METHOD AND DEVICE FOR OPERATING A BRAKE SYSTEM, BRAKE SYSTEM, AND VEHICLE

Abstract

A method for operating a brake system of a vehicle, in particular, of a motor vehicle. The brake system includes at least one electric actuator, in particular, a brake booster, which may be driven to generate a braking force, the actuator being controllable by an autonomous driving system, and as a function of manipulation of a brake pedal of the vehicle; and an emergency braking action being initiated, when the actuator is driven both by the autonomous driving system and by manipulation of a brake pedal. The control by the autonomous driving system is superimposed with a varying validation signal, a differential travel between an actuator element of the actuator and the brake pedal is monitored, and the driving of the actuator via manipulation of the brake pedal during the control by the autonomous driving system is detected, if the differential travel varies.

Claims

1-8. (canceled)

9. A method for operating a brake system of a motor vehicle, the brake system including at least one electric actuator, which may be driven to generate a braking force, the actuator being controllable by an autonomous driving system and as a function of manipulation of a brake pedal of the vehicle, the method comprising: superimposing a control signal of the actuator from the autonomous driving system with a varying validation signal; monitoring a differential travel between an actuator element of the actuator and the brake pedal; detecting a driving of the actuator by brake-pedal manipulation during the control by the autonomous driving system when the differential travel varies; and initiating an emergency braking action when the actuator is driven both by the autonomous driving system and by manipulation of the brake pedal.

10. The method as recited in claim 9, wherein the actuator is a brake booster.

11. The method as recited in claim 9, wherein the validation signal is selected in such a manner, that it differs from a time characteristic of manipulation of the brake pedal.

12. The method as recited in claim 9, wherein the validation signal is selected as a square-wave signal, or a saw-tooth signal, or a triangular signal or a sinusoidal signal.

13. The method as recited in claim 9, wherein during the control of the actuator by the autonomous driving system, the driving via manipulation of the brake pedal is detected, if a characteristic of the differential travel corresponds to a characteristic of the validation signal.

14. The method as recited in claim 9, wherein a setpoint volumetric flow rate, or a setpoint speed, or a setpoint engine torque or a setpoint current is selected as the validation signal.

15. A device for operating a brake system of a motor vehicle, the brake system including at least one actuator configured to generate a braking force, an autonomous driving system configured to automatically control the actuator, and at least one brake pedal manipulatable by a driver of the motor vehicle, the device comprising: a control unit, which, in normal use, is specially configured to: superimpose a control signal of the actuator from the autonomous driving system with a varying validation signal; monitor a differential travel between an actuator element of the actuator and the brake pedal; detect a driving of the actuator by brake-pedal manipulation during the control by the autonomous driving system when the differential travel varies; and initiate an emergency braking action when the actuator is driven both by the autonomous driving system and by manipulation of the brake pedal.

16. The device as recited in claim 15, wherein the actuator includes a brake booster.

17. A brake system for a motor vehicle, comprising: an electric actuator which may be driven to generate a braking force; an autonomous driving system which is configured to control the actuator; and a brake pedal; and a device including: a control unit, which, in normal use, is specially configured to: superimpose a control signal of the actuator from the autonomous driving system with a varying validation signal; monitor a differential travel between an actuator element of the actuator and the brake pedal; detect a driving of the actuator by brake-pedal manipulation during the control by the autonomous driving system when the differential travel varies; and initiate an emergency braking action when the actuator is driven both by the autonomous driving system and by manipulation of the brake pedal.

18. The brake system as recited in claim 17, wherein the electric actuator is a brake booster.

19. A vehicle having a brake system, the brake system comprising: an electric actuator which may be driven to generate a braking force; an autonomous driving system which is configured to control the actuator; and a brake pedal; and a device including: a control unit, which, in normal use, is specially configured to: superimpose a control signal of the actuator from the autonomous driving system with a varying validation signal, monitor a differential travel between an actuator element of the actuator and the brake pedal, detect a driving of the actuator by brake-pedal manipulation during the control by the autonomous driving system when the differential travel varies, and initiate an emergency braking action when the actuator is driven both by the autonomous driving system and by manipulation of the brake pedal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1 shows a simplified plan view of a motor vehicle.

