JPH03208750A - Method of determining frequency components in vehicle collision - Google Patents

Abstract

PURPOSE: To enhance safety by generating vehicle crashes under the condition that actuation of a passenger restraint system is not required and under the condition that it is required, and by processing frequency components indicating the vehicle crashes under respective conditions to generate a signal for actuating the passenger restraint system. CONSTITUTION: A accelerometer assembly 22 is mounted on a vehicle to generate an electric signal having frequency signal components indicating a type of crashing condition applied to the vehicle. A vehicle of a prescribed class is crashed under the condition (a) that an air bag is not required to be triggered and under the condition (b) that the air bag is required to be triggered, and electric output signals generated in an accelerometer assembly 22 are stored respectively. Frequency domain transform for the stored electric output signals is performed to identify frequency components relating to the respective output signals. The frequency components under the condition (a) are compared with the frequency components under the condition (b) to specify frequency components which are generated under the condition (b) but not generated under the condition (a).

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to actuatable passenger restraint systems for vehicles, and more particularly to a method for determining the frequency components present in a given type of crash of a vehicle. .

PRIOR ART Operable passenger restraint systems for vehicles are well known in the art. One type of operable passenger restraint system includes an inflatable air bag provided within a vehicle. Each airbag in a vehicle has a squib.
An electrically operable igniter called b) is provided. Such a device further includes an inertial sensing device for measuring the deceleration of the vehicle. When the inertial sensing device detects that the vehicle is decelerating at a rate greater than a predetermined value, a current of sufficient magnitude and duration is applied to the squib for a sufficient duration to activate the squib, causing the squib to emit combustion gases. The resulting composition is ignited or a container of pressurized gas is punctured to inflate the air bag.

Many of the known inertial sensing devices used in actuatable passenger restraint systems are mechanical in nature. Such devices are generally mounted to the vehicle frame and include mechanically operable switch contacts and resiliently biased weights. This weight, when the vehicle is decelerated,
It is configured for relative physical movement with respect to its fixture. The greater the degree of deceleration, the more the weight will move against the bias force. A switch contact is provided in association with an angled weight, and when the weight moves a predetermined distance, the weight moves onto or toward the switch contact and presses the contact. It is designed to close the contacts. When the switch contacts close, the squib is connected to a source of electrical energy sufficient to activate the squib.

Other known operable passenger restraint systems include electrical transducers or accelerometers for detecting vehicle deceleration. Such devices have a monitoring or evaluation circuit connected to the output of the transducer.

Such a transducer generates an electrical signal having a value indicative of the rate of deceleration of the vehicle. An evaluation circuit processes the transducer output signal. A typical example of this processing technique is to integrate the transducer output signal. When the output of the integrator exceeds a predetermined value, an electrical switch is actuated to connect electrical energy to the squib. One example of such a device is Brede et al.
, No. 870,894 (hereinafter referred to as the '894 patent).

The '894 patent discloses a device comprising an accelerometer, an evaluation circuit connected to the accelerometer, and an ignition circuit or squib connected to the output of the evaluation circuit. The accelerometer includes a piezoelectric transducer that generates an electrical output signal (deceleration signal) having a value indicative of the deceleration of the vehicle. The evaluation circuit has an integrator that is electrically connected to the output of the accelerometer via an amplifier. The output of the integrator is an electrical signal representing the integral value of the deceleration signal. A trigger circuit is connected to the output of the integrator. When the integrator output reaches a predetermined value, a trigger circuit activates a time delay circuit. The time delay circuit begins timing the passage of a predetermined period of time, and when the predetermined period of time has elapsed, the airbag igniter is energized.

It has been recognized that in all types of vehicle crashes, it is undesirable to inflate a vehicle's airbag. For example, it is undesirable to inflate an airbag during a low-speed "soft crash." What crashes fall into the category of "soft crashes" is determined depending on various factors related to the type of vehicle. For example, if a large vehicle traveling at 12.8 km/h (8 mph) collides with a parked vehicle,
Such a crash would be considered a "soft crash" and would not require airbags to be inflated to protect passengers. In such cases, passenger safety can only be ensured by the vehicle's seat belt. During such a "soft crash," a typical accelerometer will produce an output signal indicating that rapid deceleration is occurring. In an actuatable passenger restraint system made in accordance with the '894 patent, the airbag would be inflated at the same time as the predetermined speed difference occurs and the time delay circuit times out.

