Steering-by-wire system and method for operating steering-by-wire system

Abstract

The invention relates to a steering-by-wire system (1), the steering-by-wire system (1) having a steering column module (2) and a steering gear (3), the steering column module (2) having a first sensor module (6) and a second sensor module (7), each of which detects at least one steering wheel angle (phi), the steering column module (2) further comprises a steering wheel (4), a steering column (5), at least one actuator (8) for generating a counter torque on the steering column (5), and two controllers (11, 12) for the at least one actuator (8) for generating a counter torque, the steering gear (3) having at least two controllers (15, 16), a first control unit (11) for the at least one actuator (8) is connected to a first control unit (15) of the steering gear (3) via at least one bus connection (25, 26), and a second control unit (12) for the at least one actuator (8) is connected to a second control unit (16) of the steering gear (3) via at least one bus connection (27), the first sensor unit (6) is directly connected to a first control unit (15) of the steering gear (3) via a sensor interface (24), and the second sensor unit (7) is directly connected to a first control unit (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 system and a method for operating a steer-by-wire system. Background Art

[0002] A steer-by-wire system is usually constructed in such a way that it has a steering column module and a steering gear, which are mechanically decoupled and electrically connected. Here, the steering wheel angle is detected and transmitted to the controller of the steering gear in order to determine the setpoint steering angle, which is then set (einstellen, sometimes called regulation) with the help of a steering actuator. The steering actuator is usually an electric motor, which deflects the rack in order to set the setpoint steering angle at the wheel. Here, an actuator (Aktor, sometimes called actuator) for generating a counter-torque (Gegenmoment, sometimes called counter-torque) is arranged at the steering column, so that the vehicle driver is given a steering feel as he is familiar with from conventional steering systems. It is also known that many of the mentioned components are constructed redundantly in order to ensure failsafety (Ausfallsicherheit, sometimes called reliability) in this way. Various concepts are known here: how to ensure the corresponding redundancy or backup level.

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

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

[0005] The solution to this problem is achieved by a steering system having the features of claim 1 and a method having the features of claim 7. Further advantageous embodiments of the invention emerge from the dependent claims.

[0006] The steer-by-wire system comprises a steering column module and a steering transmission mechanism. The steering column module comprises a first sensor module and a second sensor module, wherein the first sensor module and the second sensor module respectively detect at least one steering wheel angle. The steering column module further comprises 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 the counter torque. Here, the steering wheel is generally understood to be a steering handle for presetting a desired steering angle. In addition, the first controller for the at least one actuator is connected to the first controller of the steering transmission mechanism via at least one bus connection (Busverbindung, sometimes referred to as a bus link). The second controller for the at least one actuator is connected to the second controller of the steering transmission mechanism via at least one second bus connection. In addition, the first sensor unit is directly connected to the first controller of the steering transmission mechanism via a sensor interface, and the second sensor unit is directly connected to the first controller for the at least one actuator via a sensor interface. The sensor interface is preferably configured as a SENT (single edge nibble transmission) interface. The wire control steering system is constructed in such a way that, in fault-free operation, the first controller of the at least one actuator transmits the transmission ratio to the first controller of the steering transmission mechanism, and the first sensor unit directly transmits the steering wheel angle to the first controller of the steering transmission mechanism, and the transmission ratio and the steering wheel angle are then used to calculate the theoretical steering angle. In the event of a fault in 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 mechanism and used to calculate the theoretical steering angle. The first sensor module and the first controller of the steering transmission mechanism have a common voltage supply device. As a result, the overall failure safety is improved because the transmission of the steering wheel angle is carried out via two different transmission paths, namely, one via the sensor interface and the other via the bus connection. Through the common voltage supply device of the first sensor module and the first controller of the steering transmission mechanism, the first sensor module also works even in the event of a failure of the voltage supply device of the first controller of the at least one actuator. Another advantage is the extremely fast data transmission of the steering wheel angle caused by the sensor interface. As a result, the wire control steering system can react much more dynamically as a whole. Since the transmission ratio is not subject to such dynamic changes, a slightly slower transmission via the bus system is not critical.

[0007] In one specific embodiment, the first sensor mass and the second sensor mass are designed in such a way that a hand moment (sometimes referred to as hand torque) is additionally detected.

[0008] In another embodiment, the at least one actuator for generating the counter torque is designed as an electric motor with a first set of windings and a second set of windings, the first set of windings and the second set of windings being independent of one another, wherein the first set of windings is controlled by a first controller for the actuator and the second set of windings is controlled by a second controller. This allows for a very simple and cost-effective realization of redundant actuators. For example, one set has three windings in each case. Since the first and second controllers preferably have different voltage supplies and the rotor of the electric motor is very robust and fail-safe, the actuator can function in the event of a wide variety of single faults.

