JP2002366225A - Method and device for measuring and monitoring driving variable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for accurately and simply measuring and monitoring a vehicle driving variable in order to detect an error. SOLUTION: In these method and device for measuring and monitoring a driving variable in which at least two redundant sensors (16 and 18) for measuring a driving variable generate at least two measured variables (U1 and U2), a fixed functional relation exists between the both measured variables, the measured variables are mutually compared with a prescribed tolerance range (102), and if unallowable deviation exists, an error is suspected in at least one measured variable between the measured variables, the comparison is performed on the basis of a quotient (100) between the two measured variables.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for measuring operating variables and monitoring the measured variables.

[0002]

2. Description of the Related Art German Patent Publication No. 42 45 880 discloses a method and a device for determining a driving variable in a vehicle, which indicates, for example, the position of an operating element operable by a driver. In this case, the operating variables are measured by two mutually redundant measuring devices, which are independent of each other.
Generates two measurement variables. The measuring device is selected here such that the functional relationship between the generated measuring signal and the position of the operating element is represented by two characteristic curves having different slopes. In this case, one or more measurement signals are used to control the vehicle drive unit, where it is checked for monitoring whether the measurement signals are within a permissible voltage range.

[0003] A similar method is described in DE-A-197 19.
No. 518 (U.S. Pat. No. 5,875,760). Here, the measurement of the operating variables is carried out by checking the measured variables within a synchronization tolerance (ratio between signals), and furthermore, the measured variables of one measuring device are converted to the values of the other measuring device. Even when there is no corresponding change (so-called motion detection), the detection is performed by detecting an error. In this way, a reliable measurement of the operating variables is ensured. In this case, however, it is very important to set the synchronization tolerance (the deviation between both measurement variables). However, the synchronization tolerance indicates a relative value that is relatively difficult to maintain.

[0004] In particular, in the special embodiment of measuring the accelerator pedal position with respect to the engine control device, it is furthermore important to reliably detect the idling state (driver's desire for idling). For this purpose, the release of the accelerator pedal must be reliably and clearly detected. In general, for this reason, redundant idling information is derived from both measured variables, in which case a departure from the idle range only takes place when both measured variables indicate a departure from the idle range, and thus a torque increase. Is started. This is generally done when the vehicle departs from the idling point within an undesirable dead stroke, based on the tolerances of the measured variables.

[0005] In this case, in general, the synchronization check of both measurement variables is based on a comparison of whether both measurement variables, usually voltages or digital values, are within acceptable values. As the absolute value of the measured variable increases when the measured variable changes, it is necessary to divide the range of values into various windows over the full range of values of the measured variable for checking the synchronization tolerance. In this window, different limits are placed on the synchronization tolerance.

[0006]

SUMMARY OF THE INVENTION For error detection,
It is an object of the present invention to provide a method and an apparatus for accurately and easily measuring and monitoring vehicle driving variables.

[0007]

According to the invention, at least two measurement variables are generated from at least two redundant sensors for measuring operating variables, and a fixed functional relationship is established between both measurement variables. A method for measuring and monitoring operating variables, wherein an existing and these measured variables are mutually compared with a predetermined tolerance range and an error is assumed for at least one of the measured variables if there is an unacceptable deviation. , Said comparison is made based on the quotient between both measured variables.

Further, according to the present invention, a redundant sensor for generating a measurement variable from an operation variable and a predetermined tolerance range for determining a fixed functional relationship existing between the measurement variables and checking for errors. A control unit for comparing measured variables with one another, in which case the control unit detects an error in one of the measured variables if there is an unacceptable deviation, in a measuring and monitoring device for operating variables, By forming the quotient of the two measurement variables and comparing it to a predetermined tolerance threshold, the comparison is made based on the quotient between the two measurement variables. Many advantages are achieved.

[0009] The main advantage is that very small synchronization tolerances can be set, which allow reliable testing. This advantage is particularly advantageous in measuring devices using non-contact technology, when both measurement variables are generated on the basis of the signals of two integrated switch circuits of one housing or of one integrated switch circuit. Achieved. Here, a smaller synchronization tolerance can be created for the manufacturer over the entire operating range, and the quotient formation allows testing with this smaller synchronization tolerance better than the formation of the difference.

The synchronization check interrogates, based on the formation of the quotient, for very small tolerance values within a very small absolute value of the measurement variable, while the synchronization check is insensitive in the direction of the larger absolute value. It is particularly advantageous. Therefore, switching between windows is not necessary. As a result, the software is significantly simplified.

In addition to simplifying the software, since multiple windows are not required, the complexity of the applications that exist in setting the width of multiple windows and setting switching conditions is also reduced. Error sources for incorrect application are reduced.

It is particularly advantageous to carry out the synchronization check by forming a quotient in the pedal value sensor. In this case, the position of the operating element operable by the driver is measured in at least two mutually redundant measuring devices.