Another type of electrical control device for actuatable passenger restraints is disclosed in U.S. Pat. No. 4,842,301. This U.S. patent specification discloses an air bag activation system for monitoring acoustic emissions that occurs when a vehicle of the integrally welded construction type having a pair of frame side rails extending longitudinally from the front to the rear of the vehicle collides. circuit is disclosed. According to this US patent, two acoustic vibration sensors are mounted as close as possible to the front of each side rail.

The output of each sensor is connected to a bandpass filter with a frequency range of 200-300 KHz to remove low frequency components. The output of the bandpass filter is connected to an envelope detector, and the output of the envelope detector is connected to a comparator. When the level of acoustic frequencies at the passband frequency exceeds a reference value set in the comparator, the airbag is activated.

SUMMARY OF THE INVENTION The present invention provides a method for identifying different types of vehicle crashes by detecting frequency components present in signals from reduction gear sensors generated in response to the crash conditions. It is something. Once a frequency component is detected,
The operable passenger restraint system is electrically controllable and only in the event of certain vehicle collisions that require the use of an air pack within the restraint system to protect the passenger. The air pack is controlled to inflate.

According to the present invention, a method is provided for determining frequency components indicative of a predetermined type of vehicle crash condition required to activate a passenger restraint system in a predetermined class of vehicles, the method comprising: (a) (b) generating a spatio-temporal oscillatory electrical signal corresponding to and including a frequency component indicative of a vehicle crash condition; (c) recording a spatio-temporal oscillatory electrical signal for the vehicle crash of step (b). The method further includes: (d) causing a vehicle crash of the predetermined class in at least one condition requiring actuation of a passenger restraint system; recording an electrical signal; (f) performing a frequency-space transformation of the recorded time-space electrical signal for the vehicle crash of steps (b) and (d);
identifying frequency components for the recorded electrical signal. The method further comprises (g) step (
Compare the frequency components generated in response to the vehicle collision in b) with the frequency components generated in response to the vehicle collision in step (d), and (h) determine the frequency components generated in response to the vehicle collision in step (d). is characterized in that it includes the step of identifying frequency components that did not occur in response to the vehicle collision in step (b).

According to another invention, for operating a passenger restraint system having a deceleration sensor responsive to and generating an electrical signal comprising frequency components representative of a plurality of different types of collisions of a given class of vehicles. A method of designing a filter circuit, wherein the filter circuit monitors for the generation of a frequency component indicative of a predetermined type of vehicle crash condition that requires activation of a passenger restraint system, and the filter circuit generates the frequency component. A method of designing a filter circuit is provided that is configured to generate a signal indicating that the filter circuit has been selected. The method includes: ('a) causing a vehicle crash of a predetermined class in at least one condition that does not require actuation of a passenger restraint system; and (b) detecting the deceleration sensor for the vehicle crash of step (a). Record the signal from (c)
at least one person required to activate a passenger restraint system;
(d) recording the signal from the deceleration sensor for the vehicle collision of step (c); (e) performing steps (b) and (d); Perform a functional transformation of the signal recorded in (f) step (e) for only the vehicle collision of step (c).
The method is characterized by including the step of designing a filter circuit so as to pass the frequency generated in the step.

According to yet another invention, for operating a passenger restraint system having a deceleration sensor responsive to and generating an electrical signal including frequency components representative of a plurality of different types of collisions of a predetermined class of vehicles. 2. A method of designing a filter circuit, wherein the filter circuit monitors for occurrence of a frequency component indicative of a predetermined type of vehicle crash condition that requires activation of a passenger restraint device; A filter circuit design configured to monitor for the occurrence of a frequency component indicative of a vehicle collision of another type = 15 that does not need to be activated and to generate a signal indicating that the frequency component has been generated. A method is provided, the method comprising: (a) causing a predetermined class of vehicle crashes in a plurality of conditions in which a passenger restraint system is not required to be activated; recording a signal from the deceleration sensor; (c) causing a collision of the predetermined class of vehicle in a plurality of conditions requiring activation of a passenger restraint system; and (d) step (c)
) record the signals from the deceleration sensor for each vehicle crash; (e) perform a functional transformation of the respective signals recorded in steps (b) and (d); and (f) perform the function transformation of the respective signals recorded in step (c). (g) designing a plurality of filter circuits to pass a plurality of frequencies determined to have occurred in step (e) for vehicle collisions only;
) designing the plurality of filter circuits to pass the plurality of frequencies determined to have occurred in step (e) only for vehicle collisions of (16).

