GB2342174A

GB2342174A - Device and process for monitoring an acceleration sensor

Info

Publication number: GB2342174A
Application number: GB9922943A
Authority: GB
Inventors: Rolf Kohler; Johannes Schmitt; Guenter Braun; Andreas Zoebele; Matthias Kottmann
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1998-09-30
Filing date: 1999-09-28
Publication date: 2000-04-05
Anticipated expiration: 2019-09-28
Also published as: DE19844914B4; GB9922943D0; FR2783925B1; FR2783925A1; JP2000111571A; GB2342174B; DE19844914A1

Abstract

An acceleration sensor produces a signal to describe the chronological variation of acceleration. Monitoring means are also contained to compare the acceleration variable to a threshold value. Monitoring is only implemented when a velocity variable is greater than a threshold value, and/or when for a predetermined time period the velocity is greater than a threshold value, and/or when the acceleration is greater than a threshold value.

Description

2342174 Device and process for monitoring an accgleration sensor arranged

in a vehicle

Prior art

The invention concerns a device and a process for monitoring an acceleration sensor arranged in a vehicle. Many different modifications of such devices in the process are known from the prior art. A control device with acceleration sensor and fault monitoring for powered 10 vehicles is disclosed in DE 39 -30 302. The control device contains a first acceleration sensor for detecting longitudinal accelerations and a second acceleration sensor for detecting lateral accelerations, for example. Furthermore, the control device contains a device for recording the signals of the acceleration sensors and for deriving a data value on the basis of the two signals. In a further is device the data value is compared to a predetermined comparison value and an error in one of the sensor signals is determined. The data value is produced, for example, by addition of the acceleration signals or as the root of the sum of the squares of the acceleration signals. The use of change variables that describe the chronological change in the sensor signals, is not indicated during monitoring. 20 DE 196 36 4433 A I describes a device for monitoring sensors in a vehicle. The sensors produce signals, each of which represents different physical quantities. The device contains means with which specific comparison values, that are identical for the sensors, are determined for at least two sensors and based at least 25 on the signals generated by them. The device further contains means with which a reference value is determined in relation to at least the determined comparison values. A monitoring operation is carried out for at least one sensor, based at least on the reference value. Among other things, a lateral acceleration sensor is checked in this manner, the monitoring being implemented only when an approval 30 condition is met. A check is made with the aid of the approval condition to see

2 whether the mathematical or inverse mathematical models employed during the monitoring of the sensors are valid. During the checking of the lateral acceleration sensors, there is no provision forthe evaluation of a variable that describes the chronological change in the signal of the lateral acceleration sensor.

The following morutoring of an acceleration sensor is disclosed in the publication JP 6-109761 (A) m Patent Abstracts of Japan, P 1772, 1994 Vol. 18, No. 384. The signal generated by the acceleration sensor is differentiated. The differentiated signal is then compared to a predetermined threshold value. Depending on this comparison, it is then determined whether or not the acceleration sensor is faulty.

Compliance with an approval condition is not necessary in order to carry out the check on the acceleration sensor.

Based on the afore-mentioned publication JP 6-109761 (A), the object of this invention is to create a device and a process, respectively, with which an acceleration sensor arranged in a vehicle can be monitored with the aid of the chronological change in the sensor signal, where monitoring is carried out only in those operating states of the vehicle that do not lead to falsification of the monitoring result.

Claims

This object is achieved by the features of Claim 1 and those of Claim 12. Advantages of the invention With the device according to the invention, an acceleration sensor arranged in a vehicle is monitored, by which an acceleration variable that describes the acceleration acting on the vehicle is detected. In particular, the acceleration sensor is a lateral acceleration sensor with which a lateral acceleration variable that describes the lateral acceleration acting on the vehicle is detected. 30 3 For the acceleration sensor, in order to monitor the chronological change in its sensor signal or the lateral acceleration variable detected by it, respectively, the device advantageously contains determination means with which a change variable that describes the chronological variation of the acceleration variable is determined. Advantageously, the gradient or the time derivative of the acceleration vanable, respectively, is deten-nined as a change variable. Alternatively, a difference generated from the values of the acceleration variable that are determined at successive, discrete time intervals, can be determined as a change variable. Generating the difference likewise produces a variable that has the characteristic of a chronological change. The device contains monitoring means for implementing the monitoring. A comparison between the change variables and a threshold value is made in these monitoring means. is In order to elirrunate operating states of the vehicle that would lead to a falsification of the monitoring result, the monitoring of the acceleration sensor is advantageously only carried out when a velocity variable that describes the vehicle speed is greater than a threshold value, and/or when for a predetermined time period a velocity variable that describes the vehicle speed is greater than a threshold value, and/or when the acceleration variable is greater than a threshold value. The conditions stated above can be considered as approval conditions. Consequently, the monitoring of the acceleration sensor is implemented only when at least one approval condition is met. The advantages of a first exemplary embodiment are dealt with first of all. A check is made with the aid of the first exemplary embodiment to see whether any change in the acceleration variable takes place within a predetermined time interval. If this is the case, then the acceleration sensor is to'be considered as 4 faulty. To do this, advantageously, in the first exemplary embodiment the comparison taking place m the monitoring means determmes whether the absolute value of the change variable is less than or equal to the threshold value. The value of a counter is changed in relation to this comparison. The value of the counter determines whether or not the acceleration sensor is faulty. This procedure ensures that the acceleration sensor is only faulty when the change variable exhibits an abnormal characteristic for a prolonged period of time.

