Electric Power Steering Friction Model Control
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Solution Overview
Problem
Conventional electric power steering devices do not effectively enhance the steering feel, which is crucial for driver satisfaction and control.
Innovation Solution
An electric power steering control device that calculates a steering control amount by combining a basic control amount with a friction-originated control amount, using a friction model to account for wheel angle-related values and improve the steering experience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional electric power steering devices control motor current based on vehicle speed or steering angle, then basic steering assistance is provided, but the steering feel is not effectively enhanced
Solution Approach 1:
The control amount is segmented into multiple components: basic control amount (from vehicle speed and steering angle) and friction-originated control amount (from friction model). This segmentation allows each component to address specific aspects of steering feel independently, enhancing overall steering quality without overwhelming system complexity
Solution Approach 2:
A friction model is introduced as an intermediary element that simulates friction characteristics based on wheel angle-related values. This intermediary translates mechanical friction concepts into controllable electrical signals, enabling enhanced steering feel through computational rather than purely mechanical means
2Ease of operation
If friction model is introduced to calculate friction-originated control amount, then steering feel is improved, but calculation complexity increases
Solution Approach 1:
Instead of physically measuring friction forces, the system creates a computational copy of friction behavior through a friction model. This model replicates friction characteristics using wheel angle-related values, avoiding the need for complex physical sensors while achieving the desired steering feel enhancement
Solution Approach 2:
The friction model utilizes wheel angle-related values as input parameters to dynamically calculate friction-originated control amount. By changing the parameter basis from direct friction measurement to wheel angle correlation, the system simplifies detection while maintaining steering feel quality
Data Source
AI summary
Provided is a feature which allows an electric power steering device to improve the steering feel. The electric power steering device includes: a basic control amount calculating section configured to calculate a basic control amount corresponding to steering by a driver; a frictional force calculating section configured to calculate, by using a friction model, a frictional force corresponding to a wheel angle-related value, which is a value relating to a wheel angle of a steering device, and calculate a friction-originated control amount, which originates from the calculated frictional force; and a control amount calculating section configured to calculate a steering control amount in accordance with the basic control amount and the friction-originated control amount.