According to a preferred embodiment of the invention, the step of performing a functional transformation comprises the step of performing a Fourier transform, and the step of designing a filter circuit comprises designing a bandpass filter to pass an electrical signal having frequency components corresponding to the frequency components corresponding to the frequency components, and the method further includes determining a band of frequencies spaced 3 db on each side from the determined center frequency. Contains steps.

Other features and advantages of the present invention will become apparent to those skilled in the art from reading the following detailed description of the embodiments, taken in conjunction with the drawings.

FIG. 1 schematically depicts a device 20 used to control the operation of an airbag type restraint system. Accelerometer assembly 22 is attachable to a vehicle and includes:
An oscillatory electrical output signal is generated having frequency components indicative of the type of crash condition affecting the vehicle. Output 24 of accelerometer assembly 22 is connected to an integrating circuit 26 of a type well known to those skilled in the art. Output 24 is also connected to an input terminal 28 of boost circuit 30. Boost circuit 3
0 has a bandpass filter 32 that is designed to pass frequency components in a particular frequency band present in the output signal 24 of the accelerometer assembly 22. The output 34 of the bandpass filter 32 is connected to an envelope detector circuit 36. Output 38 of integrator 26
and the output 40 of the envelope detector 36 are both connected to an adder circuit 42.

The output 44 of the adder circuit 42 is connected to one input 46 of the comparator 48.
It is connected to the. The other input 50 of the comparator 48 is connected to a node 52 of a voltage divider circuit, which is connected in series between an electrical energy source (power supply) and an electrical ground (earth). Resistors 54 and 56 are provided.

Output 58 of comparator 48 is connected to one-shot circuit 60. When the comparator detects that the output voltage 44 is larger than the voltage value Vt at the connection point 52, the one-shot circuit 60 generates a pulse signal having a predetermined time width. This pulse indicates that the vehicle is in a crash condition that requires activation of a passenger restraint system. For convenience of explanation, the passenger body restraint device described here will be an airbag.

The output 62 of the one-shot 60 is connected to an electrical switch 64, such as a field effect transistor (FET). Switch 64 is connected in series with squib 66 between power supply V and ground. The duration of the pulse from the one-shot circuit 60 is for a duration that exceeds the minimum duration specified by the manufacturer to ensure operation.
The selection is made to ensure that current is supplied to the squib 66. When the squib 66 is actuated, the airbag inflates.

Accelerometer assembly 22 includes accelerometer transducer 6
8, the transducer outputs an oscillatory electrical signal 70 having frequency components indicative of a particular type of vehicle crash condition. The output 70 of the acceleration 19 meter transducer 68 is connected to an amplifier 72 which amplifies the signal 70 to produce an output signal 24.

Referring to FIG. 2, accelerometer 68 is connected to housing 78.
It has a weight 74 suspended by a cantilevered device 76 attached to it. housing 78
can be attached to a vehicle. Four variable resistors 80 are mounted on the cantilevered device. Resistor 8
0 is electrically connected between the ground and the power supply V in a Wheatstone bridge structure.

When a vehicle collides, the weight 74 of the accelerometer 68 is thrown into the housing 7.
When the resistor 80 moves relative to the resistor 80, the resistance value of the resistor 80 changes. Due to the Wheatstone bridge structure, a voltage change occurs between terminals 82, 84, which voltage change is indicative of movement of weight 74. Transducers or accelerometers such as those described above are available in California (950
3 5) Milpitas, MaCarthy
Blvd. , 1701 IC Sensors (I
CSensors) model No. It is commercially available as 3021.

