Steer-by-wire steering system and method for operating a steer-by-wire steering system with evaluation of steering angle and of steering torque

Abstract

The present invention relates to a steer-by-wire steering system (1) for a motor vehicle, wherein a steering control element (2) can be moved between two stops starting from a central position. The steer-by-wire steering system (1) is designed to sense a steering angle introduced into the steering control element (2) and a steering torque introduced into the steering control element (2), as a steering specification, and a wheel steering adjuster (3) is designed to convert a sensed steering specification into a wheel steering angle of steerable wheels (8). The steer-by-wire steering system (1) is further designed to determine the steering specification by evaluating the sensed steering angle, during movement of the steering control element (2) between the stops, and to determine the steering specification by evaluating the sensed steering torque, once one of the stops has been reached. The invention further relates to a method for operating a steer-by-wire steering system (1) in a motor vehicle, wherein a steering angle introduced during movement of the steering control element (2) between a first stop and a second stop is sensed as a steering specification, and wherein a steering torque introduced once one of the stops has been reached during movement of the steering control element is sensed as a steering specification.

Description

[0001] thyssenkrupp Presta AG 24175-SBW - 240678P10WO thyssenkrupp AG

[0002] 1 / 16

[0003] Steer-by-wire steering system and method for operating a steer-by-wire steering system with steering angle and steering torque evaluation

[0004] The invention relates to a steer-by-wire steering system for a motor vehicle comprising a steering handle and a wheel steering actuator, wherein the steering handle is adjustable from a central position between a first stop and a second stop, wherein the steer-by-wire steering system is configured to detect a steering angle and a steering torque applied to the steering handle as a steering input, and wherein the wheel steering actuator is configured to convert a detected steering input into a wheel steering angle of steerable wheels of the motor vehicle.

[0005] Furthermore, the invention relates to a method for operating a steer-by-wire steering system in a motor vehicle, wherein a steering handle of the steer-by-wire steering system is adjusted to issue a steering command.

[0006] A steer-by-wire steering system with a joystick-type steering handle is known from JP 2023 172328 A. A steer-by-wire steering system with a steering wheel as a steering handle, in which a detected steering wheel angle and a detected steering wheel torque can be used to detect a steering input, is described in US 2022 / 0089212 A1. Furthermore, DE 10 2018 219 330 A1 discloses a method for operating a motor vehicle equipped with a steering wheel, wherein a steering wheel angle and a steering wheel torque are detected, and a wheel steering angle of the steerable wheels of the motor vehicle is determined from the detected steering wheel angle and the detected steering wheel torque.Specifically, DE 10 2018 219 330 A1 describes that for steering wheel angles up to 90°, only the steering wheel angle is used to determine the wheel steering angle, while for steering wheel angles between 90° and 120°, the measured steering wheel torque is used additionally or alternatively to determine the wheel steering angle. In this way, the steering wheel angle required to achieve the respective maximum steering position is reduced.

[0007] Against this background, an object of the present invention is to provide good steering control and high steering comfort even with a further reduced steering angle of the steering handle, particularly with alternative human-machine interfaces (HMIs) that are provided as steering handles instead of a conventional steering wheel. thyssenkrupp Presta AG 24175-SBW - 240678P10WO thyssenkrupp AG

[0008] 2 / 16

[0009] To solve this problem, a steer-by-wire steering system and a method for operating a steer-by-wire steering system in a motor vehicle are proposed according to the independent claims. Further advantageous embodiments of the invention are described in the dependent claims and the description and are illustrated in the figures.

[0010] The proposed solution provides a steer-by-wire steering system for a motor vehicle, the steer-by-wire system comprising a steering handle and a wheel steering actuator. The steering handle of the steer-by-wire system is configured to be adjusted from a neutral position between a first stop and a second stop. The steer-by-wire system, and in particular an electronic control unit associated with the steer-by-wire system, is configured to detect a steering angle and a steering torque applied to the steering handle as a steering input, wherein the wheel steering actuator is configured to convert a detected steering input into a wheel steering angle of the steerable wheels of the motor vehicle, in particular by controlling an electric motor acting on a steering gear.According to the invention, the steer-by-wire steering system is further developed to determine the steering input when the steering handle is adjusted between the first and second stops by evaluating the detected steering angle, and to determine the steering input from the point at which the first stop is reached (from the center position) or from the point at which the second stop is reached (from the center position) by evaluating the detected steering torque. Advantageously, the steering handle is therefore no longer moved, or substantially no longer moved, from the point at which the first or second stop is reached, while the wheel steering angle can still be further increased by a steering torque applied to the steering handle. The proposed steering system thus advantageously makes it possible to keep the adjustable steering angle range small without having to implement a very direct ratio between the steering angle and the set wheel steering angle.This makes precise steering maneuvers easier and more comfortable to perform.

