Electric Steering Feedback Control Using Torque-Angle Lash Detection
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Solution Overview
Problem
Modern vehicles lack the ability to detect steering lash, which can lead to unpredictable steering behavior and compromised safety due to mechanical wear, affecting driver control and steering feel.
Innovation Solution
A computer system estimates steering lash level by determining the relationship between motor angle and torque, and adjusts motor torque to provide consistent steering feedback independent of lash, using electric motors and sensors to enhance steering feel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If hydraulic power-assisted steering systems are used to reduce driver effort, then steering assistance is improved, but the system becomes difficult to tune to provide desired assistance at different vehicle speeds while maintaining satisfactory steering feel
Solution Approach 1:
The system dynamically adjusts steering assistance by monitoring vehicle speed and modifying motor torque output accordingly. The control system varies the level of power assistance based on real-time speed conditions, providing high assistance at low speeds for ease of steering and reduced assistance at high speeds to maintain steering feel and stability.
Solution Approach 2:
The system changes operational parameters by adjusting motor torque based on vehicle speed. The control algorithm modifies torque delivery characteristics dynamically, altering the assistance level as a function of speed to simultaneously achieve easy steering at low speeds and maintained steering feel at high speeds.
2Adaptability or versatility
If electric motors are used to provide steering assistance, then adaptability to different conditions is improved, but the system lacks the ability to detect steering lash and provide countermeasures
Solution Approach 1:
The system implements feedback by continuously monitoring the relationship between motor angle and motor torque. By analyzing this relationship, the control system detects signs of steering lash (abnormal torque-angle correlations) and automatically adjusts motor torque to compensate, providing countermeasures that maintain reliable steering control despite lash conditions.
Solution Approach 2:
The system replaces mechanical lash detection mechanisms with electronic sensing and computational analysis. Instead of using mechanical sensors or switches to detect lash, the system uses motor angle and torque data processed through control algorithms to identify and compensate for lash conditions, achieving detection and response without additional mechanical components.
3Duration of action of stationary object
If steering lash is present due to mechanical wear, then steering mechanism operation is maintained, but steering feel becomes unpredictable and driver control is compromised
Solution Approach 1:
The system converts the harmful effect of steering lash into a detectable signal. By monitoring torque-angle relationships, the system identifies lash-induced anomalies and uses this information to adjust motor torque in real-time, transforming the previously harmful unpredictable steering feel into a controlled and predictable driving experience while maintaining mechanism operation.
Data Source
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AI summary
A computer system includes processing circuitry configured to obtain motor angle and estimate motor toque of an electric motor of a steering system of a vehicle in motion, determine a relationship between the estimated motor torque and the obtained motor angle, estimate a steering lash level by comparing the determined relationship to predetermined relationships indicative of lash level, and modify motor torque based on the estimated steering lash level to adjust steering feedback supplied by the electric motor to a steering wheel of the vehicle. Adjustment of steering feedback responsive to the estimated steering lash level permits torque build-up to a driver of a vehicle to be applied independent of steering lash.