1 is amplified to a predetermined level by the buffer amplifier 2. By attenuating unnecessary low frequency components in the amplified acceleration signal by the bypass filter 3, the possibility of erroneous judgment due to the rise of the acceleration signal seen in the latter half of a low-speed collision is reduced. Note that the bypass filter 3 is a so-called CR type bypass filter 3 that uses a resistor and a capacitor. The output signal of the bypass filter 3 is first integrated by a low-pass filter 4a to convert it into a "velocity" dimension, and then further integrated by a low-pass filter 4a to a "displacement" dimension. The low-pass filters 4a and 4b are constructed using resistors and capacitors, and perform calculations to estimate the amount of displacement of the occupant.

The determined displacement equivalent amount is compared with a predetermined threshold value V 2 in a comparator 6. The comparison result is output as a collision determination output V, and this collision determination output V is used as a starting signal for an air pack system (not shown).

Here, the output of the linear filter 5 is shown in FIG.

The higher the collision speed, the greater the rate of change in forward displacement. Therefore, it is necessary to speed up the activation timing of the air pack. Threshold the output of linear filter 5 ■
By comparing with , it is possible to obtain characteristics that the vehicle is fast in a high-speed +ef collision, and that a low-speed collision is not judged as a collision.

In the first embodiment, a first-order bypass filter and a second-order low-pass filter are used, but it is also possible to further improve the detection accuracy by using a higher-order bypass and low-pass filter.

Second Embodiment An embodiment of the present invention is shown in FIG. This embodiment is characterized in that the air pack system does not operate in the event of a collision caused by low-speed driving, etc., where the operation of the air pack system is not required.

As shown in FIG. 4, the threshold value V+e12 of the comparator 6 is generated by the comparator 7 and the function generator 8, and as time passes, the threshold value V+e12 is increased and This is to avoid false detection. The comparator 7 takes as an input signal the output signal of the buffer amplifier 2, that is, the amplified acceleration signal, and compares it with a predetermined threshold value (2). The threshold value V 1 is determined based on the criterion of whether the value of the acceleration tell signal is a value that can be taken under normal driving conditions. Therefore, if the acceleration signal ll exceeds the threshold value V 2 , the comparison output is given to the function generator 8 .

The function generator 8 outputs a threshold value V, fl12 that gradually increases as a function of time after a certain predetermined time has elapsed. This rising point is determined by considering the slow change in acceleration during a low-speed collision, and only when the acceleration signal level is still high after a predetermined period of time has elapsed, a collision judgment is output.
It is considered to improve the reliability of collision determination by setting ut to output the collision determination output V and setting the threshold value V so as not to output the collision determination output V when the level is low.

As shown in FIG. 5, the forward leaning displacement of the occupant changes as shown in the figure with respect to the acceleration at the time of collision at each of high speed, medium speed, and low speed. However, at medium or low speeds, it is often not dangerous enough to activate the air pack.
Collision judgment output V. , there is no need to roll 1. Therefore, according to this embodiment, as shown in FIG. 5, the threshold value V output from the function generator 8 increases after a certain point, and the collision determination output V of +e+2 for low-speed collisions and the collision determination output V of +e+2 for low-speed collisions and medium-speed collisions ut works to prevent output of the collision determination output V during a part of the time. As a result, the airbag can be activated only when the vehicle tilts forward due to acceleration due to a highly dangerous collision, making it possible to reliably protect the occupants when necessary.

Although Fig. 4 shows an example in which the output characteristics of the function generator 8 change linearly, it is also possible to increase the output characteristic linearly by using a time constant circuit consisting of a capacitor and a resistor and utilizing its charge/discharge characteristics. It is also possible to use a function generator 8 having the following characteristics.

Third Embodiment A third embodiment of the present invention is shown in FIG. This embodiment is an example in which a digital filter 10 is used in place of the low-pass filters 4a and 4b made of analog filters in the first and second embodiments. For this purpose, an A/D converter 9 is interposed after the buffer amplifier 2, and the acceleration signal converted into a digital quantity by the A/D converter 9 is processed by a digital filter 10 and sent to a comparator 6. Given. The digital filter 10 is F I R (Finite impulses +
lil+e+) type digital filter, which includes multiple delay elements (Z) and a coefficient multiplier (Ko-K11).
For each delayed value, the value multiplied by the coefficient is added in an adder 11 and output.

This filter output is input to the comparator 6, and the first,
As in the second embodiment, it is compared with the threshold value V 1 +el. The comparator 6 uses the output of the adder 11 as the threshold value V
If the collision exceeds the limit, the airbag will be activated and a collision judgment output ■ will be output.

u1 Although not shown, in this third embodiment as well, malfunctions are reduced by making the threshold value V input to the comparator 6 have a characteristic that increases with time as in the second +tl embodiment. I can do something.

Further, as in the first embodiment, by configuring the digital filter 10 including bypass filter characteristics, it is also possible to prevent malfunctions due to vibrations of relatively low frequency components.

Furthermore, by determining each coefficient of the digital filter 10 from the acceleration and the degree of danger to the occupant during an actual crash test, it is possible to more accurately determine whether a dangerous crash is occurring.

〔Effect of the invention〕

As described above, according to the present invention, the acceleration signal obtained by the acceleration detection means is subjected to several-order filter processing and the calculated value is compared with the collision determination reference value, so that airbags etc. Collision detection can be performed accurately at the appropriate timing without erroneously detecting impacts that are unnecessary for the operation of the robot.

As a result, it becomes possible to operate the occupant protection device accurately and reliably.

[Brief explanation of drawings]

Fig. 1 is a diagram explaining the principle of the present invention, Fig. 2 is a block diagram of the first embodiment of the present invention, and Fig. 3 is a diagram showing the relationship between acceleration, the output of the linear filter, and the threshold value of the comparator in the first embodiment. FIG. 4 is a block diagram of the second embodiment of the present invention; FIG. 5 is a characteristic diagram showing the correspondence between acceleration, the output of the linear filter, and each threshold value in the second embodiment; FIG. 6 is a block diagram of a third embodiment of the present invention. 100... Acceleration means 200... Filter means 300... Judgment means 400... Collision judgment reference value 1... Acceleration sensor 2... Buffer amplifier 3... Bypass filter 4 a s 4 b... Low pass Filter 5... Linear filter 6... Comparator 7... Comparator 8... Function generator 9... A/D converter 10... Digital filter 11... Adder ■...・Threshold value + ef ■ ...Threshold value ell ■ ...Threshold value r! ]2 ■...Collision determination output L11

Claims (1)

[Claims] 1. Acceleration detection means (
100) and a multi-order linear filter (
200), and the filter output is set to a predetermined collision determination reference value (V_
A collision detection device for a vehicle, characterized in that it comprises a collision determination means (300) for comparing the collision detection means (r_e_f). 2. The vehicle collision detection device according to claim 1, wherein the collision determination reference value (V_r_e_f_2) is changed over time.