METHOD AND DEVICE FOR DETERMINING WHETHER AN ERROR CONDITION IS PRESENT OR NOT IN A MOTOR VEHICLE

Abstract

A method for determining whether an error is present or not in a motor vehicle, a discrete state, in which the motor vehicle is presently in, being ascertained with the aid of a state machine, a decision being made, depending on the ascertained discrete state, whether an error is present or not, whereby the states of the state machine include acceptable states and unacceptable states, then, if the ascertained discrete state is an unacceptable state, the motor vehicle is transferred into an acceptable state.

Claims

1. A method for determining whether an error is present or not in a motor vehicle, the method comprising: ascertaining a discrete state, in which the motor vehicle is presently in, with the aid of a state machine; and making a decision, depending on the ascertained discrete state, whether an error is present or not; wherein the states of the state machine include acceptable states and unacceptable states, and wherein wherein if the ascertained discrete state is an unacceptable state, the motor vehicle is transferred into an acceptable state.

2. The method of claim 1, wherein, depending on the ascertained discrete state, a continuous actual operating parameter, which describes an operating state of the motor vehicle, is ascertained or not.

3. The method of claim 2, wherein, depending on the ascertained continuous actual operating parameter, a discrete unacceptable state is recommended, into which the state machine is to be transferred.

4. The method of claim 3, wherein the ascertained continuous actual operating parameter is compared with an ascertained setpoint operating parameter, and, depending on the result of this comparison, the discrete unacceptable state is recommended.

5. The method of claim 3, wherein the state machine is transferred into the recommended, discrete, unacceptable state.

6. The method of claim 3, wherein the recommended, discrete, unacceptable state is checked for plausibility and, depending on the result of this check, the state machine is transferred into the recommended, discrete, unacceptable state.

7. The method of claim 2, wherein the ascertainment of the continuous actual operating parameter is ascertained with the aid of a characteristic diagram or a mathematical function.

8. A computer readable medium having a computer program, which is executable by a processor, comprising: a program code arrangement having program code for determining whether an error is present or not in a motor vehicle, by performing the following: ascertaining a discrete state, in which the motor vehicle is presently in, with the aid of a state machine; and making a decision, depending on the ascertained discrete state, whether an error is present or not; wherein the states of the state machine include acceptable states and unacceptable states, and wherein wherein if the ascertained discrete state is an unacceptable state, the motor vehicle is transferred into an acceptable state.

9. The computer readable medium of claim 8, wherein, depending on the ascertained discrete state, a continuous actual operating parameter, which describes an operating state of the motor vehicle, is ascertained or not.

10. A control unit for determining whether an error is present or not in a motor vehicle, comprising: a control arrangement configured to perform the following: ascertaining a discrete state, in which the motor vehicle is presently in, with the aid of a state machine; and making a decision, depending on the ascertained discrete state, whether an error is present or not; wherein the states of the state machine include acceptable states and unacceptable states, and wherein wherein if the ascertained discrete state is an unacceptable state, the motor vehicle is transferred into an acceptable state.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 schematically shows a motor vehicle.

[0023] FIG. 2 shows a structure diagram according to a first aspect of the present invention.

[0024] FIG. 3 shows signal curves according to a second aspect of the present invention.

[0025] FIG. 4 shows a flow chart of the possible sequence of a specific embodiment of the present invention.

DETAILED DESCRIPTION

[0026] FIG. 1 shows a motor vehicle 97 in which the present invention may be used. The method may, for example, be carried out by a control unit 98, in particular carried out by a computer program which is stored on a machine-readable storage medium 99 which is contained in control unit 98. Control unit 98 hereby receives signals from sensors 50 . . . 59 in a known way and controls actuators 60 . . . 69 on the basis of these sensor signals.

[0027] FIG. 2 shows a structure diagram which illustrates how the method according to the present invention may progress according to one aspect of the present invention. State machine 1, which includes states 10, 20, 30, is provided. Depending on the ascertained sensor values of sensors 50 . . . 59, state transitions are defined, which transfer state machine 1 from the present state, for example, state 20, into another state, for example, state 10. These states 10, 20, 30 are either acceptable or unacceptable. If the present state, for example state 20, is unacceptable, an error response function 411 is initiated. This causes state 20 to be transferred into another state, for example, into state 10.

[0028] The quantity of error response functions 411, 412, 413 is designated as error response block 4. Likewise, monitoring functions 211, 212, 213 are provided in a monitoring block 2, and plausibility check functions 311, 312, 313 in a plausibility check block 3.

[0029] State 10 is, for example, an acceptable state. Depending on which state state machine 1 is in, a monitoring function is called up from monitoring block 2, for example, monitoring function 211. This function detects a sensor value, for example, and a speed signal, and compares the value of this signal with a threshold value. Depending on this comparison, a plausibility check function 311 is called up, which ascertains whether the result of this comparison is compatible with the fact that the state machine is in state 10.

[0030] If the result is not compatible with the state, the state machine is transferred into unacceptable state 40. Thus, because the state machine is then in unacceptable state 40, error response function 413 is actuated.

