Steer-by-wire system and method for operating a steer-by-wire system

Abstract

The invention relates to a steer-by-wire system (1), wherein the steer-by-wire system (1) has a steering column module (2) and a steering transmission (3), wherein the steering column module (2) has a first sensor module (6) and a second sensor module (7), which each detect at least one steering wheel angle (φ), wherein the steering column module (2) furthermore has a steering wheel (4), a steering column (5), at least one actuator (8) for generating a counter torque at the steering column (5) and two controllers (11, 12) for the at least one actuator (8) for generating a counter torque, wherein the steering transmission (3) has at least two controllers (15, 16), wherein the first controller (11) for the at least one actuator (8) is connected to the first controller (15) of the steering transmission (3) via at least one bus connection (25, 26) and the second controller (12) for the at least one actuator (8) is connected to the second controller (16) of the steering transmission (3) via at least one bus connection (27), wherein the first sensor unit (6) is directly connected to the first controller (15) of the steering transmission (3) via a sensor interface (24) and the second sensor unit (7) is directly connected to the first controller (11) for the at least one actuator (8) via a sensor interface (14).

Description

TECHNICAL FIELD

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

[0002] Steer-by-wire steering systems are generally constructed in such a way that they have a steering column module and a steering transmission, which are mechanically decoupled and electrically connected. Here, the steering wheel angle is detected and transmitted to a controller of the steering transmission in order to determine therefrom a theoretical steering angle, which is then set, sometimes referred to as adjusted, by means of a steering actuator. The steering actuator is generally an electric motor, which deflects the rack in order to set the theoretical steering angle at the wheels. Here, an actuator, sometimes referred to as an actuator, for generating a counter torque is arranged at the steering column, so that the vehicle driver is given a steering feel as he is familiar from a conventional steering system. It is furthermore known here to construct a plurality of the mentioned components redundantly in order to thus ensure failure safety. A wide variety of concepts are known here: how a corresponding redundancy or backup level can be ensured.

[0003] A method for controlling an actuator for generating a counter torque at a steering wheel for a steer-by-wire steering system is known from US 2021 / 0009202 A1. SUMMARY

[0004] The technical problem of the invention is to create a steer-by-wire steering system with improved failure safety and to provide a corresponding method.

[0005] The solution to the technical problem is produced by a steering system with the features of claim 1 and a method with the features of claim 7. Further advantageous design options of the invention result from the dependent claims.

[0006] A steer-by-wire system has a steering column module and a steering transmission. The steering column module has a first sensor module and a second sensor module, which detect at least one steering wheel angle, respectively. The steering column module furthermore has a steering wheel, a steering column, at least one actuator for generating a counter torque at the steering column, and at least two controllers for the at least one actuator for generating a counter torque. Here, the steering wheel is generally to be understood as a steering handle for presetting a desired steering angle. Furthermore, a first controller for the at least one actuator is connected via at least one bus connection (sometimes referred to as bus link) with a first controller of the steering transmission. A second controller for the at least one actuator is connected via at least one second bus connection with a second controller of the steering transmission. Furthermore, a first sensor unit is directly connected via a sensor interface with the first controller of the steering transmission, and a second sensor unit is directly connected via a sensor interface with the first controller for the at least one actuator. The sensor interface is preferably configured as a SENT (Single Edge Nibble Transmission) interface. The steer-by-wire system is configured in such a way that, in the fault-free operation, the first controller of the at least one actuator transmits a transmission ratio to the first controller of the steering transmission, and the first sensor unit transmits a steering wheel angle directly to the first controller of the steering transmission, which are then used to calculate a theoretical steering angle. In the event of a fault of the first sensor unit and / or the sensor interface, the steering wheel angle and the transmission ratio of the first controller of the actuator are transmitted to the first controller of the steering transmission and used to calculate a theoretical steering angle. The first sensor module and the first controller of the steering transmission have a common voltage supply. Thereby, the fail safety is generally improved, since the transmission of the steering wheel angle takes place via two different transmission paths, namely via the sensor interface and via the bus connection. By the common voltage supply of the first sensor module and the first controller of the steering transmission, the first sensor module also works in the event of a failure of the voltage supply of the first controller of the at least one actuator. A further advantage is the extremely fast data transmission of the steering wheel angle via the sensor interface. The steer-by-wire system is thereby able to react much more dynamically as a whole. Since the transmission ratio is not subject to such dynamic changes, the slightly slower transmission via the bus system is unimportant.

