Method for operating a steer-by-wire device for an at least partially assisted motor vehicle

Abstract

The invention relates to a method for operating a steer-by-wire device (12) for an at least partially assisted motor vehicle (10), comprising the steps of: operating the steer-by-wire device (12) in an assisted driving function of the motor vehicle (10), wherein for this purpose at least one control signal (26) for a driving 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 on the steering input device (24) at least upon reaching the oversteer threshold by means of a warning device (20) of the steer-by-wire device (12). Furthermore, the invention relates to a computer program product, a computer-readable storage medium, a steer-by-wire device (12), and a motor vehicle (10).

Description

[0001] The following invention relates to a method for operating a steer-by-wire device for an at least partially assisted motor vehicle. Furthermore, the invention relates to a corresponding computer program product, a corresponding computer-readable storage medium, a corresponding steer-by-wire device, and a corresponding motor vehicle.

[0002] State-of-the-art lateral guidance functions such as steering and lane guidance assistants or lane change assistants are particularly cooperative. This means that a user or driver can influence the control at any time without deactivating the function. For example, the trajectory can be slightly adjusted to avoid a pothole that was not detected by the assistance system. However, it often happens that the function is accidentally deactivated because the user steers too forcefully. Furthermore, the moment the assistance function is deactivated, there is a drop in steering torque, which can lead to the driver influencing the trajectory too strongly and the vehicle developing a significant lateral offset, which can also be safety-critical.

[0003] To enable continuous lateral guidance, relatively high steering forces must be provided by the assistance system. External disturbances to the system, such as the transverse inclination of the road, sidewall, slight unintentional movements of the driver on the steering wheel, or the like, must also be compensated for without changing the trajectory. This requires a rigid controller, which in turn complicates cooperation. 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. Experience has shown that these thresholds also depend on the situation.

[0004] DE 10 2005 025 287 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 comprising 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 by the fact that the driving dynamics controller has at least two control units, each associated with a driving condition range, a determination means for determining a current driving condition, the current driving condition being ascertainable based on the driving condition variable, and an activation means connected to the determination means, with which a control unit associated with the ascertained driving condition range can be unlocked.

[0005] Further prior art is disclosed in DE 10 2015 215 052 A1, DE 10 2018 200 327 A1 and EP 3 390 190 B1.

[0006] 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 an improved operation of the motor vehicle is made possible.

[0007] This object is achieved 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 patent claims. Advantageous embodiments are specified in the subclaims.

[0008] One aspect of the invention relates to a method for operating a steer-by-wire device for an at least partially assisted motor vehicle. The steer-by-wire device is operated in an assisted driving function of the motor vehicle, wherein for this purpose, at least one control signal for a driving dynamics device of the steer-by-wire device is generated by means of an electronic computing device of the steer-by-wire device. An oversteer threshold at which the assisted driving function is deactivated is determined by means of the electronic computing device. A steering movement of a user of the motor vehicle at a steering input device of the steer-by-wire device is detected by means of the steering input device, and a haptic warning message is generated at the steering input device, at least upon reaching the oversteer threshold, by means of a warning device of the steer-by-wire device.

[0009] In particular, this makes it possible to implement cooperative behavior in assisted driving functions. In other words, in assisted driving mode, for example with a lane keeping assistant, the driver can continue to make small steering movements in order to avoid a pothole, for example, which the assistance system itself has not detected. However, in order not to deactivate the driving function, the driver can now be shown, in particular via a haptic warning message, whether the driver has approached the oversteer threshold and, for example, deactivation of the driving function is imminent. The driver is thus informed whether deactivation of the driving function is about to occur or whether they are in the range of potential oversteering, which would trigger deactivation of the driving function.

[0010] In particular, a threshold is specified above which deactivation occurs. This threshold is communicated to the driver, for example, by an increase in hand torque via the steer-by-wire device. A vibration caused by a high-frequency steering wheel movement can also convey this information.

[0011] This oversteer threshold can be configured to suit the situation and function. For example, after the driver exceeds this threshold, the current manual steering torque can be ramped back to the actual value of the driving situation without the driver feeling like they're "falling into a torque slump" or the vehicle developing an unwanted lateral offset.

[0012] The steering input device can be, for example, a steering wheel. The warning device can then be integrated into the steering wheel, for example, to exert a torque on the steering wheel or a vibration on the steering wheel.

[0013] In particular, since the steer-by-wire device is decoupled from a direct steering system, the steering movement can be adapted accordingly without having a direct influence on the steering movement of the vehicle.

[0014] This can, for example, also reduce the risk of the assistance system being deactivated.