[0009] In another embodiment, the first controller of the actuator and the first controller of the steering gear are connected to one another via a first bus system and a second bus system, wherein the first bus system is designed as a dedicated bus system (e.g. private CAN) via which the steering wheel angle and the transmission ratio are transmitted. The advantage is a very fast data transmission compared to other vehicle bus systems. In the event of failure of the dedicated bus system, the second bus system can then be relied upon.

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

[0011] In a further embodiment, the second control unit of the actuator is designed in such a way that the absolute steering wheel angle is determined with the aid of the rotor angle of the steering gear.

[0012] Regarding the design scheme in terms of method, full reference is made to the previous implementation scheme. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The invention is explained in more detail below with the aid of preferred exemplary embodiments.The single FIGURE shows a schematic block diagram of a steer-by-wire system. DETAILED DESCRIPTION

[0014] exist Figure 1Schematically presenting a wire-controlled steering system 1. The wire-controlled steering system 1 has a steering column module 2 and a steering gear 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 on the steering column 5, wherein the first sensor module 6 and the second sensor module 7 are configured such that the steering wheel angle is detected. and a hand torque at the steering wheel 4. In addition, the steering column module 2 has an actuator 8 for generating a counter torque at the steering wheel 4, wherein the actuator 8 is designed 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 controlled by a first controller 11 and the second set of windings 10 is controlled by a second controller 12, wherein the associated power electronics are not shown for the sake of clarity. The first controller 11 and the second controller 12 are connected to each other 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 gear 3 has a first controller 15 and a second controller 16. In addition, the steering gear 3 has two power electronics 17, 18, which respectively control half motors 19, 20. The two half motors 19 and 20 work on a common rotor 21, which is connected to a rack 22 via a gear mechanism not shown. The two controllers 15, 16 control the power electronics 17, 18. Here, as presented, one controller 15, 16 can control two power electronic devices 17, 18, or one controller 15, 16 can control one power electronic device 17, 18. In addition, a communication connection 23 between the first controller 15 and the second controller 16 is presented. The first sensor module 6 is directly connected to the first controller 15 of the steering gear 3 via a sensor interface 24. The first controller 11 of the actuator 8 is connected to the first controller 15 of the steering gear 3 via a first bus system 25 and a second bus system 26. Here, the first bus system 25 is designed as a dedicated bus system, while the second bus system 26 is designed as a vehicle bus system, on which other controllers also communicate, which is simplified by the lead-out wires. The controller 11 transmits the steering wheel angle of the second sensor module 7 via the first bus system 25. and the transmission ratio ü are transmitted to the first control unit 15 of the steering gear 3. In addition, the second control unit 12 of the actuator 8 is connected to the second control unit 16 of the steering gear 3 via another bus system 27 (which is also designed as a vehicle bus system, for example). In addition, the rotor angle is transmitted to the second control unit 16, but it can alternatively or additionally also be supplied to the first control unit 15. The voltage supply is not shown, whereby it applies that the redundant elements each have an additional voltage supply. It can also be provided that the steering column module 2 has a first and a second voltage supply, and the steering gear 3 has a first and a second voltage supply, wherein these voltage supplies can be identical or also independent of one another. Here, the voltage supply of the first sensor module 6 is identical to the voltage supply of the first control unit 15 for the steering gear 3.

[0015] In fault-free operation, the first control unit 11 transmits the transmission ratio ü to the first control unit 15 of the steering gear 3 via the bus system 25, and the first sensor unit 6 transmits the steering angle is transmitted to the first control unit 15 of the steering gear 3, which then determines the target steering angle from this and controls the power electronics 17, 18 accordingly. It should be noted that the first control unit 11 can also additionally transmit the steering wheel angle However, it is then ignored by the first control unit 15 of the steering gear 3 in the calculation of the setpoint steering angle in fault-free operation. In the event of a failure of the first sensor unit 6 and / or the sensor interface 24, the first control unit 15 of the steering gear 3 then uses the steering wheel angle transmitted from the first control unit 11 of the actuator. and transmission ratio ü. If the first controller 11 of the actuator 8 also fails, the steering wheel angle and the transmission ratio are transmitted by the second controller 12 of the actuator 8 to the second controller 16 of the steering transmission mechanism 3. In the case of failure of the first controller 11 of the actuator 8, wherein the first sensor unit 6 is intact (intakt, sometimes referred to as functioning properly), the first controller 15 of the steering transmission mechanism 3 obtains the transmission ratio from another controller (e.g., the second controller 12 of the actuator 8). In terms of data transmission speed, transmission via the sensor interface is the fastest, followed by the dedicated bus system, and the vehicle bus system is the slowest.

