Method for operating a steer-by-wire steering system of a motor vehicle and steer-by-wire steering system

Abstract

The present disclosure relates to a method for operating a steer-by-wire system of a motor vehicle and a steer-by-wire system. The steer-by-wire system has at least one road wheel actuator, a steering wheel actuator, and a control device coupled to the road wheel actuator and the steering wheel actuator. A vehicle speed is received or determined by the control device. A wheel angle limit of a steerable road wheel of the motor vehicle is determined by the control device based on at least the vehicle speed. A wheel angle request of the steerable road wheel is received by the control device. If the wheel angle request corresponds to a wheel angle of the road wheel that is greater than the determined wheel angle limit, an adapted wheel angle request is determined by the control device. The adapted wheel angle request is limited based on the wheel angle limit. A setpoint signal is output by the control device to the road wheel actuator. The setpoint signal is based on the wheel angle request or the adapted wheel angle request, depending on whether the wheel angle request corresponds to a wheel angle of the road wheel that is greater than the determined wheel angle limit.

Description

Technical Field

[0001] This disclosure generally relates to a method for operating a steer-by-wire system for motor vehicles, and the steer-by-wire system itself. Background Technology

[0002] Steer-by-wire (SBW) is a steering technology that eliminates the direct mechanical connection between the steering wheel and the wheels. This direct connection is replaced by two actuators: a steering wheel actuator that provides feedback torque to the driver via the steering wheel, and a travel wheel actuator that controls at least one, but typically multiple, steerable wheels to the desired position. The feedback torque conveys a sense of lateral guidance to the driver.

[0003] The steering circle of a motor vehicle is an important indicator of customer satisfaction. For example, in urban environments, a smaller steering circle is advantageous. The turning circle is defined by factors such as suspension geometry, tire size, and the maximum travel of the steering rack.

[0004] The maximum steering rack travel is mechanically limited by a mechanical end stop to prevent the front wheels from contacting surrounding body components, such as wheel arches, even under adverse dynamic driving conditions (typically at high vehicle speeds). In the aforementioned method, the limitation on the steering rack travel, specified using control technology, is further defined, for example, by a software control system, to ensure tolerances relative to the mechanical end stop. The mechanical end stop is thus eliminated. Even under rapid steering movements or manufacturing tolerances, it is thus possible to ensure that changes in the position of the steering rack are not achieved in a manner that results in a load on the mechanical end stop. Therefore, the function of the SBW steering system is limited by the specification of the maximum permissible steering rack travel implemented by control technology. In other words, the range of achievable steering rack positions is limited and precise in terms of tolerances, which are specified by the software control system and measured at the mechanical end stop.

[0005] US 11,052,940 B1 discloses a general-purpose SBW steering system. A steering map is used to determine the desired position of the steering rack based on the current steering wheel position. Therefore, a steering map can be selected from a set of steering maps, based, for example, on vehicle speed, vehicle direction, and driver preference. The steering map can be used to fix an adjustable maximum steering rack travel threshold (which depends on vehicle speed) for controlling the steering rack. Furthermore, for different vehicle speeds, the steering map can have different transmission ratios between the steering rack and the steering wheel.

[0006] Because of the mismatch with the permissible steering wheel travel, changes in the adjustable maximum steering rack travel threshold result in inconsistent steering feel in the end-stop areas of the steering wheel travel, as these areas conflict with the adjustable and therefore changeable maximum steering rack travel threshold. This can, for example, cause self-steering of the steering wheel or cause the driver to create undesirable high loads on the components of the SBW steering system by steering into the end-stop areas of the steering wheel travel. For example, it is also not ruled out that the wheels may still undesirably contact body components under highly dynamic driving conditions.

[0007] Therefore, it is necessary to eliminate or at least reduce known methods and drawbacks of SBW steering systems used for operating motor vehicles. Specifically, it is also necessary to achieve consistent steering behavior of the steering wheel under dynamic control conditions. Summary of the Invention

[0008] This objective is achieved through the subject matter of the independent claims. Advantageous configurations are specified in the dependent claims and the following description, wherein each configuration may constitute an aspect of this disclosure individually or in (sub)combination. Some features are interpreted in relation to the method, while others are interpreted in relation to the SBW turning system. However, corresponding aspects may be converted to each other accordingly.

[0009] According to one aspect, some embodiments of this disclosure relate to a method for operating a SBW steering system of a motor vehicle. The SBW steering system has at least one driving wheel actuator, a steering wheel actuator, and control means coupled to the driving wheel actuator and the steering wheel actuator. The method includes at least the following steps: - Vehicle speed is received or determined by the control device.

[0010] - The wheel angle limits of the steerable wheels of a motor vehicle are determined by the control device based at least on the vehicle speed.

[0011] - The control unit receives the wheel angle requirements of the steerable wheels.

[0012] If the wheel angle requirement corresponds to the wheel angle of a steerable travel wheel that is greater than the determined wheel angle limit, the control unit determines the adapted wheel angle requirement. The adapted wheel angle requirement is limited based on the wheel angle limit.

[0013] - The setpoint signal is output from the control unit to the driving wheel actuator. The setpoint signal is based on the wheel angle requirement or the adapted wheel angle requirement, depending on whether the wheel angle requirement corresponds to the wheel angle of the steerable driving wheel that is greater than the determined wheel angle limit.

[0014] This method is based on the understanding that the SBW steering system can be used to expand the possible parameter space of the steering rack travel according to driving conditions. Wheel angle limits are determined based on vehicle speed. These limits restrict wheel angle requirements and are precisely independent of the mechanical end stops or tolerance ranges required by the aforementioned methods. This allows the mechanical end stops to be shifted "outward," typically considering a larger wheel angle range. Therefore, at least for some vehicle speeds, the steerable wheels can exhibit wheel angles that cannot be achieved using the aforementioned methods. Thus, the functionality of the SBW steering system is improved. For example, a smaller turning circle can be achieved depending on vehicle speed. However, by limiting wheel angle requirements based on the determined wheel angle limits, erroneous states of the SBW steering system, such as the steerable wheels contacting the vehicle body, can be reliably prevented. This results in a consistent steering wheel position, steering rack position, and associated steering feel.

[0015] According to one aspect, some embodiments of this disclosure relate to a SBW (Steering By-Wheel) system for a motor vehicle. The SBW system includes at least one driving wheel actuator, a steering wheel actuator, and control means coupled to the driving wheel actuator and the steering wheel actuator. The control means is configured to: - Receive or determine vehicle speed.

[0016] - Determine the wheel angle limits of the steerable wheels of a motor vehicle based at least on the vehicle speed.

