JP3118980B2 - Vehicle collision determination device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle collision judging device for judging a collision of a vehicle at high speed and with high accuracy from an impact force and a change in speed.

[0002]

2. Description of the Related Art In order to reduce occupant fatal accidents due to a vehicle collision, there is an urgent need to introduce an air bag device for protecting a driver or a driver sitting in a front seat from an impact at the time of a collision.

For example, in an airbag device on the driver's seat side, an airbag is embedded in a central portion of a steering wheel of a vehicle, and an impact sensor that closes a contact when a vehicle receives an impact exceeding a certain limit due to a collision is a deployment signal. The air bag is explosively deployed by applying an operating current to a detonating element called a squib, and the deployed air bag intervenes between the steering wheel and the driver to perform a cushioning function.

However, this type of conventional airbag apparatus uses an impact sensor that mechanically closes a contact point in response to an impact force. There is a high risk that the impact sensor will malfunction due to the impact received when the vehicle rides on the curb, and furthermore, in the case where the electric pole sinks into part of the car body when the vehicle collides with the electric pole, etc. The impact sensor may not operate due to the relatively slow collision, and the reliability of the operation of the impact sensor is low.

[0005] Therefore, in order to more reliably determine the impact,
For example, as in the vehicle impact determination apparatus 1 shown in FIG. 6, an apparatus has been proposed in which the output of the acceleration sensor 2 attached to the vehicle is integrated over time and a collision is determined when the integrated value exceeds a safety limit.

The vehicle collision judging device 1 shown in FIG. 1 sends an acceleration signal detected by an acceleration sensor 2 to an amplifier circuit 4 via a high-pass filter circuit 3, and an acceleration signal G ( After t) is limited in amplitude by the limiter circuit 5, the signal is supplied to the offset integrator 6 for offset integration.

The offset integrator 6 uses the maximum value of the acceleration signal generated during normal running as the offset Gs.
For the value obtained by subtracting the offset Gs from the acceleration signal G (t)

## EQU1 ## Time integration of [G (t) -Gs] dt is performed.

The integrated output of the offset integrator 6 is supplied to a comparator 7
Is compared with a threshold value Er. When the integrated output exceeds the threshold value, it is determined that a collision has occurred, and a deployment signal is output for airbag.

[0009]

The conventional vehicle collision judging device 1 has a configuration in which the offset integrator 6 integrates the acceleration signal G (t) with time, so that it takes time until the integration result is obtained. For this reason, there is a problem that the deployment signal is easily delayed when it is necessary to determine a collision instantaneously.

If the vehicle is running at medium speed or high speed, the time required to deploy the airbag is 30 ms.
In order to ideally design the deployed airbag to receive the occupant when the occupant who leans forward due to the impact of the collision and leans forward by 12.5 cm, it is necessary to actually perform the collision. The period of delay from the occurrence of the collision to the decision of the collision is limited to a very short time, and the deployment of the airbag is not in time due to the delay of the collision decision, and a satisfactory buffer effect cannot be obtained. There were cases.

The speed change amount obtained from the offset integrator 6 is useful for judging a collision in a case where the speed change is remarkable before and after the collision. However, the speed change amount is relatively slow, for example, when the vehicle collides with a utility pole. In some cases, it is not unusual to be able to distinguish it from running on rough roads, so the airbag does not work at the time of a power pole collision, but the airbag works when running on a bad road such as a mountain road. ,
There were problems such as lack of accuracy in collision determination.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and comprises an acceleration sensor for detecting acceleration applied to a vehicle, and a section speed integration amount calculated by integrating the output of the acceleration sensor. Speed change amount calculating means, a vehicle speed, a vehicle speed at the time of a vehicle collision based on an output of the acceleration sensor ;
Band filtering means for extracting a unique frequency generated depending on the structure ; impact force calculating means for calculating an impact force by squaring the output of the band filtering means; output of the impact force calculating means and the speed change Means for weighting the output of the amount calculation means, and the speed change amount calculation means after weighting .
A first comparator for comparing the output with a preset threshold
And the output of the impact force calculating means after the weighting is applied.
Second comparing means for comparing with a set threshold value;
Multiplied by the output of the speed change amount calculating means and the weight
Adding means for adding the output of the impact force calculating means after multiplication
And comparing the output of the adding means with a preset threshold.
Third comparing means, the first comparing means, and the second comparing means.
Means for determining a logical sum of the outputs of the means and the third comparing means to determine a collision.

