METHOD FOR DETECTING A RESISTANCE ON A BRAKE PEDAL PULLED BY AN ACTUATOR AND METHOD FOR CONTROLLING AN ACTUATOR

Abstract

A method for detecting a resistance on a brake pedal of a brake system, in which a brake pedal is pulled by an actuator, in which an ease of movement of the brake pedal is determined during operation of the actuator, wherein a resistance is detected as soon as the ease of movement is no longer clearly determined, and a method for controlling an actuator, a computer program product, control unit or system comprising a plurality of control units, and a corresponding device.

Claims

1. A method for detecting a resistance on a brake pedal of a brake system, wherein said brake pedal is pulled by an actuator, in particular a brake booster, in which an ease of movement of the brake pedal is determined during an operation of the actuator, wherein the resistance is detected when the ease of movement is no longer specifically determinable.

2. A method according to claim 1, wherein the operation of the actuator is or has been triggered by a driver-independent brake request (EBR).

3. A method according to claim 1, wherein the ease of movement of the brake pedal is determined by evaluating a force acting on the brake pedal or on an input piston coupled or couplable to the brake pedal.

4. A method according to claim 1, wherein the ease of movement of the brake pedal is determined by evaluating a sum of all forces which act on the brake pedal or on the input piston coupled or couplable to the brake pedal.

5. A method according to claim 3, wherein the force or the sum of all forces is calculated or estimated.

6. A method according to s claim 1, wherein a position or a travel, such as a displacement, of an actuating element, such as a rack, of the actuator is identified or estimated.

7. A method according to claim 6, wherein a motor position signal of a motor, such as an electric motor, of the actuator is received or acquired, for example via a motor position sensor, wherein the position or the travel of the actuating element (5) of the actuator (1) is identified on the basis of the motor position signal.

8. A method according to claim 1, wherein a pedal travel or a pedal position of the brake pedal or an input piston coupled or couplable to the brake pedal, is identified.

9. A method according to claim 8, wherein a pedal travel sensor signal is received or acquired via a pedal travel sensor, wherein the pedal travel or the pedal position is identified on the basis of a pedal travel sensor signal.

10. A method according to claim 9, wherein the pedal travel sensor signal is filtered, in particular filtered via constant filtering, and/or corrected, in particular via a predetermined error correction and/or a correction algorithm.

11. A method according to claim 1, wherein a drag distance is identified and/or received, wherein the drag distance is a distance and/or a relative travel between a pedal-travel-sensor connecting element and a housing element and/or a spring element arranged between the pedal-travel-sensor connecting element and the housing element.

12. (canceled)

13. A method according to claim 1, wherein a calculation of a force or a sum of all forces is based on a model-based estimation of the force.

14. A method according to claim 13, wherein the model-based estimation takes place on the basis of a speed-dependent force component and/or a position-dependent force component.

15. (canceled)

16. A method according to claim 1, wherein the evaluation of a force or a sum of all forces takes place on the basis of a reference force curves, for example an empirically determined reference force curve.

17. A method according to claim 1, wherein a force or a sum of all forces corresponds substantially to a force or a force curve of a spring element arranged between a pedal-travel-sensor connecting element and a housing element.

18. A method according to claim 1, wherein an evaluation of a force or a sum of all forces takes place on the basis of a temporally shifting force evaluation window, in particular with a plurality of force ranges, or taking into account dynamic or quasi-static force curves.

19. A method according to claim 1, wherein a differential travel between a position and/or a travel of an actuating element, such as a rack, of the actuator and a pedal travel and/or a pedal position of the brake pedal and/or an input piston coupled or couplable to the brake pedal, is determined.

20. A method according to claim 1, wherein the determination of the ease of movement of the brake pedal and/or the evaluation takes place via a frequency analysis, in particular with a time window.

21. (canceled)

22. (canceled)

23. (canceled)

24. (canceled)

25. (canceled)

26. (canceled)

27. A method for controlling an actuator, in particular a brake booster of a brake system of a motor vehicle, wherein during an operation of the actuator triggered by a driver-independent brake request, a movement of a brake pedal or an input piston coupled or couplable to the brake pedal, is prevented when a resistance on the brake pedal pulled by the actuator is detected, wherein the detection of the resistance according to the method takes place according to claim 1.

28. A computer program product, which prompts a device to execute a method according to claim 1, and/or comprising program code to implement a method according to claim 1 when the computer program product is executed on a processor.

29. (canceled)

30. (canceled)

Description

BRIEF DESCRIPTION OF DRAWINGS

[0040] Exemplary arrangements are described in more detail below, with reference to figures in which, schematically and by way of example:

[0041] FIG. 1 shows the design and function of the mechanism or actuator; and

[0042] FIG. 2 shows the design and function of the algorithm in a schematic representation.

DETAILED DESCRIPTION

[0043] FIG. 1 shows a schematic representation of the relevant design for dynamic driver foot protection (Dynamic Driver Foot Protection System) and the function of the mechanism or actuator 1 for detecting a resistance on a brake pedal of a brake system, which brake pedal is pulled by the actuator 1.

[0044] The actuator 1 is designed as an electromechanical brake booster 1 (EBB) and is illustrated in a starting position (rest position) in FIG. 1. An ease of movement of the brake pedal may be determined during operation of the actuator 1, wherein a resistance is detected as soon as the ease of movement is no longer clearly determined.

[0045] The actuator 1 comprises an output piston 2 (output rod), which is coupled to a primary piston of a master brake cylinder (not illustrated). The actuator furthermore comprises an input piston 3 (input rod), which is coupled to the brake pedal, for example via a lever-type gear (not illustrated).