[0011] Advantageously, a virtual first transmission ratio is specified for converting a detected steering angle into a wheel steering angle, which can be linear or substantially linear. Furthermore, advantageously, a virtual second transmission ratio is specified for converting a detected steering torque into a wheel steering angle, wherein this second transmission ratio is, in particular, a transmission ratio that differs from the first. In particular, the second thyssenkrupp Presta AG 24175-SBW - 240678P10WO thyssenkrupp AG

[0012] 3 / 16

[0013] Translation ratio: a non-linear translation ratio, further advantageous an exponential translation ratio.

[0014] In particular, it is provided that the steering mechanism is designed as at least one alternative human-machine interface (HMI) that differs from a steering wheel. This alternative HMI is advantageously designed to be compact and / or easily stowed, particularly to improve the available space in a motor vehicle, especially during autonomous operation. The disadvantage of a limited and, in particular, reduced adjustable steering angle range compared to a conventional steering wheel, which can typically be greater than 500°, is advantageously overcome by switching to a steering torque-based determination of the steering input once the respective steering lock is reached.

[0015] A so-called micro-steering wheel, which is at most 50% the size of a conventional car steering wheel, can be used as the steering handle. A particularly advantageous embodiment of the steer-by-wire steering system provides that the steering handle is designed as at least one joystick, or is designed in the manner of a joystick. Specifically, exactly one joystick can be provided as the steering handle, with a steering movement advantageously being introduced into the steer-by-wire steering system by pivoting the joystick laterally, and more specifically, by pivoting it to the right or left. Advantageously, such a joystick control requires little space. Furthermore, it advantageously enables one-handed steering for a further increase in comfort.Furthermore, one embodiment provides that a joystick is arranged to the right and left of the driver as a steering handle, with one of the joysticks advantageously being operable with the left hand of a vehicle user and the other advantageously being operable with the right hand of a vehicle user. In particular, with two joysticks, it can also be provided that one joystick is assigned to each vehicle user's seat, with each joystick functioning as a steering handle.

[0016] Furthermore, it is specifically stipulated that the adjustment range of the steering handle between the first and second stops is a maximum of 240°. Advantageously, thyssenkrupp Presta AG 24175-SBW - 240678P10WO thyssenkrupp AG

[0017] 4 / 16 The steering handle can be adjusted from a central position by 120° in a first direction, in particular to the left, and by 120° in a second direction, in particular to the right. Preferably, the respective stop is reached after each 120° adjustment from the central position. In particular, the adjustment range of the steering handle between the first stop and the second stop can be a maximum of 180°, and more specifically, exactly 180°. It is further advantageous that the adjustment range of the steering handle between the first stop and the second stop is a maximum of 120°, especially if the steering handle is designed as a joystick. Advantageously, in this configuration, the steering handle can be adjusted from a central position by a maximum of 60° in a first direction, in particular to the left, and a maximum of 60° in a second direction, in particular to the right.Preferably, the first and second stops are reached after each adjustment of a maximum of 60° from the center position. The comparatively short adjustment range advantageously allows for a very compact and therefore space-saving design of the steering handle. Furthermore, this reduces the space required for the vehicle user to operate the steering handle. Both of these factors increase driving comfort.

[0018] According to an advantageous embodiment, the first stop is a first end stop and the second steering stop is a second steering stop. In this embodiment, the steering handle is therefore not adjustable beyond the first or second stop. However, another advantageous embodiment provides that, in addition to the first stop, a first end stop is provided, starting from the center position, and in addition to the second stop, a second end stop is provided, starting from the center position. Advantageously, once the first and second stops are reached, the feel for further adjustment of the steering handle changes noticeably.In particular, it is provided that the steering handle, starting from the center position, can be moved against increased steering resistance from the first stop to the first end stop, and against increased steering resistance from the second stop to the second end stop. Advantageously, adjusting the steering handle from the center position beyond the first and second stops requires significantly more force from the vehicle operator. thyssenkrupp Presta AG 24175-SBW - 240678P10WO thyssenkrupp AG.