[0031] FIG. 3 shows, by way of example, signal curves which lead to an error detection by monitoring block 211. Signal curves actually ascertained in control unit 98 are represented as dashed lines; states recognized in state machine 1 are represented with a solid line. FIG. 3a) shows a gear selection; FIG. 3b) shows a gas pedal position; FIG. 3c) shows a speed of motor vehicle 97; FIG. 3d) shows a speed of an internal combustion engine of motor vehicle 97; FIG. 3e) shows a torque generated by the internal combustion engine; and FIG. 3f) shows a signal of an idle speed controller. The discrete state of the motor vehicle recognized in state machine 1 is, in this example, a tuple of substates, which includes these six states as separate dimensions.

[0032] At starting point in time to, the vehicle is standing. The gear selection state signal shown in FIG. 3a) is in the park-neutral state; the gas pedal state signal shown in FIG. 3b) is in the gas pedal not actuated state; the speed state signal shown in FIG. 3c) is in the stopped state; the rpm state signal shown in FIG. 3d) is in the idle speed state; the torque state signal shown in FIG. 3e) is in the constant torque state; and the idle speed controller state signal shown in FIG. 3f) is in the ISC active state. The recognized discrete state of motor vehicle 97 in state machine 1 thus corresponds to the state (park-neutral, gas pedal not actuated, stopped, idle speed, constant torque, ISC active). This state corresponds to state 30 in FIG. 2.

[0033] At a point in time t1, a gear is engaged and the gear selection state signal (FIG. 3a) jumps into the drive substate, since it has been recognized that the gear selection signal is changed to 1.sup.st gear. The gas pedal state signal (FIG. 3b) remains in the gas pedal not actuated substate, since it has been recognized that the gas pedal signal remains at the value 0%. The speed state signal (FIG. 3c) jumps to the in motion substate, since it has been recognized that the speed signal has exceeded a predefinable minimum speed. The rpm state signal (FIG. 3d) remains in the idle speed substate, since it has been recognized that the rpm signal is not greater than a predefinable minimum rpm. The torque state signal (FIG. 3e) remains in the constant torque substate, since it has been recognized that the torque signal has changed by not more than a predefinable minimum torque change. The idle speed controller state signal (FIG. 3f) remains in the ISC active substate. From point in time t1, the recognized discrete state of motor vehicle 97 in state machine 1 thus corresponds to the state (drive, gas pedal not actuated, in motion, idle speed, constant torque, ISC active). This state corresponds to state 10 from FIG. 2. In this state, monitoring function 211 is actuated for monitoring the rpm of the internal combustion engine and for monitoring the torque signal.

[0034] At another point in time t2, the gear selection state signal (FIG. 3a), the gas pedal state signal (FIG. 3b), and the speed state signal (FIG. 3c) remain unchanged with respect to point in time t1. The rpm signal (FIG. 3d) increases, and monitoring function 211 recognizes that the rpm exceeds the idle speed. Monitoring function 211 therefore recommends to transfer the rpm state signal into the rpm greater than idle speed substate, since it has been recognized that the rpm signal is greater than the predefinable minimum rpm. Monitoring function 211 also recommends to transfer the torque state signal into the increasing torque state, since an increase of the torque signal has been recognized. Monitoring function 211 also recommends to transfer the idle speed controller state signal (FIG. 3f) into the ISC not active state, since it has been recognized that the idle speed controller signal fell below a predefinable idle speed controller activation degree. Monitoring function 211 thus recommends to transfer the recognized discrete state of motor vehicle 97 in state machine 1 into the state (drive, gas pedal not actuated, in motion, rpm greater than idle speed, increasing torque, ISC not active).

[0035] Plausibility check block 311 permits this transfer. From point in time t2, the recognized discrete state of motor vehicle 97 in state machine 1 therefore corresponds to the state (drive, gas pedal not actuated, in motion, rpm greater than idle speed, increasing torque, ISC not active). This state corresponds to state 40 in FIG. 2. As a reaction to the state machine transferring into state 40, error response function 413 is called up, which turns off the internal combustion engine.

[0036] Consequently, state machine 1 recognizes that the motor vehicle has been transferred into a safe state (not shown in FIG. 2), and the method begins again.

[0037] FIG. 4 illustrates the sequence of the method. The method starts in step 1000. In step 1010, the state is ascertained, in which motor vehicle 97 is in, and state machine 1 is transferred into this state.

[0038] In subsequent step 1020, it is checked whether this state is an acceptable state. If this is the case, it branches back to step 1010, where the state is updated. If this is not the case, step 1030 follows, in which a monitoring function is actuated. A continuous actual operating parameter, for example the rpm of the internal combustion engine, is detected and compared with a setpoint operating parameter, for example, the nominal idle speed. Additional variables may also be detected and compared in parallel.

[0039] Depending on the results of these comparisons, a discrete unacceptable state, into which state machine 1 is to be transferred, is recommended in following step 1040.

[0040] Step 1050 follows, in which a plausibility check function ascertains whether this recommended state is plausible with the actual state of state machine 1, for example, whether a transition from the actual state into the recommended state is stored as a possibility in a list in control unit 99. If this is not the case, the method branches back to step 1010.

[0041] If, in contrast, this is the case, state machine 1 is transferred into this recommended, discrete, unacceptable state in step 1060.

[0042] Step 1070 follows, in which an error response function is called up. The method ends here.