[0046] The input piston 3 is held in a dead-centre position by the pressure force of a spring 4 (input rod spring) and the support on the housing of the actuator 1. The actuator 1 furthermore comprises an actuating element 5 in the form of a rack 5, which is in contact with the housing 6 (ratio housing), which receives the input piston 3. The actuating element 5 and the housing 6 may be held in the dead-centre position by the pre-tensioning forces of the spring configuration (not shown), which acts on the output piston 2 from the left-hand side, and a defined motor torque of a motor of the actuator. The dead-centre position is highly dependent on temperature, tolerances and wear and may be identified at almost every ignition changeover in an initialisation routine.

[0047] In the rest position (shown in FIG. 1) of the actuator 1, the maximum relative travel can be seen between the housing 6 and a pedal-travel-sensor connecting element 7 (PTS Connector). This relative movement is divided into two components, the relative travel Drag Distance and the relative travel (x_DDFF_Spring) of a spring element 8 which is mounted in a floating manner (DDFP-Spring). The relative travel Drag Distance is between the pedal-travel-sensor connecting element 7 and the spring element 8 which is mounted in a floating manner (DDFP-Spring). The relative travel x_DDFF_Spring is between one side of the spring element 8 and the housing 6. This represents the compression travel of the spring element 8 and forms an input variable for calculating an associated force, such as a spring force (DOFF-Spring-Force).

[0048] In an application which involves a driver-independent braking procedure (EBR), a force on the actuating element 5 of the actuator 1 is generated according to the transmitted volume flow request, which force displaces the actuating element 5 (to the left in FIG. 1). The housing 6, which is in contact with the actuating element 5, is pulled along at the same time. In this case, the housing 6 displaces the spring element 8, which is mounted in a floating manner, on the input piston 3 until this spring element abuts against the pedal-travel-sensor connecting element 7. The spring element 8 is then compressed between the housing 6 and the pedal-travel-sensor connecting element 7 during the continuing displacement until a force equilibrium is established between the spring element 8 and the spring 4 of the input piston 3. This force equilibrium centers the input piston 3 in the housing 6 in a quasi-static manner.

[0049] Due to the low damping coefficient of the associated guideway and high inertia of the coupled pedal, vibrations are to be expected during a free movement (without a tensile force acting on the pedal). This alters the two relative travels Drag Distance and the relative travel of the spring element 8 (x_DDFP_Spring). This latter serves for calculating and evaluating the time-varying force of the input piston 3 or the brake pedal depending on the drag distance. It is thus possible to make a reliable statement about the ease of movement of the brake pedal.

[0050] FIG. 2 shows a schematic representation of the design and function of the algorithm with which the sum of all forces on the brake pedal may be calculated and evaluated.

[0051] To this end, a purely mechanical force sensor in the form of the spring element 8 (DDFP-Spring) is integrated in the load path from the actuating element 5 of the actuator 1 to the brake pedal, which spring element outputs or provides a relative deviation and/or position signals as a consequence of a force effect. Using these position signals, a tensile force with a defined value, which acts on the brake pedal, may be promptly detected so that it is possible to prevent a continuing forwards movement of the brake pedal, which would lead to an overshooting of a defined force limit. The algorithm or the method operates according to the basic principle of observing a free running pedal so long as no flag is set.

[0052] The coupled sensors for acquiring the motor position of the motor, such as an electric motor, the actuator 1 and the pedal travel deliver the required input signals directly or indirectly. It may be necessary to process the pedal travel (PTSavg) using routines. The processing may be realized by filtering and/or correcting the pedal travel sensor signal. Constant filtering and/or a correction algorithm may be used.

[0053] The identification of the precise rack position (xRack) may take place on the basis of the motor position sensor signal.

[0054] The information relating to the drag distance may be provided. The drag distance may be subject to processing, which is performed in the subsystem Drag Distance Correction 9. The output variable in the form of the corrected processed signal is denoted by CorrectedDragDistance or Corrected Drag Distance.

[0055] The three signals xRack, PTSavg and CorrectedDragDistance may collectively form the input variables of a force estimator 10 (DFP Spring Model). Taking into account the kinematics of the mechanism, the calculation of the force (DFP_Spring_Force), which acts on the input piston and therefore on the brake pedal, may take place.

[0056] This calculated force or force curve may form the input variable of the subsystem Evaluator 11 (DFP Spring Force Investigator) and therefore forms the evaluation basis for a free running pedal. As soon as the ease of movement may no longer be clearly detected and therefore a resistance is or has been detected, a DDFP flag may be set in this subsystem and it is thus possible to activate the dynamic driver foot protection and/or control the actuator accordingly.

[0057] In the method for detecting a resistance on the brake pedal which is pulled by the actuator 1, an ease of movement of the brake pedal may therefore be determined during operation of the actuator 1, wherein a resistance is detected as soon as the ease of movement is no longer clearly determined. Then, in the method for controlling the actuator 1, during the operation of the actuator 1, which is triggered by a driver-independent brake request, the movement of the brake pedal and/or the input piston 3, which is coupled or couplable to the brake pedal, may be prevented as soon as a resistance on the brake pedal, which is pulled by the actuator 1, is or has been detected. The method for detecting a resistance and/or for controlling the actuator 1 may be and/or implement the dynamic driver foot protection.

[0058] Moreover, in addition, please refer in particular to FIG. 1 and the associated description.

[0059] “May” is used in particular to refer to optional features in the disclosure. Consequently, there are also developments and/or exemplary arrangements in the disclosure which additionally or alternatively have the respective feature or the respective features.

[0060] Isolated features may also be extracted as required from the feature combinations disclosed in the present case and, by eliminating a second structural and/or functional connection which is possibly present between the features, may be used in combination with other features to define the subject matter of a claim. The sequence and/or number of steps of the method may be varied. The methods may be combined with one another, for example to create an overall method.