Method for Controlling a Braking Torque of a Vehicle During an at Least Partly Automated Traversal of an Incline And/or a Decline, Computing Device, and Assistance System for a Vehicle

Abstract

Systems, methods, and apparatuses are provided for controlling a braking torque of a vehicle while travelling in an at least semiautomated manner. Standstill data is received, while the vehicle is traveling in the at least semiautomated manner on an incline and/or a decline, when a temporary standstill of the vehicle is requested by the assistance system. Speed values are continuously received that describe a speed of the vehicle while the vehicle is decelerating prior to the temporary standstill. Slope data is continuously determined that describes an angle of the incline or decline. An amended speed value is continuously computed that depends on the speed value and the slope data. An electronic control signal is output to control the braking torque to bring the vehicle to the temporary standstill when the amended speed value decreases below a predetermined threshold value and the standstill data are received.

Claims

1.-9. (canceled)

10. A method for controlling a braking torque of a vehicle while travelling in an at least semiautomated manner on an incline and/or a decline using an assistance system, comprising: receiving standstill data, while the vehicle is traveling in the at least semiautomated manner on the incline and/or the decline, when a temporary standstill of the vehicle is requested by the assistance system; continually receiving one or more speed values that describe a speed of the vehicle while the vehicle is decelerating prior to the temporary standstill; continually determining slope data that describes an angle of the incline or decline; continually computing an amended speed value that depends on the speed value and the slope data; and outputting an electronic control signal to control the braking torque to bring the vehicle to the temporary standstill when the amended speed value decreases below a predetermined threshold value and the standstill data are received.

11. The method according to claim 10, further comprising: receiving and/or determining acceleration data that describe an acceleration or deceleration of the vehicle prior to the temporary standstill; and computing the amended speed value based on the acceleration data.

12. The method according to claim 11, wherein the amended speed value is computed such that the amended speed value decreases below the predetermined threshold value earlier when compared with the speed value, as the acceleration or deceleration of the vehicle increases.

13. The method according to claim 10, wherein the amended speed value is computed such that the amended speed value decreases below the predetermined threshold value earlier when compared with the speed value, as the angle of the incline or decline increases.

14. The method according to claim 10, wherein the electronic control signal is output such that the braking torque to bring the vehicle to the temporary standstill increases as the acceleration or deceleration of the vehicle increases and/or the angle of the incline or decline increases.

15. The method according to claim 10, wherein the slope data that describe the angle of the incline or decline are determined by receiving data from an acceleration sensor and/or digital map data.

16. The method according to claim 10, further comprising: computing the amended speed value if the speed value decreases below a predefined minimum speed.

17. A computing device for an assistance system of a vehicle travelling in an at least semiautomated manner on an incline and/or a decline using an assistance system, the computing device comprising: a processor; and a memory in communication with the processor and storing instructions executable by the processor to configure the computing device to: receive standstill data, while the vehicle is traveling in the at least semiautomated manner on the incline and/or the decline, when a temporary standstill of the vehicle is requested by the assistance system; continually receive one or more speed values that describe a speed of the vehicle while the vehicle is decelerating prior to the temporary standstill; continually determine slope data that describes an angle of the incline or decline; continually compute an amended speed value that depends on the speed value and the slope data; and output an electronic control signal to control the braking torque to bring the vehicle to the temporary standstill when the amended speed value decreases below a predetermined threshold value and the standstill data are received.

18. The device according to claim 17, wherein the computing device is further configured to: receive and/or determine acceleration data that describe an acceleration or deceleration of the vehicle prior to the temporary standstill; and compute the amended speed value based on the acceleration data.

19. The device according to claim 18, wherein the amended speed value is computed such that the amended speed value decreases below the predetermined threshold value earlier when compared with the speed value, as the acceleration or deceleration of the vehicle increases.

20. The device according to claim 17, wherein the amended speed value is computed such that the amended speed value decreases below the predetermined threshold value earlier when compared with the speed value, as the angle of the incline or decline increases.

21. The device according to claim 17, wherein the electronic control signal is output such that the braking torque to bring the vehicle to the temporary standstill increases as the acceleration or deceleration of the vehicle increases and/or the angle of the incline or decline increases.

22. The device according to claim 17, wherein the slope data that describe the angle of the incline or decline are determined by receiving data from an acceleration sensor and/or digital map data.