The above advantages are obtained, inter alia, by using non-contact sensors for measuring operating variables and by using characteristic curves of the measured variables having different slopes, preferably linear with respect to the operating variables. Achieved. However, the advantages described above are obtained with respect to other characteristic curve embodiments as well.

Further advantages are evident from the following description of an embodiment or from the dependent claims.

[0015]

FIG. 1 shows, in particular, a preferred embodiment with a control unit in which measurement variables originating from two mutually redundant sensors are used. In this case, the preferred field of application is electronic engine power control systems,
The method described below can be used for validating both measured variables from redundant sensors in each application. It should be understood that the above application of position measurement is not limited to this. Rather, the above-described method achieves the above advantages even when used in any application where variable operating variables are measured using at least two redundant sensors. In this context, “redundant” means that both sensors measure the same operating variable and output one evaluable signal over the entire predetermined operating range of the operating variable.

In the embodiment shown in FIG. 1, an operation element 10 operable by a driver is provided.
Is connected via a mechanical connection 12 to two sensors 16,18. Lines 20 to 22 of the measurement signals from the sensors 16, 18 lead to a control unit 24.
The line 26 of the output signal from the control unit 24 leads to a regulating element 28, which is operated as a function of at least one signal supplied via the lines 20,22.

In a preferred embodiment, the adjustment element 28
Are throttle valves or other regulating elements of the internal combustion engine that determine the power. The method described below shows the above advantages also for alternative drive designs in vehicles, for example electric motors.

The sensors 16, 18 shown in the preferred embodiment of FIG. 1 are non-contact sensors. In this case, these sensors are, depending on the embodiment, respectively, two sensors in one integrated switch circuit housing, two sensors integrated in one integrated switch circuit, or two different switch circuit housings. 2 shows two sensors contained therein. However, the above method may be used with a potentiometer.

The device shown in FIG. 1 operates as follows.
The sensors 16 and 18 are connected to lines 20 and 22 of the measurement signal.
The control unit 24 is supplied with two measurement variables (signals) representative of the position of the operating element 10 via. The driver's wishes are derived from both of these measured variables, and the driver's wishes for controlling the regulating (output) element 28 in view of the other operating variables and possibly also the target variables of the other devices. It is converted into at least one operation signal. Since the power control of the engine is performed at the driver's request guided on the basis of the measured variables, it is necessary to ensure that the measured variables read by the control unit 24 are error-free. This is carried out in a known manner by the synchronous tolerance checking method described at the outset, based on a plausibility check performed by checking the difference between the two measurement variables and / or checking the detection of motion. In the error-free operation of the device, the first measurement variable is normally used as a guide signal for the so-called driver's wishes, and the second measurement variable is used only for monitoring the guide signal. When the accelerator pedal is actuated, in known devices, the correct driver desired signal is only detected after checking the tolerance range of the synchronization tolerance between the two measured variables, and only then the engine power is increased. . Based on this determination, a dead stroke of the pedal is obtained when leaving the idling range in which no substantial output change appears despite operating the pedal. The dead stroke of this pedal is a function of a given synchronization tolerance.

The measurement variables output from the sensors 16, 18 or the measurement variables derived therefrom have a fixed mathematical functional relationship between them. This fixed mathematical function relationship can be, for example, a characteristic curve with a different slope or a characteristic curve having a predetermined interval (offset value) when indicating the measured variable or the measured variable derived therefrom for the operating variable to be measured. May be present to obtain A preferred embodiment of such a characteristic curve is shown in FIG. Depending on the embodiment, either this functional relationship or the functional relationship described above exists between the sensor signals or between variables derived from the sensor signals, for example by amplification, modulation, conversion, etc. Above and below, these variables are collectively referred to as measured variables.

In FIG. 2, the measured variables U (eg, voltage, digital values, etc.) are graduated with respect to the operating variable α (position of the operating element) to be measured. The diagram shown in FIG. 2 shows that the measured variable U1 of the first sensor has a full range of values (0 to M) over the entire range of 0-100% of the operating variable.
AX), while measuring variable U of the second sensor
2 indicates that it occupies a half value range (from 0 to MAX / 2). Therefore, in the characteristic curve shown in FIG. 2, the measured variable of U2 shows a half gradient with respect to the characteristic curve of the measured variable of U1. That is, in this particular case, the following equation is obtained as a mathematical functional relationship.

U2 = (1/2) × U1 In another embodiment, a coefficient whose slope differs by that value may be selected for the other. Furthermore, instead of a linear characteristic curve, a characteristic curve of another mathematical function may be used. In addition to the different slopes, parallel characteristic curves are also possible in which there are specific offset values.

For monitoring and validation of the measured variables, instead of the principle of difference known from the prior art, it is designed to form a quotient from both signals and to compare this quotient to a predetermined tolerance range. ing.

In this case, the following equations are used depending on the embodiment. (1) U1 / U2 ≦ (2 + Δ) (2) U1 / (2 · U2) ≦ (1 + 0.5 · Δ) (3) (0.5 · U1) / U2 ≦ (1 + 0.5 · Δ) , Δ are tolerance values.

