STEER-BY-WIRE STEERING SYSTEM AND METHOD FOR OPERATING A STEER-BY-WIRE STEERING SYSTEM

Description

[0001] The invention relates to a steer-by-wire steering system and a method for operating a steer-by-wire steering system.

[0002] A steer-by-wire steering system typically comprises a steering handle, a steering column module, and a steering gear. The steering column module and the steering gear are connected electronically but mechanically decoupled. The steering column module contains a rotation angle sensor and an actuator for generating counter-torque at the steering handle. The actuator is, for example, an electric servo motor. The actuator may receive its control signals from the steering gear or directly from the steering column module, with the counter-torque being generated, for example, as a function of the rotation angle and the vehicle speed. Such a steer-by-wire steering system is known from US 10,906,581 B2.

[0003] In modern motor vehicles where a driver assistance system completely or almost completely takes over a steering task, the driver assistance system specifies the trajectory, which is then implemented by a steering angle controller. The steering angle controller receives a target steering angle as input and adjusts the actual steering angle as closely as possible. Such a steering angle controller is known, for example, from DE 10 2017 214 380 A1.

[0004] In assisted driving, the driver retains primary control over the driving task, while the driver assistance system generates additional steering torques that are implemented by the steering gear. Due to the mechanical decoupling, the coordination is not straightforward, as a position controller in the steering gear must prioritize between the driver's inputs and those of the driver assistance system.

[0005] From EP 3 725 644 A1, a steer-by-wire steering system is known, comprising a steering handle, a steering column module, and a steering gear, wherein the steering column module and the steering gear are connected electronically. A rotary angle sensor and an actuator for generating a counter-torque at the steering handle are arranged in the steering column module. Furthermore, a steering angle controller is arranged in the steering column module, wherein the steering angle controller is connected electronically to at least one driver assistance system, by means of which autonomous steering movements are specified. The steering angle controller is configured to receive a target angle from the at least one driver assistance system and to generate a torque for setting the target angle via the actuator.

[0006] From DE 10 2018 200 327 A1, a method for adjusting the level of support of a driver assistance system in a vehicle is known, which can autonomously intervene in a vehicle unit influencing the driving dynamics, wherein a driver intervention leads to an override of an autonomous intervention carried out by the driver assistance system if the intensity of the driver intervention exceeds an adjustable threshold, wherein the threshold is set as a function of the relationship between the driving condition and the quality of the information underlying an intervention of the driver assistance system.

[0007] From DE 10 2017 215 593 A1, a steer-by-wire system is known, comprising a steering handle, a sensor for detecting a driver request, at least one steering control unit, power electronics, an electronic servo motor, a rack movable via the servo motor and an actuator for generating a feedback torque at the steering handle depending on a rack position, wherein the steering control unit is designed to subtract at least a portion of a driver request determined on the basis of the sensor data due to the feedback torque.

[0008] The invention addresses the technical problem of creating a steer-by-wire steering system that enables improved steering torque recommendations for assisted driving. A further technical problem is providing a suitable method for operating such a steer-by-wire steering system.

[0009] The solution to the technical problem is achieved by a steer-by-wire steering system with the features of claim 1 and a method for operating a steer-by-wire steering system with the features of claim 6. Further advantageous embodiments of the invention are set forth in the dependent claims.

[0010] The steer-by-wire steering system comprises a steering handle, a steering column module, and a steering gear, with the steering column module and the steering gear being interconnected electronically. The steering column module contains at least one rotary angle sensor, an actuator for generating a counter-torque at the steering handle, and a steering angle controller, the latter being interconnected electronically with at least one driver assistance system. The steering angle controller is configured to receive a target angle from the at least one driver assistance system and to generate a torque for adjusting the target angle via the actuator or another actuator. This significantly simplifies the adjustment process, as the steering gear receives only one signal from the steering column module, namely that from the rotary angle sensor.The driver feels the additional torque at the steering handle and can then determine by his hand torque whether to follow the recommendation or compensate for or ignore it by applying more hand torque.

[0011] In one embodiment, the steering angle controller is designed such that it generates a limited torque via the actuator, which can be overridden by the driver. This ensures that the driver can always ignore the steering torque recommendation of the driver assistance system by counter-steering. The torque is limited, for example, to 1 to 2 Nm.

[0012] In another embodiment, the steering angle controller is connected to the at least one driver assistance system via a bus system. This simplifies data transfer, particularly in embodiments where multiple driver assistance systems can generate steering torque recommendations.

[0013] In another embodiment, a control unit is arranged in the steering column module, which is designed to control the actuator. The control unit can receive control signals from a control unit of the steering gear or directly from the rotation angle sensor in the steering column module, in which case the counter-torque is additionally generated depending on the vehicle speed.

[0014] In another embodiment, the steer-by-wire steering system is designed such that the absolute limit can be changed by user input and / or by at least one driver assistance system. This allows the user to individually adjust the steering feel within predefined limits and / or to give more emphasis to individual steering torque recommendations from the driver assistance system according to a prioritization, as the feedback at the steering wheel is increased.

[0015] Regarding the procedural details, full reference is made to the preceding statements.

[0016] The invention is explained in more detail below with reference to a preferred embodiment. The single figure shows a schematic block diagram of a steer-by-wire steering system.