[0013]

According to the present invention, while the acceleration applied to the vehicle is integrated over the interval to calculate the interval speed change amount, the fixed speed generated at the time of the collision of the vehicle included in the acceleration depends on the vehicle speed and the vehicle structure.
Calculate the impact force by extracting the existing frequency and squaring it,
Weighting the section speed change amount and the impact force respectively,
Section speed change amount, impact force and weight after this weight is multiplied
And the added value of the impact force
Compare with each set threshold value
And, by performing the collision determination based on the logical sum of these three comparison result, the plastic collision may hurt the occupant when the vehicle collides, comprehensively judges the collision together impact force and speed variation, A high-speed and high-precision collision determination is performed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a circuit diagram showing an embodiment of a vehicle collision judging device according to the present invention, and FIG.
FIG. 3, FIG. 4, FIG. 5 are signal waveform diagrams of respective parts of the circuit shown in FIG. 1 at the time of a frontal collision, at the time of a cushion drum collision, and at the time of traveling on a rough road, respectively. FIG. 7 is a circuit configuration diagram of the bandpass filter shown in FIG. 1, FIG. 8 is a flowchart for calculating an impact force, and FIG.
10 is a flowchart for calculating the speed change amount, and FIG.
Is a flowchart for making a collision determination.

The vehicle collision judging device 11 shown in FIG. 1 converts the acceleration signal obtained by the acceleration sensor 12 into digital data by AD conversion, and performs any processing as discrete value data.

The acceleration sensor 12 uses a semiconductor acceleration in which a stress-strain gauge is formed on a semiconductor substrate. A stress-strain gauge that utilizes the fact that the piezoresistance of a semiconductor changes when it is distorted under stress is used as a vehicle. The pressure receiving surface is oriented in the direction of travel.

Before the output of the acceleration sensor 12 is converted into discrete value data, the acceleration signal is first band-limited in a low-pass filter circuit 13 for eliminating the influence of aliasing, and then synchronized with a sampling clock. The data is supplied to an AD converter 15 via an open / close switch 14 that operates, and is converted into digital data with a predetermined quantization bit.

The acceleration data G (k) obtained from the AD converter 15 is simultaneously and concurrently subjected to section integration and impact force calculation.

First, the interval integration is performed by the interval integrator 16 of the interval accumulation type, and the discrete acceleration data G is obtained.
(K) is a predetermined section according to the sampling clock,
This is performed by adding.

That is, the speed change amount ΔV (k) obtained by the interval integration is

[0021]

(Equation 2)

The predetermined interval t ₂ -t ₁ is predetermined, and the past signal is discarded every time a new acceleration signal is input. This is shown in the flowchart of FIG.

On the other hand, the calculation of the impact force is performed by first using the bandpass filtering circuit 1.
In FIG. 7, a band component affecting the human body included in the acceleration data is drawn, and the square operation unit 18 performs a square operation.

