Method for operating a steer-by-wire steering device for a motor vehicle

Abstract

Method for operating a steer-by-wire steering device (10) for a motor vehicle, in which a steering gear (12) with a first actuator (16) is synchronously controlled by means of a steering wheel (14) with a second actuator (18) using a steer-by-wire system of the steer-by-wire steering device (10), and in which the first actuator (16) and the second actuator (18) are desynchronized from each other when the motor vehicle is switched off, wherein when an unlocking device of the motor vehicle is actuated a signal (22) is transmitted to the steer-by-wire system and, depending on the signal (22), the steering wheel (14) is rotated by means of the second actuator (18) to a predetermined position (P2) and is locked in the predetermined position (P2) for further rotations, and wherein, when a gear is engaged before the motor vehicle is driven, a synchronization error is prevented by an adjustment of the first actuator. (16) is adapted using the steer-by-wire system,characterized in that, if a predetermined value of the synchronization error is exceeded, the drive torque is limited until full synchronization is achieved.

Description

[0001] The invention relates to a method for operating a steer-by-wire steering device for a motor vehicle according to the preamble of claim 1.

[0002] In conventional vehicle steering systems, such as manual or power steering, the steering wheel is mechanically connected to the wheels via a mechanism like a rack and pinion system. Steer-by-wire systems, however, have no mechanical connection between the steering wheel and the wheels. The directional command is transmitted via an electrical signal from the steering wheel to the steering gear and thus to the wheels.

[0003] From the generic document DE 10 2017 201 357 A1, a control method for a steering system is disclosed in which, particularly in steer-by-wire systems, the steering angle is automatically reset after an entry or exit process has been detected. Various vehicle states, such as the closing of the driver's door or the activation of the ignition, are used to detect the end of the entry process, so that the steering system automatically restores the previously stored steering angle.

[0004] German patent application DE 10 2004 030 685 B4 discloses a method for model-based fault detection in a steer-by-wire steering system of a vehicle, wherein the method comprises providing a steer-by-wire controlled device with electric motor actuators and sensors, as well as providing a steer-by-wire controller for implementing a closed-loop control system for the steer-by-wire controlled device. Furthermore, the method comprises providing a steer-by-wire fault detection unit that communicates electrically with the steer-by-wire controlled device and the steer-by-wire controller in order to detect faults in the steer-by-wire controlled device.

[0005] Furthermore, WO 2022 / 023 657 A1, DE 10 2019 213 821 A1 and DE 10 2020 205 325 A1 should be taken into account as significant prior art relating to the subject matter of the invention.

[0006] The object of the invention is to provide a method for operating a steer-by-wire steering device, by means of which, using the steer-by-wire steering device, getting in and out of the motor vehicle is simplified for a user.

[0007] This problem is solved by means of a method according to the invention with the features of claim 1. Advantages and advantageous embodiments of the invention can be found in the dependent claims.

[0008] One aspect of the invention relates to a method for operating a steer-by-wire steering device with a steer-by-wire system for a motor vehicle, particularly a passenger vehicle, in which a steering gear with a first actuator is synchronously controlled by a steering wheel with a second actuator using the steer-by-wire system of the steering device, wherein both actuators are electronically coupled to the steer-by-wire system. Furthermore, in this method, the first and second actuators are desynchronized from each other when the motor vehicle is switched off; that is, while the electronic coupling with the steer-by-wire system remains, an adjustment of the steering wheel does not cause an adjustment of the steering gear, as the synchronization is interrupted or blocked.In other words, detecting steering wheel movement does not lead to a corresponding adjustment of the steering gear. To carry out this process, as well as subsequent process steps, the steer-by-wire steering system includes all the necessary components, particularly electronic components. The actuators are designed, for example, as electric motor actuators with individual sensors, as well as steer-by-wire controllers for implementing closed-loop control. The steer-by-wire system is also designed to wirelessly receive input signals from various sources and to generate and wirelessly transmit output signals.In particular, the two actuators are at least partially automatically desynchronized from each other when the vehicle is stationary, meaning they are decoupled. This prevents rotation or turning of the steering wheel from adjusting the steering gear without requiring the user to initiate an action or generate a signal to reset the desynchronization. Specifically, a desynchronized steering wheel prevents unwanted adjustments to the steering gear. This also eliminates the need for a continuously engaged and therefore energy-consuming steer-by-wire system.

