Steer-by-Wire Steering Feel Control for Low-Friction Surface Detection
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Solution Overview
Problem
Existing vehicle systems do not provide operators with information about road conditions ahead, particularly low coefficient of friction surfaces, which can lead to reduced control and increased accident risk.
Innovation Solution
A system that adjusts steering feel characteristics in response to detected low friction surfaces, reducing lateral response at high speeds and increasing it closer to the surface, using alerts and steering system modifications to encourage speed reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If the vehicle maintains normal steering characteristics, then the steering system provides standard lateral response, but the vehicle operator does not receive warning about low friction surfaces ahead
Solution Approach 1:
The system performs preliminary detection of low friction surfaces using camera imaging and image processing before the vehicle reaches them. Steering feel characteristics are adjusted in advance when low friction is detected, providing warning to the operator and allowing preventive action before the vehicle encounters the hazardous surface
Solution Approach 2:
The system uses an intermediary detection mechanism (camera and image processing) to identify low friction surfaces that are not directly perceivable by the operator. This intermediary system translates road surface properties into visual information that can be processed and used to adjust steering characteristics
2Stability of the object's composition
If the steering system reduces lateral response at high speeds, then vehicle stability is improved, but the operator experiences reduced steering responsiveness
Solution Approach 1:
The steering feel characteristic is dynamically adjusted based on detected road conditions and current vehicle speed. When low friction surfaces are detected ahead, the system modifies steering feel to provide stability warning. The adjustment is temporary and condition-dependent, allowing the system to optimize between stability and responsiveness based on real-time conditions
Solution Approach 2:
The system changes steering system parameters (steering feel characteristic) in response to detected low friction conditions. By modifying parameters such as steering ratio or assist level, the system alters the relationship between steering input and wheel response to communicate road conditions to the operator without permanently reducing vehicle capability
3Reliability
If the vehicle speed is reduced, then safety on low friction surfaces is improved, but the overall travel time increases
Solution Approach 1:
The system provides advance warning of low friction surfaces through steering feel modification, allowing the operator to reduce speed in a controlled manner before reaching the hazardous area. This preliminary warning enables speed adjustment without sudden emergency braking that would waste time and disrupt traffic flow
Solution Approach 2:
The system applies preliminary counter-measures by adjusting steering feel to warn of upcoming low friction conditions. This allows the operator to take preventive action (speed reduction) before entering the low friction zone, avoiding the need for reactive emergency maneuvers that would be more time-consuming and dangerous
Data Source
AI summary
A method includes determining, responsive to a the portion of a surface has a coefficient of friction that is less than the coefficient of friction threshold, whether a vehicle speed is greater than a vehicle speed threshold; in response to determining that the vehicle speed is greater than the vehicle speed threshold: adjusting a steering feel characteristic of a steering system of the vehicle from a first value to a second value; and reducing a lateral response of the vehicle; and in response to at least one of a reduction in the vehicle speed and a distance between the vehicle and the portion of the surface having the coefficient of friction being less than a distance threshold: adjusting the steering feel characteristic from the second value to the first value; and increasing the lateral response of the vehicle.