JPH03238358A - Control system for vehicle safety apparatus - Google Patents

Abstract

PURPOSE:To prevent erroneous operation by providing the means for operation of the integration of deceleration, comparison of the integrated value and a threshold level, judgment of collision,judgment as to whether the integrated value exceeds a tolerance range or not and operating instruction only when the value does not exceeds the tolerance value. CONSTITUTION:When the integrated value of deceleration obtained with an integrating means 31 becomes abnormally high because of external radiowaves and the like at the time other than collision state, a first judging means 32 judges collision because the integrated value exceeds a threshold level. However, a second judging means 33 judges that the difference between the integrated value of the deceleration and the threshold level exceeds a tolerance range. Therefore, an operating instruction is not outputted from an operation instructing means 34. Thus, the erroneous operation of an apparatus can be prevented. At the time of actual collision, it is judged that the difference is within the tolerance range. Therefore, the apparatus is operated with the output from the means 34.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control system for a vehicle safety device using a microcomputer.

[Prior Art] As disclosed in Japanese Utility Model Application No. 2-5371, a system using a microcomputer as one of the systems for controlling vehicle safety devices such as airbags is known. The microcomputer integrates the deceleration signal from the acceleration sensor, compares this integrated value with a threshold level, and determines whether a vehicle collision has occurred. If it determines that a collision has occurred, it sends an activation command signal to the airbag drive circuit. , inflates the airbag to ensure the safety of the occupants. This control system is
It has been attracting attention recently because it can perform highly accurate collision detection using a microcomputer.

[Problems to be Solved by the Invention] In the above-mentioned control system, there is a possibility that the internal data of the microcomputer may become abnormal due to external radio waves or the like, making it impossible to accurately determine a collision. For example, even though no vehicle collision has occurred, the integral value of deceleration may become abnormally high, leading to an erroneous determination of a collision and the possibility of inflating an airbag.

Means for Solving the Problems] The present invention has been made to solve the above problems, and its gist resides in a control system for a vehicle safety device shown in FIG. Specifically, this control system includes a drive circuit 10 for the vehicle safety device 1, an acceleration sensor 20 that detects deceleration of the vehicle, and a microcontroller that controls the drive circuit 10 based on the deceleration signal from the acceleration sensor 20. A computer 30 is also provided. The microcomputer 30 includes an integral calculating means 31 that integrates the deceleration from the acceleration sensor, and a first determining means 32 that compares the integral value from the integral calculating means 30 with a threshold level to determine a collision.
A second determining means 3 that compares the integral value with a threshold level and determines whether the difference exceeds an allowable range.
3, the first determination means 32 performs collision determination, and the second
Only when the determination means 33 determines that the difference does not exceed the allowable range, the vehicle safety device 1 is provided with an operation command means 34 that sends an operation command signal to the drive circuit 10 to activate the vehicle safety device 1.

[Operation] Due to external radio waves or the like, the integral value of the deceleration obtained by the integral calculation means may become abnormally high even though the vehicle is not in a collision state. At this time, the first determining means 32 determines that the integrated value has exceeded the threshold level and determines the collision. However, since the second determining means 32 determines that the difference between the integral value of deceleration and the threshold level exceeds the permissible range, no operation command signal is output from the operation command means. As a result, malfunction of the vehicle safety device can be prevented.

When a vehicle collision actually occurs, the first determination means determines that the integral value exceeds the threshold level, and the second determination means determines that the difference between the integral value and the threshold level is within the allowable range. Therefore, an operation command signal is output from the operation command means, and the vehicle safety device can be activated.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 2 to 4. FIG. 2 schematically shows a control system for controlling the skin 1 of an airbag (vehicle safety device). The skin 1 is incorporated into a drive circuit 10. The drive circuit 10 includes a PNP type first circuit connected to one end of the skin 1 on the power supply side.
It has a transistor 11 and a second NPN transistor 12 connected to the other end of the skin 1 on the ground side. 1st
Between the transistor 11 and the power supply, in order from the first transistor 11 toward the power supply, there is an energy reservoir (not shown) consisting of a large-capacity capacitor, and a booster circuit (not shown) for making the voltage of the energy reservoir higher than the power supply voltage.
(not shown).

The control system includes first and second acceleration sensors 21 and 22 that detect the deceleration of the vehicle, and a microcomputer 30.
It is equipped with The deceleration s1. of these acceleration sensors 21.22. The voltage signal representing s2 is sent to the microcomputer 3.
Analog/digital converter ADCI built into 0
, and are respectively sent to the ADC2 and converted into digital data.

The microcomputer 30 has an output port PA.

It has PB, PC, PD and a reset terminal Re.

Output port PA is connected to one input terminal of NAND circuit 41. Output port PB is connected to one input terminal of AND circuit 42.