[0009] To solve the problem of the invention and thus provide a steer-by-wire steering device that simplifies getting in and out of a vehicle for the user, a signal is transmitted to the steer-by-wire system when a vehicle unlocking device is activated, and thus, in particular, when a driver's door is unlocked. Depending on the signal, the steering wheel is rotated to a predetermined position by the second actuator and locked in that position to prevent further rotation. Such a signal is generated or triggered, for example, by an ID transmitter for the vehicle's access control system, whereby a triggered unlocking of the vehicle is augmented with a command to lock the steering wheel. The mechanical opening of the driver's door can also be triggered in this way.In other words, the signal to block the rotation of the steering wheel is only generated and transmitted to the steer-by-wire steering system when the driver's door is opened, and not the rear doors.

[0010] The intention here is to utilize the shape of the steering wheel, meaning that the flat, and in particular no longer round, steering wheels of conventional steer-by-wire steering systems, and thus also the steering wheel according to the invention, are to be used as an aid for getting in and out of the vehicle. The steering wheel is thus intended to serve as a handle element by which a user can, for example, pull themselves into the interior of the vehicle; a horizontal position, for example, facilitates entry and exit. In other words, when the vehicle is unlocked by means of the ID transmitter, in particular by pressing a key, a signal is generated to turn the steering wheel into, for example, a horizontal position, in particular into an auxiliary position, and in particular into the locked position, thus facilitating entry.This blocked or auxiliary position is used to support the user when getting in, whereby the steering wheel is held or blocked in this position with maximum steering torque, in particular further rotation of the steering wheel is blocked to avoid unwanted rotation of the steering wheel and unsafe entry and exit.

[0011] According to the invention, when a gear is engaged before the vehicle starts moving, any synchronization error is corrected by adjusting the first actuator using the steer-by-wire system. In other words, when a gear is engaged, the remaining synchronization error is corrected by adjusting the front wheels.

[0012] It is also provided according to the invention that if a predetermined value of the synchronization error is exceeded, the drive torque is limited until complete synchronization is achieved. In other words, at this point, any excessive error at the wheel should still be limited by the drive torque until the front wheels are fully synchronized. In particular, this error compensation ensures precise synchronization of the respective actuators with each other, in order to prevent any potential steering errors caused by the steer-by-wire system while driving and thus avoid dangerous situations, accidents, or other incidents in road traffic.

[0013] In an advantageous embodiment of the invention, it is provided that after the vehicle is switched on, or after a signal to start the vehicle is transmitted, or after an operating switch to ignite the vehicle, or after activation or activation of a driving mode, or after a driving mode is made available, the blocked position of the steering wheel is released. It is initially assumed that the user or driver of the vehicle is already seated inside the vehicle or within the interior when the vehicle is switched on, and therefore the blocked position of the steering wheel is no longer required. This means that switching on the vehicle transmits a signal to the steer-by-wire steering system, or rather, the steer-by-wire system now receives the signal to release the blocked position of the steering wheel.Accordingly, the steering wheel is moved from the blocked or auxiliary position to a driving position, so that after the vehicle is switched on, the steering wheel is ready for driving. In particular, the driving position can also be adjusted depending on the user, with the steer-by-wire system applying the stored user data to provide an ergonomic seating position and steering wheel position for that user.

[0014] In a further advantageous embodiment of the invention, it is provided that after the vehicle is switched on, the first and second actuators are synchronized. Since switching on the vehicle results in the vehicle being driven, the respective actuators must be synchronized to reactivate the steer-by-wire system and thus provide the steering mechanism in such a way that turning the steering wheel, or actuating the second actuator, also actuates the first actuator; that is, turning the steering wheel also adjusts the steering gear. A synchronization structure is used here, which is implemented via control of the respective actuators, with steer-by-wire control being carried out by the steer-by-wire system.In particular, the system is designed so that the steering wheel's rotation is compared to the position of the vehicle's wheels and adjusted accordingly. For example, if the wheels are turned a predetermined angle to the left or right, the steering wheel must have a corresponding angle of rotation, meaning it rotates by this angle, especially to simulate a mechanical coupling between the steering wheel and the steering gear.