1-0 If the absolute value of the change variable is less than or equal to the threshold value, then the value of the counter, in particular, is increased by 1. On the other hand, if the absolute value of the change variable is greater than the threshold value, then the value of the counter is reset to a predetermined value, in particular zero. The resetting of the counter fillfils the following purpose. in the case where the absolute value of the change variable is less than or equal to the threshold value for a specific period of time, the acceleration sensor is possibly considered as faulty, based on the value of the counter, which is why the counter is increased.

However, as soon as the absolute value of the change variable is again greater than the threshold value, that is to say after this time period, the acceleration sensor is no longer considered to be possibly faulty. The counter is therefore reset to a predetermined value.

In order to determine whether or not the acceleration sensor is faulty, advantageously the value of the counter is compared to a threshold value. The acceleration sensor is faulty when the value of the counter is greater than the threshold value. On the other hand, the acceleration sensor is not faulty when the value of the counter is less than the threshold value. Likewise, the acceleration sensor is not faulty when the value of the counter is reset to a predetermined value, in particular zero.

So that the acceleration sensor is considered as faulty only when the value of the counter is greater than the threshold value, it is ensured that the acceleration sensor is actually considered faulty only when the absolute value of the change variable has shown an abnormal characteristic for a certain period of time, that is to say the absolute value change variable is or was less than or equal to the threshold value for a certain period of time. In this regard it would be advantageous to specify the threshold value in relation to the vehicle speed. In particular, the threshold value is specified so that the threshold value is reduced with increasing vehicle speed. In this case the functional relationship between vehicle speed and threshold value can be chosen in such a way that the threshold value is reduced with increasmg vehicle speed so that the distance covered by the vehicle always remains the same.

Advantageously, provision is made for a comparison, during which it is determined whether a velocity variable that describes the vehicle speed is greater than a threshold value. In the case where the velocity variable is less than the threshold value, the value of the counter is reset to a predetermined value, in particular zero. In the case where the velocity variable is greater than the threshold value, the comparison concerning the change variable is carried out. This procedure ensures that the monitoring of the acceleration sensor is implemented only when the vehicle speed is above a specific threshold value or the monitoring of the acceleration sensor is tenninated if the vehicle speed is no longer above this threshold value.

Advantageously, it is indicated by means of a vector value whether or not the acceleration sensor is faulty. In the case where the acceleration sensor is faulty, a first value indicating this fact is assigned to the vector value. In the case where the acceleration sensor is not faulty, a second value indicating this fact is assigned to the vector value. With the aid of this vector value, a controller is informed by the monitoring means, for example, that the acceleration sensor is faulty.

6 Using the technical doctrine underlying the first exemplary embodiment, an acceleration sensor should be detected as faulty when the signal generated with the aid of the acceleration sensor does not change during a predetermined time period or when this signal exhibits no change. For this reason a cheek is made to see whether the absolute value of the change variable is less than or equal to a threshold value.

The advantages of a second exemplary embodiment are outlined below.

With the aid of the second exemplary embodiment a check is carried out to see whether or not the acceleration sensor presents a gradient error.