In this case, it should be noted that the method according to equations (2) and (3), unlike the method according to equation (1), involves tighter tolerance requirements in the sensor calibration. In the case of equation (2) or (3), the tolerance requirement is
It is half as compared with the equation (1).

In contrast to the method of forming a difference, which can only determine the accuracy of the signal when the absolute value of the measured variable is so large that the tolerance ranges no longer overlap, in forming the quotient for error detection, In both cases, it is possible to more quickly determine the accuracy of the measurement variable. This allows
The dead stroke of the pedal is significantly reduced. This advantage over the known method is achieved in particular when non-contact sensors with small synchronization tolerances are used, in addition to quotient formation.

The method described above is advantageous not only in the characteristic curve embodiment shown in FIG. 2, but also in other characteristic curves, in particular parallel characteristic curves with a predetermined offset.

The manner in which the quotient is formed as described above for the inspection is performed within the program of the calculation elements in the control unit 24. An example for such a program is shown in the flow chart of FIG. 3, where the above equation (1)
Are described. In this case, the individual blocks represent program steps, program parts or programs, while the connection lines indicate the flow of information.

The measurement variables U1 and U2 are read.
In the division stage 100, a quotient is formed between U1 and U2. This quotient is then provided to the comparison stage 102. Furthermore, a predetermined tolerance range Δ for the synchronization tolerance between both measurement variables is set in the memory cell 104. Other memory
Numerical value 2 exists in cell 106. In the coupling stage 108, a sum is formed from the tolerance value Δ and the numerical value 2, corresponding to the above equation (1). This sum is likewise provided to the comparison stage 102. The comparison stage 102 checks whether the quotient obtained from both measured variables is less than or equal to the determined tolerance variable (2 + Δ). If this is the case, the measured variable is evaluated as correct, while if the quotient exceeds the tolerance variable (2 + Δ), an error is assumed. In this case, in a preferred embodiment, the alarm lamp 110 is turned on and / or the error memory is written when multiple errors occur and / or the vehicle output with defective measurement variables is limited and / or limited. Alternatively, it is determined and switched to a defect-free measurement variable for further control of the drive unit.

Similar processing is performed for the above equations (2) and (3). The illustrated method can be used for any type of measurement variable, such as analog, digital, pulse width modulation, and the like.

[Brief description of the drawings]

FIG. 1 is an overall block circuit diagram of a control unit according to the invention in which operating variables are measured by at least two mutually redundant sensors and monitor the measured variables.

FIG. 2 is a characteristic curve of an evaluation measurement variable with respect to a driving variable, showing a preferred embodiment of the present invention.

FIG. 3 is a flow chart illustrating a preferred embodiment of validation by forming a quotient of two measurement variables.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Operating element 12 Mechanical coupling 16, 18 Sensor 20, 22, 26 Line 24 Control unit 28 Adjusting element 100 Division stage 102 Comparison stage 104, 106 Memory cell 108 Coupling stage 110 Alarm lamp U, U1, U2 Measurement variable α operation variable

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hans-Christian Engelbrecht Germany 70469 Stuttgart, Thuringer-Wald-Strasse 22 (72) Inventor Guido Funke Germany 74354 Bezigheim-Mott Marsheim, Mundelsheimer Werk 37 (72) Inventor Thomas Clotzbucher, Germany 70635 Rudersberg, Obererweiler 9 F-term (reference) 3G084 BA05 DA27 EA11 EB08 EB22 EC04 FA10 5H223 AA10 BB04 CC03 DD09 EE02

Claims (6)

[Claims] 1. At least two means for measuring operating variables
At least two measurement variables are generated from one redundant sensor, a fixed functional relationship exists between both said measurement variables, and these measurement variables are mutually compared with a predetermined tolerance range, and an unacceptable deviation In some cases, wherein an error is inferred for at least one of the measured variables, a method of measuring and monitoring the operating variable, wherein the comparing is performed based on a quotient between both of the measured variables. A method for measuring and monitoring characteristic operating variables. 2. The method of claim 1, wherein the measurement variable is a measurement variable generated directly from the redundant sensor or a measurement variable derived therefrom. 3. The method as claimed in claim 1, wherein the characteristic curve of the measured variable with respect to the operating variable to be measured has a different slope, and both measured variables cover the entire range of the operating variable. Method. 4. The apparatus according to claim 1, wherein the measurement variable represents a position of an operation element operable by a driver.
Or any of the three methods. 5. The sensor for generating the measurement variable,
5. The method according to claim 1, wherein the sensor is a non-contact sensor. 6. A redundant sensor for generating a measured variable from an operating variable and determining a fixed functional relationship between the measured variables and determining the measured variable by a predetermined tolerance range to check for errors. Control unit (2
4) wherein in the event of an unacceptable deviation, the control unit detects an error in one of the measured variables, the operating variable measuring and monitoring device comprising: An apparatus for measuring and monitoring operating variables, which is performed based on a quotient between measured variables.