JPH06242137A - Physical quantity detecting method and its device - Google Patents

Abstract

PURPOSE:To predict a speed and a displacement quantity after the predetermined time by estimating acceleration applied to the object to be measured and its differential value on the basis of a detected acceleration signal in an integral element and estimating a physical quantity such as the acceleration, the speed, the displacement quantity, and the like at a real time. CONSTITUTION:An acceleration sensor 1 detects acceleration generated in a driver in a vehicle collision and outputs corresponding acceleration signal am(t). The first estimating means 2 estimates an acceleration signal a(t), in which noise and the like are not superimposed, on the basis of the inputted signal am(t) so as to output it with a differential value f(t) shown by a form in which the signal a(t) is differentiated one time per a time. The second estimating means 3, in which a signal a(t) is inputted, estimates displacement quantity of a driver's head toward the frontX(t), a speed V(t) and outputs them. An action predicting means 4 inputs the signal act) and the differential value f(t) from the first estimating means 2 and an estimating speed signal V(t) and estimate displacement quantity signal X(t) from the second estimating means 3, and calculates a prediction speed V(t+t1) and a prediction displacement quantityX(t+t1) so as to output them.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a physical quantity detection method and apparatus used for estimating or predicting a change in a physical quantity such as a displacement of an occupant's upper body (typically represented by a head) during a collision. Regarding

[0002]

2. Description of the Related Art For many years, I have been researching and developing technologies for measuring physical quantities related to plants and vehicles. Among them, in the field of vehicles, I have been conducting research and development related to vehicle occupant protection devices such as airbags. ing. The feature of the research and development is to predict the amount of displacement of the head etc. located at the uppermost part of the upper body of the occupant at the time of a collision, and to operate the airbag etc. in a timely manner based on the magnitude of the predicted displacement value. Yes, many inventions have been made in the past regarding this technology.

[0003]

However, in the method of predicting the displacement amount of the head or the like in the vehicle occupant protection device as described above, the head or the like is pushed forward in accordance with the inertial force in the event of a collision. We paid attention only to the displacement, and did not consider anything about the action of the seat belt or the like in the event of a collision.

For this reason, the collision determination algorithm as a vehicle occupant protection device was theoretically completed in some respects, but for me, it is still under development and is sufficiently satisfactory. It was not a problem, but left a weakness, if not a problem in optimality.

The present invention has been made in order to eliminate the weak points left in the course of development as described above, and a first object thereof is to apply an estimating means such as a Kalman filter to accelerate, speed, This is to estimate physical quantities such as displacement in real time or to predict displacement. A second object is to propose a device such as a vehicle occupant protection device in which the estimated or predicted physical quantity is added.

[0006]

To this end, the first physical quantity detecting method according to the present invention is applied to the object to be measured and is applied to the object to be measured based on the acceleration signal detected by the sensor. The acceleration or its differential value is estimated by using at least an integral element.

The second physical quantity detection device estimates the actual acceleration applied to the object to be measured based on the acceleration signal applied to the object to be measured and detected by the sensor.
The estimation means and the second estimation means for estimating at least the speed of the object to be measured based on the estimation output from the first estimation means.

The third physical quantity detecting device estimates the actual acceleration applied to the measured object based on the detected value of the acceleration signal applied to the measured object and detected by the sensor. And means for estimating at least the displacement amount of the object to be measured based on the estimated output from the first estimating means.

The fourth physical quantity detection device estimates the actual acceleration applied to the object to be measured based on the detected value of the acceleration signal applied to the object to be measured and detected by the sensor. Means, a second estimating means for estimating at least the speed of the object to be measured based on the estimated output from the first estimating means, and the acceleration signal based on the estimated outputs from the first and second estimating means. And a predicting means for predicting the speed of the object to be measured after a predetermined time from the occurrence timing of.

The fifth physical quantity detection device estimates the actual acceleration applied to the object to be measured based on the acceleration signal applied to the object to be measured and detected by the sensor.
The acceleration based on the estimation means, the second estimation means for estimating at least the velocity of the object to be measured based on the estimation output from the first estimation means, and the estimation outputs from the first and second estimation means. And a predicting means for predicting a displacement amount of the object to be measured after a predetermined time from the signal generation timing.

