Rear Wheel Steering Angle Control for Vehicle Side Slip Minimization
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Solution Overview
Problem
The existing rear wheel steering system for vehicles uses an open-loop control scheme that fails to stably control vehicle posture, leading to sluggish and unstable vehicle movement due to its reliance on a simple gear ratio between front and rear wheels, which is not adaptive to different driving modes.
Innovation Solution
A method for side slip angle variable control that determines distinct steering angle ratios for front and rear wheels based on autonomous driving and manual driving modes, adjusting the rear-wheel steering angle to minimize side slip angle and reduce driving mode differences by applying different steering angle ratios depending on the driving mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple gear ratio control scheme is used for rear wheel steering, then the device complexity is reduced, but the vehicle posture stability deteriorates
Solution Approach 1:
The patent implements dynamic control of rear wheel steering angle based on real-time detection of side slip angle and vehicle velocity. The control ratio between front and rear wheel steering angles is dynamically adjusted according to driving conditions (autonomous vs. manual mode) and velocity ranges, transforming the static gear ratio scheme into a dynamic adaptive control system that maintains vehicle posture stability across varying operating conditions.
2Ease of operation
If a fixed gear ratio is used for front and rear wheel steering, then the ease of operation is improved, but the adaptability to different driving modes deteriorates
Solution Approach 1:
The patent segments the steering control into distinct modes (autonomous driving mode and manual driving mode) with different control strategies. In autonomous mode, the system applies a first steering angle ratio optimized for minimizing side slip angle. In manual mode, it applies a second steering angle ratio that provides different steering characteristics. This segmentation allows the system to optimize performance for each specific driving mode while maintaining operational simplicity through automated mode-based control selection.
3Device complexity
If open loop control is used for rear wheel steering, then the device complexity is reduced, but the manufacturing precision of vehicle posture control deteriorates
Solution Approach 1:
The patent introduces feedback control by continuously detecting the side slip angle and vehicle velocity, then using this information to adjust the rear wheel steering angle in real-time. The control system calculates the optimal rear wheel steering angle based on the detected side slip angle and selected steering angle ratio, creating a closed-loop control system that precisely controls vehicle posture. This feedback mechanism enables accurate posture control while maintaining relatively simple system architecture.
Data Source
AI summary
A method for side slip angle variable control of a vehicle having a rear wheel steering system, may include a first step of determining a first steering angle ratio value which corresponds to a steering angle ratio of a front wheel and a rear wheel in a driver driving mode and determining a second steering angle ratio value which corresponds to the steering angle ratio of the front wheel and the rear wheel in an autonomous driving mode; a second step of determining a rear-wheel steering angle through determination by the second steering angle ratio value and comparing the rear-wheel steering angle with a predetermined maximum steering angle of a rear wheel steering (RWS); and a third step of determining any one driving mode of the driver driving mode and the autonomous driving mode when the rear-wheel steering angle is determined to be smaller than the RWS maximum steering angle.