[0015] An embodiment of the invention has also proven advantageous in which, instead of switching on the motor vehicle by connecting a belt, the blocked position of the steering wheel is released and / or the first actuator and the second actuator are synchronized with each other again and / or, during synchronization, the position of the second actuator is adjusted to the position of the first actuator depending on the position of the first actuator.This process does not involve switching on the vehicle to generate a signal used to initiate the aforementioned functions. Instead, it involves attaching a seatbelt, which is connected to at least one electronic computer or control unit. Contact between the seatbelt and a buckle, or between the seatbelt tongue and the belt itself, generates a signal that is transmitted to the steer-by-wire system to initiate the functions. Besides the seatbelt, other methods exist to initiate this function. For example, sensors could be located under the vehicle seat to detect pressure and signal that the driver is seated and ready to drive.

[0016] In a further advantageous embodiment of the invention, the position of the second actuator is adjusted during synchronization, depending on the position of the first actuator, thereby adapting the steering wheel to the steering gear. This indicates to the driver the position, or angle, of the vehicle's wheels relative to the direction of travel. For example, this adjustment of the steering wheel position, and thus the rotation of the steering wheel, can be performed at a predetermined speed to provide the driver with sufficient time to process the information. A display device coupled to the steer-by-wire steering system can also show the position of the steering gear and simulate further procedures for starting and driving the vehicle.Furthermore, a signal can also be generated after synchronization and transmitted to the driver to inform him acoustically and / or visually about the synchronization.

[0017] In a further advantageous embodiment of the invention, it is provided that the synchronization of the actuators is interrupted when the steering wheel is held during a synchronization rotation. In particular, this means that intervention by the driver interrupts the rotation or the synchronization of the actuators with each other, for example, when intervening with a steering torque, especially below two Newton meters, wherein this intervention is detected, for example, by means of a sensor device, which in turn transmits a signal to the steer-by-wire system to interrupt the synchronization.

[0018] In a further advantageous embodiment of the invention, it is provided that, when the motor vehicle is unlocked, at least a second signal for adjusting the steering wheel is transmitted to the steer-by-wire system. Adjusting the steering wheel here does not mean rotating the steering wheel by a predetermined angle, but rather adjusting the steering wheel angle towards the driver, i.e., that this angle, for example, sets a distance between the steering wheel and the driver, and this adjustment is adjustable depending on the driver. Such a setting can, for example, be pre-programmed and reset when the steer-by-wire steering system is used.

[0019] Finally, in a further advantageous embodiment of the invention, at least a third signal is transmitted to the vehicle when the vehicle is unlocked, allowing for the adjustment of a vehicle seat. Analogous to the adjustment of the steering wheel, a vehicle seat can also be adjusted forwards and backwards to improve the ergonomics of the steer-by-wire steering system. For example, a preset position can also be stored here to adjust it at least partially automatically when entering the vehicle.

[0020] In other words, the inventive method makes it possible to enable comfortable entry and exit from the vehicle and to provide a high-quality welcome and living customer experience. The steer-by-wire system is thus adapted to the user, ensuring guaranteed synchronization of the respective actuators. The wheels are actuated by means of an electromechanical drive control system. An electromechanical steering wheel control system is used to simulate the steering feel of a conventional mechanically coupled steering system. The electromechanical steering wheel control system is referred to as manual steering feel or steering wheel control system.

[0021] Further advantages, features, and details of the invention will become apparent from the following description of a preferred embodiment and from the drawings. The features and combinations of features mentioned above in the description, as well as those mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention.

[0022] This shows: Fig. 1. A first pictorial diagram to illustrate a steer-by-wire steering device for a motor vehicle during a standstill; Fig. 2 a second diagram illustrating a method according to the invention for operating the steer-by-wire steering device for the motor vehicle; Fig. 3 a third diagram to illustrate synchronization of the steer-by-wire steering device; Fig. 4 a first functional structure of an SRU for carrying out the method according to the invention; and Fig. 5 a second functional structure of an SWU with SYNC and Easy Entry or with a steering wheel grip and an entry position for carrying out the method according to the invention.

[0023] The figures contain identical and functionally equivalent elements that are marked with the same reference symbols.

[0024] Fig. Figure 1 shows a first diagram illustrating a steer-by-wire steering system 10 for a motor vehicle while stationary. A steering gear 12 with a first actuator 16 and a steering wheel 14 with a second actuator, both attached to the steer-by-wire steering system 10, are shown. The steering gear 12 and the steering wheel 14 point in opposite directions to represent a desynchronized position of the first actuator 16 relative to the second actuator 18. Such desynchronization is possible, in particular, when the motor vehicle is stationary.