The sixth physical quantity detection device estimates the actual acceleration applied to the object to be measured and its differential value based on the detected value of the acceleration signal detected by the sensor. The first estimating means, the second estimating means for estimating the velocity and the amount of displacement of the object to be measured based on the estimated output from the first estimating means, and the estimated output from the first and second estimating means. And a predicting unit for predicting a displacement amount of the measured object after a predetermined time from the generation timing of the acceleration signal.

The seventh physical quantity detecting device estimates the actual acceleration applied to the object to be measured and its differential value based on the detected value of the acceleration signal detected by the sensor. Based on the estimated outputs from the first and second estimating means, and the second estimating means for estimating at least the velocity of the object to be measured based on the estimated output from the first estimating means. And a predicting means for predicting the speed of the object to be measured after a predetermined time from the generation timing of the acceleration signal.

The eighth physical quantity detection device calculates the amount of movement of a part of the occupant's body by simulating a physical phenomenon at the time of vehicle collision as a mass system consisting of mass, springs and dampers.

The ninth physical quantity detection method is to predict the displacement amount and speed of a part of the body of an occupant after a predetermined time at the time of a vehicle collision based on the acceleration acting on the occupant.

[0015]

According to the method of the present invention, physical quantities such as acceleration, speed and displacement can be easily estimated in real time, and physical quantities such as speed and displacement after a predetermined time can be easily predicted. it can.

Further, according to the device of the present invention, a signal indicating a physical quantity such as acceleration and velocity without noise can be extracted in real time from a signal with a lot of noise generated at the time of collision with a simple circuit configuration. You can Further, by using these physical quantities, it is possible to easily obtain an unprecedented device such as a vehicle occupant protection device.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, as is clear from the drawings, the outline of an embodiment according to the present invention is the actual acceleration excluding noise from the acceleration signal measured by a sensor, its differential value,
One for estimating physical quantities such as speed and displacement and predicting the quantity of displacement and speed after a predetermined time, and one of the specific examples made by using those physical quantities,
That is, the vehicle occupant protection device is disclosed.

The constants and variables in the following formulas used in this embodiment are defined in advance. That is, t: time tf: airbag deployment delay time a (t): actual acceleration, which is the absolute acceleration that acts on the mass point derived when the upper body of the driver is regarded as one mass point system and considered together. (t): Differential value of a (t) am (t): Accelerometer output V (t): Mass point when the upper body of the driver is regarded as one mass point system (head is considered to be representative) at the time of collision Relative speed with respect to the vehicle body thrown forward V0: Absolute speed of vehicle immediately before collision X (t): When considering the upper body of the driver as one mass system,
Relative displacement with respect to the vehicle body in which the mass point is thrown forward in a collision na (t): Measurement noise superimposed on the output of the acceleration sensor Ra: Variance of measurement noise na (t) W1 (t): Time of absolute acceleration a (t) Random noise of differential value (system noise) W2 (t): Random noise of absolute acceleration a (t) (system noise) Q1: Variance value of system noise W1 (t) Q2: Variance value of system noise W2 (t) m : Mass of upper body of driver moving at the time of collision d: Damping coefficient of body movement of driver k: Elastic coefficient of seat belt when seat belt is tightened,
Or driver reaction characteristics L1: Distance from bumper to front frame L2: Distance from front frame to engine L3: Displacement of engine due to collision

The embodiment described here is premised on modeling and handling a vehicle collision phenomenon as follows, which will be described with reference to FIGS. 1 to 4. That is, in FIGS. 1 and 3, 100 is the velocity V immediately before the collision is V0.
A vehicle whose velocity V is 0 due to a collision, 101 is a road surface, 102 is a driver's head, 103 is a driver's legs, 104 is a steering wheel, 105 is an engine body, 106
Is a front frame that supports the engine body 105, and 107 is a front object with which the vehicle 100 collides.

In such a structure, when the state shown in FIG. 1 changes to the state shown in FIG. 3 due to a collision, that is, when the vehicle 100 collides with the front object 107 at a speed V0 and stops, the bumper first located at the tip of the vehicle. From then on, the collision starts, and gradually the portion up to the below-mentioned front frame 106 (the portion indicated by L3 in FIG. 1), which is the soft structure portion of the vehicle tip portion, is destroyed.

Next, the engine body 105 is supported and L
Front frame 1 that is stiffer than the part indicated by 3
The portion 06 (the portion indicated by L2 in FIG. 1) is destroyed. A portion of the engine main body 105 that is further structurally structured (a portion indicated by L1 in FIG. 1)
Will be destroyed or displaced backwards.

