Steering-by-Wire Limit Feedback for Backup Steering Stability
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Solution Overview
Problem
The steering-by-wire (SBW) system in vehicles faces issues with loss of steering function due to wire defects, leading to a difference between the required and actual steering values, which affects steering stability and backup steering performance.
Innovation Solution
A steering apparatus and control method that calculate a maximum limit steering value based on vehicle speed and road surface conditions, provide a warning and reaction force feedback to the steering wheel when the required steering value exceeds the limit, and assist in steering by estimating the steering endpoint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the SBW system is used to transfer steering intention electrically, then the mechanical connection between steering wheel and wheels is eliminated, but steering function is lost when wire defect occurs
Solution Approach 1:
The system calculates a maximum limit steering value in advance based on vehicle speed and road surface conditions, and prepares backup steering control strategies beforehand. When wire defects occur, the pre-calculated limit values and backup control methods ensure continuous steering functionality without complete system failure.
Solution Approach 2:
The system dynamically changes the maximum limit steering value parameter based on vehicle speed and road surface conditions. At higher speeds or on slippery surfaces, the limit is reduced to prevent excessive steering inputs that could compromise stability, while allowing greater steering freedom at lower speeds on stable surfaces.
2Reliability
If backup steering is performed when steering function is lost, then the vehicle can still steer, but steering stability is degraded
Solution Approach 1:
The system provides reaction force feedback to the steering wheel based on the maximum limit steering value. When the driver's steering input approaches or exceeds the calculated limit, the reaction force increases to guide the driver back to stable steering inputs, maintaining steering stability even during backup steering operation.
Solution Approach 2:
The system applies preliminary counteracting reaction forces to prevent excessive steering inputs before they can cause instability. By monitoring steering input against the maximum limit and applying opposing reaction forces when limits are approached, the system proactively maintains steering stability rather than reacting after instability occurs.
3Stability of the object's composition
If the maximum limit steering value is calculated based on vehicle speed and road surface condition, then steering stability is maintained, but the system complexity increases
Solution Approach 1:
The system replaces complex mechanical steering linkages with electronic control and software-based calculations. The maximum limit steering value is computed through software algorithms that process sensor data about vehicle speed and road conditions, eliminating the need for complex mechanical limit-setting mechanisms while achieving adaptive steering control.
Data Source
AI summary
A control method for a vehicle for steering based on a steering-by-wire (SBW) system, the control method for a vehicle comprising: calculating a maximum limit steering value of a steering wheel when an abnormality occurs in the SBW system; calculating a correction coefficient for the maximum limit steering value on the basis of a speed of the vehicle and a road surface condition; generating endpoint reaction force feeling for the steering wheel; determining whether a required steering value input to the steering wheel exceeds the maximum limit steering value; and transmitting a warning sound and applying a reaction force to the steering wheel when a determination is made that the required steering value exceeds the maximum limit steering value.