Rear-Wheel Steering Control for Faster Yaw Response and Stability
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Solution Overview
Problem
Four-wheel drive vehicles experience steering heterogeneity and delayed handling reactions due to continuous rear wheel steering, leading to a slower steering feel and reduced stability during high-speed turning.
Innovation Solution
An apparatus and method for controlling rear wheel steering that includes a turning state estimator, normal state lateral acceleration predictor, and rear wheel steering angle calculator, which adjust rear wheel steering based on steering angle and torque information to reduce yaw rate-roll delay and generate rapid lateral forces, minimizing control amounts in normal states to enhance stability and unity during turning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If rear wheel steering is continuously performed during driver's steering, then vehicle stability is improved, but handling reaction speed deteriorates and steering heterogeneity occurs
Solution Approach 1:
The system predicts the normal state lateral acceleration in advance based on the steering angle and steering speed before the actual steering action is completed. This predictive approach allows the rear wheel steering angle to be calculated proactively, reducing the delay between driver input and vehicle response while maintaining stability control.
Solution Approach 2:
The rear wheel steering control system dynamically adjusts the rear wheel steering angle based on real-time steering angle and steering speed measurements. The control strategy changes according to the driving state, transitioning between different control modes to optimize both responsiveness and stability across varying operating conditions.
2Stability of the object's composition
If rear wheel steering is continuously performed during driver's steering, then vehicle stability is improved, but steering homogeneity deteriorates
Solution Approach 1:
By predicting the normal state lateral acceleration in advance based on steering angle and steering speed, the system proactively calculates the appropriate rear wheel steering angle. This predictive control reduces the perceptible delay between driver input and vehicle response, creating a more homogeneous and natural steering feel that masks the presence of rear wheel steering intervention.
Solution Approach 2:
The system continuously monitors steering angle and steering speed, using this feedback to dynamically adjust the rear wheel steering angle. This closed-loop control ensures that the rear wheel steering intervention is precisely tailored to the driver's intentions, maintaining steering homogeneity while providing stability enhancement.
3Speed
If delay increases between steering angle and yaw rate, then steering responsiveness deteriorates, but system complexity increases
Solution Approach 1:
The system performs preliminary calculation of the normal state lateral acceleration based on steering angle and steering speed before the actual steering maneuver is complete. This advance calculation allows the rear wheel steering angle to be determined proactively, reducing the perceived delay between steering input and vehicle response without requiring complex real-time intervention systems.
Solution Approach 2:
The patent replaces complex mechanical steering linkages with an electronic control system that uses sensors, processors, and actuators. This substitution allows for flexible, software-based control strategies that can dynamically adjust rear wheel steering angles based on predicted lateral acceleration, achieving rapid responsiveness through electronic rather than mechanical means.
Data Source
AI summary
An apparatus for controlling rear wheel steering is provided. The apparatus includes a turning state estimator that acquires steering angle information from a steering angle sensor and estimates a turning state by calculating a required steering speed from the steering angle information. A normal state lateral acceleration predictor predicts a normal state lateral acceleration to match the required steering speed in response to determining that the required steering speed is equal to or greater than a speed threshold value. A rear wheel steering angle calculator calculates a rear wheel steering angle based on the steering angle and the lateral acceleration.