[0015] FIGS. 2A and 2B show graphs for explaining an advantageous method of operating a brake system of the motor vehicle, in accordance with an example embodiment of the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0016] FIG. 1 shows a simplified plan view of a motor vehicle 1, which includes a brake system 2, as well as an autonomous driving system 3. Autonomous driving system 3 is configured to guide motor vehicle 1 fully autonomously to a destination as a function of the selected destination. In this context, driving system 3 is optionally connected to a surround-sensor system 4 that includes a plurality of surround sensors 5, such as radar, ultrasonic or laser sensors, which monitor the surrounding area of motor vehicle 1 for potential danger. If, for example, with the aid of surround-sensor system 4, driving system 3 determines that motor vehicle 1 is moving towards an object or a vehicle traveling ahead, at a speed, which could result in motor vehicle 1 crashing into the object, then driving system 3 is configured to trigger brake system 2 to initiate emergency braking for decelerating motor vehicle 1, through which the crash is intended to be prevented.

[0017] The brake system 2 at hand includes an electromechanical brake booster 6, which may be driven electrically to increase a hydraulic pressure in brake system 2, in order to provide an increased brake pressure and/or an increased braking force at wheel brakes 7. In this context, brake booster 6 is controlled as a function of manipulation of a brake pedal 8 by a driver of motor vehicle 1. Thus, brake booster 6 constitutes an actuator 9 for increasing the braking force.

[0018] Brake booster 6 is also connected to driving system 3 in a manner allowing transmission of signals, so that driving system 3 is also able to control brake booster 6, in order to be able to initiate or carry out, in particular, an autonomous braking action, as already explained above. The hydraulic pressure generated by brake booster 6 is then made available to one or more brake circuits represented in FIG. 1 in a simplified manner by a box 10. In this context, a control unit 11 of motor vehicle 1 monitors brake booster 6, as well as driving system 3 and brake pedal 8, in the manner described in the following, in order to check the plausibility of a request for emergency braking by driving system 3. If driving system 3 requests emergency braking by triggering actuator 6 to increase the braking force, then control unit 11 ensures that the control signal of driving system 3 is superimposed with a validation signal, which has a varying characteristic.

[0019] In this regard, FIG. 2A shows a simplified graph of the characteristic of validation signal VS across braking-request signal B1 of driving system 3. Validation signal VS is selected to be a signal having a sinusoidal characteristic. Alternatively, a square-wave characteristic, a saw-tooth characteristic, or a triangular characteristic of the validation signal is possible. Validation signal VS is such that, with regard to its dynamics, it may not be generated by a human driver via manipulation of the brake pedal. Due to the variation, the validation signal is superimposed on the actual request signal and results in a predefined brake value. In this context, the braking request is implemented, using a volumetric flow rate request of the driving system to electromechanical brake booster 6. Thus, validation signal VS relates to volumetric flow rate request V.

[0020] Brake pedal 8 is coupled to actuator 9 in such a manner, that in response to a request for an increased braking torque, an actuator element of actuator 9 drives brake pedal 8 at the presence of a predefined differential travel X, using a mechanical catch. In this connection, one speaks of a negative differential travel between the actuator element and the brake pedal. If a positive differential travel X, that is, greater than 0, is present, then, by manipulating the brake pedal, the driver is requesting a higher pressure than autonomous driving system 3, which results in the increased pressure request of the driver being implemented. If differential travel X indicates a value between the minimum value and 0, then it is inferred that the driver did manipulate the pedal, but that autonomous driving system 3 specifies the intensity of the braking. FIG. 2B shows differential travel X versus time t in accordance with the volumetric flow rate request shown in FIG. 2A.

[0021] For the case in which the pedal is manipulated by the driver, the characteristic curve of the validation signal may be detected in the differential travel (signal). As long as the mechanical catch (x.sub.max) is not yet reached, the variation of the validation signal is detectable in the request and, therefore, in differential travel X. In this manner, the driver may even be detected in the case of low pedal forces on the brake pedal. Only when, in addition to the request by driving system 3, manipulation of brake pedal 8 is detected in the differential travel X via the determination of the characteristic curve of the validation signal, is the request for emergency braking by driving system 3 checked for plausibility and carried out. If the characteristic signal is added, then differential travel X is only consistently equal to a specified value, when the mechanical catch is already reached. In this case, the driver does not manipulate the pedal. In all other cases, manipulation of the brake pedal by the driver may be inferred unequivocally by evaluating the non-constant differential travel X, that is, non-uniform differential travel X. In particular, the sinusoidal characteristic of the validation signal is apparent in the differential travel, as is shown by a superposed sinusoidal curve in FIG. 2B. Thus, the manipulation of the driver may be deduced directly from the non-constant differential travel (signal). Noise of the signal is preferably taken into account and filtered, in order to prevent misinterpretation. Since the method is independent of mechanical tolerances, this increases the operative range of the detection of brake-pedal manipulation, as indicated by a range I in FIG. 2B.