[0019] 5 / 16

[0020] In particular, the stop and the end stop are designed so that the respective stop is already perceived as the end stop by a vehicle operator. A further adjustment range, which is particularly small, from the first or second stop towards the respective end stop allows for a more precise detection of the steering torque applied to the steering handle. This advantageously increases steering precision when setting large wheel steering angles and makes operation more comfortable. Specifically, it can be provided that the steering handle, upon reaching the first or second stop, engages a spring and / or damping element, which is compressed under a corresponding force. The respective end stop is reached, in particular, at maximum compression of the spring and / or damping element.

[0021] The adjustment range between the first stop and the first end stop, as well as between the second stop and the second end stop, can be defined in different ways relative to the adjustment range between the center position and the first stop, or relative to the adjustment range between the center position and the second stop, which can advantageously also depend on the type of steering mechanism chosen. It may even be possible to design the respective stop and its associated end stop to be configurable, particularly depending on the current driving situation.

[0022] According to an advantageous embodiment, the adjustment range between the first stop and the first end stop is a maximum of 3% of the adjustment range between the center position and the first stop, and in particular a maximum of 1% of the adjustment range between the center position and the first stop. Similarly, the adjustment range between the second stop and the second end stop is advantageously a maximum of 3% of the adjustment range between the center position and the second stop, and in particular a maximum of 1% of the adjustment range between the center position and the second stop. In particular, the further adjustment range between the stop and the end stop can be less than 1.5°. Advantageously, the respective stop and the end stop thus coincide almost exactly. The steering angle range of the handlebars thus remains advantageously small.However, determining the steering input by detecting the steering torque applied to the steering handle can be improved, and the wheel steering angle to be set can advantageously be specified more precisely by a vehicle operator. thyssenkrupp Presta AG 24175-SBW - 240678P10WO thyssenkrupp AG.

[0023] 6 / 16

[0024] Another advantageous embodiment provides that the steer-by-wire steering system includes a steering request evaluation unit. This steering request evaluation unit is advantageously configured to evaluate the current driving situation of the vehicle. Furthermore, the steering request evaluation unit is advantageously configured to activate or deactivate the detection of the steering input by evaluating the detected steering torque, depending on a steering request associated with the evaluated driving situation. In particular, depending on a steering request associated with the evaluated driving situation, the unit is configured to allow or suppress the detection of the steering input by evaluating the detected steering torque.The steering demand evaluation unit can assess the current driving situation by evaluating current driving conditions, particularly information regarding current driving condition variables such as current vehicle speed, current vehicle acceleration, and / or current vehicle yaw moment. Advantageously, the steering demand evaluation unit further improves the steerability and steering comfort of the steer-by-wire steering system by advantageously activating or deactivating the determination of a steering input based on a detected steering torque, depending on the driving situation. This also advantageously increases driving safety because, for example, setting large steering angles—advantageously achieved by detecting steering torques applied to the steering mechanism—is advantageously prevented in driving situations where such large steering angles would lead to an unsafe vehicle condition.Advantageously, the steering request evaluation unit allows switching between steering angle-dependent and steering torque-dependent steering control depending on the situation.

[0025] According to an advantageous further development, the steering requirement evaluation unit is further configured to activate the detection of the steering input by evaluating the detected steering torque in a driving situation assessed as driving at low speed, particularly when the vehicle is stationary or traveling at a maximum of 15 km / h (km: kilometers; h: hour). This allows, in particular, the detection of the steering input by evaluating the detected steering torque. Advantageously, this enables the setting of large wheel steering angles, in addition to the advantages already mentioned.

[0026] According to a further advantageous embodiment, the steering request evaluation unit is further designed to detect the steering input in a driving situation assessed as high-speed driving, particularly when the vehicle is traveling at more than 80 km / h. thyssenkrupp Presta AG 24175-SBW - 240678P10WO thyssenkrupp AG

[0027] 7 / 16 to deactivate by evaluating the detected steering torque, in particular to suppress the detection of the steering input by evaluating the detected steering torque. Advantageously, this prevents the setting of large wheel steering angles at high speeds.

[0028] In particular, the steering requirement evaluation unit is designed to deactivate, or in particular suppress, the detection of the steering input by evaluating the detected steering torque in driving situations assessed as having low steering requirements, especially situations with a required wheel steering angle of less than 15°. Advantageously, the steering requirement evaluation unit is further designed to activate, or in particular allow, the detection of the steering input by evaluating the detected steering torque in driving situations assessed as having high steering requirements, especially situations with a required wheel steering angle of more than 20°.Advantageously, this method allows for improvements in comfort and safety.