[0007] In an embodiment, the first sensor module and the second sensor module are configured in such a way that an additional hand torque is detected.

[0008] In another embodiment, the at least one actuator for generating a counter torque is configured as an electric motor with a first set of windings and a second set of windings, which are independent of one another, wherein the first set of windings is operated by a first controller for the actuator and the second set of windings is operated by a second controller. This makes it possible to implement a redundant actuator very simply and cost-effectively. For example, one set has three windings each. Since the first and second controllers preferably have different voltage supplies and the rotor of the electric motor is very robust and failsafe, the actuator can function in the event of a wide variety of individual faults.

[0009] In another embodiment, the first controller of the actuator and the first controller of the steering transmission are connected to one another via a first bus system and a second bus system, wherein the first bus system is configured as a dedicated bus system, for example a private CAN, via which the steering wheel angle and the transmission ratio are transmitted. The advantage is very fast data transmission compared to other vehicle bus systems. In the event of a failure of the dedicated bus system, then recourse can be had to the second bus system.

[0010] In another embodiment, the first controller and the second controller of the at least one actuator have a communication connection, wherein the steer-by-wire system is configured such that the first controller transmits at least one steering wheel angle starting value to the second controller. The communication preferably takes place continuously, so that the second controller knows the current steering wheel angle and transmission ratio. The communication connection can likewise be configured as a dedicated bus connection, for example a private CAN.

[0011] In another embodiment, the second controller of the actuator is configured such that the absolute steering wheel angle is determined by means of the rotor angle of the steering transmission.

[0012] With regard to the design proposals in method terms, reference is made in full to the preceding embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0013] The application is explained in more detail below by means of a preferred embodiment. The sole drawing shows a schematic block diagram of a steer-by-wire system. DETAILED DESCRIPTION

[0014] In Figure 1A steer-by-wire steering system 1 is presented schematically. The steer-by-wire steering system 1 has a steering column module 2 and a steering transmission 3. The steering column module 2 has a steering wheel 4 and a steering column 5. A first sensor module 6 and a second sensor module 7 are arranged at the steering column 5, wherein the first sensor module 6 and the second sensor module 7 are configured such that a steering wheel angle and a hand torque at the steering wheel 4 are detected. Furthermore, the steering column module 2 has an actuator 8 for generating a counter torque at the steering wheel 4, wherein the actuator 8 is configured as an electric motor with a first set of windings 9 and a second set of windings 10, wherein the first set of windings 9 is operated by a first controller 11 and the second set of windings 10 is operated by a second controller 12, wherein the associated power electronics are not presented for the sake of clarity. The first controller 11 and the second controller 12 are connected to one another via a communication connection 13. The second sensor module 7 is connected to the first controller 11 for the actuator 8 via a sensor interface 14. The steering transmission 3 has a first controller 15 and a second controller 16. Furthermore, the steering transmission 3 has two power electronics 17, 18, which operate a half motor 19, 20, respectively. The two half motors 19 and 20 work on a common rotor 21, which is connected to a rack 22 via a transmission that is not presented. The two controllers 15, 16 operate the power electronics 17, 18. Here, as presented, a respective one of the controllers 15, 16 is able to operate both power electronics 17, 18, or, however, a respective one of the controllers 15, 16 operates a respective one of the power electronics 17, 18. Furthermore, a communication connection 23 between the first controller 15 and the second controller 16 is presented. The first sensor module 6 is connected directly to the first controller 15 of the steering transmission 3 via a sensor interface 24. The first controller 11 of the actuator 8 is connected to the first controller 15 of the steering transmission 3 via a first bus system 25 and a second bus system 26. Here, the first bus system 25 is configured as a dedicated bus system, while the second bus system 26 is configured as a vehicle bus system, on which further controllers also communicate, which is sketched by the outgoing wires. The controller 11 transmits the steering wheel angle and the transmission ratio u of the second sensor module 7 to the first controller 15 of the steering transmission 3 via the first bus system 25. Furthermore, the second controller 12 of the actuator 8 is connected to the second controller 16 of the steering transmission 3 via a further bus system 27, which is also configured as a vehicle bus system, for example. Furthermore, a rotor angle is transmitted to the second controller 16, but it can alternatively or additionally also be delivered to the first controller 15. The voltage supply is not represented, it being applicable that the redundant elements each have a further voltage supply. It is further possible here for the steering column module 2 to have a first and a second voltage supply and for the steering gear 3 to have a first and a second voltage supply, wherein these voltage supplies can be identical or can also be independent of one another. Here, the voltage supply of the first sensor module 6 is identical to the voltage supply of the first controller 15 for the steering gear 3.

