DE102018218566A1 - Device and method for fault diagnosis in a vehicle - Google Patents

Abstract

Device and method for fault diagnosis in a vehicle, comprising determining (404) a first value for a first variable depending on information about an operating variable of the vehicle, determining (404) a second value for a second variable depending on information about the operating variable of the vehicle, wherein the sizes of different functional units define information about the operating variable that is acquired independently of one another, determining (406) a diagnostic result depending on the first value, the second value and a physical system model of the vehicle, which defines a relationship between the first variable and the second variable that is superior to the functional units .

Description

State of the art

In a fault diagnosis for a vehicle, a functional unit, i.e. a subsystem or a component of the vehicle, sensor signals measured by sensors in a vehicle. Depending on the measured sensor signals, it is checked whether there is an error. For example, redundant sensors are used to plausibility check the redundant sensor signals. To isolate a fault, i.e. To locate the faulty sensor signal, three redundant sensor signals can be used.

In contrast, it is desirable to further improve the fault diagnosis.

Disclosure of the invention

This is achieved through the subject matter of the independent claims.

The method for fault diagnosis in a vehicle comprises the steps of determining a first value for a first variable depending on information about an operating variable of a vehicle, determining a second value for a second variable depending on information about the operating variable of the vehicle, the sizes of different functional units Define information about the operating variable that is acquired independently of one another, determine a diagnostic result depending on the first value, the second value and a physical system model of the vehicle, which defines a relationship between the first variable and the second variable that is superior to the functional unit. This indicates the presence of an error in the system.

In the following, size, which defines information about the operating size recorded by the functional units, is understood to mean, for example, a variable whose value characterizes an operating size that is to be monitored in the error diagnosis.

Operating variables such as currents, voltages and speeds are recorded by sensors.

Information about an operating variable is understood to mean, for example, a sensor signal or a signal determined from at least one sensor signal by a calculation rule.

The sensor signal is, for example, a rotational speed of an engine, a transmission or a wheel of the vehicle.

The signal determined from sensor signals by a calculation rule is, for example, an engine speed which is determined from sensor signals for a transmission output speed by means of an instantaneous transmission ratio. Further examples are a transmission speed that is determined from sensor signals for an engine output speed by means of an instantaneous gear ratio or a vehicle speed that is determined from a wheel speed.

In the following, a functional unit is to be understood as a control unit or a subsystem or a component of the vehicle, for example.

The fault diagnosis provides, for example, to determine the diagnostic result for an operating variable of the vehicle as a function of two independently determined values, the first value and the second value, both of which contain information about the same operating variable.

The relationship characterizes, for example, a calculation rule or an equation. Due to the relationship between the first variable and the second variable, values of these variables can be converted into one another. The diagnostic result is determined, for example, by checking whether the first value and the second value can be converted into one another by the relationship.

The physical system model of the vehicle characterizes a relationship between a first physical operating variable and a second physical operating variable. The first physical operating variable is, for example, a rotational speed of an engine of the vehicle. The second physical operating variable is, for example, a rotational speed on an output of a transmission of the vehicle, which can be driven by the engine.

Both physical operating variables are recorded, for example, as information about operating variables from different sensors and different functional units. Depending on this, the two quantities are determined and their values compared using the relationship. The relationship characterizes the gear ratio in this example.

For example, an error is output as the diagnosis result if the values differ too much from one another.

The method preferably includes receiving information about an operating variable of a vehicle from at least two different functional units of the vehicle.

It is preferably provided that the relationship comprises an overdetermined bipartite graph, which assigns equations of the system model and unknown variables of the system model, and the diagnosis result is determined depending on the equations from the overdetermined bipartite graph. This indicates the presence of an error in the system.

It is preferably provided that the information about the operating variable is defined by sensor data, and the system model depicts a large number of sensor data of different functional units of the vehicle and their physical relationship to one another. This is a particularly well-suited representation.

It is preferably provided that the system model defines a bipartite graph that includes the overdetermined biparite graph. This is a particularly well-suited procedure.