23. The device according to claim 17, wherein the computing device is further configured to: compute the amended speed value if the speed value decreases below a predefined minimum speed.

24. An assistance system for a vehicle, comprising: the computing device according to claim 17, wherein the assistance system is configured for at least semiautomated longitudinal guidance of the vehicle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIG. 1 shows a schematic representation of a vehicle that comprises a computing device for carrying out a method for controlling a braking torque of a vehicle,

[0037] FIG. 2 shows the vehicle shown in FIG. 1 while it is travelling on an incline in combination with subsequent travel, during which another road user is in front of the vehicle,

[0038] FIG. 3 shows, among other things a time characteristic of the speed of the vehicle shown in FIG. 2, wherein adaptive cruise control slows the vehicle to a standstill on account of the other road user and the vehicle rolls back on account of the incline, and

[0039] FIG. 4 shows among other things a time characteristic of the speed similarly to FIG. 3, wherein the computing device controls the braking torque of the vehicle such that the vehicle is prevented from rolling back.

DETAILED DESCRIPTION OF THE DRAWINGS

[0040] In the figures, identical or functionally identical elements are provided with the same reference signs.

[0041] FIG. 1 shows a schematic representation of a vehicle 1, which is in the form of a passenger car, in a plan view. The vehicle 1 comprises a computing device 2 that is used to control a braking torque of the vehicle 1 while it is travelling in an at least semiautomated manner on an incline 7 and/or a decline using an assistance system 3. The vehicle 1 or the assistance system 3 also comprises a speed sensor 4 that can be used to provide speed values vx.

[0042] By way of example, the assistance system 3 can be a system for adaptive cruise control with a stop-and-go function. The assistance system 3 can be used to regulate a speed or longitudinal speed of the vehicle 1 to a predefined desired speed. Moreover, a distance from a road user 8 travelling ahead can be regulated. The assistance system 3 can be used to reduce the speed to a temporary standstill, for example when the road user 8 travelling ahead slows.

[0043] As soon as a future temporary standstill of the vehicle 1 is required, for example because another road user 8 travelling ahead is braking, the computing device 2 can receive standstill data provided by the assistance system 3. Furthermore, the computing device 2 continually receives the speed values vx provided by the speed sensor 4 of the vehicle 1, for example. These speed values vx describe the current speed of the vehicle 1 while the vehicle 1 is decelerating prior to the temporary standstill.

[0044] The computing device 2 can also continually determine slope data that describe an angle of the incline or decline of a roadway 7. The angle of the incline or decline can be determined for example based on data from an acceleration sensor, which is not shown here, and/or based on digital map data. The angle can be determined for the current position of the vehicle 1 and/or for a region of the roadway 7 in which the standstill is likely to occur.

[0045] Based on the standstill data, the speed values vx and the slope data, the computing device 2 can continually compute an amended speed value vx.sub.ge. This amended speed value vx.sub.ge can be dependent on the speed value vx and the slope data. Moreover, the amended speed value vx.sub.ge can be dependent on the acceleration or deceleration of the vehicle 1 prior to the standstill. If the amended speed value vx.sub.ge decreases below a predetermined threshold value 14 and the standstill data are received by the computing device 2, the computing device 2 can output an electronic control signal 5 to control the braking torque for achieving the temporary standstill of the vehicle 1. The braking torque can be provided by the respective brakes 6 of the vehicle 1 and can achieve the temporary standstill of the vehicle 1.

[0046] FIG. 2 shows the vehicle 1 shown in FIG. 1 while it is travelling on a roadway 7 having an incline in combination with subsequent travel, during which another road user 8 is in front of the vehicle 1. The driver of the vehicle 1 can predefine a desired speed, for example. The assistance system 3 can automatically regulate the speed of the vehicle 1 to maintain a minimum distance from the road user 8. If the other road user 8 travelling ahead decelerates, for example, the assistance system 3 reduces the speed of the vehicle 1, so that comfortable queued driving for the driver of the vehicle 1 is possible. If the other road user 8 comes to a standstill, the assistance system 3 of the vehicle 1 can slow the vehicle 1 to a standstill.