[0016] Reference Numbers List

[0017] 1) Steer-by-wire system

[0018] 2) Steering column module

[0019] 3) Steering transmission mechanism

[0020] 4) Steering wheel

[0021] 5) Steering column

[0022] 6) First sensor module

[0023] 7) Second sensor module

[0024] 8) Actuator

[0025] 9) The first winding

[0026] 10) The second winding

[0027] 11) First controller for actuator

[0028] 12) Second controller for actuator

[0029] 13) Communication connection

[0030] 14) Sensor interface

[0031] 15) A first controller for a steering gear mechanism 16) A second controller for a steering gear mechanism 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) Other bus systems Steering wheel angle

[0042] ü) Transmission ratio Rotor angle

Claims

1. A steer-by-wire system (1), wherein: The steer-by-wire system (1) comprises a steering column module (2) and a steering transmission mechanism (3), wherein the steering column module (2) comprises a first sensor module (6) and a second sensor module (7), wherein the first sensor module (6) and the second sensor module (7) respectively detect at least one steering wheel angle (φ), wherein the steering column module (2) further comprises 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 control devices for the at least one actuator (8) for generating a counter torque. The invention relates to a control device (11, 12), wherein the steering gear (3) has at least two controllers (15, 16), wherein a first controller (11) for the at least one actuator (8) is connected to a first controller (15) of the steering gear (3) via at least one bus connection (25, 26), and a second controller (12) for the at least one actuator (8) is connected to a second controller (16) of the steering gear (3) via at least one bus connection (27), wherein the first sensor unit (6) is connected to the at least one actuator via a sensor interface (24). The invention relates to a steering system (1) comprising a first control unit (15) directly connected to a first control unit (15) of the steering gear (3), and a second sensor unit (7) directly connected to a first control unit (11) for the at least one actuator (8) via a sensor interface (14), wherein the steer-by-wire system (1) is designed such that, in fault-free operation, the first control unit (11) of the actuator (8) transmits a transmission ratio (ü) to the first control unit (15) of the steering gear (3), and the first sensor unit (6) transmits a steering wheel angle (φ) directly to the steering gear At the first controller (15) of the mechanism (3), the transmission ratio (ü) and the steering wheel angle (φ) are then used to calculate a theoretical steering angle, wherein, in the event of a failure of 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 mechanism (3) and used to calculate the theoretical steering angle, wherein the first sensor module (6) and the first controller (15) of the steering transmission mechanism (3) have a common voltage supply device.

2. The steer-by-wire system according to claim 1, characterized in that: The first sensor module (6) and the second sensor module (7) are designed in such a way that they additionally detect hand torques.

3. A steer-by-wire system according to any one of the preceding claims, characterised in that The at least one actuator (8) for generating a counter-torque is constructed as an electric motor having a first group of windings (9) and a second group of windings (10), wherein the first group of windings (9) and the second group of windings (10) are independent of each other, wherein the first group of windings (9) is controlled by a first controller (11) for the actuator (8), and the second group of windings (10) is controlled by the second controller (12).

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

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

6. The steer-by-wire system according to claim 5, characterized in that: The second controller (12) is designed such that, by means of the rotor angle (φ) of the steering gear R ) determines the absolute steering wheel angle.

7. A method for operating a steer-by-wire system, wherein: The steer-by-wire system (1) comprises a steering column module (2) and a steering gear (3), wherein the steering column module (2) comprises a first sensor module (6) and a second sensor module (7), wherein the first sensor module (6) and the second sensor module (7) each detect at least one steering wheel angle (φ), wherein the steering column module (2) further comprises 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 gear (3) comprises at least two controllers (15, 16), wherein a first controller (11) for the at least one actuator (8) is connected to a first controller (15) of the steering gear (3) via at least one bus connection (25, 26), and a second controller (12) for the at least one actuator (8) is connected to a second controller (16) of the steering gear (3) via at least one bus connection (27), wherein the first sensor module (6) is connected to a second controller (16) of the steering gear (3) via at least one bus connection (25, 26), wherein the first sensor module (6) is connected to a second controller (16) of the steering gear (3) via at least one bus connection (27 ... The sensor unit (24) is directly connected to a first control unit (15) of the steering gear (3), and the second sensor unit (7) is directly connected to a first control unit (11) for the at least one actuator (8) via the sensor interface (14), wherein, in fault-free operation, the first control unit (11) of the actuator (8) transmits a transmission ratio (ü) to the first control unit (15) of the steering gear (3), and the first sensor unit (6) transmits a steering wheel angle (φ) directly to the steering gear (3). The transmission ratio (ü) and the steering wheel angle (φ) are then used to calculate a theoretical steering angle at a first controller (15) of the steering gear (3), wherein, in the event of a failure of 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 gear (3) and used to calculate the theoretical steering angle, wherein the first sensor module (6) and the first controller (15) of the steering gear (3) have a common voltage supply device.

8. The method according to claim 7, characterized in that The first sensor module (6) and the second sensor module (7) additionally detect hand torques.

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

10. The method according to any one of claims 7 to 9, characterized in that A first controller (11) and a 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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