[0017] -Receive wheel angle requirements for steerable driving wheels.

[0018] - If the wheel angle requirement corresponds to the wheel angle of a steerable travel wheel that is greater than the determined wheel angle limit, then the appropriate wheel angle requirement is determined. The appropriate wheel angle requirement is limited based on the wheel angle limit.

[0019] - Output a setpoint signal to the driving wheel actuator. The setpoint signal is based on the wheel angle requirement or an adapted wheel angle requirement, depending on whether the wheel angle requirement corresponds to the wheel angle of the steerable driving wheel that is greater than the determined wheel angle limit.

[0020] The advantages achieved by the method described in this paper are also correspondingly obtained through the SBW steering system. Specifically, the determination of the speed-dependent wheel angle limits means that the wheel angle requirements can be limited according to driving conditions; however, the range of achievable wheel angles is maximized and optimized according to speed.

[0021] Wheel angle requirements are arbitrarily based on: - The steering wheel angle of the SBW steering system detected by the steering wheel sensor, or - The steering wheel angle specified by the advanced driver control system on the steering wheel, or -Steering angle specified by the advanced driver control system, or - The simulated steering wheel angle by the control unit depends on whether the corresponding detected or specified steering wheel angle exceeds the steering wheel angle limit determined by the control unit based at least on the steering ratio and the determined wheel angle limits and / or vehicle speed. The simulated steering wheel angle corresponds to the determined steering wheel angle limit.

[0022] The wheel angle requirements for steerable wheels can therefore be traditionally based on the steering wheel angle or the specifications of an advanced driver control system (ADAS). The ADAS, for example, can perform autonomous or semi-autonomous driving functions, and in this connection, specifies the steering wheel angle or wheel angle of the steerable wheels set by the steering wheel actuator. Therefore, based on autonomous or semi-autonomous driving functions, the vehicle can be guided by the ADAS according to a predefined trajectory, and also guided in terms of lateral guidance. Furthermore, the control device determines the steering wheel angle limits, for example, based on vehicle speed and / or wheel angle limits determined considering the steering ratio. If the detected or specified steering wheel angle exceeds the steering wheel angle limits, the control device simulates a steering wheel angle corresponding to the determined steering wheel angle limits for the wheel angle requirements. Therefore, the determined steering wheel angle limits will not be exceeded in terms of wheel angle requirements, but may be exceeded in terms of actual steering wheel position. Thus, the parameter space of the wheel angle requirements is effectively limited, corresponding to the limitations of the wheel angle requirements. This ensures consistent control between the wheel angle requirements and the steering wheel angle.

[0023] Even in scenarios where the advanced driver control unit (ADAS) directly specifies the wheel angles of the steerable wheels, the control unit also determines the wheel angle limits of the steerable wheels based at least on the vehicle speed. These determined wheel angle limits are also considered by the control unit. This means that if the wheel angle requirement (of the ADAS) corresponds to a wheel angle of the steerable wheels greater than the determined wheel angle limits, the appropriate wheel angle requirement is also determined by the control unit. The appropriate wheel angle requirement is then correspondingly limited based on the wheel angle limits. In this case, the control unit also outputs a setpoint signal to the wheel actuators. The setpoint signal is based, in turn, on either the wheel angle requirement or the appropriate wheel angle requirement, depending on whether the wheel angle requirement corresponds to a wheel angle of the steerable wheels greater than the determined wheel angle limits. However, in this case, relatively speaking, the steering wheel can move less relative to the steerable wheels. This means using a changed steering ratio. Finally, since the driver control unit performs lateral guidance of the vehicle, the steering wheel can also remain stationary. Furthermore, since the steering wheel is rotated to a lesser extent or optionally not at all, the determination of the steering wheel angle may not be necessary.

[0024] Optionally, if the corresponding detected or specified steering wheel angle exceeds the determined steering wheel angle limit, a dynamic steering wheel end stop is simulated by the steering wheel actuator through a feedback torque applied at least indirectly to the steering wheel. The feedback torque used to simulate the dynamic steering wheel end stop can be particularly large in this paper, making it so that the driver can only overcome it with considerable effort. This effectively prevents the driver from steering into areas where the wheel angle specification is, in any case, covered by the simulated wheel angle specification.

[0025] The simulated dynamic end stop, also known as the DES (Dynamic End Stop) function, simulates the steering wheel end stop at the DES position. In this paper, the DES position corresponds to a defined steering wheel angle limit, and the simulated steering wheel end stop is based on this defined limit. Once the detected or specified steering wheel angle exceeds the defined steering wheel angle limit, a steering wheel angle corresponding to the defined limit is simulated for the wheel angle requirements. At the steering wheel angle limit position, i.e., the DES position, a feedback torque is subsequently activated and output to the steering wheel, also known as the so-called DES feedback torque. The DES feedback torque is particularly large to prevent the driver from turning the steering wheel beyond the defined steering wheel angle limit.

[0026] According to one aspect, the determined steering wheel angle limits can be maintained by a simulated dynamic steering wheel end stop independently of changes in the determined wheel angle limits and / or vehicle speed, until the corresponding detected or specified steering wheel angle drops below the maintained determined steering wheel angle limits. The simulated dynamic steering wheel end stop is applied only if the detected or specified steering wheel angle has previously exceeded the steering wheel angle limits. Typically, a change in vehicle speed or wheel angle limits may now mean that the steering wheel angle limits actually have to change. However, the previously determined and applied steering wheel angle limits remain constant until the detected or specified steering wheel angle (depending on its application at the control time) drops below the previously determined and applied steering wheel angle limits in the direction of the permissible steering wheel angle. Therefore, inconsistent control states of the SBW steering system can be prevented. Furthermore, the control is thus particularly tight.

[0027] If the detected or specified steering wheel angle drops below the maintained defined steering wheel angle limit, the offset caused by the simultaneous change of the maintained defined steering wheel angle limit and the defined wheel angle limit and / or vehicle speed preferably decreases continuously within a specified time period or during the steering wheel angle interval. Although the steering wheel angle limit is maintained constant as described above, a change in vehicle speed or wheel angle limit may mean that the steering wheel angle limit will actually have to change. Therefore, an offset typically occurs between the defined and constantly applied steering wheel angle limit and the steering wheel angle limit actually measured at the corresponding control time. As described above, this offset decreases once the detected or specified steering wheel angle drops below the constantly applied steering wheel angle limit.

[0028] Optionally, the control unit determines the steering wheel angle limits based on lookup tables and / or algorithms. Therefore, it exhibits particularly low complexity in control and the control system is compact in determining the steering wheel angle limits.

[0029] In some implementations, the control device determines the wheel angle limits based on lookup tables and / or algorithms. Therefore, the wheel angle limits can also be determined in a particularly compact manner.

[0030] While lookup tables enable particularly compact control mechanisms, adaptability and higher resolution of control behavior, especially during operation, can be ensured through algorithms (e.g., algorithms that depend on variable parameters). On the other hand, lookup tables can interpolate between individual parameter values ​​stored in the lookup table if needed.

[0031] When determining wheel angle limits, the control device preferably considers at least one of the following: changes in the longitudinal speed of the vehicle, changes in the lateral speed of the vehicle, and / or the vertical wheel travel of at least one of the vehicle's traveling wheels. Therefore, different parameters that affect the lateral guidance of the vehicle can be considered. Consequently, the accuracy of the wheel angle limits with respect to the corresponding vehicle characteristics is improved.

[0032] The motor vehicle optionally has at least one wheel speed sensor or is at least indirectly connected to said wheel speed sensor. The wheel speed sensor detects the wheel speed of at least one traveling wheel in the circumferential direction. The control device determines the vehicle speed based at least on the detected wheel speed, or receives the vehicle speed determined based on the detected wheel speed. Thus, for example, the slip of each wheel can be determined and taken into account by the control device based on the detected wheel speed.

[0033] Motor vehicles can, of course, have multiple wheel speed sensors, which, for example, detect the wheel speeds of different traveling wheels. Therefore, the average vehicle speed can be determined.

[0034] By determining the slippage of each wheel, the vehicle state can be precisely characterized by the control device. For example, the vehicle can thus also be characterized based on its dominant speed change values ​​at specific points in time (i.e., speed changes in the longitudinal, lateral, and vertical directions of the vehicle). Alternatively or additionally, the SBW steering system may have a pinion sensor configured to detect forces applied to a pinion by the drive wheel actuators, to which the steerable drive wheels are at least indirectly coupled. These parameters (e.g., the slippage of each wheel and the forces applied by the drive wheel actuators) are then considered by the control device, for example, when determining a feedback torque specification to be applied to the steering wheel by the steering wheel actuators to convey a sense of lateral guidance of the vehicle to the driver.

[0035] In some implementations, the control device determines wheel angle limits to prevent contact between the wheel and body components while taking tolerance clearances into account. Here, the tolerance clearances can optionally be variably formed by the control device based on the vehicle speed. While short tolerance clearances are sufficient at low vehicle speeds, larger tolerance clearances can be selected for higher vehicle speeds. Therefore, the available wheel angle range can be optimally used for the lateral guidance of the vehicle.

[0036] Optionally or cumulatively, the control device determines wheel angle limits such that the range of wheel angles of the steerable wheels limited by the determined wheel angle limits is shorter than the range of mechanical wheel angles of the steerable wheels defined by the mechanical end stop. Therefore, loads limiting the wheel angles on the mechanical end stop are prevented, thereby extending its service life. Furthermore, tolerance ranges can also be considered, for example, in the case of production and quantity fluctuations.

[0037] The driving wheel actuator is at least indirectly connected to the steerable driving wheel. The driving wheel actuator may also optionally be at least indirectly connected to multiple steerable driving wheels simultaneously, for example via the steering rack of the SBW steering system.

[0038] In an alternative embodiment, the motor vehicle may also have at least one second driving wheel actuator, which may be coupled, for example, to the steerable rear wheel of the motor vehicle, such as via an additional steering rack of the SBW steering system.

[0039] Multiple driving wheel actuators can be controlled by a control device.

[0040] Each driving wheel actuator has an electric motor to apply torque to change the orientation of the steerable driving wheel. As an example, the driving wheel actuator can apply torque to the steering rack to enable setting the steering rack position as needed. The electric motor can have, for example, a coil group with three coils, i.e., a three-phase coil group. Optionally, the electric motor can also have more coil groups.

[0041] The steering wheel actuator is configured to apply feedback torque to the steering wheel at least indirectly, for example, via a steering column coupled to the steering wheel. The feedback torque induced by the steering wheel actuator is also used herein to provide torque feedback to the driver regarding the lateral guidance of the vehicle.

[0042] Typically, steering wheel actuators have an electric motor to apply feedback torque to the steering wheel. The electric motor may have, for example, a coil group with three coils, i.e., a three-phase coil group. Optionally, the electric motor may also have more coil groups.

[0043] The setpoint signal output from the control device to the travel wheel actuator can be analog or digital, preferably digital. The travel wheel actuator uses the received setpoint signal to determine the torque output with the assistance of its electric motor, such that the wheel angle of the steerable travel wheel corresponds as closely as possible to the specified or adapted wheel angle requirements. The limitation on the adapted wheel angle requirements by wheel angle limits corresponds to the specified threshold of the setpoint signal that cannot be exceeded. This means that the parameter space available for the setpoint signal is effectively limited or at least adapted, which is taken into account by the travel wheel actuator when determining the torque required to change the wheel angle of the steerable travel wheel. This has the advantage of not having to change the inherent control of the travel wheel actuator and being able to be implemented in a compact manner.

[0044] The steering ratio corresponds to the distribution between the corresponding steering wheel position and the wheel angle of the steerable driving wheel in an SBW steering system. Throughout the parameter space—that is, within the available range of steering wheel angles limited by steering wheel angle limits or within the range of achievable wheel angles limited by wheel angle limits—the steering ratio in this paper is not necessarily constant. Instead, the steering ratio can have a variable progression.

[0045] This method is preferably developed by detecting the wheel angles of the steerable wheels of a motor vehicle, which are received or determined by a control device. The wheel angles can be detected using wheel angle sensors. Based on the detected wheel angles of the steerable wheels, a feedback torque specification corresponding to the feedback torque that will be applied to the steering wheel, at least indirectly, by the steering wheel actuator, can be determined by the control device. This provides the driver with a sense of lateral guidance for the vehicle.

[0046] The control device may optionally output a steering wheel setpoint signal to the steering wheel actuator based on a determined feedback torque to be applied, and the steering wheel actuator uses the steering wheel setpoint signal to adjust the applied feedback torque according to the feedback torque specification.

[0047] The control unit optionally determines the feedback torque specification based at least on the variable steering ratio. Therefore, the scenario-specific properties of the SBW steering system can be taken into account to achieve a consistent steering feel.

[0048] In some implementations, the control device determines the feedback torque specification based on lookup tables and / or algorithms.

[0049] In an optional implementation, the wheel angle limit may relate to the steering rack travel limit, according to which the steering rack travel of the SBW steering system is limited. The steering rack travel limit is determined by the control unit based on the vehicle speed. In this case, the wheel angle requirement relates to the steering rack position requirement, which is adapted by the control unit if it corresponds to a steering rack position outside the steering rack travel limit. Therefore, the adapted steering rack position requirement is limited by the steering rack travel limit. The setpoint signal output to the drive wheel actuator then corresponds to the steering rack position requirement or the adapted steering rack position requirement. In this case, a steering rack sensor can be used to detect the steering rack position. Based on the steering rack position, the feedback torque requirement measured in the context can be determined by the control unit. Furthermore, the control unit may consider the steering rack travel limit when determining the steering wheel angle limit.

[0050] According to another aspect, this disclosure also relates to a computer program product comprising commands that, when executed by a computer, cause the computer to perform the methods described herein. The advantages achieved by the methods described herein are also correspondingly obtained through the computer program product.

[0051] According to another aspect, this disclosure also relates to a computer-readable storage medium comprising commands that, when executed by a computer, cause the computer to perform the methods described herein. The advantages achieved by the methods described herein are also correspondingly obtained through a computer-readable storage medium.

[0052] According to another aspect, some embodiments of this disclosure relate to motor vehicles having an SBW steering system as described herein.

[0053] The advantages achieved by the SBW steering system described in this article can also be obtained through motor vehicles.

[0054] Within the meaning of this disclosure, motor vehicles can specifically include land vehicles, i.e., (especially) off-road and on-road vehicles, such as passenger cars, buses, trucks, and other commercial vehicles. Motor vehicles can be manned or unmanned. Motor vehicles are at least partially electrically driven and therefore have an electric motor for propulsion. Furthermore, motor vehicles may optionally have an internal combustion engine.

[0055] All features explained about each aspect can be combined individually or in (sub)combinations with other aspects. Attached Figure Description

[0056] The following explanation and description, based on examples illustrated in the accompanying drawings, further elaborate on the present disclosure and its advantageous embodiments and development. In the accompanying drawings: - Figure 1 A simplified schematic illustration of a motor vehicle with an SBW steering system according to one embodiment is shown. - Figure 2 A simplified schematic illustration of a method for operating an SBW steering system according to one embodiment is shown. - Figure 3 A simplified schematic diagram of the maximum permissible steering rack travel for the adaptation is shown. - Figure 4A and Figure 4B A simplified schematic diagram of the time correlation curves for different parameters of the SBW steering system is shown, as well as - Figure 5A and Figure 5B A simplified schematic diagram of the offset considered in the time-dependent curves of different parameters of the SBW steering system is shown. Detailed Implementation

[0057] The following detailed description, taken in conjunction with the accompanying drawings (where like numerals denote like elements), is intended to describe different embodiments of the disclosed subject matter and is not intended to constitute the only embodiment. Each embodiment described in this disclosure is used only as an example or illustration and should not be construed as preferred or advantageous over other embodiments. The illustrative examples included herein do not claim any completeness and do not limit the claimed subject matter to the exact form of the disclosure. Various modifications to the described embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of the described embodiments. Therefore, the described embodiments are not limited to the embodiments shown but have the maximum possible scope of application compatible with the features and principles disclosed herein.

[0058] All features disclosed below with respect to exemplary embodiments and / or drawings may be combined individually or in any sub-combination with features of the corresponding aspects of this disclosure (including features of preferred embodiments), provided that the resulting combination of features is meaningful to those skilled in the art.

[0059] For the purposes of this disclosure, the term "at least one of A, B, and C" means, for example, (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C), including all other possible combinations when more than three elements are listed. In other words, the term "at least one of A and B" generally means "A and / or B," i.e., "A" alone, "B" alone, or "A and B."

[0060] Figure 1 A simplified schematic illustration of a motor vehicle 10 having an SBW steering system 12 according to one embodiment is shown.

[0061] The SBW steering system 12 includes a control unit 14, a driving wheel actuator 16, and a steering wheel actuator 18.

[0062] The driving wheel actuator 16 is indirectly connected to the steerable driving wheel 20 of the motor vehicle 10. For this purpose, the driving wheel actuator is connected to the steering rack 22, which is connected to the steerable driving wheel 20 of the motor vehicle 10.

[0063] The motor vehicle 10 also has wheel speed sensors 24, which are coupled to the driving wheels 20 and configured to detect the speed of the driving wheels 20 in the circumferential direction and transmit it to the control unit 14. For example, the slippage of each wheel can be determined based on the detected speed, which allows the motor vehicle 10 to be characterized according to the corresponding driving conditions. Typically, one wheel speed sensor 24 is associated with each driving wheel 20.

[0064] The SBW steering system 12 optionally includes at least one wheel angle sensor 25 or is at least indirectly connected to said at least one wheel angle sensor 25. The wheel angle sensor 25 detects the wheel angle of at least one steerable travel wheel 20 about a wheel angle axis. For example, the control device 14 may take the detected wheel angle into account when determining the feedback torque specification.

[0065] Optionally or additionally, the SBW steering system 12 includes a steering rack sensor 26, which is integrated herein with the driving wheel actuator 16. The steering rack sensor 26 is configured to detect, for example, the steering rack position relative to a reference position of the steering rack 22. The control unit 14 can also determine the wheel angle of the steerable driving wheel 20 based on the steering rack position.

[0066] In another alternative implementation, the SBW steering system 12 may also have a pinion sensor that detects a corresponding measurement variable, based on which the control device 14 can determine the steering angle of the steerable driving wheel 20.

[0067] Additionally, the SBW steering system 12 has a mechanical end stop 28, which is formed herein with reference to the steering rack 22. This means that the steering rack 22 can only be deflected by the drive wheel actuator 16 to the extent that the steering rack 22 strikes the mechanical end stop 28. Of course, the mechanical end stop 28 is provided at two opposite ends for the available steering rack travel. Therefore, the maximum mechanical steering rack travel 30 is defined by the mechanical end stop 28. The maximum mechanical steering rack travel 30 thus limits the range of achievable steering angles of the steerable drive wheel 20.

