DE102006007099A1 - Method for functional testing of a measuring transducer and vehicle control unit with a measuring transducer - Google Patents

Abstract

The method involves producing a stimulation signal with a distinguishable signal form when a functional testing of a measuring sensor takes place during normal operation of the sensor. The stimulation signal for functional testing during the normal operation is produced in a frequency spectrum, which is not actuation-significant for actuation of an actuation system e.g. passenger protection system. The stimulation signal is selected with a signal amplitude larger than 50 percent of measuring range. Independent claims are also included for the following: (1) a measuring sensor comprising an evaluating processor unit (2) an actuation system comprising a measuring sensor.

Description

at today's sensors are usually included as proof of its functionality Commissioning (Power On / ignition key passive ➔ active) checked by an initiated test phase, whether the transducer on for a test excitation at a designated input at the output a corresponding expected signal is shown / generated due to its shape and amplitude to the correct functionality, in particular the gain and filter characteristics of being able to close the sensor.

These Tests are currently only during the self-test phase of the system performed as a review during the cyclic operation of the transducer (Driving operation of the motor vehicle), the signals produced at the output from the downstream μC (Calculation unit outside of the sensor) or evaluation unit (algorithm) erroneously as a trigger signal, in the case of an occupant protection system e.g. interpreted as a crash signal could / would.

task The invention is a sensor with a continuous test concept, which also cyclically during of active operation in the system can be imagined so as a result of it possible expectant cyclic tests even during active use (Driving of the motor vehicle) achieved an increase in safety in the system can be.

These The object is solved by the features of the independent claims. advantageous Further developments can be found in the dependent claims.

For this purpose, the invention proposes that during normal operation at least once a functional test of a transducer takes place with an excitation signal with a distinguishable waveform, for example in a frequency spectrum, which / s of the downstream μC (calculation unit outside the sensor ( 1 )) or evaluation unit (algorithm) can not be detected or distinguished from a trigger-critical signal part or by appropriate measures (eg compensation measures at the output of the sensor) to ensure that the "test responses" from the downstream μC (calculation unit outside the transducer ( 1 )) or evaluation unit (algorithm) can not be detected.

However, the "blocking" (filtering out of the test signal from the useful signal) of the test responses does not necessarily have to take place exclusively in the ASIC, but can also take place in the μC (calculation unit outside the measuring transducer ( 1 )) or be perceived by the latter before the acceleration signals are fed to the algorithm.

Likewise, it is also conceivable that both in the ASIC ( 2 ) as well as in μC (calculation unit outside the measuring transducer ( 1 )) in each case certain test components are suppressed or filtered out or first fed.

It So is a method for functional testing of a transducer, For example, an accelerometer of an occupant protection system described. Also conventional Occupant protection systems already have a functional test phase in which the accelerometer by applying at least an excitation signal is tested for its operation. in the Normal operation, however, generates the accelerometer depending on from the outside acting acceleration forces Signals with which the occupant protection system depends the signals are triggered becomes.

According to the invention but still during the normal operation at least once a functional test of a Accelerometer / sensor, wherein the excitation signal with of a distinguishable waveform, i. from the outside, triggering significant acceleration forces can be distinguished.

The Excitation signal for functional testing during the Normal operation takes place for example in a frequency spectrum, which for the trigger the occupant protection system is not triggers, in particular which does not capture the occupant protection system through a filter is not forwarded to the occupant protection system, or at least not on a triggering case indicates and therefore no danger of a false trip or a tripping prevention in the event of a crash.

Preferably takes place in the Meßaufnehmers a Preprocessing of the signal and is through the functional test also Check this preprocessing by using that superimposed with the excitation signal Output signal of the measuring transducer at least parts of this preprocessing goes through and one Evaluation of the output signal at the end of this part of preprocessing he follows.

One Accelerometer points to the implementation of this method therefore an excitation device for coupling an excitation on the transducer while of normal operation and an evaluation unit for evaluating the output signal of the sensor to the excitation signal taking into account the superimposed acting from outside personnel on.

Of the Sensor is preferably equipped with a filter which in the Output signal eliminates the portion based on the excitation signal and so the influence of the Excitation signal adjusted output signal to the output for passing to a connectable Release system / occupant protection system provides.

alternative can the trigger system an evaluation unit for evaluating the output signal of the sensor to the excitation signal taking into account the superimposed from the outside acting forces exhibit.

The Invention will be described below with reference to exemplary embodiments Reference to the figures closer described. Show it:

1 : Accelerometer / sensor with preprocessing provided in or on the sensor and a second evaluation in the central unit

2 : Excitation signals for a two-channel transducer For the implementation of the inventive concept several design examples are possible. These are described below with uniform reference to the figures.

configuration example 1:

The cyclical checks are carried out, for example, by means of a relatively high amplitude (preferably> 50% of the measuring control range), the frequency preferably being selected to be at least 2 times greater than the bandwidth or upper limit frequency which is possible at the output from the externally acting, tripping-relevant forces ( Quasi as "spike" which of the downstream μC (calculation unit outside the sensor ( 1 )) or evaluation unit (algorithm) can not be detected), whereby the evaluation ( 2.6 ) of the "chain" g-cell / transducer ( 3 ), A / D converter ( 2.1 ), High pass ( 2.2 ), Low pass ( 2.3 ) & Amplifiers ( 2.4 ) in the ASIC ( 2 ) itself, and via an interface / SPI ( 5 ) the downstream μC (calculation unit outside the sensor ( 1 )) is provided as a result.

configuration example 2:

The cyclical checks take place, for example, by means of a relatively low amplitude (preferably <50% of the measuring range), the frequency preferably being selected to be at least 2 times smaller than the bandwidth or lower limit frequency of the externally acting, triggering acceleration forces. Quasi as "beating or offset drift" which of the downstream μC (calculation unit outside the sensor ( 1 )) or evaluation unit (algorithm) can not be detected), whereby the evaluation ( 2.6 ) of the "chain" g-cell / transducer (3), A / D converter ( 2.1 ), High pass ( 2.2 ), Low pass ( 2.3 ) & Amplifiers ( 2.4 ) in the ASIC ( 2 ) itself, and via an interface / SPI ( 5 ) the downstream μC (calculation unit outside the sensor ( 1 )) is provided as a result.

configuration example 3:

The cyclic checks are carried out, for example, by means of a PN sequence (psoido-noise noise), the evaluation ( 2.6 ) of the "chain" g-cell / transducer ( 3 ), A / D converter ( 2.1 ), High pass ( 2.2 ), Low pass ( 2.3 ) & Amplifiers ( 2.4 ) in the ASIC ( 2 ) is effected by correlating with the signal obtained at the end of the chain. The result is the pulse response of the transmission chain, from which, for example, the attenuation and the phase response can be determined as a function of the frequency.

• – im Selbsttest/einmalig bei der Inbetriebnahme die komplette Signalkette geprüft wird, und
• – sich die zyklischen Prüfungen während des Betriebs auf Teile der Signalkette, insbesondere dem ASIC (2), beschränken.

• Der oben benutzte Begriff „zyklische Überprüfung" ist derart zu verstehen, dass hierunter sowohl
• – eine kontinuierliche Überprüfung,
• – eine periodische Überprüfung während des Fahrzyklus,
• – eine a-periodische Überprüfung während des Fahrzyklus (zur Verringerung von Faltungs- und Schwebungseffekten) zu verstehen ist/sind.

As an alternative test option / realization for these 3 illustrated methods, it should be mentioned that the test can also be restricted to parts of the signal chain, for example by

• - in the self-test / once during commissioning the complete signal chain is checked, and
• - the cyclical checks during operation are based on parts of the signal chain, in particular the ASIC ( 2 ), restrict.

• The term "cyclic verification" used above should be understood to include both
• - a continuous review,
• - a periodic check during the driving cycle,
• - an a-periodic review during the driving cycle (to reduce folding and beating effects) is / are to be understood.

moreover becomes a vehicle control unit with one according to this Method presented to be tested sensor, wherein the vehicle control unit, for example a control unit an occupant protection system, an ABS system, or the like. This controller has the possibility on, the sensor connected to it, but certainly at one can be arranged in another position in the vehicle, specifically with a stimulate given waveform, at least for the functional tests while of normal driving so chosen are that the corresponding proportion differed in the pickup signal and thus filtered out or in the subsequent evaluation can be ignored.

For multi-channel sensors, the consistent correct channel assignment, an over speak or a similar channel coupling can be achieved by suitably applying the test signatures.

Like from the 2 can be seen, a crosstalk from channel 1 to channel 2 and vice versa can be detected by applying the test pulses is offset in time. Likewise, by applying positive and negative pulses per channel, the functionality in both sign directions can also be determined.

The Invention is for both Lateral accelerometer and spin pickup and other transducers suitable.

Claims (12)

Method for functional testing of a measuring transducer ( 1 ) of a triggering system, characterized in that during normal operation at least once a functional test of a measuring transducer takes place, wherein the excitation signal (test / ST) takes place with a distinguishable signal form. Method according to claim 1, characterized in that that the excitation signal for functional testing during normal operation in a frequency spectrum, which is responsible for the triggering of the triggering system not triggerable is. Method according to claim 2, characterized in that that the excitation signal for functional testing during normal operation in a frequency spectrum that does not detect the triggering system. A method according to claim 2, characterized in that the excitation signal for functional testing during normal operation in a frequency spectrum, which by a filter ( 2 ) is not forwarded to the triggering system. Method according to one of claims 2 to 4, characterized that the excitation signal has a signal amplitude of greater than 50% of the measuring range and a frequency at least factor 2 greater than the possible at the exit upper limit frequency of the externally applied, tripping significant forces chosen becomes. Method according to one of claims 2 to 4, characterized that the excitation signal has a signal amplitude of less than 50% of the measuring range and a frequency at least factor 2 smaller as the possible at the exit Lower limit frequency of the externally acting, tripping significant forces chosen becomes. Method according to claim 2, characterized in that that the excitation signal is a pseudo-noise sequence and the output signal is correlated with this pseudo-noise sequence. Method according to one of the preceding claims, characterized in that in the measuring transducer ( 1 ) a preprocessing ( 2 ) of the signal is carried out and this preprocessing is also checked by the functional test, in that the output signal of the measuring sensor superimposed with the excitation signal at least parts of this preprocessing ( 2 ) and evaluates the output signal at the end of this part of the preprocessing. Method according to one of the preceding claims, characterized in that in the case of a two-channel measuring transducer the excitation signal for the channels is generated offset in time and / or with opposite sign ( 2 ). Transducer for carrying out a method according to one of the preceding claims, wherein the transducer ( 1 ) an excitation device for coupling an excitation to the transducer during normal operation and an evaluation unit ( 2 ) for evaluating the output signal of the sensor to the excitation signal, taking into account the superimposed externally applied forces. A transducer according to claim 10, wherein the transducer ( 1 ) has a filter which eliminates the portion based on the excitation signal in the output signal and thus provides the output signal adjusted to the influence of the excitation signal to the output for transmission to a connectable triggering system. release system with a sensor for implementation A method according to any one of the preceding claims, wherein of the transducer an excitation device for coupling an excitation on the Sensor during the Normal operation and the trigger system an evaluation unit for evaluating the output signal of the measuring transducer to the excitation signal taking into account the superimposed from the outside acting forces having.