At this time, by thinking that the upper half of the body of the driver who fastens the seat belt is thrown forward against the elasticity of the seat belt, the arm holding the steering wheel, the slack of the leg, etc. The physical model shown in 4) is constructed. That is, this physical model is considered to form one mass system consisting of a mass, a spring, and a damper, and the mass 110 portion of the driver's upper body pushed forward is represented by the driver's head 102. Think Therefore, it is considered that the elasticity of the seat belt and the swelling of the arms and legs act as the spring 109 and the damper 108 with respect to the force of displacement of the mass 110.

FIG. 2 of this physical model shows immediately before a collision, in which no acceleration acts on the driver's head 102, and
02 is stationary with respect to the vehicle body 100. However, in the diagram shown in FIG. 4, since the acceleration due to the collision acts on the driver's head 102, the acceleration a (t), the speed V (t), and the displacement amount X (t) corresponding to the magnitude of the collision are generated. To do.

Now, an embodiment of the present invention will be described in detail with reference to FIG. Reference numeral 1 is a semiconductor acceleration sensor that detects an acceleration generated in an occupant such as a driver due to a vehicle collision and outputs an analog acceleration signal am (t) corresponding to the detected acceleration. The state equation of the acceleration sensor is as follows. Shown in.

[0025]

[Equation 1]

[0026]

[Equation 2]

The coefficients and variables of the equation of state are shown in the following matrix.

[0028]

[Equation 3]

Reference numeral 2 denotes a measured acceleration signal am (t) output from the acceleration sensor 1 (high-frequency noise, low-frequency noise, measurement noise na (t) in a broad sense such as offset is superimposed). The first estimating means for input estimates and extracts the acceleration signal a (t) in which noise or the like is not superposed based on the input acceleration signal am (t), and outputs it from the output terminal 2b. Output. The actual acceleration signal a (t) acts as a force for pushing the upper half of the occupant such as a driver forward.

Further, the first estimating means 2 outputs from the output terminal 2a a differential value f (t) shown in a form in which the estimated acceleration signal a (t) is differentiated once with respect to time. The first estimating means 2 is composed of a Kalman filter here, and its input signal am (t) and output signal a
The relational expression showing the relation with (t) and f (t) is

[0031]

[Equation 4]

The coefficients and variables in the relational expression are shown as follows.

[0033]

[Equation 5] Also, the coefficient of the equation shown in Equation 4 is

[0034]

[Equation 6] It is represented by the matrix shown in.

Reference numeral 3 is a second estimating means, which is the first estimating means 2.
By inputting the acceleration a (t) estimated by the above, the amount of forward displacement X (t) and the velocity V (t) located at the upper end of the driver's upper body and represented by the mass point in the physical model are represented. ),
It is estimated by the following Equation 7 and output.

[0036]

[Equation 7]

The coefficients and variables in the equation shown in Equation 7 are

[0038]

[Equation 8] Shown in.

Further, in the above Equation 7, while the driver is pushed forward at the time of a collision, the upper half of the body is complicated due to the complicated relations such as the stretching force of the seat belt, the muscular force of the arm gripping the steering wheel, and the tense force of the foot. It is considered that the restoring force that tries to return the vehicle to the state just before the collision occurs. That is,
In Equation 7, the natural angular frequency ω of the vibration (vibration that moves the body back and forth) generated by these relationships and the damping coefficient ζ related to the force that pushes the upper half of the driver forward are considered, and Is defined as.

[0040]

[Equation 9]

The force related to the damping coefficient ζ is a physical quantity related to the elasticity of the seat belt in the lengthwise direction, the strength of the muscular force of the arm holding the steering wheel, the tension of the foot, and the like.

Reference numeral 4 is a motion predicting means, which is the first estimating means 2
The actual acceleration signal a (t) and the differential value f (t) of the actual acceleration signal a (t), the estimated speed signal V (t) and the estimated displacement amount signal X (t from the second estimating means 3 are estimated. ), The estimated velocity V (t), the predicted velocity V (t + t1) and the predicted displacement X (t + t1) after t1 hours of the displacement X (t) are input.