[0029] In the method proposed for solving the aforementioned problem of operating a steer-by-wire steering system in a motor vehicle, a steering handle of the steer-by-wire steering system is adjusted to provide a steering input, wherein a steering angle applied to the steering handle during adjustment is recorded as the steering input when the steering handle is adjusted between a first stop and a second stop, and wherein a steering torque applied to the steering handle during adjustment is recorded as the steering input when the steering handle is operated further from the center position after reaching the first or second stop, in particular when it is further adjusted, wherein a wheel steering actuator of the steer-by-wire steering system converts the recorded steering input into a wheel steering angle of steerable wheels of the motor vehicle.Like the proposed steer-by-wire steering system, the proposed method also realizes the advantages described in connection with the proposed steer-by-wire steering system. In particular, the method enables the use of a steer-by-wire steering system with a steering handle that has only a small steering angle range, especially a steer-by-wire steering system with a steering handle designed as a joystick. Despite this, a high level of steering comfort and precision can still be achieved. thyssenkrupp Presta AG 24175-SBW - 240678P10WO thyssenkrupp AG.

[0030] 8 / 16

[0031] In particular, the method provides that, starting from the center position of the steering handle, the steering resistance is increased, and especially significantly increased, upon reaching the first or second stop, preferably to such an extent that any adjustment movement of the steering handle is essentially stopped. Advantageously, this further increases ease of use.

[0032] Advantageously, the method assesses the current driving situation and, depending on a steering requirement associated with that situation, activates or deactivates the detection of the steering input by evaluating the detected steering torque. In particular, it allows or suppresses the detection of the steering input based on the detected steering torque. Deactivating or suppressing the determination of a steering input based on a detected steering torque applied to the steering system is particularly advantageous in driving situations where setting large steering angles is unnecessary or could even be critical for driving safety.Activating or allowing the determination of a steering input based on a detected steering torque introduced into the steering handle is advantageously particularly in driving situations where large wheel steering angles can be requested, especially during parking maneuvers.

[0033] According to a further advantageous embodiment of the method, in a driving situation assessed as driving at low speed, particularly when the vehicle is stationary or traveling at a maximum of 15 km / h, the detection of the steering input by evaluating the detected steering torque is activated, or in particular, the detection of the steering input by evaluating the detected steering torque is permitted. Furthermore, advantageously, in a driving situation assessed as driving at high speed, particularly when the vehicle is traveling at more than 80 km / h, the detection of the steering input by evaluating the detected steering torque is deactivated, or in particular, the detection of the steering input by evaluating the detected steering torque is suppressed.In particular, in a driving situation assessed as having low steering requirements, especially a driving situation with a required wheel steering angle of less than 15°, the detection of the steering input by evaluating the detected steering torque is deactivated, specifically suppressed. Furthermore, in a driving situation assessed as having high steering requirements, especially a driving situation with thyssenkrupp Presta AG 24175-SBW - 240678P10WO thyssenkrupp AG.

[0034] 9 / 16 a required wheel steering angle of more than 20°, the detection of the steering input by an evaluation of the detected steering torque is activated, in particular the detection of the steering input by an evaluation of the detected steering torque is permitted.

[0035] It is further advantageous that the steer-by-wire steering system is designed as a steer-by-wire steering system according to the invention. It is also further advantageous to propose a steer-by-wire steering system that is designed to be operated according to a method developed according to the invention. The steer-by-wire steering system has, in particular, the features described in connection with the steer-by-wire steering system, either individually or in combination.

[0036] Further advantageous details, features and embodiments of the invention are explained in more detail in connection with the exemplary embodiments illustrated in the figures (hereinafter Fig.: figure). The figures show:

[0037] Fig. 1 shows a simplified perspective view of an embodiment of a steer-by-wire steering system designed according to the invention;

[0038] Fig. 2 is a block diagram to illustrate an embodiment of a method designed according to the invention for operating a steer-by-wire steering system in a motor vehicle;

[0039] Fig. 3 shows a diagram illustrating an embodiment of the relationship between a steering angle and a steering torque applied to a steering handle and a wheel steering angle; and

[0040] Fig. 4 shows a schematic representation of an embodiment of a steering handle and its adjustment range of a steer-by-wire steering system designed according to the invention.