[0047] Ordinarily, such a braking maneuver to slow the vehicle 1 to a standstill is performed such that stopping is as comfortable as possible for the driver of the vehicle 1. In particular, the slowing or stopping of the vehicle 1 is thus not intended to occur in a jerky manner. This can be achieved for example by reducing the braking torque of the vehicle 1 toward the end of the braking maneuver. If the speed of the vehicle 1 decreases below a threshold value 14, ordinarily an additional braking torque is provided that ensures the temporary standstill of the vehicle 1. When travelling on an incline and also a decline, it can happen that the temporary standstill of the vehicle 1 occurs more quickly than the braking torque for achieving the temporary standstill is present at the brakes 6 of the vehicle 1. As a result, the vehicle 1 could briefly roll back when travelling on an incline.

[0048] The computing device 2 can be used to prevent such a response by controlling the braking torque for achieving the standstill of the vehicle 1. In other words, a comfortable braking maneuver is thus firstly possible, and secondly, the temporary standstill of the vehicle 1 can be simultaneously ensured for all slopes.

[0049] FIG. 3 shows, among other things, a time characteristic of the speed values vx of the vehicle 1 shown in FIG. 2, wherein the assistance system 3 slows the vehicle 1 to a standstill on account of the other road user 8 travelling ahead and the vehicle 1 rolls back on account of the incline. Furthermore, FIG. 3 shows a time characteristic of a wheel speed 10. FIG. 3 also shows a time characteristic of a specified braking torque 11 and of an actual braking torque 12. Finally, FIG. 3 shows a state 13 associated with dynamic driving, a state 13 associated with a temporary standstill and the threshold value 14.

[0050] It can be seen that the change of state from the state 13, or the dynamic driving state, to the state 13, or the temporary standstill state of the vehicle 1, takes place precisely when the time characteristic of the speed values vx decreases below the threshold value 14. On account of the incline of the roadway 7, the vehicle 1 briefly rolls back, however. This can be identified based on the time characteristic of the wheel speed 10. The time characteristic of the wheel speed 10 is negative while the vehicle is rolling back. The time characteristic of the speed values vx of the vehicle 1 represents the absolute value of the speed and is therefore positive while the vehicle is rolling back, even though a temporary standstill is requested by the assistance system 3 of the vehicle 1.

[0051] FIG. 4 shows among other things a time characteristic of the speed values vx similarly to FIG. 3, wherein the computing device 2 controls the braking torque of the vehicle 1 such that the vehicle 1 is prevented from rolling back. To this end, the computing device 2 continually computes amended speed values vx.sub.ge, the time characteristic of which is shown in FIG. 4. In the present case, the amended speed value vx.sub.ge is computed as soon as the speed value vx decreases below a minimum speed 16. The amended speed value vx.sub.ge can be continually computed using the following formula:

[00001]${\mathrm{vx}}_{\mathrm{ge}}=\mathrm{vx}+\mathrm{ax}*?t.$

[0052] Here, ?t describes an angle-dependent timing element determined based on the slope data and ax describes the acceleration of the vehicle 1. The acceleration in this case is negative, since it is a deceleration. The addition of the vehicle acceleration ax multiplied by a time delta ?t that can be applied on an incline-dependent basis produces a speed reserve that ends up being higher the higher the deceleration or the incline.

[0053] As soon as the time characteristic of the amended speed value vx.sub.ge decreases below the threshold value 14, a change of state from a dynamic driving state 13 to a temporary standstill state 13 can take place. In this case, the time characteristic of the amended speed value vx.sub.ge decreases below the threshold value 14 earlier than the time characteristic of the speed value vx. This allows the vehicle 1 to be prevented from rolling back. This is evident from the fact that the time characteristic of the wheel speed 10 is continuously positive. In particular, compared with FIG. 3, it can be seen that the time characteristic of the specified braking torque 11 and of the actual braking torque 12 is brought forward in time. This means that the braking torque for achieving the temporary standstill 13 of the vehicle 1 is present at the brakes 6 of the vehicle 1 precisely when the vehicle 1 comes to a standstill, or the assistance system 3, e.g., the adaptive cruise control, has slowed the vehicle.

[0054] That the change of state from a dynamic driving state to a temporary standstill of the vehicle 1 takes place extremely comfortably for the driver of the vehicle 1 is evident from the fact that the speed of the vehicle 1 is reduced slowly and steadily. In particular, the time characteristic of the speed approaches a zero value continuously and evenly: