Method for operating a steer-by-wire device-for a motor vehicle which is operated in an at least partially assisted manner

Abstract

The invention relates to a method for operating a steer-by-wire device (12) for a motor vehicle (10) which is operated in an at least partially assisted manner, said method comprising the steps of: operating the steer-by-wire device (12) in a driving function, operated in an assisted manner, of the motor vehicle (10), wherein for this purpose at least one control signal (26) for a driving dynamics unit (14) of the steer-by-wire device (12) is generated by means of an electronic computing unit (18) of the steer-by-wire device (12); determining an over-steering threshold at which the driving function operated in an assisted manner is deactivated, by means of the electronic computing unit (18); detecting a steering movement of a user (28) of the motor vehicle (10) at a steering input unit (24) of the steer-by-wire device (10), by means of the steering input unit (24); and generating a haptic warning message at the steering input unit (24) at least when the over-steering threshold is reached, by means of a warning unit (20) of the steer-by-wire device (12). The invention also relates to a computer program product, a computer-readable storage medium, a steer-by-wire device (12) and a motor vehicle (10).

Description

[0001] Method for operating a steer-by-wire device for a motor vehicle that is at least partially assisted

[0002] The following invention relates to a method for operating a steer-by-wire device for a motor vehicle that is at least partially assisted according to claim 1. The invention further relates to a corresponding computer program product, a corresponding computer-readable storage medium, a corresponding steer-by-wire device, and a corresponding motor vehicle.

[0003] Lateral guidance functions such as steering and lane keeping assistants or lane change assistants are, in the current state of the art, primarily designed to be cooperative. This means that a user or driver can influence the control system at any time without deactivating the function. For example, the trajectory can be easily adjusted to avoid a pothole that the assistance system has not detected. It very often happens that the function is deactivated accidentally because the user has steered too strongly. Furthermore, at the moment the assistance function is deactivated, there is a drop in steering torque, which can lead to the driver over-influencing the trajectory and the vehicle developing a large lateral displacement, which can also be safety-critical.

[0004] To enable continuous lateral control, the assistance system must provide relatively high steering forces. External disturbances affecting the system, such as road camber, road surface, slight unintentional movements of the driver at the steering wheel, or similar factors, must also be compensated for without altering the trajectory. This requires a rigid controller, which in turn makes cooperation more difficult. The driver must be able to recognize the extent to which they can influence the system before it deactivates. With existing steering systems, such as hydraulic steering or EPS, this oversteer threshold is very difficult to communicate to the driver. The driver needs experience with the system to know how much oversteer is permissible. These thresholds are also situation-dependent, based on experience.DE 102005 025287 A1 relates to a device for controlling the driving dynamics of a vehicle, comprising means for detecting at least one driving state representing a driving condition and a driving dynamics controller for determining an additional steering angle after a steering movement can be executed in addition to the steering movement commanded by a driver. The device is particularly distinguished in that the driving dynamics controller has at least two control units, each assigned to a driving condition range, that it has a determining means for ascertaining a current driving condition, wherein the current driving condition can be determined based on the driving condition variable, and that it has an activation means connected to the determining means with which a control unit assigned to the determined driving condition range can be unlocked.

[0005] The object of the present invention is to provide a method, a computer program product, a computer-readable storage medium, a steer-by-wire device and a motor vehicle, by means of which improved operation of the motor vehicle is made possible.

[0006] This problem is solved by a method, a computer program product, a computer-readable storage medium, a steer-by-wire device, and a motor vehicle according to the independent claims. Advantageous embodiments are specified in the dependent claims.

[0007] One aspect of the invention relates to a method for operating a steer-by-wire device for a motor vehicle with at least partial driver assistance. The steer-by-wire device is operated in a driver-assisted driving function of the motor vehicle. For this purpose, an electronic computing unit of the steer-by-wire device generates at least one control signal for a vehicle dynamics component of the steer-by-wire device. An oversteer threshold, at which the driver-assisted driving function is deactivated, is determined by the electronic computing unit. A steering movement by the user of the motor vehicle is detected at a steering input device of the steer-by-wire device by means of the steering input device, and a haptic warning message is generated at the steering input device, at least when the oversteer threshold is reached, by means of a warning device of the steer-by-wire device.In particular, this enables cooperative behavior from the driver even with assisted driving functions. In other words, during assisted driving, for example with a lane keeping assist system, the driver can still make small steering adjustments to avoid a pothole that the system itself has not detected. However, to prevent the driving function from being deactivated, the driver can now be notified, particularly via a haptic warning, whether they are approaching the steering threshold and whether, for example, the driving function is about to be deactivated. Thus, the driver is informed whether the driving function is about to be deactivated or whether they are within the range of potential oversteering, which would trigger deactivation.

[0008] In particular, a threshold is defined above which deactivation occurs. This threshold is communicated to the driver, for example, by an increase in hand torque via the steer-by-wire system. A vibration from a high-frequency steering wheel movement can also convey this information.

[0009] This steering threshold can be designed to be situation- and function-specific. For example, after the driver exceeds this threshold, the current steering torque can be ramped back to the value actually required by the driving situation, without the driver feeling like they are "falling into a torque hole" or the vehicle developing an unwanted lateral displacement.

[0010] The steering input device could, for example, be a steering wheel. The warning device could then be integrated into the steering wheel to, for example, apply a torque to the steering wheel or cause a vibration in the steering wheel.

[0011] In particular, since the steer-by-wire device is decoupled from a direct steering system, the steering movement can be adapted accordingly without directly influencing the steering movement of the vehicle.

[0012] This can, for example, reduce the risk of the assistance system being deactivated. Additionally, it can be implemented, for instance, that a visual warning message is generated, indicating to the driver when they exceed the threshold and the assistance function is about to be deactivated.

[0013] According to an advantageous embodiment, the assisted driving function is provided as a lane keeping assistant, lane change assistant, parking assistant, lane departure assistant, and / or collision assistant. Furthermore, collision avoidance or a warning of approaching a guardrail or other potentially hazardous object can also be considered a corresponding assistance system, or a corresponding haptic warning message can be generated upon approach. In particular, different steering thresholds can be provided depending on the driving function. Thus, reliable operation of the vehicle with the steer-by-wire system can be implemented.

[0014] Another advantageous embodiment provides for the generation of a haptic warning signal at the steering input device, either a vibration or a steering torque at the steering input device. A steering torque at the steering input device is particularly preferred. In other words, if the driver approaches the steering threshold, a counter-torque can be generated at the steering input device, or the force required by the driver to make a steering movement at the steering input device can be increased. Thus, it is very easy for the driver to perceive haptically that they are approaching or have exceeded the steering threshold.

[0015] It is also advantageous if the warning message intensity increases as the steering input approaches the oversteer threshold. This allows the driver to be guided into a state of awareness that the oversteer threshold is approaching. For example, when the oversteer threshold is exceeded, the steering torque can be maximized accordingly. In other words, a range can be defined in which the oversteer threshold has not yet been exceeded, but the driver is already informed that they are near the threshold and a corresponding warning message is generated even before it is actually crossed. This allows for improved vehicle operation. It has also proven advantageous if, after the oversteer threshold is reached, a control signal for the vehicle dynamics system is adjusted depending on the detected steering input.In particular, the assistance function can be deactivated once the steering threshold is reached. Specifically, after exceeding the steering threshold, the current steering torque can then be ramped back to the value actually required by the driving situation, without the driver feeling like they are falling into a torque dip or the vehicle developing an unwanted lateral displacement. This ensures safe operation of the vehicle.

[0016] Furthermore, it has proven advantageous to suppress user-initiated steering movements depending on the type of assisted driving system. For example, with a parking assistant, the driver might inadvertently make a steering movement. Even slight steering wheel movements can affect the parking trajectory, potentially making it impossible to reach the parking space. Therefore, it can be implemented that the driver is warned accordingly, but steering input is suppressed below a certain threshold. This ensures reliable parking of the vehicle.

[0017] The presented method is, in particular, a computer-implemented method. Therefore, a further aspect of the invention relates to a computer program product with program code means which, when the program code means are executed by the electronic computing device, cause it to carry out a method according to the preceding aspect.

[0018] A further aspect of the invention relates to a computer-readable storage medium containing at least one computer program product according to the preceding aspect.