[0068] On the other hand, the control device 14 is configured to use control technology (e.g., software) to further limit the steering angle of the steerable wheel 20. For this purpose, the control device 14 can consider a wheel angle limit 32, which influences and specifically limits the range of achievable wheel angles of the steerable wheel 20, depending on the situation. Of course, the wheel angle limit 32 can be achieved through a corresponding steering rack position limit (or a corresponding pinion position limit). Therefore, the range of achievable wheel angles of the steerable wheel 20 is limited by software. Because the wheel angle limit 32 depends on vehicle speed, the possibility of shifting the mechanical end stop 28 is provided, allowing for a generally larger range of achievable steering angles for the steerable wheel 20 after adaptation. The wheel angle limit 32 ensures limitation based on driving conditions according to vehicle speed.

[0069] The SBW steering system 12 also includes a steering wheel 34, to which a steering wheel actuator 18 is at least indirectly connected, for example, via the steering column. The steering wheel actuator 18 is configured to apply feedback torque to the steering wheel 34, such that a sense of lateral guidance of the vehicle 10 is transmitted to the driver of the vehicle 10.

[0070] The steering wheel actuator 18 has an electric motor. The electric motor of the steering wheel actuator 18 includes at least one coil group. Each coil group of the electric motor is three-phase and is configured to drive the rotor of the electric motor. Therefore, feedback torque can be provided to the driver at the steering wheel 34 of the motor vehicle 10 via the electric motor to convey the feeling of lateral guidance of the motor vehicle 10 to the driver or to ensure autonomous or semi-autonomous lateral guidance.

[0071] The driver of the motor vehicle 10 can provide steering input to the motor vehicle 10 via the steering wheel 34.

[0072] Additionally, the SBW steering system 12 includes at least one steering wheel sensor 36 configured to detect the steering wheel angle of the steering wheel 34 relative to a reference position (e.g., directly in front), i.e., the steering wheel position. The steering wheel 34 may be deflected in accordance with the maximum permissible steering wheel travel 38 herein. The wheel angle requirement for the steerable driving wheels 20 is typically defined by the detected steering wheel angle.

[0073] In this embodiment, the steering wheel sensor 36 is integrated with the steering wheel actuator 18. However, in other embodiments, the steering wheel sensor 36 may be separate from the steering wheel actuator 18. The steering wheel sensor 36 is configured to transmit the detected steering wheel angle to the control device 14.

[0074] The maximum permissible steering wheel travel 38 of the steering wheel 34 is also limited by the mechanical end stop 40.

[0075] Additionally, control device 14 is configured to determine a steering wheel angle limit 42, which is used to simulate the steering wheel angle required for wheel angle requirements—if the detected steering wheel angle exceeds the steering wheel angle limit 42. The steering wheel angle limit 42 is dependent on vehicle speed. Therefore, while the range of achievable steering wheel angles for steering wheel 34 is generally unrestricted, the actual steering wheel angle outside the steering wheel angle limit 42 has no effect on controlling the steering angle of the steerable wheels 20. Furthermore, when the steering wheel angle limit 42 is exceeded, a high feedback torque applied by steering wheel actuator 18 can be achieved at steering wheel 34. Therefore, it is difficult for the driver to further deflect the steering wheel 34, resulting in a reduced load on mechanical end stop 40.

[0076] The control unit 14 includes a data processing unit. Optionally, when outputting a setpoint signal to the drive wheel actuator 16, the control unit 14 may consider further parameters of the motor vehicle 10, such as vehicle speed or speed change value. Of course, these values ​​may also be considered when controlling the feedback torque applied to the steering wheel 34 by the steering wheel actuator 18.

[0077] Of course, the SBW steering system 12 can also have multiple components of the same type and generally the same function, such as multiple steering wheel sensors 36, which results in redundancy.

[0078] According to this embodiment, the motor vehicle 10 has an advanced driving control device 44 configured to apply autonomous or semi-autonomous driving functions. For example, the advanced driving control device 44 can autonomously guide the lateral movement of the motor vehicle 10 in this manner. To this end, the advanced driving control device 44 may, for example, specify the steering wheel angle of the steering wheel 34 or the wheel angle of the steerable wheels 20, and then, if the steering wheel angle does not exceed the steering wheel angle limit 42, the control device 14 takes that steering wheel angle as a wheel angle requirement.

[0079] The SBW steering system 12 is illustrated herein as a front axle steering system. The motor vehicle 10 and the SBW steering system 12 may also optionally have further steerable driving wheels 20, such as the rear wheels, which are coupled to additional common driving wheel actuators 16.

[0080] Each driving wheel actuator 16 has an electric motor. The electric motor has at least one coil group, which includes a set of coils. Each coil group is configured such that the phase current available to drive the rotor of the electric motor generates the coils below when a power supply signal such as a phase voltage is applied. The rotor can then be coupled to a corresponding component of the SBW steering system (e.g., steering rack 22), and thus enable the steerable driving wheel 20 to move. Typically, the electric motor may also have more than one coil group.

[0081] Each coil group is typically three-phase, so that the electric motor is designed as a whole to be at least three-phase, and optionally six-phase or nine-phase.

[0082] If there are multiple coil groups, each coil group can move the rotor of the electric motor independently of the other coil groups. This means that the coil groups are independent of each other.

[0083] Figure 2 A simplified schematic illustration of a method for operating the SBW steering system 12 according to one embodiment is shown. Optional steps are illustrated with dashed lines.

[0084] In optional step S2 of the method, at least one wheel speed sensor 24 is used to detect the wheel speed of at least one traveling wheel 20 in the circumferential direction and transmit it to the control device 14.

[0085] In the next step S4 of the method, the vehicle speed is received or determined by the control device 14. The control device 14 determines the vehicle speed of the motor vehicle 10 based on the received wheel speeds. Of course, the wheel speeds of different driving wheels 20 can be considered herein. In addition, the detection of wheel speeds allows the control device 14 to determine the slippage of each wheel for each driving wheel 20.

[0086] In an alternative embodiment, the motor vehicle 10 may also have a speed sensor configured to directly detect the vehicle speed of the motor vehicle 10 and transmit it to the control device 14.

[0087] The method then includes step S6, in which the control device 14 determines the wheel angle limit 32 of the steerable driving wheel 20 based at least on the vehicle speed. The wheel angle limit 32 is thus matched to the corresponding vehicle speed, and specifically, generally independently of the tolerance range with respect to the mechanical end stop 28.

[0088] The wheel angle limit 32 in this paper depends on the vehicle speed, such that if the first vehicle speed value is less than the second vehicle speed value, the wheel angle limit 32 for the first vehicle speed value is greater than the wheel angle limit 32 for the second vehicle speed value. This means that the wheel angle limit 32 for the higher vehicle speed of the motor vehicle 10 is lower than the wheel angle limit 32 for the lower vehicle speed. This is in Figure 3 The example is shown below. Figure 3 This is a simplified schematic diagram of the wheel angle limit 32 as a function of vehicle speed (x-axis). The wheel angle limit 32, determined by the control device 14, is depicted on the y-axis. Therefore, it can be considered that the available range of wheel angles can be optimally used for vehicle configurations with low driving dynamics (i.e., low vehicle speeds).

[0089] In an alternative embodiment, the wheel angle limit 32 may also depend on the vehicle speed, such that if the first vehicle speed value is less than the second vehicle speed value, the wheel angle limit 32 for the first vehicle speed value is less than the wheel angle limit 32 for the second vehicle speed value. For example, the wheel angle limit 32 of a stationary motor vehicle 10 may have a lower value than that of a moving motor vehicle 10 with a low vehicle speed. Therefore, the driving wheel actuator 16 can have a smaller size because the force required to move the steering rack 22 is greatest when the motor vehicle 10 is stationary and near the end stop 28.

[0090] In a further alternative embodiment, the wheel angle limit 32 may also be constant over a specific range of vehicle speeds.

[0091] In an alternative implementation, the wheel angle limit 32 can be defined herein as the limit of the steering rack travel, which depends on a variable controlling the wheel angle of the steerable driving wheel 20. In other words, the illustrated control mechanism can be designed accordingly based on the steering rack 22 and the corresponding threshold. Instead of the wheel angle limit 32, a software-based steering rack travel threshold is then determined as a function of vehicle speed.

[0092] In the next step S8, the control device 14 receives the wheel angle requirement for the steerable driving wheel 20.

[0093] Step S8 can be developed in different ways through optional steps S10 to S16.

[0094] According to optional step S10, the wheel angle requirement received by control device 14 in step S8 is based on the steering wheel angle of steering wheel 34 detected by steering wheel sensor 36, or based on the steering wheel angle of steering wheel 34 specified by advanced driving control device 44, or based on the wheel angle of steerable wheels 20 specified by the latter, or based on the steering wheel angle simulated by control device 14. This depends on whether the corresponding detected or specified steering wheel angle exceeds steering wheel angle limit 42, which is determined by control device 14 based at least on steering ratio and determined wheel angle limit 32 and / or vehicle speed. If the steering wheel angle limit 42 is exceeded, the steering wheel angle simulated by control device 14 is used for the wheel angle requirement from step S8. The simulated steering wheel angle herein corresponds to and is therefore limited by the determined steering wheel angle limit 42.

[0095] Alternatively, an optional step S12 can be provided, wherein if the corresponding detected or specified steering wheel angle of the steering wheel 34 exceeds the determined steering wheel angle limit 42, a dynamic steering wheel end stop is simulated by the steering wheel actuator 18 through a feedback torque applied at least indirectly to the steering wheel 34. The feedback torque used to simulate the dynamic steering wheel end stop is particularly high herein, and therefore can only be exceeded with effort by the driver. Thus, the simulation of the dynamic end stop by the steering wheel actuator 18 can be initiated by a setpoint signal from the control device 14.

[0096] According to the optional step S14 below, independently of changes to the determined wheel angle limit 32 and / or changes in vehicle speed, the steering wheel angle limit 42 determined in optional step S10 is maintained for the simulated dynamic steering wheel end stop (although these changes will actually affect the steering wheel angle limit 42) until the correspondingly detected or specified steering wheel angle drops below the maintained determined steering wheel angle limit 42. In other words, once the simulation of the dynamic steering wheel end stop (based on a specifically determined steering wheel angle limit 42) has been initiated, this setting is maintained without any change to the steering wheel angle limit 42 until this value drops below the simulated dynamic steering wheel end stop in the direction of the permissible steering wheel angle.

[0097] In optional step S14, an offset can occur between the determined steering wheel angle limit 42 of the simulated dynamic steering wheel end stop and the steering wheel angle limit 42 that actually has to be used due to changes in the determined wheel angle limit 32 and / or changes in vehicle speed. According to optional step S16, after this value has dropped below the simulated dynamic steering wheel end stop, this offset decreases continuously within the steering wheel angle range or over a specified duration, specifically not abruptly. This prevents the SBW steering system 12 from exhibiting discontinuous steering behavior.

[0098] According to step S18 of the method following step S8, if the wheel angle requirement from step S8 corresponds to a wheel angle of the steerable wheel 20 that is greater than the determined wheel angle limit 32, then the appropriate wheel angle requirement is determined by the control device 14. In this document, the appropriate wheel angle requirement is limited by the control device 14 based on the wheel angle limit 32. Therefore, the wheel angle requirement can be standardized to the speed-related wheel angle limit 32.

[0099] Additionally, in step S18 of the method, the control device 14 determines a feedback torque specification for the feedback torque, which will be applied at least indirectly to the steering wheel 34 by the steering wheel actuator 18. Of course, a simulated dynamic end stop from optional step S12 can be considered to adapt the magnitude of the feedback torque specification as needed.

[0100] Furthermore, step S18 can be developed via optional step S20. Thus, the wheel angle of at least one steerable travel wheel 20 is detected at least indirectly by a sensor (e.g., wheel angle sensor 25). In an alternative embodiment, the steering rack position of the steering rack 22 can be detected by a steering rack sensor 26, or by the pinion position, which is at least indirectly connected to the travel wheel actuator 16. Because both the pinion and the steering rack are at least indirectly connected to the steerable travel wheel 20, the travel angle of the steerable travel wheel 20 can be determined in the same manner from all measurements, for example, by the control device 14. Based on the detected measurements, the determined torque specification can therefore be more accurately adapted to the lateral guidance of the motor vehicle 10.

[0101] Next, according to the optional step S22, based on the feedback torque specification determined in step S18, the control device 14 outputs a steering wheel setpoint signal to the steering wheel actuator 18, so that the steering wheel actuator 18 can adjust the output feedback torque at the steering wheel 34 accordingly.

[0102] Additionally, the method includes a step S24 following step S22. In step S24, the control device 14 outputs a setpoint signal to the travel wheel actuator 16. The setpoint signal output to the travel wheel actuator 16 is based on a wheel angle requirement or an adapted wheel angle requirement, depending on whether the wheel angle requirement corresponds to a wheel angle of the steerable travel wheel 20 that is greater than the determined wheel angle limit 32. If the wheel angle requirement corresponds to a wheel angle greater than the determined wheel angle limit 32, the adapted wheel angle requirement is used and used as the basis for the output setpoint signal. Therefore, the travel wheel actuator 16 can adjust the wheel angle of the travel wheel 20 according to the speed based on the setpoint signal, without considering predetermined conditions, such as tolerance ranges, regarding the mechanical end stop 28.