That is, it can be seen that the band component of the acceleration data which affects the human body shows a frequency distribution peculiar to each vehicle type, but shows a large change according to the severity of the collision, that is, the magnitude of the impact. Therefore, by focusing on these band components, it is possible to detect an impact force that cannot be understood only by tracking the speed change amount. FIG. 7 shows a specific circuit configuration of the bandpass filter. Here, the acceleration data G (k) converted into the discrete value data is cascade-delayed by four delayers 17a for delaying the signal by one sample period, and each delay output is sent to coefficient units 17e to 17b. And multiplied by the coefficients of E, -D, C, and -B, and fed back, and added to the input acceleration data G (k) by the adder 17f.
Further, the second-stage delayed output obtained by multiplying the fourth-stage delayed output by -2 by the coefficient unit 17g is added together with the output of the adder 17f by the adder 17h, and finally, the output of the adder 17h is added to the coefficient unit 17i. And output K times. Therefore, the z-transform transfer characteristic H (z) of the bandpass filter 17 is:

(Equation 3) It is represented by

Further, since the square computing unit 18 squares the above-mentioned band component which changes in the positive and negative directions, the magnitude of the impact force can be accurately grasped regardless of the positive or negative of the acceleration. In the means 20, it is possible to determine that the collision requires the operation of the airbag, in distinction from an impact or the like caused by running on a rough road or riding on a curb. FIG. 8 shows a flowchart for calculating the impact force △ E (k).

The section integral output and the impact force calculation output are each weighted and supplied to the judging means 20, where they are subjected to collision judgment according to the collision judgment map shown in FIG.

The judging means 20 shown in the embodiment employs an impact force △
A collision determination is performed on a plane having two axes of E (k) and a speed change amount ΔV (k), with a determination curve defining a collision area and a non-collision area as a boundary.

That is, the judgment means 20 determines that the impact force ΔE
(K) and the speed change amount ΔV (k) as a parameter (parameter
First)

(Equation 4) Arithmetic operation, and the operation result is

(Equation 5) If the following relationship is satisfied, a collision is determined, and the entire circuit is composed of arithmetic operation means.

In the equation, K ₁ and K ₂ are speed change amounts ΔV.
(K) is a weighting coefficient on a collision determination map having two axes of impact force （E (k), and K ₃ is a constant. K ₁ , K ₂ ,
K ₃ is to take a unique value for vehicle type can be determined empirically optimal value by repeating the actual crash test for each vehicle type.

The collision determination map shown in FIG. 2 includes, in addition to a frontal collision at a medium speed and a frontal collision at a high speed, a collision with a cushion drum made of a can-shaped body having a cushioning function, a telephone pole, a pole, and the like. For each case such as a collision with a pole, the region where the impact force △ E (k) and the speed change amount △ V (k) have the deepest correlation is indicated by a dotted line.

In the area inside the judgment curve, the judgment means 20 judges that there is no collision, such as under-carriage or running on a rough road, which indicates a normal driving or a collision without danger of only the chassis portion of the vehicle body. In this case, the regions where the correlation between the impact force △ E (k) and the speed change amount △ V (k) are deepest are each surrounded by a dotted line.

These classification patterns are created on the basis of data obtained during an actual collision test using a vehicle, and include an impact force △ E (k) and a speed change amount △ V
If (k) is known, it indicates that collision and non-collision can be clearly distinguished according to the determination curve.

In fact, for example, in the case of a frontal collision at a speed of about 50 km / h, as shown in FIG.
Both (k) and the speed change amount ΔV (k) show a change exceeding a certain limit at an early stage, so that a collision judgment can be made from a comprehensive judgment.

Therefore, the airbag can be deployed at an early stage of the collision, and the occupant can be protected safely.

When the vehicle hits the cushion drum at a speed of about 30 km / h, as shown in FIG.
Although E (k) itself is small, the airbag can be deployed when the speed change amount ΔV (k) exceeds a certain level.

Therefore, in the collision with the cushion drum,
It can be seen that the speed change amount ΔV (k) occupies the dominant factor in the collision determination.

Further, when the vehicle is traveling on a rough road where it has been difficult to discriminate the vehicle from a pole collision, as shown in FIG. 5, the impact force ΔE (k) suddenly reaches a certain level. However, since the speed change amount ΔV (k) does not reach the specified level, the collision is not erroneously determined. FIG. 10 is a flowchart for judging a collision when the judging means 20 performs a process using software, and the weighting factor K1 is added to the speed change amount ΔV (k).
Used and multiplied by (901), multiplied by the weighting coefficient K ₂ to the impact force △ E (k) to (902), speed variation △ V
If (k) exceeds a certain value (903), the impact force ΔE
(K) exceeds a certain value (904), and K ₁ △
When V (k) + K ₂ ΔE (k) exceeds a certain value (9
05) shows that a development signal is output.

As described above, according to the vehicle collision judging device 11, the front part of the vehicle is regarded as a plastic spring in which a myriad of spring bodies are combined, so that the acceleration signal in the process of stopping the vehicle due to the collision is determined. By extracting specific band components that are remarkable at the time of collision and affect the human body from various vibration waveforms generated by countless spring bodies superimposed on sine waves, the impact force that cannot be understood only by tracking the speed change amount is obtained. It can be detected, thereby distinguishing from impacts caused by running on a rough road or climbing a curb, etc., together with the amount of speed change, by comprehensively determining whether or not the collision requires the operation of the airbag, High-speed and high-precision collision determination is possible.

The impact force ΔE (k) and the speed change ΔV
When (k) is given, these are functionally calculated, and the collision can be determined based on which side of the inside or outside of the curve demarcating the collision area and the non-collision area, and the result of the operation is determined by the type of vehicle. Even if the judgment curves are different, it can be dealt with simply by replacing the function, so that it has excellent versatility.

[0040]

As described above, according to the present invention, the section speed is integrated by calculating the section speed change amount by integrating the acceleration applied to the vehicle.
The impact force is calculated by extracting and squaring a specific frequency generated depending on the body structure, and calculating the above-mentioned section speed change amount and impact force.
Weight is applied to each impact, and the section after this weight is applied
Section speed change after multiplying speed change amount, impact force and weight
Addition amount and impact force, and set for each of these
With the thresholds obtained, and these three comparison results
The collision judgment is made based on the logical sum of the vehicle speed. Therefore, it is possible to detect the impact force that cannot be understood only by tracking the speed change amount, and therefore, the vehicle speed that appears in both positive and negative directions
A collision that requires the operation of a safety device, distinguishing it from the impact force obtained by squaring the inherent frequency generated depending on the vehicle body structure from the impact caused by running on a rough road or climbing a curb, etc. High-speed and high-precision collision judgment is possible by making a judgment and comprehensively judging the collision together with the speed change amount. A collision judgment device suitable for a single point sensor system using a single sensor in the vehicle interior for collision detection. And so on.

Further, the present invention provides an acceleration sensor
By using a semiconductor acceleration sensor with a stress-strain gauge formed on a semiconductor substrate, a stress-strain gauge that utilizes the fact that the piezoresistance of a semiconductor changes when it is distorted under stress is applied to the pressure-receiving surface in the traveling direction of the vehicle. By incorporating the sensor in a small size, acceleration can be detected with a sufficient dynamic range even if it is small. Particularly in the case of a diffusion type sensor in which a semiconductor substrate and a stress strain gauge are integrated, a highly accurate one can be obtained at low cost. Therefore, there is an effect that the overall manufacturing cost can be reduced.

The speed change amount calculating means includes an acceleration
The output of the sensor is set to a preset value up to the current value.
By using a section integrator that integrates between factors, factors such as vibration received from a bad road during normal driving or a speed change received when a vehicle gets on a curb may easily cause collision judgment to be out of order. In addition, there is an effect that accumulation does not occur due to section integration.

Further, as the band filtering means, a band component showing a remarkable change peculiar to the collision, including a frequency band harmful to the human body, is drawn out of an acceleration vibration waveform at the front portion of the vehicle which plastically deforms during the collision, It has the effect of being able to be effectively used for collision determination as a measure of impact force.