[0041] In the various figures, identical parts are generally marked with the same reference symbols and are therefore sometimes only explained in connection with one of the figures. thyssenkrupp Presta AG 24175-SBW - 240678P10WO thyssenkrupp AG

[0042] 10 / 16

[0043] Figure 1 shows a simplified embodiment of a steer-by-wire steering system 1 for a motor vehicle according to the invention. In this embodiment, the steer-by-wire steering system 1 comprises a steering handle 2 designed as a joystick, by means of which a vehicle operator can steer the motor vehicle. Figure 4 sketches advantageous design details of a possible embodiment of the steering handle 2 designed as a joystick. Starting from a center position 21, the steering handle 2 is adjustable between a first stop 22 and a second stop 23, resulting in an adjustment range 26 between the first stop 22 and the second stop.

[0044] In this embodiment, the adjustment range 26 of the steering handle 2 between the first stop 22 and the second stop 23 is 90°, specifically 45° towards the first stop 22 and 45° towards the second stop 23 when starting from the center position 21 of the steering handle 2. Furthermore, in the embodiment sketched in Fig. 4, the steering handle 2 can be moved from the center position 21 against increased steering resistance from the first stop 22 to a first end stop 24, and from the center position 21 against increased steering resistance from the second stop 23 to a second end stop 25. The total adjustment range 27 between the first end stop 24 and the second end stop 25 is thus greater than the adjustment range 26.In this embodiment, the adjustment range between a stop 22, 23 and the associated end stop 24, 25 can be, in particular, 1°, resulting in a total adjustment range 27 of 92°. The stops 22, 23 are designed such that normal steering movement is limited or stopped by these stops 22, 23, and adjustment of the steering handle 2 beyond one of the stops 22, 23 is only possible with increased force. In particular, it is further provided that the end stops 24, 25 are not reached during normal operation.

[0045] A control unit 100 of the steer-by-wire steering system 1 is designed to detect an adjustment movement performed by a vehicle user via the steering handle 2, wherein several steering parameters are associated with the adjustment movement, which are detected by sensors and transmitted to the control unit 100. In this exemplary embodiment, the detected steering parameters include, in particular, a steering angle set via the steering handle 2, a steering torque applied to the steering handle 2, and an adjustment speed, i.e., a speed at which the steering angle is adjusted. thyssenkrupp Presta AG 24175-SBW - 240678P10WO thyssenkrupp AG

[0046] 11 / 16

[0047] In this embodiment, the control unit 100 is further developed to determine a steering input by evaluating a steering angle that is set when the steering handle 2 is adjusted between the first stop 22 and the second stop 23, and from the point at which the first stop 22 or the second stop 23 is reached, starting from the center position 21 of the steering handle 2, i.e. when the steering handle 2 is operated beyond the adjustment range 26, the steering input is determined by evaluating a detected steering torque 5 exerted on the steering handle 2 by a vehicle user.It is therefore evident that the end stops 24, 25 are not required to detect a further adjustment range, but rather the extended adjustment range between the first stop 22 and the first end stop 24 or between the second stop 23 and the second end stop 25 is advantageous for improved detection of a steering torque exerted on the steering handle 2, whereby the steering handle 2 is also advantageously better protected against overloading by steering torques exerted on the steering handle 2 by this extended adjustment range.

[0048] In this embodiment, a signal line 10 is configured to transmit the steering input to be implemented to a wheel steering actuator 3 of the steer-by-wire steering system 1. The wheel steering actuator 3 is configured to convert the steering input into a steering angle 6 of the steerable wheels 8 of the vehicle via a steering gear 7. In this embodiment, the wheel steering actuator 3 comprises an electric motor 31 and a control unit 32 that controls this electric motor 31. The electric motor 31 acts via a transmission belt 73 on a spindle drive 72, which is operatively connected to a connecting rod 71 designed as a rack. By appropriately controlling the electric motor 31 by means of the motor control unit 32, the spindle drive 72 is driven to convert a steering input into a steering movement of the steerable wheels 8.The wheel steering actuator 3 acts on the connecting rod 71 via the spindle drive 72, which is driven by the electric motor 31, thus initiating a steering movement of the steerable wheels 8 of the motor vehicle. In this embodiment, the steerable wheels 8 are connected to the connecting rod 71 in a known manner via tie rods 9. The tie rods 9 themselves are connected to each steered wheel 8 via steering knuckles in a known manner.

