Variable-Gear Steering Column Speed-Dependent Control
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Solution Overview
Problem
Existing power steering systems with variable-gear steering columns do not provide a "natural" variation of the gear ratio to the driver, leading to discomfort and potential safety issues due to abrupt changes.
Innovation Solution
A method for fine-tuning the gear ratio of a power steering system based on vehicle speed, using the equation G=(p2+p1/V)n, where n=1 or -1, to define a relationship between the gear ratio and vehicle speed, ensuring a natural and comfortable driving experience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a variable gear ratio is implemented to improve handling at low speed and stability at high speed, then vehicle dynamics performance is improved, but driver comfort deteriorates due to unnatural and abrupt gear ratio variations
Solution Approach 1:
The patent applies parameter changes by modifying the gear ratio according to a specific mathematical function of vehicle speed (G=(p2+p1/V)^n). This transforms the gear ratio from a fixed or linearly variable parameter to one that changes non-linearly with speed, creating a more natural perception for the driver while maintaining the benefits of variable gearing for handling and stability.
Solution Approach 2:
The patent implements dynamics by making the gear ratio dynamically adjustable based on vehicle speed through the equation G=(p2+p1/V)^n. The system transitions from a static gear ratio to a dynamic one that automatically adapts to driving conditions, improving both vehicle performance and driver comfort through smooth, predictable variations.
2Adaptability or versatility
If a variable gear ratio system is used to provide adaptive steering, then steering performance is improved, but system complexity increases
Solution Approach 1:
The patent reduces system complexity by changing the approach from complex multi-parameter control to a simple mathematical relationship (G=(p2+p1/V)^n) with only two parameters (p1, p2) to identify. This parameter change strategy simplifies the control system while maintaining steering adaptability across different vehicle speeds.
3Speed
If conventional variable gear ratio adjustment is implemented, then steering response is improved, but driver adaptation time increases due to unnatural variation
Solution Approach 1:
The patent eliminates driver adaptation time by changing the gear ratio variation pattern to follow the function G=(p2+p1/V)^n. This parameter change creates a natural, predictable relationship between speed and gear ratio that drivers intuitively understand, allowing immediate acceptance without adaptation period while maintaining fast steering response.
Data Source
AI summary
A method for fine-tuning a variable-gear steering column according to a speed of the vehicle, the method includes: a step of characterizing a desired handling of the vehicle for a speed V1 and of characterizing a desired stability for a speed V2; a step of determining a value G1 of the gear ratio allowing obtaining the desired handling at the speed V1, and a value G2 of the gear ratio allowing obtaining the desired stability at the speed V2, a step of calculating a parameter p1 and a parameter p2 according to the speed V1, the speed V2, the value G1 and the value G2 so that the relationship between the gear ratio and the speed of the vehicle is defined by the equation G=p2+p1/V, when the speed is included between a first threshold and a second threshold.