The method preferably includes determining a third value for a third variable depending on information about the operating variable of the vehicle, which is recorded by a third functional unit of the vehicle, determining the diagnostic result depending on the first value, the second value, the third value and one overdetermined physical system model of the vehicle, which defines a superordinate relationship between the first size, second size and third size of the functional unit, an error being identified by a comparison of the first size, the second size and the third size, the sizes depending on the parent context defined relations between the sizes are compared. In this way, sensor signals of the same operating parameters are localized and identified.

It is preferably provided that a remainder is determined depending on the equations of the overdetermined bipartite graph, and a check is carried out to determine whether the remainder has reached or fallen below a limit value, an error being recognized if the remainder is greater than the limit value. The error is thus determined by a simple evaluation of analytical redundancy relationships of the equations from the overdetermined graph.

A device for fault diagnosis in a vehicle comprises a microprocessor and a memory with instructions, the method of which, when executed by the microprocessor, is carried out.

• 1 schematisch Teile eines Fahrzeugs,
• 2 schematisch Teile einer Vorrichtung zur Fehlerdiagnose,
• 3 Teile eines Systemmodells,
• 4 Schritte in einem Verfahren zur Fehlerdiagnose.

Further advantageous configurations result from the following description and the drawing. The drawing shows:

• 1 schematically parts of a vehicle,
• 2nd schematically parts of a device for fault diagnosis,
• 3rd Parts of a system model,
• 4th Steps in a troubleshooting procedure.

1 shows schematically parts of a vehicle 100 . The vehicle includes an inverter 102 , a DC / DC converter 104 , air conditioning 106 , an engine M , a gear 108 and a landing gear 110 .

The motor M , for example an electric motor, rotates at a speed ωe and generates an engine torque Te . The gear 108 is from the engine M powered and drives the chassis 110 at one speed ωm and a moment Tm .

The chassis 110 moves the vehicle at one speed Vveh . On the chassis 110 act forces Fl .

A battery 112 , in the example a high-voltage power supply with a battery voltage Ubatt between the first battery terminals HV + and the second battery terminal HV- , supplies the vehicle 100 with a battery power Ibatt.

The second battery clamp HV- is with the engine M , the DC / DC converter 104 and the air conditioning 106 via a return line 114 connected. The first battery clamp HV + is with the air conditioner 106 via a supply line 116 and a first resistance Rcab1 connected, and supplies a voltage Uhvac and a current Ihvac . The first battery clamp HV + is with the DC / DC converter 104 via a supply line 116 and a second resistor Rcab2 connected, and provides a converter voltage Udcdc and a converter current Idcdc . The first battery clamp HV + is with the inverter 102 about a third resistance Rcab3 connected and provides an inverter voltage Uinv and an inveter stream linv .

The motor M is from the inverter 102 over three phase lines with three current phases Yes , Ib , Ic provided.

A device 200 is used to diagnose errors 2nd described. The device 200 comprises a computing device 202 , for example a microcontroller, and a memory 204 for instructions when they are executed by the computing device 202 a procedure described below is running. The memory and the computing device 202 are on a data line 206 connected. In the example, the instructions are a computer program.

The computing device 202 is in the example via a data bus 208 with a first functional unit 210 , a second functional unit 212 and a third functional unit 214 connectable.

In the example is the first functional unit 210 a battery control unit for the battery 102 . In the example is the second functional unit 212 an inverter control unit for the inverter 102 . In the example is the third functional unit 214 a battery control unit for the DC / DC converter 104 . Additional functional units can control units for the air conditioning system 106 and the landing gear 110 form.

Functional units are control units for subsystems or components of the vehicle. Sensor signals required for the functional units are recorded by sensors. The sensors provide information about the operating parameters of the vehicle, such as currents, voltages and speeds.

The first functional unit 210 captures sensor data from a first sensor 216 . In the example, the voltage is the first variable Ubatt detected. The second functional unit 212 captures sensor data from a second sensor 218 . In the example, the inverter voltage is the second variable Uinv detected. The third functional unit 214 captures sensor data from a third sensor 220 . In the example, the transformer voltage is the third variable Udcdc detected. Other functional units can have other voltages, for example the voltage Ihvac to capture.