[0049] Optionally, the steer-by-wire steering system 1, in particular the control unit 100 of the steer-by-wire steering system 1, can include a steering request evaluation unit not explicitly shown in Fig. 1. This steering request evaluation unit is then used for thyssenkrupp Presta AG 24175-SBW - 240678P10WO thyssenkrupp AG

[0050] The system, trained in 12 / 16, is capable of evaluating a current driving situation and, depending on a steering request associated with that situation, activating or deactivating the steering input detection by evaluating the detected steering torque. Specifically, the steering request evaluation unit allows switching between steering angle-dependent and steering torque-dependent steering control, depending on the specific driving situation. If steering input detection is deactivated by evaluating the detected steering torque, the steering input is determined taking into account a detected steering angle. If steering input detection is activated by evaluating the detected steering torque, the steering input is determined either by considering a detected steering torque or by considering both a detected steering angle and a detected steering torque.

[0051] With reference to Fig. 2 and Fig. 3, an advantageous embodiment of a method for operating a steer-by-wire steering system 1 in a motor vehicle is explained below, wherein the steer-by-wire steering system 1 can be designed in particular as described with reference to Fig. 1 and Fig. 4.

[0052] The method provides that a steering handle 2 of the steer-by-wire steering system 1, in particular a joystick, is adjusted to execute a steering input. A steering angle 4 introduced into the steering handle 2 during its adjustment is recorded as a steering input when the steering handle 2 is adjusted between a first stop 22 and a second stop 23. Furthermore, the method provides that a steering torque 5 introduced into the steering handle 2 during its adjustment can be recorded as a steering input if the steering handle 2 continues to be operated from a neutral position 21 after reaching the first stop 22 or the second stop 23, and in particular if a force, and thus a steering torque, continues to be exerted on the steering handle 2 after reaching one of the stops 22 or 23.

[0053] Whether a steering torque 5 applied to the steering handle 2 during adjustment is detected as a steering input and converted into a corresponding wheel steering angle 6 depends, in this embodiment, on an assessment of the current driving situation of the vehicle. In this embodiment, this assessment is performed by a steering input evaluation unit 110, which may, in particular, be comprised of a control unit 100 associated with the steer-by-wire steering system 1. thyssenkrupp Presta AG 24175-SBW - 240678P10WO thyssenkrupp AG 13 / 16

[0054] The steering request evaluation unit assesses a current driving situation, whereby, depending on a steering request associated with the assessed driving situation, the detection of the steering input by evaluating the detected steering torque 5 is either permitted or suppressed. The steering request evaluation unit 110 receives a plurality of current vehicle parameters VP, in particular current vehicle speed, current vehicle accelerations, and current vehicle yaw moments. Furthermore, the steering request evaluation unit 110 receives current steering parameters SP, in particular a steering angle 4, a steering torque 5, and / or a steering angle velocity.

[0055] Based on the detected parameters VP and SP, the steering requirement evaluation unit 110 assesses the current driving situation and determines whether the steering torque 5 applied to the steering handle 2 is detected as a steering input and thus used to determine the wheel steering angle 6. In this embodiment, the steering requirement evaluation unit 110 is configured such that, in a driving situation assessed as having a low steering requirement, the detection of the steering input by evaluating the detected steering torque 5 is suppressed, and thus a wheel steering angle 6 is not determined based on a detected steering torque 5. Conversely, in a driving situation assessed as having a high steering requirement, the detection of the steering input by evaluating the detected steering torque 5 is permitted, and thus a wheel steering angle 6 is determined based on a detected steering torque 5.

[0056] In this embodiment, in a driving situation which is assessed by the steering requirement evaluation unit 110 as driving at a speed of up to 12 km / h, the detection of the steering input by an evaluation of the detected steering torque 5 is permitted, and in a driving situation which is assessed as driving at a speed of more than 65 km / h, the detection of the steering input by an evaluation of the detected steering torque 5 is suppressed.

[0057] If the detection of the steering input is suppressed by an evaluation of the detected steering torque 5, then in case A a steering angle control is applied in which a wheel steering angle 6 is determined based on the detected steering angle 4. A wheel steering actuator 3 of the steer-by-wire steering system 1 converts the steering input determined based on the detected steering angle 4 into a wheel steering angle 6 of steerable wheels 8 of the vehicle. An essentially linear virtual transmission ratio can be defined between the steering angle 4 entered in the steering handle 2 and the wheel steering angle 6 to be set.

[0058] If the steering requirement evaluation unit 110 allows the steering input to be determined by evaluating the detected steering torque 5, then in case B, a steering torque control is applied in which a wheel steering angle 6 is determined based on the detected steering torque 5. A wheel steering actuator 3 of the steer-by-wire steering system 1 converts the steering input determined based on the detected steering torque 5 into a wheel steering angle 6 of steerable wheels 8 of the vehicle. In particular, a sharply increasing non-linear virtual transmission ratio between the steering torque 5 applied to the steering handle 2 and the wheel steering angle 6 to be set can be defined.