[0015] In the event of a fault-free operation, the first controller 11 transmits the transmission ratio u to the first controller 15 of the steering gear 3 via the bus system 25, and the first sensor unit 6 transmits the steering angle to the first controller 15 of the steering gear 3, which first controller 15 then determines the theoretical steering angle therefrom and actuates the power electronics 17, 18 accordingly. It should be noted here that the first controller 11 can additionally transmit the steering wheel angle but this is then ignored by the first controller 15 of the steering gear 3 in the calculation of the theoretical steering angle in the event of a fault in the first sensor unit 6 and / or the sensor interface 24. In the event of a fault in the first controller 11 of the actuator 8, the steering wheel angle and the transmission ratio u are then transmitted by the second controller 12 of the actuator 8 to the second controller 16 of the steering gear 3. In the event of a fault in the first controller 11 of the actuator 8, in which the first sensor unit 6 is intact, the first controller 15 of the steering gear 3 obtains the transmission ratio from another controller, for example the second controller 12 of the actuator 8. In terms of the speed of data transmission, the transmission via the sensor interface is the fastest, followed by the dedicated bus system, while the vehicle bus system is the slowest.

[0016] Reference List

[0017] 1) steer-by-wire system

[0018] 2) steering column module

[0019] 3) steering gear

[0020] 4) steering wheel

[0021] 5) steering column

[0022] 6) first sensor module

[0023] 7) second sensor module

[0024] 8) actuator

[0025] 9) first set of windings

[0026] 10) second set of windings

[0027] 11) first controller for the actuator

[0028] 12) second controller for the actuator

[0029] 13) communication connection

[0030] 14) sensor interface

[0031] 15) first controller for the steering gear 16) second controller for the steering gear 17) power electronics

[0032] 18) power electronics

[0033] 19) half-motor

[0034] 20) half-motor

[0035] 21) common rotor

[0036] 22) rack

[0037] 23) communication connection

[0038] 24) sensor interface

[0039] 25) first bus system

[0040] 26) second bus system

[0041] 27) further bus system steering wheel angle

[0042] ü) transmission ratio rotor angle

Claims

1. A steer-by-wire system (1), wherein The steer-by-wire system (1) has a steering column module (2) and a steering transmission (3), wherein the steering column module (2) has a first sensor module (6) and a second sensor module (7), which each detect at least one steering wheel angle (φ), wherein the steering column module (2) furthermore has a steering wheel (4), a steering column (5), at least one actuator (8) for generating a counter torque at the steering column (5) and two controllers (11, 12) for the at least one actuator (8) for generating a counter torque, wherein the steering transmission (3) has at least two controllers (15, 16), wherein the first controller (11) for the at least one actuator (8) is connected to the first controller (15) of the steering transmission (3) via at least one bus connection (25, 26) and the second controller (12) for the at least one actuator (8) is connected to the second controller (16) of the steering transmission (3) via at least one bus connection (27), wherein the first sensor unit (6) is directly connected to the first controller (15) of the steering transmission (3) via a sensor interface (24) and the second sensor unit (7) is directly connected to the first controller (11) for the at least one actuator (8) via a sensor interface (14), wherein the steer-by-wire system (1) is designed in such a way that, in the case of fault-free operation, the first controller (11) of the actuator (8) transmits a transmission ratio (ü) to the first controller (15) of the steering transmission (3) and the first sensor unit (6) transmits a steering wheel angle (φ) directly to the first controller (15) of the steering transmission (3), which are then used to calculate a theoretical steering angle, wherein, in the case of a fault in the first sensor unit (6) and / or the sensor interface (24), the steering wheel angle (φ) and the transmission ratio (ü) of the first controller (11) are transmitted to the first controller (15) of the steering transmission (3) and used to calculate a theoretical steering angle, wherein the first sensor module (6) and the first controller (15) of the steering transmission (3) have a common voltage supply.