[0015] In addition, it can also be provided, for example, that a visual warning message is generated which shows the driver when he or she exceeds the threshold and when the assistance function is about to be deactivated.

[0016] According to an advantageous embodiment, the assisted driving function is provided as a lane keeping assistant and / or a lane change assistant and / or a parking assistant and / or a lane departure assistant and / or a collision assistant. Furthermore, collision avoidance or the warning of an approach to a guardrail or another 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 oversteer thresholds can then be provided depending on the driving function. Thus, reliable operation of the motor vehicle with the steer-by-wire device can be realized.

[0017] A further advantageous embodiment provides that a vibration at the steering input device and / or a steering force moment is generated at the steering input device as a haptic warning message. Preferably, a steering force moment is generated at the steering input device. In other words, if the driver approaches the oversteer threshold, a counter-torque can be generated at the steering input device, for example, or the force required by the driver to perform a steering movement at the steering input device can be increased. Thus, it is very easy for the driver to haptically perceive that they are approaching the oversteer threshold or have exceeded the oversteer threshold.

[0018] It is also advantageous if the intensity of the warning message increases as the steering movement approaches the oversteer threshold. This can alert the driver that they are approaching the oversteer threshold. For example, when the oversteer threshold is exceeded, the steering force moment can be correspondingly maximum. 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 approaching the oversteer threshold, and a corresponding warning message is generated even before the threshold is actually exceeded. This allows for improved operation of the vehicle.

[0019] It has also proven advantageous if, after the oversteer threshold is reached, a control signal for the dynamic driving system is adjusted depending on the detected steering input. In particular, after the oversteer threshold is reached, the assistance function can then be deactivated, for example. Especially after the oversteer threshold is exceeded, the current manual steering torque can then be "ramped" back to the actual value prevailing in the driving situation, without the driver feeling like they are falling into a torque slump or the vehicle developing an unwanted lateral offset. This ensures safe operation of the vehicle.

[0020] Furthermore, it has proven advantageous if, depending on the type of assisted driving mode, a user-initiated steering movement is suppressed. For example, with a parking assistant, the driver may accidentally move the steering wheel. However, with the parking assistant, even slight steering wheel movements can influence the parking trajectory, making it impossible to reach the parking space, for example. Thus, it can also be provided that the driver is warned accordingly, but below the corresponding oversteer threshold, the driver's steering is suppressed. This allows for reliable parking of the vehicle.

[0021] The method presented is, in particular, a computer-implemented method. Therefore, a further aspect of the invention relates to a computer program product with program code means that, when the program code means are processed by the electronic computing device, cause an electronic computing device to perform a method according to the preceding aspect.

[0022] Yet another aspect of the invention relates to a computer-readable storage medium having at least one computer program product according to the preceding aspect.

[0023] Furthermore, the invention also relates to a steer-by-wire device for an at least partially assisted motor vehicle, comprising at least one driving dynamics device, an electronic computing device, a warning device, and a steering input device, wherein the steer-by-wire device is designed to carry out a method according to the preceding aspect. In particular, the method is carried out by means of the steer-by-wire device.

[0024] The invention also relates to a motor vehicle with a steer-by-wire device according to the preceding aspect. The motor vehicle is designed, in particular, as an at least partially assisted motor vehicle.

[0025] Advantageous embodiments of the method 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 have material features for this purpose in order to be able to carry out corresponding method steps.

[0026] A computing unit / electronic computing device can be understood, in particular, as a data processing device that contains a processing circuit. The computing unit can therefore, in particular, process data to perform computing operations. This may also include operations for performing indexed access to a data structure, for example, a look-up table (LUT).

[0027] 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 single-chip systems (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 network of computers or other of the aforementioned units.

[0028] In various embodiments, the computing unit includes one or more hardware and / or software interfaces and / or one or more memory units.

[0029] A memory unit can be a volatile data memory, for example a dynamic random access memory (DRAM) or a static random access memory (SRAM), or a non-volatile data memory, for example a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a flash memory or flash EEPROM, a ferroelectric random access memory (FRAM), a magnetoresistive random access memory,MRAM (magnetoresistive random access memory) or phase-change random access memory (PCRAM).

[0030] Further features of the invention emerge from the claims, the figure, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figure, can be used not only in the respective specified combination, but also in other combinations or on their own.

[0031] The invention will now be explained in more detail using a preferred embodiment and with reference to the drawing. The sole figure shows: Fig. 1 a schematic side view of an embodiment of a motor vehicle with an embodiment of a steer-by-wire device.