[0025] Fig. Figure 2 shows a second diagram illustrating a method according to the invention for operating the steer-by-wire steering device 10 for the motor vehicle, in which the steering gear 12 with the first actuator 16 is synchronously controlled with the second actuator 18 by means of the steering wheel 14 using a steer-by-wire system of the steer-by-wire steering device 10, and in which the first actuator 16 and the second actuator 18 are desynchronized from each other when the motor vehicle is switched off and synchronized from each other when the motor vehicle is switched on. When the motor vehicle is unlocked by means of an ID sensor 20, a signal 22 is transmitted to the steer-by-wire system, and depending on the signal 22, the steering wheel 14 is rotated to a predetermined position by means of the second actuator 18 and locked in the predetermined position P2 to prevent further rotations.In particular, the steering wheel 14 is adjusted horizontally in the locked position P2 to facilitate entry into the vehicle. During this process, the steering gear 12 with the first actuator 16 remains unaffected.

[0026] Fig. Figure 3 shows a third diagram illustrating the synchronization of the steer-by-wire steering device 10. According to the invention, after the vehicle is switched on, the blocked position P2 of the steering wheel 14 is released. After the vehicle is switched on, the first actuator 16 and the second actuator 18 are also synchronized, whereby during synchronization the position P1, P2, P3 of the second actuator 18 is adjusted to the position of the first actuator 16, depending on the position P3 of the first actuator 16.It is also possible, instead of switching on the motor vehicle, to use a strap to release the blocked position P2 of the steering wheel 14 and / or to resynchronize the first actuator 16 and the second actuator 18 and / or, during synchronization, to adjust the positions P1, P2, P3 of the second actuator 18 to the position P3 of the first actuator 16, depending on the position P3 of the first actuator 16. In particular, it is also provided according to the invention that if the steering wheel 14 is held during a synchronization rotation, the synchronization of the actuators 16, 18 is interrupted.

[0027] Finally, according to the invention, when a gear is engaged before the vehicle is driven, a synchronization error is compensated for by adjusting the first actuator 16 via the steer-by-wire system. If a predetermined value of the synchronization error is exceeded, the drive torque is limited until full synchronization is achieved; that is, the steering wheel 14 is adjusted to the steering gear 12 before the steer-by-wire steering device 10 is enabled for the driver. Finally, it is also provided that when the vehicle is unlocked by means of an ID transmitter 20, at least a second signal 24 is transmitted to the steer-by-wire system to adjust the steering wheel 14. This second signal 24 can thus adjust the steering wheel 14 to improve ergonomics, with adjustments being stored based on user-defined data.It is also possible that when the vehicle is unlocked, at least one further third signal 26 is transmitted to the vehicle to adjust a vehicle seat. Analogous to the adjustment of the steering wheel 14, the ergonomics for the driver can also be improved here.

[0028] Fig. Figure 4 represents a first functional structure 28 of an SRU for carrying out the method according to the invention. Here, after the start by transmitting the signal 22, the functional structure 28 is started, whereby the synchronization of the actuators 16 and 18 is queried and, depending on the result, the synchronization is carried out again or further steps for the application of the steering wheel 14 are allowed. Verknüpfungen Name Komandos(commands) Kodierung (Code) B1 SRU SLEEP C1 Wakeup via NM B2 SRU INIT C2 SRU INIT = OKAND Variant Coding= OK ANDISW_Stat = ON B3 SRU ENABLE C2.1 Loop B4 SRU STEER C2.2 Loop B5 SRU SYNC1 C3 ISW_Stat<2 B6 SRU SYNC2 C4 SYNC = OK AND(PT_rdy = 1 ORStandstill = 0) B7 SRU SWU-Fallback C5 SYNC = NOKgleichsinnig AND(PT_rdy = 1 ORStandstill =0) B8 SRU OFF CH FR C6 SYNC = NOKgegensinnig AND(PT_rdy = 1 ORStandstill =0) B9 SRU OFF CH CAN C7 SYNC = OK AND(PT_rdy = 1 ORStandstill =0) B10 SRU OFF C8 SYNC = OK AND(PT_rdy = 1 ORStandstill =0) C9 (PT_rdy ANDStandstill =1) OR(Gaming = 1 ANDGear = P ANDPT_rdy=1) C10 SWU_status= OFF C11 SWU_status =STEER C12 Command C13 Command C14 Command C15 Command C16 Loop