Bridge resistor 80 is connected to amplifier 72 which produces an output signal 24 having a value indicative of the amount of movement of weight 74. That is, the output terminal 82 of the bridge resistor is connected to a non-inverting input 86 of an operational amplifier (op amp) 88. An output 90 of operational amplifier 88 is connected through a feedback resistor 94 to an inverting input 92 of the operational amplifier.

On the other hand, the output terminal 84 is the non-inverting input 96 of the operational amplifier 98.
It is connected to the. An output 100 of operational amplifier 98 is connected to an inverting input 102 of operational amplifier 98 via a feedback resistor 104 .

Inverting input 92 of operational amplifier 88 and inverting input 102 of operational amplifier 98 are connected together by variable resistor 106 .

The output 90 of operational amplifier 88 is also connected to resistors 112, 114.
It is connected to the non-inverting input 108 of the operational amplifier 110 via a resistive voltage divider circuit consisting of a resistive voltage divider circuit. filter capacitor 1
16 is connected between the connection point of resistors 112 and 114 and ground. Output 100 of operational amplifier 98 is also connected via resistor 120 to inverting input 118 of operational amplifier 110. The output 122 of operational amplifier 110 is connected to inverting input 118 through a parallel connected resistor 124 and capacitor 126.

Resistors 94, 104, 112, 114, 120 and 12
4 have equal resistance values R, and the value of the variable resistor 106 is Rv
When ar is assumed, the gain G of the amplifier 72 is expressed by the following formula.

G=1+(2R/Rvar) FIG. 3 shows the boost circuit 30 of FIG. 1 in detail. Bandpass filter 32 has an input terminal 28;
This terminal 28 is connected to the output 24 of the amplifier 72. The amplitude of the input signal is determined by resistors 140 and 142 connected in series.
divided by.

The junction of resistors 140 and 142 is connected to an inverting input 144 of an operational amplifier 146 via a capacitor 148. Non-inverting input 150 of operational amplifier 146 is connected to ground. Output 152 of operational amplifier 146 is connected to resistor 1
54 to the inverting input 144. resistance 1
The connection point between 40 and 142 is connected to the output 152 of the operational amplifier 146 via a capacitor 156.

When selecting component values for the bandpass filter 32,
A frequency F midway between f1 and f2 is chosen that defines the frequency band limit that the filter passes. Q value is frequency F
is set equal to the value obtained by dividing the frequency F by the frequency bandwidth, which is a value that is 3 dB lower than the peak value of the frequency F.

Let the value of the resistor 140 be Rl4[1. The values of all other resistors are similarly designated as Rxxx, where XXX represents the symbol of the resistor in the drawing. The value of capacitor 148 is C
,48. Similarly, change the values of other capacitors C XXX
where XXX represents the code of the capacitor in the drawing. The frequency F is expressed by the following formula. F=(1/2
π)・[1/ (RI54XCI48XCI56)
X(1/Rl40 +1/RI42) The gain G of the l/2 bandpass filter 32 is expressed by the following formula:
I54/ [RI40X (1+C+sa/C+4g)
] Therefore, the value of the resistance is determined by the following formula: 23 RI40 = Q/ (G XC + ssX 2
yr X F )RI42 = Q/[(2XQ2-G
)xC, 56x2πxF]RI54 = 2 X Q
/ (c + s6

A cathode 164 of diode 160 is connected to a resistor 166 and a capacitor 168 that are connected in parallel.

Referring now to FIG. 4, the output 24 of the accelerometer assembly 22 is plotted with amplitude on the Y-axis and time on the X-axis. The disturbance in the output signal 24 in the graph is due to the vibration of the weight 74 during a vehicle collision. The output 38 of integrator 26 is also depicted. FIG. 5 graphically depicts the Fourier transform of the accelerometer signal shown in FIG. Amplitude is plotted on the Y-axis and frequency is plotted on the X-axis. The Fourier transform transforms the time-space output signal from accelerometer assembly 22 into a frequency-space signal. The Fourier transform shows what frequency components exist in the temporal and spatial signals.

It has been determined that the output 24 of the accelerometer assembly 22 includes particular frequency components representative of particular types of vehicle collisions affecting the vehicle.