[0103] Optionally, in step S6 and / or optional step S10, the lookup table 46 and / or algorithm 48 for determining the wheel angle limit 32 and / or steering wheel angle limit 42 may be considered by the control device 14.

[0104] Furthermore, in step S18, when the appropriate wheel angle requirement and / or feedback torque requirement are determined and / or when the corresponding setpoint signal is determined, the control device 14 may also consider looking up table 46 and / or algorithm 48. On the one hand, this allows for the implementation of compact control technology; on the other hand, it allows for the implementation of control technology with high resolution.

[0105] The wheel angle limit 32 is preferably determined by the control device 14 in step S6 to ensure the tolerance clearance between the steerable driving wheel 20 and the body components of the motor vehicle 10. Furthermore, the control device 14 can determine the wheel angle limit 32 such that, as a result, only a wheel angle range shorter than the wheel angle range defined by the mechanical end stop 28 can be achieved. Therefore, on the one hand, the load on the mechanical end stop 28 can be minimized, and on the other hand, undesirable contact between the driving wheel 20 and the body components of the motor vehicle 10 can be prevented.

[0106] Optionally, when determining the wheel angle limit 32, steering wheel angle limit 42, suitable wheel angle requirements, and / or feedback torque requirements, the control device 14 may also consider other parameters of the vehicle 10, such as changes in the longitudinal speed of the vehicle 10, changes in the lateral speed of the vehicle 10, and / or the vertical wheel travel of at least one of the driving wheels 20 of the vehicle 10. Therefore, the corresponding parameters can be adapted in a customized manner to the corresponding attributes of the driving conditions of the vehicle 10.

[0107] Figure 4A and Figure 4BA simplified schematic diagram showing time-dependent curves of different parameters of the SBW steering system 12 by way of example. In each case, time is plotted on the x-axis. Figure 4A where the y-axis shows the curve of the uncorrected DES position (i.e., the DES position independent of vehicle speed), the curve of the wheel angle limit 32, the curve of the steering wheel angle with DES function (i.e., the DES position formed depending on speed) and the curve of the wheel angle. Different dotted lines, dash-dotted lines and dashed lines are used for better understanding. The speed curve of the vehicle speed of the motor vehicle 10 is as shown in Figure 4B .

[0108] From Figure 4A it can be seen that at time t2, the wheel angle limit 32 is reduced by the control device 14 on the basis of the increased vehicle speed (see Figure 4B ) until time t3. At time t3, the wheel angle limit 32 is reduced enough to prevent an undesired configuration of the SBW steering system 12, even if the vehicle speed of the motor vehicle 10 continues to increase. The undesired configuration may, for example, be related to contact between the steerable running wheels 20 of the motor vehicle 10 and body components.

[0109] However, in previous conservative approaches, the wheel angle limit 32 would have to be limited for all vehicle speeds to the value that the wheel angle limit 32 herein has on the basis of the method presented only between time t3 and t4. This means that the parameter space of the corresponding allowable wheel angles can be expanded compared to conservative approaches of the speed-dependent wheel angle limit 32 based on other time frames, where herein: t<t3 and t>t4. Thus, the functionality of the SBW steering system 12 is improved.

[0110] After the first deflection starting from time t1, the wheel angle follows the curve of the wheel angle limit 32.

[0111] Without extending the DES function, the driver would return to the steering wheel position corresponding to the wheel angle, because the DES position would follow the wheel angle limit 32, as shown in Figure 4A illustrated on the basis of the uncorrected DES position (dash-dotted line). This means that the DES position at the steering wheel position beyond the DES position defined by the steering wheel angle limit 42 and when the vehicle speed increases is shifted due to the change of the wheel angle limit 32. In particular, the DES position is shifted inward. Thus, through DES simulation, the driver will experience a high feedback torque that pushes the driver back inward to the reference position. This makes the driver feel uncomfortable and confused. In the case of decreasing vehicle speed, the opposite situation occurs. The DES position will migrate outward. In this case, the driver will have to steer further in order to maintain the wheel angle at the wheel angle limit 32.

[0112] The speed-dependent extension of the DES function by control device 14 now enables the driver to have a consistent steering feel and prevents the driver from experiencing changes in the DES position with inconsistent steering feel. Conversely, if the detected or specified steering wheel angle exceeds the simulated steering wheel angle limit 42, the steering wheel angle limit 42 is maintained. Specifically, the DES position remains constant during the time interval between t2 and t5, during which the driver wishes to maintain the wheel angle at the wheel angle limit 32 and the vehicle speed is still changing, precisely depending on the steering wheel angle limit 42 determined at time t2. Therefore, the simulated dynamic steering wheel end stop (DES position) does not change for the driver, and in this respect, no adaptive feedback torque is applied until the detected or specified steering wheel angle drops below the DES position in the direction of the permissible steering wheel angle value, by which the driver is pushed towards the reference position.

[0113] To prevent (sudden) changes in the steering behavior of the SBW steering system 12 for the driver of motor vehicle 10, control device 14 introduces an offset 52. Offset 52 is derived from the quotient between the steering wheel 34 detected or specified at the control time and the applied steering ratio, minus the wheel angle of the steerable wheels 20 detected at the control time. Thus, Figure 5A and Figure 5B A simplified schematic illustration of offset 52 considered in time-dependent curves of different parameters of the SBW steering system 12 is shown. In this exemplary configuration, the driver turns the steering wheel 34 back to the zero position (directly forward position) at time tx. Offset 52 is reduced by the control device 14 within a specified time interval and / or a specified steering wheel travel and / or a specified wheel angle range, so that the turn is continuous and smooth for the driver of the motor vehicle. Thus, a consistent steering feel can be achieved without any sudden, perceptible change. The determination of offset 52 is advantageously configured such that offset 52 is determined when the driver turns back toward a reference position and is subsequently reduced only.

[0114] Alternatively, offset 52 can also be described by referring to the steering wheel angle. Offset 52 is then defined as the value between the steering wheel angle detected or specified at the control time and the detected wheel angle multiplied by the steering ratio.

[0115] The specific embodiments disclosed herein use circuits (e.g., one or more circuits) to implement the standards, protocols, methods, or techniques disclosed herein to functionally connect two or more components, generate information, process information, analyze information, generate signals, encode / decode signals, convert signals, transmit and / or receive signals, control other devices, etc. Any type of circuit can be used.