As an alternative or in addition to voltages, other quantities can also be recorded or used. Examples of these quantities are the current to the functional units, the speed ωe of the motor M , the speed ωm of the transmission or a speed of a wheel speed sensor or the vehicle speed calculated therefrom Vveh be.

The sensors provide information about operating variables for fault diagnosis and can be integrated into the respective functional unit or via a respective sensor line 222 be connected to the respective functional unit. The functional units record the information independently of one another.

The device 200 For fault diagnosis, it is designed to receive the information about an operating variable of the vehicle from at least two different functional units of the vehicle. On the basis of this information, it can be checked whether there is an error or not, based on two different variables that are determined by two different functional units independently of one another for the same, in particular, physical operating variable. For example, there is an error if the two different sizes differ too much. A physical relation of the two different quantities is shown in this consideration using a physical system model 300 for fault diagnosis, which is based on the 3rd is described. The physical system model 300 in the example defines a first relationship that is superior to the functional units R1 between battery voltage Ubatt , Inverter voltage Uinv , Converter voltage Udcdc and the voltage Uhvac. The physical system model 300 in the example defines a second relationship that is superior to the functional units R2 immediate rpm ωe of the motor M and speed ωm of the transmission.

With such a system model 300 Both a plausibility check of the sensor signals and isolation, ie localization of a faulty sensor signal is possible.

It is sufficient for the plausibility check of the sensor signals if the relationship between two of the variables is defined.

For a large number of sensor signals of a large number of different functional units, the assignment of a large number of sizes to a large number of relations is used. The relations can be defined, for example, by equations of a vehicle model or a part thereof.

The relationship includes, for example, an overdetermined bipartite graph, the equations of the system model 300 and unknown variables of the system model 300 assigns. In the example is the first assignment R1 by the voltage equations for a parallel connection of a first series connection, a second series connection, a third series connection with the battery voltage Ubatt described. The first series connection comprises the first resistor Rcab1 and the air conditioning 106 , the second series circuit comprises the second resistor Rcab2 and the DC / DC converter 104 , and the third series circuit comprises the third resistor Rcab 3rd and the inverter 102 . For the second assignment R2 can the gear ratio of the gear 108 be used.

In the example, the diagnosis result is determined depending on the equations from the overdetermined bipartite graph, which relate to the variables to be checked for plausibility. The variables of the equations correspond to the variables for fault diagnosis and the values of the variables are checked for plausibility by calculating the values of the variables. Since the graph is overdetermined, the presence of an error in the system can be recognized.

Depending on the equations of the overdetermined bipartite graph, for example, a remainder, ie a value by which the value of one or the values of several variables deviate from the values that lead to a solution of the equation, is first determined.

In this case it is checked whether the rest reaches or falls below a limit value. If the remainder is zero, the equations are satisfied and there is no error. Small deviations can be tolerances that do not mean errors. An error is detected when the rest is greater than the limit. The error is thus determined by a simple evaluation of analytical redundancy relationships of the equations from the overdetermined graph.

The rest characterizes in the example an error component of a measured signal with respect to an error-free signal. The error-free signal is defined for the error-free case.

4th shows steps in a procedure for fault diagnosis. In the example, the battery voltage should be used as the operating variable Ubatt be monitored. One of the speeds or a current could be monitored analogously.

The process looks in one step 402 receive information about the operating size of the vehicle from at least two mutually different functional units of the vehicle.

In the example, the first parameter is the battery voltage Ubatt received by the first functional unit of the vehicle, ie the battery control unit.

The second parameter is the inverter voltage Uinv , which is detected by the second functional unit of the vehicle, ie the inverter control unit.

The transformer voltage is also optionally available as a third variable Udcdc received, which is detected by the third functional unit of the vehicle, ie the converter control units.

Optionally, other variables such as the voltage Uhvac can be received at the air conditioning system.

Then one step 404 executed.