[0019] The invention further relates to a steer-by-wire device for a motor vehicle with at least partial driver assistance, comprising at least one vehicle dynamics unit, an electronic computing unit, a warning unit, and a steering input unit, wherein the steer-by-wire device is configured to perform a method according to the preceding aspect. In particular, the method is performed by means of the steer-by-wire device. The invention also relates to a motor vehicle with a steer-by-wire device according to the preceding aspect. The motor vehicle is specifically configured as a motor vehicle with at least partial driver assistance.

[0020] Advantageous embodiments of the process are to be regarded as advantageous embodiments of the computer program product, the computer-readable storage medium, the steer-by-wire device, and the motor vehicle. The steer-by-wire device and the motor vehicle possess tangible features to enable the corresponding process steps to be carried out.

[0021] A computing unit / electronic computing device can be understood, in particular, as a data processing device containing a processing circuit. The computing unit can therefore process data to perform arithmetic operations. This may also include operations to perform indexed access to a data structure, such as a lookup table (LUT).

[0022] The computing unit may, in particular, contain one or more computers, one or more microcontrollers, and / or one or more integrated circuits, for example, one or more application-specific integrated circuits (ASICs), one or more field-programmable gate arrays (FPGAs), and / or one or more systems on a chip (SoCs). The computing unit may also contain one or more processors, for example, one or more microprocessors, one or more central processing units (CPUs), one or more graphics processing units (GPUs), and / or one or more signal processors, in particular one or more digital signal processors (DSPs). The computing unit may also include a physical or virtual array of computers or other units of the aforementioned type.

[0023] In various embodiments, the computing unit includes one or more hardware and / or software interfaces and / or one or more storage units.

[0024] A storage unit can be volatile data storage, for example as dynamic random access memory (DRAM) or static random access memory (SRAM), or as non-volatile data storage, for example as read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory or flash EEPROM, ferroelectric random access memory (FRAM), or magnetoresistive random access memory.It can be designed as MRAM (magnetoresistive random access memory) or as phase-change random access memory, PCRAM (phase-change random access memory).

[0025] Further features of the invention will become apparent from the claims, the figure, and the figure description. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the figure description and / or shown in the figure alone, are not only usable in the combinations specified, but also in other combinations or on their own.

[0026] The invention will now be explained in more detail with reference to a preferred embodiment and the drawing. The drawing shows the single figure:

[0027] Fig. 1 a schematic side view of an embodiment of a

[0028] Motor vehicle with an embodiment of a steer-by-wire device.

[0029] In the figure, identical or functionally equivalent elements are provided with the same reference symbols.

[0030] Fig. 1 shows a schematic side view of an embodiment of a motor vehicle 10. The motor vehicle 10 is, in particular, at least partially assisted. The motor vehicle 10 has a steer-by-wire device 12. The steer-by-wire device 12 has at least one vehicle dynamics unit 14, for example, for steering wheels 16. Furthermore, the steer-by-wire device 12 has an electronic computing unit 18, a warning device 20, and a steering input unit 24. It is also shown, in particular, that in the steer-by-wire device 12, a steering input is transmitted via a control unit 22 to a steering input unit 24 as a control signal 26 to the vehicle dynamics unit 14.

[0031] In the inventive method for operating the steer-by-wire device 12, it is particularly provided that the steer-by-wire device 12 is operated in an assisted driving mode or in an assisted driving function of the motor vehicle 10, wherein, for this purpose, at least the control signal 26 for the vehicle dynamics device 14 is generated by means of the electronic computing unit 18 of the steer-by-wire device 12. A steering threshold is determined by means of the electronic computing unit 18, at which the assisted driving function is deactivated.A steering movement of a user 28 of the motor vehicle 10 is then detected at the steering input device 24 of the steer-by-wire device 12 by means of the steering input device 24 and a haptic warning message is generated at the steering input device 24 at least when the oversteering threshold is reached by means of the warning device 20 of the steer-by-wire device 12.

[0032] In particular, it is intended that the assisted driving function will be provided as a lane keeping assistant and / or as a lane change assistant and / or as a parking assistant and / or as a lane departure assistant and / or as a collision assistant.

[0033] Furthermore, it may be provided that a vibration at the steering input device 24 and / or a steering force torque at the steering input device 24 is generated as a haptic warning message.