[0059] Figure 3 shows an exemplary embodiment for a possible determination of a transmission ratio between the applied steering angle 4 (abscissa; section A) and the adjustable wheel steering angle 6 (ordinate) and the applied steering torque 5 (abscissa; section B) and the adjustable wheel steering angle 6 (ordinate), wherein it is particularly provided that the assignment can be configured differently, especially depending on the vehicle speed. The dashed line symbolizes the technically maximum adjustable wheel steering angle 61.

[0060] In the example sketched in Fig. 3, the wheel steering angle 6 is determined in area A (corresponding to case A in Fig. 2) based on the set steering angle 4. For this purpose, the full adjustment range of the steering handle 2, from the center position 21 to one of the stops 22, 23, is used to determine a steering angle 4. As can be seen in Fig. 3, the maximum adjustable wheel steering angle 61 cannot be set in this adjustment range by steering angle-controlled steering (case A).

[0061] To set larger wheel steering angles 6, the steering request evaluation unit 110 must allow the determination of a steering input based on the steering torque 5 applied to the steering handle 2 (case B). If this is the case, a wheel steering angle 6 up to the maximum adjustable wheel steering angle 61 can be implemented, as shown in area B in Fig. 3. The steering handle 21 continues to be operated when one of the stops 22, 23 is reached, and the steering torque 5 exerted on the steering handle 21 is transmitted from the wheel steering actuator 3 of the steer-by-wire steering system 1 via a substantially linear assignment (in this embodiment) to the wheel steering actuator 3 of the steer-by-wire steering system 1.

[0062] 15 / 16 implements the corresponding wheel steering angle 6. The virtual transmission ratio is chosen to be more direct in case B, resulting in a steeper increase in the wheel steering angle 6 in region B compared to region A in Fig. 3.

[0063] The embodiments shown in the figures and explained in connection with them serve to illustrate the invention and are not limiting to it.

[0064] Reference symbol list

[0065] 1 Steer-by-wire steering system

[0066] 2 Steering handle

[0067] 21 Center position

[0068] 22 first attack

[0069] 23 second attack

[0070] 24 first end stop

[0071] 25 second end stop

[0072] 26 Adjustment range of the steering handle (2) between the first stop (22) and the second stop (23)

[0073] 27 total adjustment range

[0074] 3 Wheel steering adjusters

[0075] 31 Electric motor of the wheel steering actuator (3)

[0076] 32 Control unit of the wheel steering actuator (3)

[0077] 4 Steering angle

[0078] 5 Steering torque

[0079] 6 Wheel steering angle

[0080] 61 maximum wheel steering angle

[0081] 7 Steering gear

[0082] 71 Connecting rod (rack and pinion)

[0083] 72 Spindle drive

[0084] 73 Transmission belts

[0085] 8 steerable wheels

[0086] 9 tie rod

[0087] 10 Signal cable thyssenkrupp Presta AG 24175-SBW - 240678P10WO thyssenkrupp AG

[0088] 16 / 16

[0089] 100 control units

[0090] 110 Steering Requirement Assessment Unit

[0091] A Determination of the steering input based on the detected steering angle (4)

[0092] B Determination of the steering input based on the detected steering torque (5) VP Driving condition variables

[0093] SP steering sizes

Claims

thyssenkrupp Presta AG 24175-SBW - 240678P10WO thyssenkrupp AG 1 / 4 Claims 1. Steer-by-wire steering system (1) for a motor vehicle comprising a steering handle (2) and a wheel steering actuator (3), wherein the steering handle (2) is adjustable from a center position (21) between a first stop (22) and a second stop (23), wherein the steer-by-wire steering system (1) is configured to detect a steering angle (4) and a steering torque (5) applied to the steering handle (2) as a steering input, and wherein the wheel steering actuator (3) is configured to convert a detected steering input into a wheel steering angle (6) of steerable wheels (8) of the motor vehicle, characterized in that the steer-by-wire steering system (1) is further configured to evaluate the detected steering input when the steering handle (2) is adjusted between the first stop (22) and the second stop (23). to determine steering angle (4),and to determine the steering input from the first stop (22) or the second stop (23) onwards, starting from the center position (21), by evaluating the detected steering torque (5).

2. Steer-by-wire steering system (1) according to claim 1, characterized in that the steering handle (2) is designed as an alternative human-machine interface that differs from a steering wheel.

