Steer-by-wire systems and methods of operating thereof in vehicles
Described herein are steer-by-wire systems and methods of operating these systems in vehicles. A steer-by-wire system comprises a steering wheel assembly, comprising a steering wheel, sensors, and a torque generator. The system comprises a rack assembly, comprising a steering rack, sensors, and a rack actuator. The steering wheel assembly and the rack assembly are communicatively coupled by a steer-by-wire system controller, without having any direct mechanical links between the assemblies. In some examples, the controller instructs the rack assembly to control the steering rack position based on the steering input, such as changes in the steering wheel position. A steering map is used to determine the desired steering rack position based on the current steering wheel position. In some examples, a steering map is selected from a steering map set based on, e.g., the vehicle speed, vehicle direction, driver preference, and the like.
1. A vehicle comprising:
a vehicle network;
a first communication link;
a second communication link; and
a steer-by-wire system comprising a steering wheel controller configured to control one or more components of a steering wheel assembly, the steering wheel controller communicatively coupled to the vehicle network using the first communication link and communicatively coupled separately to the vehicle network using the second communication link, wherein:
the steering wheel controller comprises a first steering wheel electronic control unit (ECU) communicatively coupled to the vehicle network using the first communication link,
the steering wheel controller further comprises a second steering wheel ECU communicatively coupled to the vehicle network using the second communication link and communicatively coupled separately to the first steering wheel ECU using a steering wheel internal-communication bus (ICB), and
the first steering wheel ECU, the second steering wheel ECU, and the steering wheel ICB are configured such that switching between the first communication link and the second communication link does not require switching between the first steering wheel ECU and the second steering wheel ECU.
2. The vehicle of claim 1 , wherein the steer-by-wire system is configured to use the first steering wheel ECU when the first communication link becomes unavailable to support one or more operations.
3. The vehicle of claim 1 , wherein the steer-by-wire system is configured to communicatively couple the first steering wheel ECU to the vehicle network using the steering wheel ICB, the second steering wheel ECU, and the second communication link when the first communication link becomes unavailable to support one or more operations.
4. The vehicle of claim 1 , wherein the steer-by-wire system is configured such that switching operations between the first steering wheel ECU and the second steering wheel ECU does not require switching between the first communication link and the second communication link.
5. The vehicle of claim 1 , wherein the steer-by-wire system is configured to use the first communication link when the first steering wheel ECU becomes unavailable to support one or more operations.
6. The vehicle of claim 1 , wherein the steer-by-wire system is configured to communicatively couple the second steering wheel ECU to the vehicle network through the first communication link, the first steering wheel ECU, and the steering wheel ICB when the first steering wheel ECU becomes unavailable to support one or more operations.
7. The vehicle of claim 1 , wherein the steer-by-wire system further comprises:
a first steering rack ECU communicatively coupled to the first steering wheel ECU using the first communication link; and
a second steering rack ECU communicatively coupled to the second steering wheel ECU using the second communication link and communicatively coupled separately to the first steering rack ECU using a steering rack ICB, and
wherein the first steering rack ECU, the steering rack ICB, and the second steering rack ECU are configured such that switching between the first communication link and the second communication link does not require switching between the first steering rack ECU and the second steering rack ECU.
8. The vehicle of claim 7 , wherein the steer-by-wire system is configured to use the first steering rack ECU when the first communication link becomes unavailable to support one or more operations.
9. The vehicle of claim 7 , wherein the steer-by-wire system is configured to communicatively couple the first steering rack ECU to the vehicle network using the steering rack ICB, the second steering rack ECU, and the second communication link when the first communication link becomes unavailable to support one or more operations.
10. The vehicle of claim 7 , wherein the steer-by-wire system is configured such that switching operations between the first steering rack ECU and the second steering rack ECU does not require switching between the first communication link and the second communication link.
11. The vehicle of claim 7 , wherein the steer-by-wire system is configured to use the first communication link when the first steering rack ECU becomes unavailable to support one or more operations.
12. The vehicle of claim 7 , wherein the steer-by-wire system is configured to communicatively couple the second steering rack ECU to the vehicle network through the first communication link, the first steering rack ECU, and the steering rack ICB when the first steering rack ECU becomes unavailable to support one or more operations.
13. The vehicle of claim 1 , wherein the steer-by-wire system is configured to restore operation of the first communication link, the second communication link, the first steering wheel ECU, or the second steering wheel ECU when the first communication link, the second communication link, the first steering wheel ECU, or the second steering wheel ECU respectively becomes available.
14. The vehicle of claim 1 , wherein each of the first communication link and the second communication link comprises one or more of: a controller area network (CAN) bus, an Ethernet bus system, a local interconnected network (LIN), a FlexRay bus system, an optical fiber system, a dedicated hardware connection, and a wireless system.
15. The vehicle of claim 1 , wherein the steering wheel controller is further configured to:
receive sensor measurements related to an angular position of a steering wheel of the steering wheel assembly from a steering wheel position sensor; and
receive sensor measurements related to a torque applied to the steering wheel by a driver from a steering wheel torque sensor.
16. The vehicle of claim 15 , wherein, to control the one or more components of the steering wheel assembly, the steering wheel controller is configured to control a steering wheel actuator based on the measurements related to the angular position of the steering wheel and the torque applied to the steering wheel.
17. The vehicle of claim 16 , wherein the steering wheel controller is configured to control the steering wheel actuator in order to rotate the steering wheel.
18. The vehicle of claim 16 , wherein the steering wheel controller is configured to control the steering wheel actuator in order to set a tunable steering wheel limit for the steering wheel.
19. The vehicle of claim 18 , wherein the steering wheel controller is further configured to control the steering wheel actuator in order to apply a resistive torque to the steering wheel in response to the torque applied to the steering wheel by the driver reaching or exceeding the tunable steering wheel limit.
20. The vehicle of claim 16 , wherein the steering wheel controller is configured to control the steering wheel actuator in order to apply a set torque to the steering wheel.
21. The vehicle of claim 1 , wherein the steer-by-wire system is configured such that:
the first steering wheel ECU is configured to operate as a primary steering wheel ECU;
the first steering wheel ECU is configured to receive input data over the first communication link; and
in response to the input data not being received over the first communication link or the input data being received more reliably over the second communication link, the first steering wheel ECU is configured to receive the input data from the second communication link via the second steering wheel ECU without the second steering wheel ECU switching to operate as the primary steering wheel ECU.