As shown in FIG. 5, if there is no frequency component between the frequency values f1 and f2, the frequency f
1 and f2 have an amplitude smaller than a predetermined value, or do not have a large value compared to the amplitudes of frequency components located elsewhere in the spectrum.

Referring now to FIGS. 6 and 7, time-space and frequency-space graphs, respectively, of heavy collisions are shown. As shown in Fig. 7, in a heavy collision, the frequency f1
A frequency division actually exists between and f2.

Once it is possible to determine, for a particular type of vehicle, which frequency components are present during severe crashes and absent during light crashes, continuously monitor the output 24 for these frequency components; It has been found that the airbag can be activated when these frequency components are detected.

Referring to FIG. 8, there is shown an apparatus 180 which is configured to generate signals generated by an accelerometer assembly 22 mounted on a vehicle during different types of crash conditions experienced by the vehicle, namely, severe crashes and light crashes. Determine the frequency components to be used. A severe crash is one that requires airbag inflation. Furthermore, a minor collision is a collision in which it is undesirable to inflate an airbag.

Accelerometer assembly 22 is as described above.

Output 24 of accelerometer assembly 22 is connected to an analog/digital (A/D) converter 182. A collision detection enable circuit 184 is connected to the output 24 of the accelerometer assembly 22 and the output of the circuit 184 is connected to the A/D converter 182. Collision detection enable circuit 1
84 monitors the accelerometer signal 24. When the amplitude of signal 24 becomes greater than a predetermined value, collision detection enable circuit 184 causes the A/D converter to begin a conversion operation. The converted data is stored 26 in memory 186.

Once the test data is obtained and stored, the data is then processed by digital conversion processor 190. Digital transform processor 190 may take one of several forms, such as a Fourier transformer, a cosine transformer, or some other type of equipment known to those skilled in the art. Output 19 of conversion processor 190
2 is connected to a microcomputer 194. The microcomputer 194 considers the relationship between the characteristics of the collision parameters and the measured frequencies detected by the digital conversion processor. In other words, consider whether the collision occurred in a heavy collision condition or in a light collision condition.

Microcomputer 194 then determines the frequency components that are present during heavy collisions and absent during light collisions.

Alternatively, the output of the digital conversion processor can be displayed on an oscilloscope. From the display of the conversion data for both the heavy collision condition and the light collision condition, the observer can confirm the frequencies that are present in the heavy collision condition but not in the light collision condition.

Accelerometer assembly 22, A/D converter 182, crash detection enable circuit 184, and memory 186 may be mounted on the vehicle under test. Digital conversion processor 190 and microcomputer 192 are located outside the vehicle. Once the vehicle has collided and the data is stored in memory 186, digital conversion processor 190 is coupled to memory 186 for further processing and analysis.

FIG. 9 shows a flowchart of the control process of the present invention for obtaining frequency components for heavy and light vehicle crashes. The control process is intended for each product and model of vehicle. This is necessary because the frequency content for the same type of crash condition may vary depending on the type and class of vehicle.

Step 250 begins the control process. Step 2
At 52, a particular type of vehicle may be provided with, for example, 12.
8Km/h (8 miles/hour) Causes a light collision, such as the Noharia collision. The output 24 of the accelerometer assembly for the minor crash condition performed in step 252 is
Recorded at 4. The output signal 24 from the accelerometer assembly 22 during such a minor crash condition is shown in the graph of FIG. In step 256, a Fourier transform is performed on the minor crash data recorded in memory 184. The conversion data is shown in the graph of FIG. As can be seen from the graph in FIG. 5, in the case of a light collision, there are almost no frequency components in the frequency band between frequencies f1 and f2.

In step 258, vehicles of the same type are collided in a severe collision condition, such as a low speed simulated collision. The output signal 24 of the accelerometer assembly for the severe crash condition performed in step 258 is recorded in step 260. The output signal 24 from the accelerometer assembly 22 during such a severe crash condition is
As shown in the graph of figure. In step 262, a Fourier transform is performed on the stored heavy collision data. The converted data is shown in the graph of FIG. As can be seen from the graph of FIG. 7, in the case of a heavy collision, important frequency components exist in the frequency band between frequencies f1 and f2.

Based on this information, in step 264, the frequency f
1 and f2 to pass the signal that exists between them.
The frequency band of the bandpass filter is set. The component values for the bandpass filter are determined according to the equations above.

Referring to FIGS. 4 and 6, the integrator 26 for both light crash conditions (FIG. 4) and heavy crash conditions (FIG. 6)
The output 38 of is shown. FIG. 10 shows the same minor crash as shown in FIG. Also shown in FIG. 10 are the output 34 of bandpass filter 32 and the output 44 of adder circuit 42, where output 34 is the sum of the outputs of integrator circuit 26 and boost circuit 30. The output of the bandpass filter 32 is shown shifted on the Y-axis for clarity. A threshold value Vt is selected that is greater than output 44 for all light crash conditions. A light crash condition with the boost circuit is performed in step 266 of FIG.

The Fourier transform of the bandpass filter output is shown in FIG. There are a few frequency components between frequencies f1 and f2. The amplitudes of these frequency components are not large compared to the output of the bandpass filter during light collision conditions. In step 268 of FIG. 9, a threshold value Vt is selected. Based on the selected value Vt,
The resistance values of resistors 54, 56 are selected such that the voltage at node 52 is equal to Vt. Determining the frequency components present in a light collision condition and the frequency components present in a heavy collision condition, designing a bandpass filter based on this information, and selecting an operating threshold value are performed in step 270 of FIG. .

Referring to FIG. 12, the output 24 of the accelerometer assembly 22 is shown during the same severe crash condition shown in FIG. Also shown are the output 34 of bandpass filter 32 and the output 44 of summing circuit 42. FIG. 13 shows the Fourier transform output of the bandpass filter 32 when this heavy collision state occurs. There are frequency components between frequencies f1 and f2, and these frequency components have large amplitudes compared to the values shown in FIG. It will be appreciated that by using the boost circuit 30, the output 44 of the summing circuit 42 rises rapidly compared to the output of the integrator circuit.

The device constructed in accordance with the present invention and shown schematically in FIG. 1 allows discrimination between heavy crash conditions with long velocity change pulses and light barrier crash conditions with low speed, thereby causing airbag activation. can be controlled better. The device according to the invention can also act to ignore the occurrence of certain situations in which it is undesirable to deploy the airbag. For example, if the vehicle is subjected to high frequency vibration strikes, these frequencies are filtered out by a bandpass filter. Even if a blow is received, the integrator output does not change because the duration of the blow is short.

Another embodiment of the invention is schematically shown in FIG. An accelerator assembly 22 having an output 24 is provided, this accelerator assembly being similar to that described above. The output 24 of the accelerator assembly 22 is connected to a heavy crash circuit 300 and a light crash circuit 302. It has been found that when a particular type of vehicle is subjected to different types of light crash conditions, certain frequency components are present that are not present during a heavy crash condition. Conversely, it has been found that when a particular type of vehicle is subjected to different types of severe crash conditions, certain frequency components are present that are not present during light crash conditions. Based on this fact, the control of the passenger restraint system can be carried out by evaluating a plurality of distinct frequency bands during a vehicle crash. Airbag control is performed depending on whether there is a more severe heavy collision frequency component or a lighter collision frequency component.

The heavy collision circuit 300 includes a plurality of bandpass filters 320 and 32.
2, 324, and 326, all of which are connected to the output 24 of the accelerator assembly 22. The frequencies passed by the bandpass filter of the heavy crash circuit are determined by colliding the same type of vehicle in several different heavy crash conditions and finding frequency components that are present in the heavy crash condition but not in the light crash condition. This is determined by the experimental method described above. Positive envelope detectors 330, 332, 334, 336 are bandpass filters 32
0, 322, 324, and 326. The outputs of the envelope detectors 330, 332, 334, 336 are connected to a summing circuit 340.

The light collision circuit 302 includes a plurality of bandpass filters 350, 35.
2, 354, and 356, all of which are connected to the output 24 of the accelerator assembly 22. The frequencies passed by the bandpass filter of the light crash circuit are determined by collisions of the same type of vehicle in several different light crash conditions, and the frequencies that are present in the light crash conditions but not in the experimental heavy crash conditions. is determined using the experimental method described above.

Negative envelope detectors 360, 362, 364, 366 are connected to bandpass filters 350, 352, 354, 356, respectively. Envelope detectors 360, 362, 364
, 366 are connected to the adder circuit 340.

FIG. 15 schematically depicts a negative envelope detector configured for use in the light crash circuit 302. The negative envelope detector includes a diode 370 having a cathode 372 connected to the output of the light collision bandpass filter. An anode 374 of diode 370 is connected to a resistor 376 and a capacitor 378 that are connected in parallel. Anode 374 is connected to adder circuit 340.

When a signal is generated by the accelerometer assembly 22 during a vehicle crash, frequencies indicative of a light or severe crash condition are passed through an appropriate bandpass filter. The summed result is filtered by filter circuit 380. The output of filter 380 is connected to the input 386 of comparator 388. The other input 390 of the comparator 388 is connected to the reference voltage Vt mentioned above. Output 392 of comparator 388 is connected to one-shot circuit 60 described above. When the value obtained by subtracting the light impact frequency component from the heavy impact frequency component exceeds the value Vt, the squib is actuated.

It will be appreciated that in the embodiment of FIG. 14, the need for an integrator can be reduced or eliminated if the number of heavy collision bandpass filters and light collision bandpass filters is sufficient. Dew. Although the device shown in FIG. 14 does not have integrators connected in parallel, they can be connected in that way.

All bandpass filters used in the various embodiments described herein are set to pass frequency components below 3 KHz.

Although the invention has been described with reference to preferred embodiments, modifications and alterations will occur to others upon a reading and understanding of this specification. For example, the boost circuit shown in FIG. 1 may be replaced with a deletion circuit that monitors the accelerometer output signal for the presence of frequency components indicative of a minor crash condition. This deletion circuit reduces the integrator signal to prevent false severe crash indications. Additionally, although the preferred embodiment has been described in connection with the operation of an air bag-type restraint system, the methods and apparatus of the present invention are also applicable to other restraint systems. For example, the actuation signal can be used to lock the seat belt of a lockable seat belt system or to activate a seat belt pretensioner for a seat belt tractor of a seat belt system. All changes and modifications as described above are included in the present invention as long as they fall within the technical scope of the present invention.

[Brief explanation of drawings]

1 is a schematic diagram of the apparatus of the present invention for controlling the operation of a vehicle restraint system; FIG. 2 is a schematic diagram of the accelerometer assembly shown in FIG. 1; FIG. 3 is a schematic diagram of the accelerometer assembly shown in FIG. FIG. 4 is a graph showing the output of the accelerometer assembly when a vehicle encounters an actual barrier collision; FIG. 5 is a schematic diagram of the output signal shown in FIG. Graph showing the Fourier transform output: Figure 6 is a graph showing the output of the accelerometer assembly when the vehicle encounters a severe crash condition with long velocity changes; Figure 7 is the Fourier transform output of the accelerometer output shown in Figure 6. FIG. 8 is a schematic block diagram showing the hardware arrangement for obtaining experimental data in accordance with the present invention; FIG. 9 is a diagram for determining the frequency content during a vehicle crash; Flow showing the control process. Figure; Figure 10 shows the output signal from the accelerometer during an actual barrier collision, superimposed on the output of the adder circuit shown in Figure 1 and the output of the bandpass filter shown in Figure 1, for clarity. FIG. 11 is a graph showing the Fourier transform output of the output of the bandpass filter shown in FIG. 10; FIG. 12 is a graph showing the output of the accelerometer assembly as the output of the adder circuit shown in FIG. A graph that overlaps the output of the bandpass filter shown in FIG. 1 and shifts them for clarity; FIG. 13 is a graph showing the Fourier transform output of the output of the bandpass filter shown in FIG. 12; FIG. , an apparatus for controlling operation of a passenger restraint system implemented in accordance with another embodiment of the present invention; and FIG. 15 is a schematic diagram of the negative envelope detector shown in FIG. 14. 22: 26: 32: 36: 42: 60 74: 76 = Accelerometer assembly Integrator circuit Bandpass filter Envelope detector Adder circuit One-shot circuit Weight Cantilever member -39

Claims (1)

