Steer-By-Wire Steering Ratio Control to Prevent Wheel Movement
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Solution Overview
Problem
Existing steer-by-wire steering systems face challenges in efficiently and safely varying the steering ratio due to limitations imposed by fixed values, which can lead to reduced performance and inability to prevent wheel movement during certain driving conditions.
Innovation Solution
A method is introduced to dynamically adjust the steering ratio using a variable change characteristic, limited by a dynamically determined change factor, such as a time gradient, which is calculated based on steering specifications and vehicle speed, enhancing operational safety and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed value is used to limit the change in steering ratio, then the system structure is simple, but the operational safety is reduced and wheel movement cannot be prevented during certain driving conditions
Solution Approach 1:
The patent applies the dynamics principle by replacing the fixed limit value with a dynamically determined change characteristic. The change characteristic is calculated based on current driving conditions including steering angle, steering speed, and vehicle speed, allowing the steering ratio change to be adaptively limited according to the actual operating state, thereby improving operational safety while maintaining reasonable system complexity
Solution Approach 2:
The patent implements parameter changes by making the change characteristic a variable parameter that changes with driving conditions. Instead of using a constant fixed value, the system calculates the change characteristic dynamically based on multiple parameters (steering angle, steering speed, vehicle speed), enabling the steering ratio limitation to adapt to different driving scenarios and prevent wheel movement during acceleration
2Productivity
If a fixed value is used to limit the change in steering ratio, then the control logic is simple, but the performance efficiency is reduced
Solution Approach 1:
The system uses dynamic determination of the change characteristic based on real-time driving conditions, which improves performance efficiency by allowing optimal steering ratio changes for each driving scenario while the control logic remains structured and manageable
Solution Approach 2:
The patent implements feedback mechanisms by continuously monitoring steering angle, steering speed, and vehicle speed to dynamically calculate the change characteristic. This feedback loop enables the system to adjust the steering ratio limitation based on actual driving conditions, improving performance efficiency while maintaining clear control logic
3Ease of operation
If the steering ratio is varied dynamically, then the driving behavior is improved, but the risk of wheel movement during acceleration increases
Solution Approach 1:
The patent applies preliminary anti-action by proactively limiting the change in steering ratio based on predicted wheel movement risks. When acceleration is detected, the system preemptively restricts steering ratio changes to prevent wheel movement, while still allowing dynamic steering ratio variation during normal driving to maintain good driving behavior
Solution Approach 2:
The system changes the change characteristic parameter dynamically based on vehicle acceleration state. During acceleration, the change characteristic is restricted to prevent wheel movement, while during normal driving conditions, the full dynamic steering ratio variation is permitted to maintain good driving behavior
Data Source
AI summary
A steering system is configured as a steer-by-wire steering system and includes an operating unit having at least one steering handle as well as at least one wheel steering angle control element operatively connected to the operating unit for changing a wheel steering angle of at least one vehicle wheel. The variable steering ratio defines an adjustable gear ratio between a steering specification on the steering handle and the wheel steering angle of the vehicle wheel. In a method for assuring a change in the variable steering ratio in the steering system, particularly during operation of the steering system in a vehicle, the change in the variable steering ratio is limited by a dynamically determined change characteristic.