Steer-by-Wire Control Using Adaptive Steering Maps
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Solution Overview
Problem
Conventional mechanically-linked steering systems lack flexibility in vehicle design and operation, limiting independent control of steering wheels and road wheels, which hinders advancements in vehicle systems like autonomous driving and cabin packaging.
Innovation Solution
A steer-by-wire system with a steering wheel assembly and a rack assembly, communicatively coupled by a controller, allows independent control of steering and road wheels using steering maps that adapt to vehicle speed, direction, and driver preferences, eliminating mechanical links.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If mechanically-linked steering systems are used, then steering alignment is maintained through direct mechanical links, but flexibility in vehicle design and operation is limited
Solution Approach 1:
The patent replaces the mechanical linkage system with an electronic control system. Sensors detect steering wheel position and vehicle state parameters, the controller processes this information using steering maps, and actuators adjust the steering rack position accordingly. This substitution eliminates physical mechanical links while maintaining steering functionality and enabling greater design flexibility.
Solution Approach 2:
The patent introduces a controller as an intermediary between the steering wheel assembly and rack assembly. This controller receives input from sensors, processes steering commands through steering maps, and sends control signals to actuators. The intermediary enables independent control of steering wheel and road wheels, resolving the contradiction between maintaining alignment and achieving design flexibility.
2Adaptability or versatility
If steer-by-wire systems are used, then independent control of steering wheel and road wheels is achieved, but maintaining steering alignment becomes more challenging
Solution Approach 1:
The patent implements a feedback control system where sensors continuously monitor steering wheel position and vehicle operating conditions. The controller compares actual steering rack position with target position determined from steering maps, and adjusts actuator commands to maintain proper alignment. This closed-loop feedback ensures reliable steering alignment despite the absence of mechanical links.
Solution Approach 2:
The patent employs dynamic steering maps that adapt to varying vehicle operating conditions such as speed, direction, and driver preference. The controller dynamically selects and adjusts steering parameters based on real-time sensor inputs, enabling the system to maintain optimal steering alignment across different driving scenarios while preserving independent control capability.
Data Source
AI summary
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.