[0029] Fig. Figure 5 presents a second functional structure 30 of an SWU with SYNC and Easy Entry, or with a steering wheel grip and an entry position, for carrying out the method according to the invention. Here, the steering wheel position, or the position of the second actuator 18, is queried and synchronized depending on the first actuator 16, whereby holding the steering wheel 14, in particular by the hands of a driver, also leads to an interruption of the synchronization. Verknüpfungen Name Komandos(commands) Kodierung (Code) D1 SWU SLEEP E1 Wake up via NM D2 SWU INIT E2 SWU INIT = OK AND Variantcoding = OK D3 SWU HOLD E3 Stwhl_angl_ST3= 180° OR 0° OR 180° OR Hands = ON D4 SWU GAMING E4 Command D5 SWU EASY ENTRY E5 Gaming = 1 & Gear= P & PT_rdy =1 D6 SWU SYNC AUTO E6 Gaming = 0 D7 SWU STEER E7 Driver Door = closed AND Standstill =1 AND SYNC =N OK AND Hands = OFF AND ISW_Stat = 0 D8 SWU SRU-Fallback E8 Driver Door = Open AND Standstill = 1 D9 SWU OFF E9 PT_rdy = 1 ORStandstill = 0 E10 SYNC = OK ORHands = ON E11 Driver Door = openAND Standstill = 1 E12 PT_rdy = 1 ORStillstand = 0 E13 Loop E14 Command E15 Loop E16 SRU_Stat = OFFOR ERROR

[0030] In other words, the invention enables the entry and / or exit of a motor vehicle using the steering wheel 14 as an aid, as well as a synchronization function for steer-by-wire systems to block the steering wheel from its possible rotation during the assistance.

Claims

[1] Method for operating a steer-by-wire steering device (10) for a motor vehicle, in which a steering gear (12) with a first actuator (16) is synchronously controlled by means of a steering wheel (14) with a second actuator (18) using a steer-by-wire system of the steer-by-wire steering device (10), and in which the first actuator (16) and the second actuator (18) are desynchronized from each other when the motor vehicle is switched off, wherein when an unlocking device of the motor vehicle is actuated a signal (22) is transmitted to the steer-by-wire system and, depending on the signal (22), the steering wheel (14) is rotated by means of the second actuator (18) to a predetermined position (P2) and is locked in the predetermined position (P2) for further rotations,and wherein, when a gear is engaged before the motor vehicle starts moving, a synchronization error is adjusted by adjusting the first actuator (16) by means of the steer-by-wire system, characterized by , that if a predetermined value of the synchronization error is exceeded, the drive torque is limited until full synchronization is achieved. [2] Method according to claim 1, characterized by , that after the motor vehicle is switched on, the blocked position (P2) of the steering wheel (14) is released again. [3] Method according to claim 2, characterized by , that after the motor vehicle is switched on, a synchronization of the first actuator (16) and the second actuator (18) is carried out with each other. [4] Method according to claim 1, characterized by, that when a belt is connected, the blocked position (P2) of the steering wheel (14) is released again and / or the first actuator (16) and the second actuator (18) are synchronized again and / or during synchronization a position (P1, P2, P3) of the second actuator (18) is adjusted to the position (P3) of the first actuator (16) depending on a position (P3) of the first actuator (16). [5] Method according to any one of the preceding claims, characterized by , that during synchronization a position (P1, P2, P3) of the second actuator (18) is adjusted to the position (P3) of the first actuator (16) depending on the position (P3) of the first actuator (16). [6] Method according to any one of the preceding claims, characterized by , that if the steering wheel (14) is held during a synchronization rotation, the synchronization of the actuators (16, 18) is interrupted. [7] Method according to any one of the preceding claims, characterized by , that when the motor vehicle is unlocked, at least a second signal (24) is transmitted to the steer-by-wire system for adjusting the steering wheel (14). [8] Method according to any one of the preceding claims, characterized by , that when the motor vehicle is unlocked, at least a further third signal (26) is transmitted to the motor vehicle for adjusting a vehicle seat.

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