[0034] It can also be provided that the intensity of the warning message increases as the steering movement approaches the oversteer threshold. Furthermore, after reaching the oversteer threshold, a control signal for the vehicle dynamics unit 14 can be adjusted depending on the detected steering input. Additionally, depending on the type of assisted ferry operation, a steering movement initiated by the user 28 can be suppressed.

[0035] In particular, it is therefore provided that the steering threshold is provided, whereby the assisted driving function is deactivated as soon as the steering threshold is reached or exceeded. This steering threshold can be communicated to the user 28 by a virtual increase in the steering wheel torque or hand torque via the steer-by-wire device 12. A vibration caused by a high-frequency steering wheel movement can also convey this information.

[0036] This steering threshold can be designed to be situation- and function-specific. After the user 28 exceeds the steering threshold, the current steering torque can be ramped back to the value actually present due to the driving situation, without the driver experiencing a perceived lack of torque or the vehicle 10 developing an unwanted lateral displacement. The inventive method can also be used accordingly with the parking assistant. During an assisted parking maneuver, the trajectory must not be influenced by the user 28 as much as possible, otherwise the parking space cannot be parked properly. The vehicle 10 might collide with other parked vehicles, be parked at an angle in the space, or not be able to enter the space with the planned maneuvers.

[0037] Here too, a steering threshold and / or vibration can be provided to user 28 when the steering is initiated. However, if user 28 does not exceed this threshold, the steering movement is not implemented by the system. Only when user 28's clear intention to oversteer is detected is the steering wheel movement implemented and the assisted parking maneuver aborted. This prevents user 28 from accidentally aborting the control, while still allowing the steer-by-wire device 12 to oversteer very comfortably if desired.

[0038] Reference symbol list

[0039] motor vehicle

[0040] Steer-by-wire device, vehicle dynamics device, wheel electronic computing device

[0041] Warning device

[0042] Control unit

[0043] Steering input device control signal

[0044] users

Claims

Patent claims 1. Method for operating a steer-by-wire device (12) for a motor vehicle (10) that is at least partially assisted, comprising the steps: Operating the steer-by-wire device (12) in an assisted driving function of the motor vehicle (10), wherein at least one control signal (26) for a vehicle dynamics device (14) of the steer-by-wire device (12) is generated by means of an electronic computing device (18) of the steer-by-wire device (12); Determining an oversteer threshold at which the assisted driving function is deactivated by means of the electronic computing device (18); detecting a steering movement of a user (28) of the motor vehicle (10) at a steering input device (24) of the steer-by-wire device (10) by means of the steering input device (24); and Generating a haptic warning message at the steering input device (24) at least when the oversteer threshold is reached by means of a warning device (20) of the steer-by-wire device (12).

2. Method according to claim 1, characterized in that the assisted driving function is provided as a lane keeping assistant and / or as a lane change assistant and / or as a parking assistant and / or as a lane departure assistant and / or as a collision assistant.

3. Method according to claim 1 or 2, characterized in that a vibration at the steering input device (24) and / or a steering force torque at the steering input device (24) is generated as a haptic warning message.

4. Method according to one of the preceding claims, characterized in that the intensity of the warning message is increased when the steering movement approaches the oversteer threshold.

5. Method according to one of the preceding claims, characterized in that, after reaching the oversteer threshold, a further control signal for the vehicle dynamics device (14) is adapted depending on the detected steering input.

6. Method according to one of the preceding claims, characterized in that, depending on a type of assisted ferry operation, a steering movement initiated by the user (28) is suppressed.

7. Computer program product comprising program code means which cause an electronic computing device (18) to perform a method according to one of claims 1 to 6 when the program code means are executed by the electronic computing device (18).

8. Computer-readable storage medium comprising at least one computer program product according to claim 7.

9. Steer-by-wire device (12) for a motor vehicle (10) that is at least partially assisted, comprising at least one vehicle dynamics device (14), one electronic computing device (18), one warning device (20) and one steering input device (24), wherein the steer-by-wire device (12) is configured to perform a method according to one of claims 1 to 6.

10. Motor vehicle (10) with a steer-by-wire device (12) according to claim 9.

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