For this, in the second exemplary embodiment, advantageously, it is determined in the comparison taking place in the monitoring means whether the absolute value 1.5 of the change vanable is greater than the threshold value. Depending on this comparison, it is determined whether or not the acceleration sensor is faulty. If the absolute value of the change variable is greater than the threshold value, then the acceleration sensor is faulty. If the absolute value of the change variable is less than the threshold value, then the acceleration sensor is not faulty. 20 Since, according to the second exemplary embodiment the acceleration sensor should be recognised as faulty, if the gradient of the signal that is generated with the aid of the acceleration sensor is greater than a threshold value, a cheek is made in the second exemplary embodiment to see whether the absolute value of the 25 change variable is greater than the threshold value.

Further advantages, as well as advantageous developments, can be inferred from the sub-claims, the drawing and the description of the exemplary embodiment.

7 Drawing The drawing comprises Figures I to 3. The device according to the invention for implementing the process according to the invention is illustrated in a general arrangement in Figure 1. With the aid of a flowchart, Figures 21 and 3' each show for an exemplary embodiment a step sequence for implementing the process according to the invention.

Exemplary embodiments The device according to the invention on which the two exemplary embodiments are based, is illustrated in Figure 1, which will be described first.

Block 101 represents an acceleration sensor with which an acceleration variable that describes the acceleration action on the vehicle is detected. In this exemplary embodiment the acceleration sensor is a lateral acceleration sensor with which a lateral acceleration variable aq is detected. The lateral acceleration variable aq is fed to a block 102, a block 104 and also to a block 105.

Block 102 involves determination means with which a change variable daq that describes the chronological change in the acceleration variable aq is determined.

The gradient or the time derivative of the acceleration variable aq is determined as a change variable daq, for example. This can be realised, for example, by using suitable electrical components, for example a capacitor. A corresponding implementation as a computer algorithm is also conceivable. Alternatively, a difference generated from the values of the acceleration variable aq, that are determined at successive, discrete time intervals, is determined as the change variable. So that the successive, discrete time intervals are equidistant, the difference of the corresponding values of the acceleration variable likewise represents a change variable with a time reference. The change variable daq is fed ftom the block 102 to a block 104.

Block 104 involves monitoring means in which, for the monitoring of the lateral acceleration sensor, a comparison is made between the change variable daq and a threshold value. The result of this comparison is fed from the block 104 to the block 105 with the aid of a vector value Faq.

In addition to the implementation of the comparison for the monitoring of the lateral acceleration sensor, a check is made in the block 104 to see whether various approval conditions are met. Monitoring of the acceleration sensor is carried out only when these approval conditions are fulfilled. This is achieved in the following manner: if it is determined in the block 104 that the approval conditions are met then this is conveyed to the deterniination means 102 by the block 104 via the enabling variable. The effect of this message is to enable the deterniiination means, that is to say, the lateral acceleration variable aq can be read and the change variable daq that is necessary for the comparison can be generated. If the approval conditions are not met, then the determination means 102 are not enabled, that is to say the lateral acceleration variable aq is not read, which means that the change variable daq cannot be generated. Consequently, the comparison necessary for the monitoring of the lateral acceleration sensor cannot be implemented.

Apart from the lateral acceleration variable aq, various variables or signals, denoted by Si 1, are fed from the block 105 to the monitoring means 104 to check whether the approval conditions are met. For example, a velocity variable that describes the vehicle speed is contained in the variables or signals Sil. The approval conditions are fulfilled when the velocity variable is greater than a threshold value and/or when for a predetermined time period the velocity variable is greater than a threshold value and/or when the acceleration variable aq is greater 9 than a threshold value. As already mentioned, if the approval conditions are met, this fact is conveyed to the determination means 102 by the enabling variable.

Block 105 is a controller. Open-loop or closed-loop control with which the lateral dynamic performance of the vehicle is influenced.

To record the vehicle situation, wheel speed variables nij detected with the aid of wheel speed sensors 103ij, as well as the lateral acceleration variable aq, are fed to the controller 105. The index i indicates whether a front wheel (v) or a rear wheel (h) is involved. The index j indicates whether this is a right-hand (r) or a left-hand (1) wheel.

In order to influence the lateral dynamic performance of the vehicle, the controller outputs signals or variables S12, that are fed to a block 106 that represents actuators contained in the vehicle. Here actuators can on the one hand be those devices with which the engine or the engine torque output by it is influenced.

Depending on whether this involves a sparkAgnition engine or a Diesel engine, control of the throttle valve angle, the ignition timing (ignition angle), the amount of fuel supplied or the boost pressure can be provided. On the other hand, intervention in the clutch with which the power transmission between engine and driving wheels is influenced, or intervention in the gearbox, can be provided. As an example of intervention in the gearbox it is conceivable to shift up a gear in order to reduce the driving torque. Intervention m the braking of the vehicle is also conceivable. Influencing the driving torque can bring about a limitation, a reduction or an increase in the driving torque.