Further, by using, as the impact force calculating means, a square calculator for calculating the square of the acceleration data converted into a discrete value by AD conversion, a reliable and accurate square calculation using a digital multiplier can be performed. There are effects such as being effective in determining an impact force requiring high-speed calculation.

Furthermore, by using an arithmetic operation means for making a collision judgment on a plane which defines the collision area and the non-collision area on a plane having two axes of the impact force and the speed change amount, the collision operation is performed. When the force and the speed change amount are given, these are arithmetically operated, and it is possible to determine the collision based on which side of the curve that divides the collision area and the non-collision area exists inside or outside the curve. In particular, even if the determination curve differs depending on the type of vehicle or the like, it can be dealt with only by replacing the function, so that there is an effect such as excellent versatility.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a vehicle collision determination device according to the present invention.

FIG. 2 is a diagram illustrating a collision determination map used for a determination unit illustrated in FIG. 1;

3 is a signal waveform diagram of each section of the circuit shown in FIG. 1 at the time of a frontal collision.

4 is a signal waveform diagram of each part of the circuit shown in FIG. 1 at the time of collision with a cushion drum.

FIG. 5 is a signal waveform diagram of each section of the circuit shown in FIG. 1 when traveling on a rough road.

FIG. 6 is a circuit diagram illustrating an example of a conventional vehicle collision determination device.

FIG. 7 is a circuit configuration diagram of the bandpass filter shown in FIG. 1;

FIG. 8 is a flowchart for calculating an impact force.

FIG. 9 is a flowchart for calculating a speed change amount.

FIG. 10 is a flowchart in the case where a determination unit makes a collision determination.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Vehicle collision determination apparatus 12 Acceleration sensor 13 Aliasing means (low-pass filtering circuit) 14 On / off switch (sampling circuit) 15 AD converter 16 Integrating means (section integrator) 17 Band filtering means (band filtering circuit) 18 Impact force calculation Means (square operation unit) 191 Weight coefficient 192 Weight coefficient 20 Judgment means

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B60R 21/32 B60R 21/16 G01P 15/00

Claims (6)

(57) [Claims] 1. An acceleration sensor for detecting an acceleration applied to a vehicle, a speed change amount calculating means for calculating an interval speed change amount by integrating an output of the acceleration sensor in a zone, and a speed change amount calculating unit for calculating a section speed change amount based on an output of the acceleration sensor. Body speed, body structure
Band filtering means for extracting a unique frequency generated dependently, shock force calculating means for calculating an impact force by squaring the output of the band filtering means, output of the shock force calculating means and calculation of the speed change amount Means for weighting the output of the means, and the output of the speed change amount calculating means after the weighting.
First comparing means for comparing with a preset threshold value,
Preset the output of the impact force calculating means after weighting
Second comparing means for comparing the weight with the threshold value,
Multiplied by the output of the speed change amount calculating means after the
Adding means for adding the output of the subsequent impact force calculating means;
Comparing the output of the adding means with a preset threshold value;
Comparing means, the first comparing means, the second comparing means and
Determining means for determining a collision by taking a logical sum of outputs of the third and third comparing means . 2. The vehicle collision judging device according to claim 1, wherein the acceleration sensor is a semiconductor acceleration sensor having a stress-strain gauge formed on a semiconductor substrate. Wherein the speed change amount calculation means, the acceleration
The output of the sensor is set to a preset value up to the current value.
The apparatus according to claim 1, wherein the apparatus is a section integrator that integrates between them . 4. The vehicle collision judging device according to claim 1, wherein said band filtering means is a band filtering circuit having a filtering center in a frequency band determined by a vehicle body. 5. The collision judging device for a vehicle according to claim 1, wherein said impact force calculating means is a square calculator for calculating a square of acceleration data which has been digitized by AD conversion. 6. The arithmetic operation means for judging a collision with a collision curve defining a collision area and a non-collision area as a boundary on a plane having two axes of an impact force and a speed change amount. The vehicle collision determination device according to claim 1, wherein: