Steer-by-wire steering system and method
A steer-by-wire steering system for a vehicle is disclosed. The steering system has a steering wheel, a first sensor for capturing a steering angle of the steering wheel, a processing logic unit for determining a wheel setting angle requirement on the basis of the captured steering angle, and an actuator unit for setting a wheel setting angle at wheels of the vehicle according to the wheel setting angle requirement determined by the processing logic unit. The sensor is electrically connected to the actuator unit and is supplied with electrical energy via the actuator unit. There is at least one further sensor for capturing a steering angle of the steering wheel, which further sensor is used as a fallback solution if the first sensor fails, wherein the processing logic unit is configured to process primarily a signal from the first sensor and to process the signal from the further sensor only if the first sensor fails.
1 . A steer-by-wire steering system for a vehicle, comprising: a steering wheel,
a first steering-angle sensor configured to directly measure an absolute steering angle of the steering wheel, the first steering-angle sensor being electrically powered via an actuator unit of the steering system;
wherein the actuator unit is configured to set a wheel setting angle at the vehicle wheels,
a steering unit comprising a steering actuator for applying torque to the steering wheel;
a second sensor comprising a position sensor of the steering actuator, the second sensor being configured to derive a steering-angle of the steering wheel based on a position of the steering actuator,
a processing logic configured to:
use a steering-angle signal from the first steering-angle sensor during operation, and
use the steering-angle signal derived from the position of the steering actuator via the second steering-angle sensor when the first steering-angle sensor fails, and
two processing paths, including a first processing path and a second processing path, each comprising its own processing logic, actuator unit and position-sensor based steering-angle acquisition,
wherein the first processing path determines a wheel-setting angle requirement ahead of the second processing path during normal operation, and
wherein the steering angles determined by the position sensors of the respective processing paths are cross-checked against the output of the first steering-angle sensor of the second processing path to identify a faulty position sensor.
2 . The steer-by-wire steering system as claimed in claim 1 , wherein the first steering-angle sensor is directly connected to the actuator unit via a signal line.
3 . The steer-by-wire steering system as claimed in claim 1 , wherein the processing logic unit is integrated in the steering unit and/or in the actuator unit.
4 . The steer-by-wire steering system as claimed in claim 3 , wherein the steering unit and the actuator unit are connected to one another via a communication line.
5 . The steer-by-wire steering system as claimed in claim 1 , wherein the steering unit and the actuator unit are connected to one another via a communication line.
6 . The steer-by-wire steering system as claimed in- claim 2 , wherein the steering unit and the actuator unit are electrically connected directly to the vehicle electrical system and are supplied with electrical energy via the vehicle electrical system.
7 . The steer-by-wire steering system as claimed in claim 1 , wherein the steering unit and the actuator unit are electrically connected directly to the vehicle electrical system and are supplied with electrical energy via the vehicle electrical system.
8 . The steer-by-wire steering system as claimed in claim 1 , wherein the first processing path is a master path which, during normal operation, captures a steering angle and determines the wheel setting angle requirement ahead of the second processing path.
9 . The steer-by-wire steering system as claimed in claim 8 , wherein the actuator units of the first and the second processing path are each connected to one another in terms of signaling via communication lines.
10 . The steer-by-wire steering system as claimed in claim 8 , wherein the power supplies for the processing paths are independent of one another.
11 . The steer-by-wire steering system as claimed in claim 8 , wherein a sensor for capturing a steering angle of the steering wheel of a second processing path is electrically connected to the steering unit and is supplied with electrical energy via the second processing path.
12 . The steer-by-wire steering system as claimed in claim 8 , wherein the first sensor of two processing paths is electrically connected to the respective actuator unit and is supplied with electrical energy via the actuator unit.
13 . A method for operating a steer-by-wire steering system as claimed in claim 1 , wherein a wheel setting angle requirement is determined by the processing logic unit during normal operation of the steering system on the basis of the steering angle captured by the first sensor, and the steering angle is captured by the second sensor if the first sensor fails.
14 . The method for operating a steer-by-wire steering system as claimed in claim 13 , wherein a wheel setting angle requirement is determined by the processing logic unit during normal operation of the steering system on the basis of the steering angle captured by the first sensor of a first processing path, and the steering angle is captured by a position sensor of the steering unit of the first and/or of a second processing path if the first sensor of the first processing path fails.
15 . The method as claimed in claim 14 , wherein, if the steering angles captured by the position sensors of the steering unit of the first and the second processing path differ from one another, the steering angles captured by the position sensors are compared with the steering angle captured by the first sensor of the second processing path.
16 . The system of claim 1 , wherein the position of the steering actuator is obtained from a motor-position sensor integrated into the steering unit.
17 . The system of claim 1 , wherein steering-angle derivation from actuator position includes compensation from actuator zero-offset stored at vehicle start.
18 . The system of claim 1 , wherein each processing path has an independent vehicle electrical system.
19 . The system of claim 1 , wherein the cross-checking logic identifies a correct position sensor by matching to the first steering-angle sensor of the redundant processing path.