[0043]

[Equation 10]

[0044]

[Equation 11]

The predicted speed V (t + t1) is calculated from the output terminal 4a, and the predicted displacement X (t + t1) is calculated from the output terminal 4a.
Output from b.

[0046]

[Equation 12]

[0047]

[Equation 13]

[0048]

[Equation 14]

[0049]

[Equation 15]

[0050]

[Equation 16]

[0051]

[Equation 17]

[0052]

[Equation 18]

[0053]

[Formula 19]

[0054]

[Equation 20]

Reference numeral 5 denotes a judging circuit, which is the acceleration signal a (t) from the first estimating circuit 2 and its differential value f (t), and the predicted velocity V (t + t1) and predicted displacement from the motion predicting means 4. Quantity X (t + t
Enter 1) and determine whether to activate the vehicle occupant protection device such as an airbag based on the relative magnitude relationship between them and the comparison result of those values with the reference value. Then, when it is determined that it should be operated, a high level drive signal A is output from the output terminal. The judgment standard in the judgment circuit 5 is experimentally obtained.

Next, the first estimating means 2, the second estimating means 3 and the motion predicting means 4 having the outline described above will be described with reference to FIG.

First, the first estimating means 2 will be described. That is, the first and second coefficient circuits 21 and 22 are connected in parallel to the output terminals of the acceleration sensor 1, and the acceleration signal am (t) is input from the acceleration sensor 1 to the first coefficient circuit. 21 multiplies the coefficient k1 in Equation 6,
Further, the second coefficient circuit 22 similarly multiplies the coefficient k2 in the equation (6). The output signal from the first coefficient circuit 21 is
The output signal supplied to the first subtraction circuit 23 outputs a value obtained by subtracting the output signal from the fourth coefficient circuit 29 described later. The subtracted value is supplied to the first integration circuit 24, integrated, and output as a differential value f (t) of the actual acceleration signal a (t) output from the second integration circuit 27 described later.

The integrated output f (t) output from the first integrating circuit 24 is supplied to the second subtracting circuit 25, and the second subtracting circuit 25
The output signal from the coefficient circuit 22 is subtracted, and the subtracted value is supplied to the third subtraction circuit 26. Third
The subtraction circuit 26 subtracts the signal supplied from the third coefficient circuit 28 described later from the signal supplied from the second subtraction circuit 25, and outputs the subtracted value.

The value output from the third subtraction circuit 26 is integrated by the second integration circuit 27 in the next stage, and the acceleration signal am (t) measured by the acceleration sensor 1 (that is, noise is superimposed). The actual acceleration signal a (t) with no noise is estimated and output.

The estimated actual acceleration signal a (t) output from the second integrating circuit 27 is supplied to the third coefficient circuit 28, and its value a (t) is set to the predetermined value in the equation (6). It is multiplied by a coefficient k2 and supplied to the third subtraction circuit 26. The output signal a (t) of the second integration circuit 27 is also supplied to the fourth coefficient circuit 29, multiplied by the predetermined coefficient k1 in the equation 6, and the result is supplied to the first subtraction circuit 23. .

Next, the second estimating circuit (3) will be described in detail. That is, the final output stage 27 of the first estimation circuit 2
The actual acceleration signal a (t) output from the fourth subtraction circuit 31
The value output from the sixth coefficient circuit 36 described later is subtracted from the input actual acceleration signal a (t), and the subtraction result is supplied to the fifth subtraction circuit 32.

The fifth subtraction circuit 32 is the fourth subtraction circuit 3
A value obtained by subtracting the signal supplied from the later-described fifth coefficient circuit 35 from the value supplied from 1 is output, and the output is integrated by the third integrating circuit 33 and output as the estimated speed signal V (t). While being output from the terminal 3a, the estimated speed signal V (t) is also supplied to the fifth coefficient circuit 35, and the value is multiplied by a predetermined coefficient 2ζω in Equation 9 and output. Also, the estimated speed signal V (t) which is the integrated output
Is supplied to the fourth integration circuit 34, and the estimated displacement amount signal X
It is calculated as (t), is output from the output terminal 3b, is supplied to the sixth coefficient circuit 36, is multiplied by the predetermined coefficient ω ² in the equation 9, and is output.

The signal output from the third integrating circuit 33 is input and integrated, and the integrated value is output as the estimated displacement signal X (t). Reference numeral 35 is a fifth coefficient circuit, which is the third integration circuit 3
The estimated speed signal V (t) output from 3 is multiplied by a predetermined coefficient and supplied to the fifth subtraction circuit 32. Reference numeral 36 denotes a sixth coefficient circuit, which is an estimated displacement signal X output from the fourth integration circuit 34.
Multiply (t) by a specified value and output.

[0064]

As described above, according to the present invention, physical quantities such as acceleration, speed, and displacement are easily estimated, and physical quantities such as speed and displacement after a predetermined time are easily predicted. The effect of being able to do is exhibited.

Further, with a simple circuit configuration, it is possible to extract a signal indicating a physical quantity such as acceleration and velocity without noise from a signal with a lot of noise generated at the time of collision. Further, by using these physical quantities, a special effect that the vehicle occupant protection device can be easily obtained is exhibited.

[Brief description of drawings]

FIG. 1 is an explanatory diagram before a vehicle collision.

FIG. 2 is a physical model of the explanatory view shown in FIG.

FIG. 3 is an explanatory diagram after a vehicle collision.

4 is a physical model of the explanatory diagram shown in FIG.

FIG. 5 is a circuit block diagram for explaining an embodiment according to the present invention.

FIG. 6 is an explanatory diagram showing the circuit block shown in FIG. 5 as a more detailed circuit block.

[Explanation of symbols]

 1 Acceleration sensor 2 1st estimation circuit 3 2nd estimation circuit 4 Prediction circuit 5 Judgment circuit

Claims (9)

[Claims] 1. Estimating an actual acceleration applied to an object to be measured and based on an acceleration signal detected by a sensor, or a differential value thereof, at least by using an integral element. Characteristic physical quantity detection method. 2. A first estimating means for estimating an actual acceleration applied to the object to be measured and based on an acceleration signal detected by a sensor, and an estimation from the first estimating means. A physical quantity detection device comprising: a second estimation means for estimating at least the speed of the object to be measured based on the output. 3. A first estimating means for estimating an actual acceleration applied to an object to be measured based on a detected value of an acceleration signal applied to the object to be measured and detected by a sensor, and the first estimating means. A physical quantity detection device comprising: at least second estimation means for estimating a displacement amount of the object to be measured based on an estimation output from the estimation means. 4. A first estimating means for estimating an actual acceleration applied to an object to be measured based on a detected value of an acceleration signal applied to the object to be measured and detected by a sensor, and the first estimating means. Based on the estimated output from the estimating means, at least the second estimating means for estimating the speed of the object to be measured, and based on the estimated outputs from the first and second estimating means, a predetermined timing from the generation timing of the acceleration signal. A physical quantity detection device comprising: a prediction unit that predicts the speed of the measured object after a lapse of time. 5. A first estimating means for estimating an actual acceleration applied to an object to be measured based on an acceleration signal detected by a sensor, and an estimation from the first estimating means. Second estimation means for estimating at least the velocity of the object to be measured based on the output, and the measured object after a predetermined time from the generation timing of the acceleration signal based on the estimated outputs from the first and second estimating means. A physical quantity detection device comprising: a prediction unit that predicts a displacement amount of an object. 6. A first estimating means for estimating an actual acceleration applied to the object to be measured and a differential value thereof based on a detected value of an acceleration signal detected by a sensor. , Second estimating means for estimating the velocity and displacement amount of the object to be measured based on the estimated output from the first estimating means, and the acceleration signal based on the estimated outputs from the first and second estimating means And a predicting means for predicting a displacement amount of the object to be measured after a predetermined time from the occurrence timing of the physical quantity detecting device. 7. A first estimating means for estimating the actual acceleration applied to the object to be measured and its differential value based on the detected value of the acceleration signal detected by the sensor. , At least second estimating means for estimating the velocity of the object to be measured based on the estimated output from the first estimating means, and generation of the acceleration signal based on the estimated outputs from the first and second estimating means. A physical quantity detection device comprising: a prediction unit that predicts a speed of the measured object after a predetermined time from a timing. 8. A physical quantity detection device for calculating a movement amount of a part of an occupant's body by simulating a physical phenomenon at the time of a vehicle collision as a mass system composed of a mass, a spring and a damper. 9. A physical quantity detection method, comprising: predicting a displacement amount and a velocity of a part of an occupant's body at a vehicle collision after a predetermined time based on an acceleration acting on the occupant.