JPH03201752A - Circuit device for signal fault identification - Google Patents

Abstract

PURPOSE: To easily identify the influence of a signal fault by always comparing identification data with belonging digital signals send from an A/D converter by means of a computer and triggering an error identifier when the digital signal is deviated from the identification data in an unallowable degree. CONSTITUTION: When a vehicle is started, a routine which always identifies passing faulty influences is also started and identification data KU usually filed until the influences pass are compared with a digital signal value UD. Then the value of 'X' (X=KD-UD) is obtained by forming the difference between the data KU and value UD and whether the value X is smaller than or equal to the maximum allowance XM is checked. Only when the absolute value of X is larger than that of the value of XM, a computer 2 forms an error identifier FK. The identifier FK works so that the actuation of a safety device cannot be made as far as the identifier FK exists and reset on a RESET input side only when the absolute value of X again stays within an allowable limit. Therefore, the influence of a signal fault can be identified easily.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The invention relates to a circuit arrangement for identifying signal disturbances in a computing device, which is equipped with an analog/digital converter and is integrated, for example, in a safety system of a motor vehicle. /a digital converter has a plurality of analog inputs, on the input side of the converter an analog signal is applied and on the output side a digitized signal is supplied to a calculator, which has access to a memory; The present invention relates to a signal fault identification circuit device.

In automotive safety systems, it is often important to identify the effects of disturbances caused by external electromagnetic fields in order to avoid false triggering of the safety system. This is particularly important in rear support devices for automobiles. In the backplane, the accelerometer signal is detected via an analog/digital converter and is used for accident identification in order to activate the backplane and, for example, inflate an airbag in a few milliseconds.

In order to identify the influence of disturbances, the signals emitted by the sensors are transmitted in duplicate via different signal lines and checked for mutual agreement and correctness by comparison. However, such dual signal transmission is very expensive.

OBJECT OF THE INVENTION The object of the invention is to identify the effects of signal disturbances in a simple manner.

Means for Solving the Problems According to the present invention, at least one predetermined identification data of an analog signal is stored in the memory, and the calculator constantly receives the identification data from the analog/digital converter. The calculation device of the vehicle is always equipped with a memory, which is configured to compare with the assigned digital signal and trigger an error identifier in case of an unacceptable deviation from the identification data. Contains data. Therefore, only a small memory outlay is required to file at least one identification data of the analog signal and to carry out error identification on the basis of this identification data. In this case, the calculator constantly compares the identification data with the associated digital signal received from the analog/digital converter and can form an error identifier if the deviation is unacceptable. The error identifier is used in the computing device to prevent the rear support device from being activated incorrectly.

The identification data filed in the memory may be sensor signal identification data or reference signal identification data. If the identification data belong to the sensor signal, it is of course necessary that, for example, certain limit values of the sensor signal are known.

This limit value can be filed in memory as identification data. As a result, an excess of a limit value, that is to say a fault in this case, is identified, but preferably an additional analog reference signal is supplied to the input of the analog/digital converter. The voltage value of the reference signal is stored in memory as identification data. If the analog reference signal is disturbed by strong transmitters, spark discharges or other corresponding external influences, the calculator identifies this disturbance by comparison with the stored digitized voltage values. here,
Consider that the signals supplied to the analog-to-digital converter are more likely to affect each other's crosstalk.

That is, a snowfall effect occurring on one line also occurs on other input lines or input sides, at least in a weakened form. Therefore, in order to obtain information about disturbances occurring on all inputs, it is sufficient to monitor one of the inputs for occurring electromagnetic interference effects.

This is exploited in the circuit arrangement according to the invention in order to be able to identify disturbance effects with low circuit outlays.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a motor vehicle safety device in the form of a block circuit diagram. Safety device is analog/digital converter 1
, a calculator 2 configured as a microprocessor, and a memory 3. analog/digital converter l
On the input side of the sensor S1, S2 are connected via the signal line 4.5.
However, a reference voltage source R3 is also connected via the signal line 6. The reference voltage source delivers an analog reference voltage tJA to the analog/digital converter 1. The reference voltage is supplied to the calculator 2 as a digital signal UD. Calculator 2 is always connected to memory 3, and digital identification data tJK is filed in the memory. The digital identification data represents the voltage value of the reference voltage UA.

The signals of sensors S1, S2 are transmitted accordingly to a calculator 2,
A computer controls the safety device in a known manner as a function of sensor signals. Sensors S1, S2 are crash sensors, acceleration sensors that can be used to identify accidents, so that the calculator 2 can trigger a rear support device, for example an airbag, on the basis of corresponding sensor signals. In order to avoid false triggering of the rear support device, an error identification routine is executed by the calculator 2.

The memory 3 furthermore contains, for example, further identification data KU1. KU2 can be filed.

This identification data represents the limit value of the sensor signal of sensor S1. This identification data KUI, KU2 can be additionally or optionally independently evaluated in order to identify signal disturbances due to external electromagnetic influences. Identification data KU
If I, KU2 is exceeded, an error recognition can be triggered by the calculator 2 as well.

In FIG. 2, the routine described above for identifying the interfering influence of external interfering electromagnetic fields is explained on the basis of a flowchart. When the vehicle is started, a constantly running routine for identifying nuisance effects also starts. This routine then normally proceeds: First, the stored identification data KU is compared with the digital signal value UD. KU-UD
-X difference formation yields the value of "X 1), which is subsequently checked for being less than or equal to the maximum permissible XM.

If this value X is still within the permissible limits, this will not trigger an error identification. Only when the value X exceeds the value XM in absolute value does the calculator 2 issue an error identifier FK.
is formed. As long as this error identifier FK exists, the safety device is not activated. The error identifier FK is only reset at the RESET input once the absolute value of the value X is again within the permissible limits. The safety device then becomes operational again.

Effects of the Invention According to the present invention, the effects of signal disturbances can be easily identified.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram of an embodiment according to the invention, and FIG. 2 is a flowchart for a test routine. ■-Analog/digital converter, 2-Calculator 3-Memory" Fig, 2

Claims (1)

[Claims] 1. A circuit device for identifying signal disturbances in a computing device equipped with an analog/digital converter, the circuit device comprising:
A digital converter has a plurality of analog inputs, on the input side of the converter an analog signal is applied, and on the output side a digitized signal is supplied to a calculator, which accesses the memory, the signal In the fault identification circuit device, the memory (3) contains at least one analog signal (UA).
One predetermined identification data (KU) is filed,
Calculator (2) always sends identification data (UA) to analog/
The error identifier (F
K) A circuit device for signal failure identification, characterized in that it triggers. 2. A reference voltage (UA) is applied to the analog input side of the analog/digital converter (1), and the digitized voltage value of the reference voltage is filed in the memory (3) as identification data (KU). The circuit device according to claim 1. 3. The circuit arrangement according to claim 1, wherein the limit values of the analog signal (S1) whose voltage range is known are stored in the memory as digital identification data (KU1, KU2).