2. The steer-by-wire steering system of claim 1, wherein, The first sensor module (6) and the second sensor module (7) are designed in such a way that an additional hand torque is detected.

3. The steer-by-wire steering system of any of the preceding claims, characterized in that, The at least one actuator (8) for generating a counter torque is designed as an electric motor with a first set of windings (9) and a second set of windings (10), which are independent of one another, wherein the first set of windings (9) is actuated by the first controller (11) for the actuator (8) and the second set of windings (10) is actuated by the second controller (12). The at least one actuator (8) for generating a counter torque is designed as an electric motor with a first set of windings (9) and a second set of windings (10), which are independent of one another, wherein the first set of windings (9) is actuated by the first controller (11) for the actuator (8) and the second set of windings (10) is actuated by the second controller (12).

4. A steer-by-wire steering system according to any one of the preceding claims, characterized in that The first controller (11) of the actuator (8) and the first controller (15) of the steering transmission (3) are connected to one another via a first bus system (25) and a second bus system (28), wherein the first bus system (25) is configured as a dedicated bus system via which the steering wheel angle (φ) and the transmission ratio (u) are transmitted.

5. A steer-by-wire steering system according to any one of the preceding claims, characterized in that The first controller (11) and the second controller (12) of the at least one actuator (8) have a communication connection (13), wherein the steer-by-wire system (1) is configured in such a way that the first controller (11) transmits at least one steering wheel angle starting value to the second controller (12).

6. The steer-by-wire steering system of claim 5, wherein, The second controller (12) is constructed in such a way that the absolute steering wheel angle is determined by means of the rotor angle (φ R ) of the steering transmission.

7. A method for operating a steer-by-wire system, wherein The steer-by-wire system (1) has a steering column module (2) and a steering transmission (3), wherein the steering column module (2) has a first sensor module (6) and a second sensor module (7), which each detect at least one steering wheel angle (φ), wherein the steering column module (2) furthermore has a steering wheel (4), a steering column (5), at least one actuator (8) for generating a counter torque at the steering column (5) and two controllers (11, 12) for the at least one actuator (8) for generating a counter torque, wherein the steering transmission (3) has at least two controllers (15, 16), wherein the first controller (11) for the at least one actuator (8) is connected to the first controller (15) of the steering transmission (3) via at least one bus connection (25, 26) and the second controller (12) for the at least one actuator (8) is connected to the second controller (16) of the steering transmission (3) via at least one bus connection (27), wherein the first sensor unit (6) is directly connected to the first controller (15) of the steering transmission (3) via a sensor interface (24) and the second sensor unit (7) is directly connected to the first controller (11) for the at least one actuator (8) via a sensor interface (14), wherein in the fault-free mode of operation the first controller (11) of the actuator (8) transmits a transmission ratio (u) to the first controller (15) of the steering transmission (3) and the first sensor unit (6) transmits a steering wheel angle (φ) directly to the first controller (15) of the steering transmission (3), which are then used to calculate a theoretical steering angle, wherein in the event of a fault in the first sensor unit (6) and / or the sensor interface (24) the steering wheel angle (φ) and the transmission ratio (u) of the first controller (11) are transmitted to the first controller (15) of the steering transmission (3) and used to calculate a theoretical steering angle, wherein the first sensor module (6) and the first controller (15) of the steering transmission (3) have a common voltage supply.

8. The method of claim 7, wherein, The first sensor module (6) and the second sensor module (7) additionally detect a hand torque.

9. The method according to claim 7 or 8, characterized in that, The first controller (11) of the actuator (8) and the first controller (15) of the steering transmission (3) are connected to one another via a first bus system (25) and a second bus system (28), wherein the first bus system (25) is configured as a dedicated bus system via which the steering wheel angle (φ) and the transmission ratio (u) are transmitted.

10. The method according to any one of claims 7 to 9, characterized in that, The first controller (11) and the second controller (12) of the at least one actuator (8) have a communication connection (13), wherein the first controller (11) transmits at least one steering wheel angle starting value to the second controller (12).

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