In step 404 a first value is determined for the first size. The first value becomes dependent on information about the size of the operation, which is provided by the first functional unit 210 was received, ie in the example of the value of the battery voltage Ubatt , certainly.

In step 404 a second value is also determined for the second variable. The second value becomes dependent on information about the size of the operation by the second functional unit 212 was received, ie in the example of the value of the inverter voltage Uinv , certainly.

Optional is in step 404 a third value is determined for the third size. The third value is dependent on information about the size of the operation by the third functional unit 214 was received, ie in the example of the value of the converter voltage Udcdc , certainly.

Then one step 406 executed.

In step 406 a diagnostic result is determined. The diagnostic result is dependent on the first value, the second value, optionally also the third value, and the higher-level physical system model 300 of the vehicle determines which defines a relationship between the first variable and the second variable and optionally also the third variable, which is superior to the functional unit.

The overarching relationship includes the overdetermined bipartite graph, the equations of the system model 300 and unknown variables of the system model 300 assigns. The system model 300 In particular, defines a bipartite graph that includes the overdetermined bipartite graph. In the example, the diagnostic result is determined depending on the equations from the overdetermined bipartite graph.

The information about the company size is defined by the sensor data. The system model 300 depicts a large number of sensor data from different functional units of the vehicle and their physical relationship to one another.

An error is identified, for example, by comparing the first variable, the second variable and optionally the third variable, the variables being compared depending on the relationships between the variables defined by the relationship.

In one aspect, a remainder is determined from the equations of the overdetermined bipartite graph. In this aspect, it is checked whether the remainder reaches or falls below a limit value and an error is recognized if the remainder is greater than the limit value. The error is thus determined by a simple evaluation of analytical redundancy relationships of the equations from the overdetermined graph.

Then, for example, the steps 402 to 406 executed again in this or another order.

Claims (10)

Method for fault diagnosis in a vehicle, characterized by determining (404) a first value for a first variable depending on information about an operating variable of the vehicle, Determining (404) a second value for a second variable depending on information about the operating variable of the vehicle, the sizes of different functional units defining information about the size of the business that is acquired independently of one another, Determining (406) a diagnostic result as a function of the first value, the second value and a physical system model (300) of the vehicle, which defines a relationship between the first variable and the second variable that is superior to the functional units. Procedure according to Claim 1 , characterized by receiving (402) information about an operating variable of a vehicle from at least two mutually different functional units of the vehicle. Procedure according to Claim 1 or 2nd , characterized in that the context comprises an overdetermined bipartite graph, which assigns equations of the system model (300) and unknown variables of the system model (300), and the diagnosis result is determined depending on the equations from the overdetermined bipartite graph. Method according to one of the preceding claims, characterized in that the information about the operating variable is defined by sensor data, and wherein the system model (300) depicts a large number of sensor data of different functional units of the vehicle and their physical relationship to one another. Method according to one of the preceding claims, characterized in that the system model (300) defines a bipartite graph which comprises the overdetermined biparite graph. Method according to one of the preceding claims, characterized by determining (404) a third value for a third variable depending on information about the operating variable of the vehicle, which is detected by a third functional unit of the vehicle, determining (406) the diagnostic result depending on the first value, of the second value, of the third value and of an overdetermined physical system model (300) of the vehicle, which defines a relationship between the first size, second size and third size that is superior to the functional unit, an error being obtained by comparing the first size, the second size and of the third variable is recognized, the variables being compared depending on the relations (R1, R2) defined by the superordinate relationship between the variables. Procedure according to one of the Claims 5 or 6 , characterized in that depending on the equations of the overdetermined bipartite graph, a remainder is determined (406), and a check is carried out to determine whether the remainder reaches or falls below a limit value, an error being detected if the remainder is greater than the limit value. Device (200) for fault diagnosis in a vehicle, characterized by a microprocessor (202) and a memory (204) with instructions, when executed by the microprocessor, the method according to one of the Claims 1 to 7 expires. Computer program, characterized by instructions, when executed by a computer, the method according to one of the Claims 1 to 7 expires. Computer program product, characterized in that the instructions on the computer program product Claim 9 are saved.

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