[0017] The in Fig. 1The steer-by-wire steering system 1 shown comprises a steering handle 2, a steering column module 3, and a steering gear 4. The steering handle 2 is mechanically connected to a steering column 5. The steering column module 3 further includes at least one rotary angle sensor 6, an actuator 7, a control unit 8, and a steering angle controller 9. The steering gear 4 comprises a control unit 10 and two half-motors 11, 12, each with its own power electronics 13, 14. The two half-motors 11, 12 drive a common rotor 15, which is coupled to a rack 16 via a gearbox (not shown). The half-motors 11, 12 and their respective power electronics 13, 14 are each supplied with energy by an independent power supply U1, U2.

[0018] The operation of the steer-by-wire steering system 1 is as follows. When the driver turns the steering handle 2, the set steering angle φ is measured by the rotation angle sensor 6 and transmitted to the control unit 10. The control unit 10 then determines a rack force to be applied to the rack 16 via the transmission (not shown) and transmits control signals to the two power electronics units 13 and 14. The control unit 10 also takes into account at least the vehicle speed V. The steering gear 4 is fail-safe due to its division into two power electronics units 13 and 14 and two half-motors 11 and 12.

[0019] The control unit 10 simultaneously transmits a signal to the control unit 8, which then activates the actuator 7. The actuator 7 then generates a haptic counter-torque at the steering column 5, which is felt at the steering handle 2. The actuator 7 is, for example, an electric motor and is also referred to as a force feedback actuator.

[0020] If a driver assistance system 17 wants to generate a steering torque recommendation for the driver, it transmits a target angle φ to the steering angle controller 9, whereby the driver assistance system 17 receives the current actual angle φ, for example, from the control unit 10. The steering angle controller 9 is connected to the actuator 7 and generates an additional torque to set the target angle φ, with the actual angle φ being fed back to the steering angle controller 9. The magnitude of the torque is limited such that the driver can always override it, but still feels the torque. If the driver then wants to follow the steering torque recommendation, they simply do not need to apply any counteracting manual torque. As a result, the steering angle φ (or actual angle) changes. This changed steering angle is transmitted to the control unit 10 and implemented by the steering gear 4.If, however, the driver overrides the torque by applying a corresponding hand torque, the steering system will only follow the driver's steering input.

[0021] The user can adjust the amount of torque via a control unit (not shown). In simpler terms, this determines how noticeable the steering input should be. Limits can be set within which the user can define the maximum torque. Alternatively, the driver assistance system 17 can also vary the maximum torque. For this, the steering angle control 9 is adjusted to provide a higher torque. Reference symbol list

[0022] 1 Steer-by-wire steering system 2 Steering handle 3 Steering column module 4 Steering gear 5 Steering column 6 Steering angle sensor 7 Actuator 8 Control unit 9 Steering angle controller 10 Control unit 11, 12 Semi-motor 13, 14 Power electronics 15 Rotor 16 Rack and pinion 17 Driver assistance system φ Steering angle φ Target angle V Vehicle speed

Claims

1. Steer-by-wire steering system (1), comprising a steering handle (2), a steering column module (3) and a steering gear (4), wherein the steering column module (3) and the steering gear (4) are connected for data transmission, wherein a rotary position sensor (6) and an actuator (7) for generating a counter-torque on the steering handle (2) are arranged in the steering column module (3), wherein a steering angle controller (9) is arranged in the steering column module (3), wherein the steering angle controller (9) is connected to at least one driver assistance system (17) for data transmission, wherein the steering angle controller (9) is designed to receive a target angle (φsoll) from the at least one driver assistance system (17) and to generate, via the actuator or a further actuator (7), a torque for setting the target angle (φsoll), characterized in that the steering gear (4) receives only one signal from the steering column module (3), specifically that from the rotary position sensor (6).

2. Steer-by-wire steering system according to claim 1, characterized in that the steering angle controller (9) is designed such that the steering angle controller (9) generates a torque, which is limited in terms of amount, by means of the actuator (7), which torque can be overridden by a motor vehicle driver.

3. Steer-by-wire steering system according to claim 1 or 2, characterized in that the steering angle controller (9) is connected to the at least one driver assistance system (17) via a bus system.

4. Steer-by-wire steering system according to any of the preceding claims, characterized in that a control device (8) is arranged in the steering column module (3), which is designed to control the actuator (7).

5. Steer-by-wire steering system according to any of claims 2 to 4, characterized in that the steer-by-wire steering system (1) is designed such that the amount limit can be changed by a user input and / or the at least one driver assistance system (17).

6. Method for operating a steer-by-wire steering system (1) by means of a steering handle (2), a steering column module (3) and a steering gear (4), wherein the steering column module (3) and the steering gear (4) are connected for data transmission, wherein a rotary position sensor (6), an actuator (7) for generating a counter-torque on the steering handle (2), and a steering angle controller (9) are arranged in the steering column module (3), wherein the steering angle controller (9) receives a target angle (φsoll) from at least one driver assistance system (17) and generates, via the actuator (7) or a further actuator, a torque for setting the target angle (φsoll), characterized in that the steering gear (4) receives only one signal from the steering column module (3), specifically that from the rotary position sensor (6).

7. Method according to claim 6, characterized in that the steering angle controller (9) generates a torque, which is limited in terms of amount, by means of the actuator (7), which can be overridden by a motor vehicle driver.

8. Method according to claim 6 or claim 7, characterized in that the driver assistance system (17) communicates with the steering angle controller (9) via a bus system.

9. Method according to any of claims 6 to 8, characterized in that the actuator (7) is controlled by means of a control device (8) in the steering column module (3).

10. Method according to any of claims 6 to 9, characterized in that the amount limit is changed by a user input and / or the at least one driver assistance system (17).