[0116] In one embodiment, the circuitry, such as the control device, particularly includes one or more data processing devices, such as a processor (e.g., a microprocessor), a central processing unit (CPU), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a system-on-a-chip (SoC), or the like or any combination thereof, and may include discrete digital or analog circuit elements or electronic devices or combinations thereof. In one embodiment, the circuitry includes hardware circuitry implementations (e.g., implementations in analog circuitry, implementations in digital circuitry, etc., and combinations thereof).

[0117] In one embodiment, the circuit includes a combination of circuitry and a computer program product having software or firmware instructions stored on one or more computer-readable storage media and interacting to cause the device to perform one or more of the protocols, methods, or techniques described herein. In one embodiment, the circuitry technology includes circuitry, such as a microprocessor or components thereof, whose operation requires software, firmware, etc. In one embodiment, the circuitry includes one or more processors or components thereof, along with associated software, firmware, hardware, etc.

[0118] In this disclosure, reference may be made to quantities and numbers. Unless otherwise expressly stated, these quantities and numbers should not be considered limiting, but rather as examples of quantities and numbers possible in the context of this disclosure. In this context, the term "multiple" may also be used to refer to quantities and numbers. In this document, the term "multiple" means any number greater than 1, such as 2, 3, 4, 5, etc. The terms "approximately," "about," "close to," etc., refer to adding or subtracting 5% of the stated value.

[0119] Although this disclosure has been described and illustrated with reference to one or more embodiments, those skilled in the art will be able to make equivalent changes and modifications after reading and understanding this specification and the accompanying drawings.

Claims

1. A method for operating a steer-by-wire system (12) of a motor vehicle (10), the steer-by-wire system (12) comprising at least one driving wheel actuator (16), a steering wheel actuator (18), and a control device (14) coupled to the driving wheel actuator (16) and the steering wheel actuator (18), wherein the method comprises at least the following steps: - The vehicle speed is received or determined by the control device (14). -The control device (14) determines the wheel angle limits of the steerable wheels (20) of the motor vehicle (10) based at least on the vehicle speed. -The control device (14) receives the wheel angle requirements of the steerable driving wheel (20). If the wheel angle requirement corresponds to a wheel angle of the steerable wheel (20) that is greater than the determined wheel angle limit, then the control device (14) determines an appropriate wheel angle requirement, wherein the appropriate wheel angle requirement is limited based on the wheel angle limit, and - The control device (14) outputs a setpoint signal to the driving wheel actuator (16), wherein the setpoint signal is based on the wheel angle requirement or the adapted wheel angle requirement, depending on whether the wheel angle requirement corresponds to the wheel angle of the steerable driving wheel (20) which is greater than the determined wheel angle limit.

2. The method according to claim 1, characterized in that, The wheel angle requirement is based on: - The steering wheel angle of the steering wheel (34) of the steer-by-wire system (12) detected by the steering wheel sensor (36), or - The steering wheel angle specified by the advanced driving control device (44) of the steering wheel (34), or - The wheel angle of the steerable driving wheel (20) as specified by the advanced driving control device (44), or - The steering wheel angle simulated by the control device (14) depends on whether the corresponding detected or specified steering wheel angle exceeds the steering wheel angle limit determined by the control device (14) at least based on the steering ratio and the determined wheel angle limit and / or the vehicle speed, wherein the simulated steering wheel angle corresponds to the determined steering wheel angle limit.

3. The method according to claim 2, characterized in that, If the corresponding detected or specified steering wheel angle of the steering wheel (34) exceeds the determined steering wheel angle limit, the steering wheel actuator (18) simulates a dynamic steering wheel end stop by applying feedback torque to the steering wheel (34) at least indirectly.

4. The method according to claim 3, characterized in that, Independent of changes in the determined wheel angle limits and / or changes in the vehicle speed, the determined steering wheel angle limits are maintained for a simulated dynamic steering wheel end stop until the correspondingly detected or specified steering wheel angle drops below the maintained determined steering wheel angle limits.

5. The method according to claim 4, characterized in that, If the corresponding detected or specified steering wheel angle falls below the maintained defined steering wheel angle limit, the deviation caused by the simultaneous change of the maintained defined steering wheel angle limit, the defined wheel angle limit, and / or the vehicle speed will continuously decrease within the specified time period or within the steering wheel angle interval.

6. The method according to any one of claims 2 to 5, characterized in that, The control device (14) determines the steering wheel angle limit based on a lookup table (46) and / or an algorithm (48).

7. The method according to any one of the preceding claims, characterized in that, The control device (14) determines the wheel angle limit based on a lookup table (46) and / or an algorithm (48).

8. The method according to any one of the preceding claims, characterized in that, When determining the wheel angle limit, the control device (14) considers at least one of the following: changes in the longitudinal speed of the motor vehicle (10), changes in the lateral speed of the motor vehicle (10), and / or the vertical wheel travel of at least one of the driving wheels (20) of the motor vehicle (10).

9. The method according to any one of the preceding claims, characterized in that, The motor vehicle (10) has at least one wheel speed sensor (24) or is at least indirectly connected to the at least one wheel speed sensor (24), wherein the wheel speed sensor (24) detects the wheel speed of at least one driving wheel (20), and wherein the control device (14) determines the vehicle speed based at least on the detected wheel speed or receives the vehicle speed determined based on the detected wheel speed.

10. The method according to any one of the preceding claims, characterized in that, The control device (14) determines the wheel angle limit such that: - To prevent contact between the running wheels (20) and body components, thereby taking into account tolerance clearances, and / or - The wheel angle range of the steerable wheel (20) limited by the determined wheel angle limit is shorter than the mechanical wheel angle range of the steerable wheel (20) defined by the mechanical end stop (28).

11. A steer-by-wire system (12) for a motor vehicle (10), comprising at least one driving wheel actuator (16), a steering wheel actuator (18), and a control device (14) coupled to the driving wheel actuator (16) and the steering wheel actuator (18), wherein the control device (14) is configured to: - Receive or determine vehicle speed -The wheel angle limits of the steerable wheels (20) of the motor vehicle (10) are determined at least based on the vehicle speed. -Receive the wheel angle requirement of the steerable driving wheel (20), - If the wheel angle requirement corresponds to a wheel angle of the steerable wheel (20) that is greater than the determined wheel angle limit, then a suitable wheel angle requirement is determined, wherein the suitable wheel angle requirement is limited based on the wheel angle limit, and - Output a setpoint signal to the driving wheel actuator (16), wherein the setpoint signal is based on the wheel angle requirement or the adapted wheel angle requirement, depending on whether the wheel angle requirement corresponds to a wheel angle of the steerable driving wheel (20) that is greater than the determined wheel angle limit.

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