3. Steer-by-wire steering system (1) according to claim 1 or claim 2, characterized in that the steering handle (2) is designed as at least one joystick.

4. Steer-by-wire steering system (1) according to one of the preceding claims, characterized in that an adjustment range (26) of the steering handle (2) between the first stop (22) and the second stop (23) is a maximum of 240°.

5. Steer-by-wire steering system (1) according to one of the preceding claims, characterized in that an adjustment range (26) of the steering handle (2) between the first stop (22) and the second stop (23) is a maximum of 120°. thyssenkrupp Presta AG 24175-SBW - 240678P10WO thyssenkrupp AG 2 / 4 6. Steer-by-wire steering system (1) according to one of the preceding claims, characterized in that the steering handle (2) can be moved against an increased steering resistance from the first stop (22) to a first end stop (24) and against an increased steering resistance from the second stop (23) to a second end stop (25).

7. Steer-by-wire steering system (1) according to claim 6, characterized in that the adjustment travel between the first stop (22) and the first end stop (24) is a maximum of 3% of the adjustment travel between the center position (21) and the first stop (22), and that the adjustment travel between the second stop (23) and the second end stop (25) is a maximum of 3% of the adjustment travel between the center position (21) and the second stop (23).

8. Steer-by-wire steering system (1) according to one of the preceding claims, characterized by a steering request evaluation unit (110), wherein the steering request evaluation unit (110) is configured to evaluate a current driving situation and, depending on a steering request associated with the evaluated driving situation, to activate or deactivate the detection of the steering input by evaluating the detected steering torque (5).

9. Steer-by-wire steering system (1) according to claim 8, characterized in that the steering request evaluation unit (110) is further configured to allow the detection of the steering input by an evaluation of the detected steering torque (5) in a driving situation which is assessed as driving at low speed.

10. Steer-by-wire steering system (1) according to claim 8 or claim 9, characterized in that the steering request evaluation unit (110) is further configured to deactivate the detection of the steering input by evaluating the detected steering torque (5) in a driving situation which is assessed as driving at high speed.

11. Steer-by-wire steering system (1) according to one of claims 8 to 10, characterized in that the steering request evaluation unit (110) is further configured to, in a driving situation which is a driving situation with low steering request thyssenkrupp Presta AG 24175-SBW - 240678P10WO thyssenkrupp AG 3 / 4 is rated to deactivate the recording of the steering input by evaluating the recorded steering torque (5).

12. Steer-by-wire steering system (1) according to one of claims 8 to 11, characterized in that the steering request evaluation unit (110) is further configured to activate the detection of the steering input by evaluating the detected steering torque (5) in a driving situation which is rated as a driving situation with a high steering requirement.

13. Method for operating a steer-by-wire steering system (1) in a motor vehicle, wherein a steering handle (2) of the steer-by-wire steering system (1) is adjusted to provide a steering input, wherein a steering angle (4) applied to the steering handle (2) when adjusting it is detected as the steering input when the steering handle (2) is adjusted between a first stop (22) and a second stop (23), and wherein a steering torque (5) applied to the steering handle (2) when adjusting it is detected as the steering input when the steering handle (2) is operated further from the center position (21) after reaching the first stop (22) or the second stop (23), wherein a wheel steering actuator (3) of the steer-by-wire steering system (1) transmits the detected steering input translates into a wheel steering angle (6) of steerable wheels (8) of the motor vehicle.

14. Method according to claim 13, characterized in that steering resistance is increased upon reaching the first stop (22) or the second stop (23).

15. Method according to claim 13 or 14, characterized in that a current driving situation is evaluated and, depending on a steering requirement associated with the evaluated driving situation, the detection of the steering input is activated or deactivated by an evaluation of the detected steering torque (5), wherein, in particular, in a driving situation that is evaluated as driving at low speed, the detection of the steering input is activated by an evaluation of the detected steering torque (5); and / or in a driving situation that is evaluated as driving at high speed, the detection of the steering input is deactivated by an evaluation of the detected steering torque (5); and / or in a driving situation that is evaluated as a driving situation with low steering requirements, thyssenkrupp Presta AG 24175-SBW - 240678P10WO thyssenkrupp AG 4 / 4 the detection of the steering input is deactivated by an evaluation of the detected steering torque (5); and / or in a driving situation which is assessed as a driving situation with high steering requirements, the detection of the steering input is activated by an evaluation of the detected steering torque (5).

16. Method according to one of claims 13 to 15, characterized in that the steer-by-wire steering system is designed according to one of claims 1 to 12.

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