Claims: 1. A method for determining a frequency component indicative of a predetermined type of vehicle crash condition required to activate a passenger restraint system in a predetermined class of vehicle, comprising: (a) determining the vehicle crash condition; (b) causing a collision of a predetermined class of vehicle in at least one condition that does not require actuation of a passenger restraint system; (c) recording a spatio-temporal vibratory electrical signal for the vehicle crash of step (b); and (d) causing a vehicle crash of said predetermined class in at least one condition requiring activation of a passenger restraint system. (e) recording a spatio-temporal vibratory electrical signal for the vehicle collision of step (d); and (f) frequency-spatio-transforming the recorded spatio-temporal electrical signal for the vehicle collision of steps (b) and (d). (g) identify the frequency components for the recorded electrical signal that occurred for the vehicle collision of step (b) and the frequency components that occurred for the vehicle collision of step (d); and (h) identifying a frequency component that occurred in response to the vehicle collision in step (d) but not in response to the vehicle collision in step (b). A vehicle collision frequency component determination method. 2. A filter circuit design method for operating a passenger restraint system having a deceleration sensor that responds to frequency components representing a plurality of different types of collisions of a predetermined class of vehicles and generates an electrical signal including the frequency components. and wherein the filter circuit monitors for generation of a frequency component indicative of a predetermined type of vehicle crash condition requiring activation of a passenger restraint system, and generates a signal indicative of generation of the frequency component. (a) causing a collision of a predetermined class of vehicle in at least one condition that does not require actuation of a passenger restraint system; and (b) step (a) (c) causing a collision with another vehicle of said predetermined class in at least one condition requiring activation of a passenger restraint system; (d) ) recording the signal from the deceleration sensor for the vehicle crash of step (c); (e) performing a functional transformation of the signals recorded in steps (b) and (d); (f) step (c) A method for designing a filter circuit, comprising the step of designing a filter circuit so as to pass the frequency generated in step (e) only in response to a vehicle collision. 3. A filter circuit designing method according to claim 2, wherein the step of performing the function transformation includes the step of performing a Fourier transform. 4. The method of claim 2, wherein the step of designing a filter circuit includes designing a bandpass filter that passes an electrical signal having frequency components corresponding to the frequency components present in the signal recorded in step (d). A filter circuit design method characterized by comprising: 5. The method of designing a filter circuit according to claim 4, further comprising the step of determining frequency bands 3 dB apart on both sides from the determined center frequency. 6. A filter circuit design method for operating a passenger restraint system having a deceleration sensor that responds to and generates an electrical signal including frequency components representative of a plurality of different types of collisions of a vehicle of a predetermined class. and wherein the filter circuit monitors for occurrence of frequency components indicative of a predetermined type of vehicle crash condition that requires activation of a passenger restraint system, and that otherwise does not require activation of a passenger restraint system. A filter circuit design method configured to monitor for the occurrence of a frequency component indicative of a vehicle collision of the type and to generate a signal indicative of the occurrence of the frequency component, comprising: (a) a passenger body; (b) recording the signal from the deceleration sensor for each vehicle crash of step (a) in a plurality of conditions where the restraint system does not need to be activated; (b) recording the signal from the deceleration sensor for each vehicle crash of step (a); (d) recording a signal from the deceleration sensor for each vehicle crash of step (c) in a plurality of conditions requiring activation of the body restraint system; (d) recording a signal from the deceleration sensor for each vehicle crash of step (c); ) step (b)
and (d) performing a functional transformation of each signal recorded in step (d); and (f) passing the plurality of frequencies determined to have occurred in step (e) only for the vehicle collision of step (c). (g) designing a plurality of filter circuits to pass the plurality of frequencies determined to have occurred in step (e) only for the vehicle collision of step (a); A filter circuit design method comprising the steps of: 7. A filter circuit designing method according to claim 6, wherein the step of performing the function transformation includes the step of performing a Fourier transform. 8. The method of claim 6, wherein the step of designing a filter circuit comprises designing a bandpass filter that passes an electrical signal having frequency components corresponding to the frequency components present in the signal recorded in step (d). A filter circuit design method characterized by comprising: 9. The method of designing a filter circuit according to claim 8, further comprising the step of determining frequency bands 3 dB apart on both sides from the determined center frequency.