Output port PC is connected to NAND circuit 41 . It is connected to the other input terminal of the AND circuit 42. This delay circuit 50 has a resistor 51 and a capacitor 52 connected in order from the output hoard PC toward the ground side, and the voltage at the connection point between the resistor 51 and the capacitor 52 is connected to the NAND gate via the buffer 53. Circuit 41. A
The signal is sent to the ND circuit 42. The delay time of the delay circuit 50 is
This time is set to be longer than the set time of a watchdog timer 60, which will be described later.

Said NAND circuit 41. The output terminal of the AND circuit 42 is
They are connected to the bases of transistors 11 and 12, respectively. Only when the outputs of the output ports PA and PC both become high level, the output of the NAND circuit 41 becomes low level and the first transistor 11 is turned on. Also,
Only when the outputs of the output ports PB and PC both become high level, the output of the AAND circuit 42 becomes high level and the second transistor 12 is turned on.

Squib 1 receives current from the energy reservoir and ignites only when both transformers 11 and 12 are turned on, in other words, when the outputs of the three output capacitors (PAPB) and PC are all at high level. and inflate the airbag.

A watchdog timer 60 is interposed between the output port PD of the microcomputer 30 and the reset terminal Re.

In the above configuration, the microcomputer 30
Execute the timer interrupt routine shown in the figure at every set time. First, the deceleration S from the first acceleration sensor 21 is integrated (step 100). That is, the currently input deceleration SI is added to the first integral value Δv1 stored in the RAM.

Next, the deceleration S from the second acceleration sensor 21 is integrated (step 101). That is, the second integral value Δ■,
The deceleration S input this time is added to.

Next, determine whether the output port PA is at low level (
Step 102). When it is determined that the level is low, the first integral value ΔV is determined in accordance with the deceleration S, and the thread level Th is determined.

(step 103).

If it is determined in step 103 that the first integral value ΔV is less than the Sureno/Hort level Th, it is determined whether the output port PB is at a low level (step 104).
. If it is determined that the level is low, the second integral value Δ■
, is compared with a threshold level Th, which is determined corresponding to the deceleration S2 (step 105). If it is determined that the second integral value Δv2 is less than the threshold level Th, the output level of the output port PD is switched (step 106), and the process returns to the main routine described later.

In normal times, that is, when no vehicle collision has occurred, steps 100 to 106 described above are executed every timer interrupt.

By switching the output level of the PD (output capo) in step 106, this output level repeats high and low at a cycle twice the timer interrupt setting time, indicating that the program is being executed normally. It becomes a signal. The watchdog timer 60 is, for example, output capo-1-P.
It is reset every time it receives a high level output from D.

Since the set time of the watchdog timer 60 is longer than the period during which it does not receive this high level output, during normal operation, the watchdog timer 60 is not connected to the microcomputer 30.
does not output a reset signal.

When a collision occurs, the first integral value Δv1 exceeds the threshold level Th, and the second integral value ΔV exceeds the threshold level Th2. therefore,
A negative determination is made in steps 103 and 105.

If a negative determination is made in step 103, the first integral value Δv1 is written to the RAM as ΔV (step 107), and the threshold level Th is also written to the RAM as T.
h,' is written (step 108), and the output port PA is set to the NO 1 level (step 109).

If a negative determination is made in step 105, the second integral value ΔV is written in the RAM as ΔV (step 110), and the threshold level Th is also written in the RAM as Th.
, write as (step 111), output)
PB is brought to the noi level (step 112).

The above Δv++Th,' represents the first integral value and threshold level when the collision determination is made in step 103. Similarly, ΔV.

Th, represents the second integral value and the threshold level when the collision determination is made in step 105.

In addition, in steps 109 and 112 above, the outgoing capo) PA,
In the timer interrupt routine after setting PB to high level, a negative determination is made in steps 102 and 104, so
Steps 103, 107, 108, 109 and steps 105, 110, 111, 112 are not executed.

The microcomputer 30 executes the main routine shown in FIG. Specifically, if a negative determination is made in either step 120) of determining whether the output port PA is at a high level or step 121) of determining whether the output port PA is at a high level, , these steps 120 and 121 are repeatedly executed.

When affirmative judgments are made in both steps 120 and 121, judgments in steps 122 and 123 are made. That is, in step 122, the first integral value Δv,' and the threshold level Th are determined at the time of collision determination.

The difference is compared with a predetermined value α representing an allowable range, and step 1
In step 23, the difference between the second integral value ΔV and the threshold level T h ,' at the time of collision determination is compared with a predetermined value α. If it is determined in steps 122 and 123 that the difference is less than α, it is determined that the integral value ΔVΔv,′ is normal data, and the output port PC is set at a high level (step 124). As a result, three output ports PA, PB
.

Since all PCs become high level, squib 1 is ignited and the air pack expands.