The actions described above influence the stability of the vehicle within its limits and thus assist the driver in critical driving situations. The manoeuvrability of the vehicle is increased in the forward direction, the vehicle tends to understeer to a lesser degree. Variables or signals S0) that indicate the state of the respective actuators and are taken into account during closed-loop or open-loop control, are fed to the controller 105 from the actuators 106.

Figure 2, which illustrates the sequence of the process according to the invention '%vith the aid of a flowchart, on which the first exemplary embodiment is based, is dealt with below.

In the first exemplary embodiment, the lateral acceleration sensor is to be monitored for the following errors with the aid of the process according to the 1.0 invention- if a vehicle is moving at above a certain speed, then this is inevitably linked to movements in the lateral direction of the vehicle. Consequently, an existing lateral acceleration sensor in the vehicle must generate corresponding signals or lateral acceleration variables detected with the aid of said sensor must be seen to change with respect to time. If no change in the lateral acceleration 1.5 variable above such a speed is now detected for a prolonged period, then this is an indication that the lateral acceleration sensor is faulty. This problem underlies the first exemplary embodiment of the process according to the invention.

The process according to the invention commences at step 20 1, followed by a step -)o 202. In step 202 the predefined values employed in the process according to the invention are assigned at the beginning of the process according to the invention.

On the one hand this involves a counter taq which represents a time counter, as is described in more detail below. The value zero is assigned to the counter taq. On the other hand, there is a vector value Faq which indicates whether or not the lateral acceleration sensor is faulty. The value FALSE is assigned to the vector value Faq. A step 203 is executed after step 202.

A check is made in step 203 to see if the approval conditions are met. This ensures that the monitoring of the lateral acceleration sensor is not carried out in those driving conditions of the vehicle that could possibly lead to a wrong decision in relation to the monitoring of the lateral acceleration sensor. If the approval conditions are not fulfilled, then step 203 is executed again. If, on the other hand, the approval conditions are met, then a step 204 is executed after step 20,3).

In step 204 a comparison is carried out, in which it is determined whether the velocity variable vf that describes the vehicle speed, is greater than a threshold value S 1. If it is determined in step 204 that the velocity variable is less than the threshold value, it is assumed in this situation that due to the low vehicle speed incorrect decisions can possibly occur during the monitoring of the lateral 10 acceleration sensor. For this reason, either no monitoring of the lateral acceleration sensor is carried out, or morUtoring of the lateral acceleration sensor already in progress is terminated. For this, a step 2 10 is executed after step 204. On the one hand the value zero is assigned to the counter taq in step 2 10. On the other hand, the value FALSE is assigned to the vector value Faq instep 210 since no false is entry has been made. Following step 210, step 203 is carried out again. On the other hand, if it is established in step 204 that the velocity variable vf is greater than the threshold value S 1, which is synonymous with a vehicle condition in which monitoring of the lateral acceleration sensor can take place, then a step 20 205 is executed after step 204. Through a comparison in step 205 it is established whether the absolute value of the change variable daq is less than or equal to a threshold value S2. In other words, a check is made to see if the change variable daq has such a value that it 25 can be assumed that a chronological change in the lateral acceleration variable aq has occurred. As already stated above, this change variable daq is the gradient or the time derivative of the lateral acceleration variable aq. Alternatively, a difference obtained from the values of the lateral acceleration variable aq, that are determined at successive, discrete time intervals, can be determined as the change 30 variable daq. The threshold value S2 preferably corresponds to the value zero. In 12 this special case, a check is made in step 205 to seewhether the change variable equals zero, that is to say whether there really is a change in the lateral acceleration variable aq.

If it is determined in step 205 that the absolute value of the change variable daq is greater than the threshold value S2, which is synonymous with there being a noticeable change in the lateral acceleration variable aq, and the lateral acceleration sensor is therefore not to be considered as faulty, then the step 2 10 is carried out after step 205. On the other hand, if it is established in step 205 that 1.0 the absolute value of the change variable daq is less than or equal to the threshold value S2, and it is therefore assumed that the lateral acceleration sensor is faulty, then a step 206 is executed after step 205. In step 206 the counter taq is incremented by 1. The counter taq has the function of a time counter. Because it is incremented by 1 every time it was established M step 205 that the absolute value of the change variable daq is less than or equal to the threshold value S2, the value of the counter taq represents the time period during which the absolute value of the change variable daq is less than or equal to the threshold value S2, and consequently there is no noticeable change in the 20 lateral acceleration variable aq. Following step 206, a step 207 is carried out, in which the time counter taq, that is to say its value, is compared to a threshold value S3). If it is established in step 207 that the value of the counter taq is greater than the threshold value S-33, which 25 is synonymous with the lateral acceleration sensor being faulty, since for a predetermined, prolonged period no change in the lateral acceleration variable aq was detected, then a step 209 is carried out after step 207, in which the value TRUE is assigned to the vector value Faq. Following step 209, a step 211 is executed, in which the process according to the invention is ended. 30 13 If, on the other hand, it is established in step 207 that the value of the counter taq is less than the threshold value S3, which is synonymous with the lateral acceleration sensor not being faulty, since the predetermined time period is not exceeded, then following step 207, a step 208 is carried out, in which the value FALSE is assigned to the vector value Faq. Step 203 is carried out again after step 208.

It has proved advantageous to make the threshold value dependent on the vehicle speed. As an example, the following functional relationships between the threshold value and the vehicle speed can be considered:

S3 = (DISTANCE 3.6)/vf or S3 = S3OFF - vf FACTOR In the first equation the DISTANCE variable is a fixed specified path length. In the second equation the S30FF variable is the maximum possible value for the threshold value S3.

Figure 3 is now dealt with. Here the process according to the invention on which the second exemplary embodiment is based is described with the aid of a flowchart. The process according to the invention of the second exemplary embodiment starts 25 with a step 301, followed by a step 302. In this step 3302, corresponding to step 202, the value FALSE is assigned to the vector value Faq. Following step 302, a step 303 is executed, in which, corresponding to step 203, a check is made to see whether the approval conditions are met. If it is established in step 303 that the approval conditions are not met then step 3303 is carried out again. If, on the other 30 hand, it is established in step 303 that the approval conditions are met, then a step 304 is executed after step 303.

In step 304 a check is made to see if the absolute value of the change variable daq is greater than a threshold S4. If it is established in step 3 04 that the absolute value of the change variable daq is greater than the threshold value S4, which is synonymous With the change in the lateral acceleration variable aq being above the specified permitted value and the lateral acceleration sensor is therefore faulty, then a step 305 is carded out after step 304. A fault entry takes place in step 305.

For this, the value TRUE is assigned to the vector value Faq. A step 3 307, with which the process according to the invention is ended, is executed after step '105.

304 that the absolute value of the On the other hand, if it established in step) change variable daq is less than the threshold value S4, which is synonymous with the change in the lateral acceleration variable aq being below the permitted value, and therefore the lateral acceleration sensor is not faulty, then following step 304, a step 306 is implemented, in which the value FALSE is assigned to the vector value Faq. Step 30-3) is carried out again after step 306.

In the second exemplary embodiment, it is intended that a fault in a lateral acceleration sensor shall be detected with the aid of the process according to the invention, which makes it obvious that the change variable daq is greater than a threshold value that represents the maximum permissible value for the change variable daq. This fault is thus synonymous with the fact that the lateral acceleration variable aq, or the signal detected by means of the lateral acceleration sensor, has changed to a greater extent than would normally be expected for the lateral acceleration sensor.

If the queries posed in step 205 or 304, respectively, with regard to the change variable daq are combined, then two value ranges are obtained for the lateral acceleration variable, which are specified by the threshold values S2 and S4, respectively. If the value of the change variable daq lies within these two ranges, then it can be assumed that the lateral acceleration sensor is not faulty.

The process steps described in Figures 2 and 3, respectively, run in the block 104 illustrated in Figure 1.

In the case where the lateral acceleration sensor was likely to be faulty, it is possible to use a lateral acceleration variable that is determined in relation to the non-driven wheels, instead of the lateral acceleration variable determined with the aid of the lateral acceleration sensor.

Finally, it should be noted that the chosen form. of the two exemplary embodiments in the description and the selected representations in the figures, respectively, are not intended to have any restrictive influence on the concept that is essential for the invention. The device and the process according to the invention can therefore also be employed for acceleration sensors which detect a longitudinal acceleration or an acceleration in the vertical direction of the vehicle, Claims 1. Device for monitoring an acceleration sensor (101) arranged in a vehicle, with which an acceleration variable (aq) that describes an acceleration acting on the vehicle is detected, in particular where the acceleration sensor is a lateral acceleration sensor with which a lateral acceleration variable (aq) that describes the lateral acceleration acting on the vehicle is detected, wherein the device contains determination means (102) with which a change variable (daq) that describes the chronological variation of the acceleration variable is determined, and contains monitoring means (104) M which, in order to monitor the acceleration sensor, a comparison is made between the change variable (daq) and a threshold value (S2, S4), characterised in that the monitoring of the acceleration sensor is only implemented when a velocity variable that describes the vehicle speed is greater than a threshold value, and/or when for a predetermined time period a velocity vanable that describes the vehicle speed is greater than a threshold value, and/or when the acceleration variable is greater than a threshold value.

2. Device according to Claim 1, characterised in that as a change variable the gradient or the time derivative of the acceleration variable is determined, or that as a change variable a difference is determined that results from the values of the acceleration variable, that are determined at successive discrete time intervals.

3. Device according to Claim 1, characterised in that during the comparison it is determined whether the absolute value of the change variable is greater than the threshold value (S4), and that, depending on this comparison, it is determined whether or not the acceleration sensor is faulty.

17

4. Device according to Claim 3, characterised in that the acceleration sensor is faulty when the absolute value of the change variable is greater than the threshold value, and/or that the acceleration sensor is not faulty when the absolute value of the change variable is less than the threshold value.

5. Device according to Claim 1, characterised in that during the comparison it is determined whether the absolute value of the change variable is less than or equal to the threshold value (S2), and that, depending on this comparison, the value of a counter (taq) is changed, wherein, depending on the value of the counter, it is determined whether or not the acceleration sensor is faulty.

6. Device according to Claim 5, characterised in that the value of the counter is increased, in particular by 1, if the absolute value of the change variable is less than or equal to the threshold value and/or that the value of the counter is reset to a predetermined value, in particular 0, if the absolute value of the change variable is greater than the threshold value.

7. Device according to Claim 5, characterised in that a comparison is carried out in which it is determined whether a velocity variable that describes the vehicle speed is greater than a threshold value (S 1), wherein for the case where the velocity variable is less than the threshold value, the value of the counter is reset to a predetermined value, in particular 0, and/or wherein for the case where the velocity variable is greater than the threshold value, the comparison concerning the change variable is carried out.

8. Device according to Claim 5, characterised in that in order todetermine whether or not the acceleration sensor is faulty, the value of the counter is compared to a threshold value (S3).

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9. Device according to Claim 8 characterised in that the acceleration sensor is faulty when the value of the counter is greater than the threshold value and/or that the acceleration sensor is not faulty when the value of the counter is less than the threshold value, or when the value of the counter is reset to a predetermined value, in particular 0.

10. Device according to Claim 8, characterised in that the threshold value is specified according to the vehicle speed, in particular, the threshold value is spec led so that the threshold value is reduced with increasing vehicle speed.

Device according to Claim 3 or 5, characterised in that it is indicated with the aid of a vector value (Faq) whether or not the acceleration sensor is faulty, wherein, for the case where the acceleration sensor is faulty, a first value (TRUE) indicating this fact is assigned to the vector value, and/or for the case where the acceleration sensor is not faulty, a second value (FALSE) indicating this fact is assigned to the vector value.

12. Process for monitoring an acceleration sensor (10 1) arTanged in a vehicle, M which an acceleration variable (aq) that describes an acceleration acting on the vehicle is detected with the acceleration sensor, in particular where the acceleration sensor is a lateral acceleration sensor with which a lateral acceleration variable (aq) that describes the lateral acceleration acting on the vehicle is detected, in which a change variable (daq) that describes the chronological variation of the acceleration variable is determined, and in which, in order to monitor the acceleration sensor, a comparison is made between the change variable (daq) and a threshold value (S2, S4), characterised in that the monitoring of the acceleration sensor is only implemented when a velocity variable that describes the vehicle speed is greater than a threshold value, and/or when for a predetermined time period a velocity variable that describes the vehicle 19 speed is greater than a threshold value, and/or when the acceleration variable is greater than a threshold value.

13. Either of the devices for monitoring an acceleration sensor arranged in a vehicle, substantially as hereinbefore described with reference to the accompanying drawings.

14. Either of the processes for monitoring an acceleration sensor arranged in a vehicle, substantially as herembefore described with reference to the accompanying drawings.