[0032] In the figure, identical or functionally identical elements are provided with the same reference numerals.

[0033] Fig.1 shows a schematic side view of an embodiment of a motor vehicle 10. The motor vehicle 10 is, in particular, operated at least partially with assistance. The motor vehicle 10 has a steer-by-wire device 12. The steer-by-wire device 12 has at least one driving dynamics device 14, for example, for steering wheels 16. Furthermore, the steer-by-wire device 12 has an electronic computing device 18, a warning device 20, and a steering input device 24. Furthermore, it is shown in particular that in the steer-by-wire device 12, a steering input at a steering input device 24 is transmitted as a control signal 26 to the driving dynamics device 14 via a control device 22.

[0034] In the method according to the invention for operating the steer-by-wire device 12, it is provided, in particular, 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 driving dynamics device 14 is generated by means of the electronic computing device 18 of the steer-by-wire device 12. An oversteer threshold at which the assisted driving function is deactivated is determined by means of the electronic computing device 18.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 oversteer threshold is reached by means of the warning device 20 of the steer-by-wire device 12.

[0035] In particular, it is intended 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.

[0036] Furthermore, it can be provided that a vibration on the steering input device 24 and / or a steering force moment on the steering input device 24 are generated as a haptic warning message.

[0037] It can also be provided that the intensity of the warning message is increased as the steering movement approaches the oversteer threshold. Furthermore, after the oversteer threshold is reached, a control signal for the dynamic driving device 14 can be adjusted depending on the detected steering input. Furthermore, depending on the type of assisted driving mode, a steering movement initiated by the user 28 can be suppressed.

[0038] In particular, it is thus provided that the oversteer threshold is provided, whereby the assisted driving function is deactivated upon reaching or exceeding the oversteer threshold. This oversteer threshold can be communicated to the user 28 by a virtual increase in the steering wheel torque or manual torque via the steer-by-wire device 12. A vibration caused by a high-frequency steering wheel movement can also convey this information.

[0039] This oversteer threshold can be configured to suit the specific situation and function. After the oversteer threshold is exceeded by the user 28, the current manual steering torque can be "ramped" back to the actual value prevailing in the driving situation, without the driver feeling like they are falling into a torque slump or the motor vehicle 10 developing an unwanted lateral offset. The method according to the invention can also be used accordingly with a parking assistant. During an assisted parking maneuver, the trajectory must be virtually uninfluenced by the user 28, since otherwise the parking space can no longer be parked adequately. The motor vehicle 10 could potentially collide with other parked vehicles, enter the parking space at an angle, or even be unable to enter the parking space with the planned maneuvers.

[0040] Here, too, an oversteer threshold and / or vibration can be provided to the user 28 when intervening in the steering. However, if the user 28 does not exceed this threshold, the steering movement will not be implemented by the system. Only when the user 28's clear intention to oversteer is detected will the steering wheel movement be implemented and the assisted parking process aborted. This prevents the user 28 from accidentally aborting the control, but still allows the user 28 to very comfortably oversteer the steer-by-wire device 12 if desired. List of reference symbols 10 motor vehicle 12 Steer-by-wire device 14 driving dynamics device 16 wheels 18 electronic computing device 20 Warning device 22 Control device 24 Steering input device 26 Control signal 28 users

Claims

[1] Method for operating a steer-by-wire device (12) for an at least partially assisted motor vehicle (10), comprising the steps: - Operating the steer-by-wire device (12) in an assisted driving function of the motor vehicle (10), wherein for this purpose at least one control signal (26) for a driving 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 on 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 by 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 by that a vibration on the steering input device (24) and / or a steering force moment on the steering input device (24) is generated as a haptic warning message. [4] Method according to one of the preceding claims, characterized by that when the steering movement approaches the oversteer threshold the intensity of the warning message is increased. [5] Method according to one of the preceding claims, characterized bythat after reaching the oversteer threshold, a further control signal for the driving dynamics device (14) is adapted depending on the detected steering input. [6] Method according to one of the preceding claims, characterized by that, depending on a type of assisted driving operation, a steering movement initiated by the user (28) is suppressed. [7] Computer program product with program code means which cause an electronic computing device (18) to carry out a method according to one of claims 1 to 6 when the program code means are processed by the electronic computing device (18). [8] A computer-readable storage medium comprising at least one computer program product according to claim 7. [9] Steer-by-wire device (12) for an at least partially assisted motor vehicle (10), with at least one driving dynamics device (14), an electronic computing device (18), a warning device (20) and a steering input device (24), wherein the steer-by-wire device (12) is designed to carry out 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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