If the data of the first integral value ΔV or the second integral value Δv,', which is the object of the collision determination, is abnormal due to radio wave interference, in step 122 or 123, the difference is set to a predetermined value α. It is determined that this is the above. At this time, output ports PA and PB are returned to low level (step 125
). As a result, the squib 1 is not ignited, and malfunction of the air bank can be prevented.

As is clear from the above explanation, the integral calculation means 3 in FIG.
1 substantially consists of steps 100 and 101. The first determining means 32 includes steps 103 and 105. The second determination means 33 performs step 12.
2,123. The operation command means 34 is constituted by steps 109, 112, and 124. The operation command signal is sent to three output ports PA, PB, PC
It is composed of high level output from.

When the microcomputer 30 goes out of control, step 106 is not executed and no program run signal is output, so the watchdog timer 60 outputs a reset signal after a set time and the microcomputer 30 is reset. By the way, at the time of the runaway, the three output ports P within the set time of the watchdog timer 60.
It is also possible that the outputs of A, PB, and PC all become high level. However, the high level output from the output port PC is transmitted to the watchdog timer 60 by the delay circuit 50.
After a delay longer than the set time of NAND circuit 41. A
In order to reach the ND circuit 42, the watchdog timer 60
It is possible to eliminate the possibility that the transistors 11 and 12 will turn on within the set time. Also from this point of view, malfunction of the air pack can be prevented.

Note that the delay time by the delay circuit 50 is set to be sufficiently short so that when a vehicle collision actually occurs, the elapsed time from the time of the collision to the inflation of the air pack is long enough to ensure the safety of the occupants. Of course there are.

The present invention is not limited to the above embodiments, and various embodiments are possible. For example, the microcomputer 30 may execute the timer interrupt routine shown in FIG. In this timer interrupt routine, the steps corresponding to those in FIG. 3 are given the same numbers and the explanation thereof will be omitted. In the routine of FIG. 5, in step 103, the first integral value Δv
When it is determined that 1 is above the threshold level Th, it is determined in step 200 whether the difference between the first integral value Δv1 and the threshold level Th is smaller than α, and only if it is small, the capo is output. The PA is set to high level (step 109). Similarly, if it is determined in step 105 that the second integral value ΔV is equal to or higher than the threshold level Th, then in step 201 the second integral value ΔV
, and the threshold level Th is smaller than α, and only if it is smaller, output port PB is set to high level (step 112). When executing such a routine, squib 1 is ignited simply by setting the output port PAPB to a high level. In this case, NAN
A transistor is used instead of the D circuit 41, and
Circuit 42. Output port PC becomes unnecessary. Further, the routine shown in FIG. 4 is also unnecessary.

When multiple acceleration sensors are used, when a collision is determined based on the deceleration signal from one acceleration sensor, the vehicle safety device is activated regardless of calculations based on the deceleration signals from other acceleration sensors. It may be activated. Alternatively, calculation may be performed based on signals from all acceleration sensors, and whether or not a collision has occurred may be determined by majority vote.

The threshold levels Th, , Th, may be set to a constant value.

The control system of the present invention can be applied not only to airbag control but also to seatbelt control.

[Effects of the Invention] As explained above, in the present invention, even when a collision is determined because the integral value of deceleration exceeds the threshold level, the vehicle safety device is not activated immediately, and this integral value is abnormal. Since the vehicle safety device is checked to see if it is abnormal and the operation of the vehicle safety device is prohibited if it is abnormal, it is possible to prevent inconveniences such as the vehicle safety device erroneously operating due to data abnormality caused by external radio waves or the like.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the basic configuration of the present invention, Fig. 2 is a circuit diagram schematically showing an embodiment of the invention, and Fig. 3 is a block diagram showing the basic configuration of the present invention.
FIG. 4 is a flowchart showing the main routine, and FIG. 5 is a diagram showing another aspect of the timer interrupt routine. ■... Vehicle safety device, 10... Drive circuit, 20, 21
22 - Acceleration sensor, 30... Microcomputer, 31... Integral calculation means, 32... First judgment means, 33... Second judgment means, 34... Operation command means.

Claims (1)

[Scope of Claim] A control system comprising a drive circuit for a vehicle safety device, an acceleration sensor that detects deceleration of the vehicle, and a microcomputer that controls the drive circuit based on the deceleration from the acceleration sensor. A control system for a vehicle safety device, characterized by having the following configuration: (b) Integral calculation means that integrates the deceleration from the acceleration sensor. (b) First determining means for determining a collision by comparing the integral value from the integral calculating means with a threshold level. (c) A second determining means that compares the integral value with a threshold level and determines whether the difference exceeds an allowable range. (d) Only when the first determining means determines the collision and the second determining means determines that the difference does not exceed the allowable range, an activation command signal for activating the vehicle safety device is sent to the drive circuit. Operation command means to send.