Vehicle Steering Control with Speed-Adaptive Road-Surface Torque
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Solution Overview
Problem
Conventional vehicle steering systems struggle to accurately reflect both road surface conditions and vehicle states, such as vehicle speed and steering angle, leading to inconsistent steering feelings.
Innovation Solution
A control device that adjusts steering reaction force based on road surface reaction force torque estimation and vehicle state, using gain ratios to modulate steering torque and motor current compensation values, ensuring the steering feeling reflects road conditions and vehicle states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If road surface reaction force torque estimation is applied to steering reaction force, then steering feeling reflecting road surface conditions is improved, but steering feeling consistency across different vehicle states deteriorates
Solution Approach 1:
The patent applies dynamics by making the gain ratio variable based on vehicle state parameters (vehicle speed and steering angle). The gain ratio dynamically adjusts the contribution of road surface reaction force torque estimation to the steering reaction force, allowing the system to adapt to different driving conditions while maintaining accurate road surface condition reflection.
Solution Approach 2:
The patent changes the parameter of gain ratio based on vehicle speed and steering angle to resolve the contradiction. By adjusting this parameter, the system can emphasize road surface condition reflection when appropriate while maintaining overall steering feeling consistency across different vehicle states.
2Measurement precision
If steering reaction force is increased to reflect road surface conditions, then driver feedback accuracy is improved, but steering effort required from driver increases
Solution Approach 1:
The patent uses parameter changes by adjusting the gain ratio based on vehicle speed and steering angle. This allows the system to provide accurate driver feedback about road surface conditions while modulating the overall steering effort to remain appropriate for different driving scenarios, preventing excessive steering effort at high speeds or extreme steering angles.
Data Source
AI summary
A control device of a vehicle steering system capable of obtaining a steering feeling reflecting a situation of a road surface and a state of a vehicle. The control device includes: a current compensation value generation unit configured to generate a reaction force motor current compensation value increasing or decreasing depending on a road surface reaction force torque estimation value estimated based on at least a first turning motor current command value; and a gain ratio generation unit configured to generate a first gain increasing or decreasing depending on a vehicle speed Vs of a vehicle, and a second gain having a sum of the first gain (Ga) and the second gain of 1.