Rear Wheel Steering Control Using Torque and Speed Feedback
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Solution Overview
Problem
Conventional rear wheel steering systems prioritize responsiveness at low speeds and stability at high speeds, failing to effectively prevent collisions with suddenly appearing obstacles by not quickly identifying the driver's avoidance steering intention.
Innovation Solution
An apparatus and method that utilize a steering angle sensor, vehicle speed sensor, and steering torque sensor to calculate a rear wheel angle compensation factor, improving responsiveness by adjusting the target rear wheel angle based on steering torque, steering angle velocity, and vehicle speed, without requiring additional devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the conventional rear wheel steering system prioritizes driving stability at high speeds by steering rear wheels in the same direction as front wheels, then driving stability is improved, but rear wheel steering responsiveness is degraded and collision avoidance capability is reduced
Solution Approach 1:
The patent implements dynamic switching of rear wheel steering control modes based on vehicle operating conditions. The control unit determines whether to apply same-direction steering (for stability at high speeds) or opposite-direction steering (for responsiveness at low speeds or during emergency maneuvers) by evaluating real-time vehicle speed and steering angle rate of change, making the system adaptable rather than fixed
Solution Approach 2:
The patent changes the steering control parameter (steering direction of rear wheels) based on the rate of change of steering angle. When the steering angle changes rapidly (indicating emergency avoidance maneuver), the system switches to opposite-direction rear wheel steering to enhance responsiveness and reduce turning radius, while maintaining same-direction steering during normal operation for stability
2Speed
If the conventional rear wheel steering system prioritizes steering responsiveness at low speeds by steering rear wheels in the opposite direction to front wheels, then rear wheel steering responsiveness is improved, but driving stability is degraded
Solution Approach 1:
The system dynamically adjusts rear wheel steering behavior based on real-time detection of steering angle rate of change. During normal low-speed operation, same-direction steering maintains stability, but during rapid steering inputs (emergency avoidance), the system switches to opposite-direction steering to maximize responsiveness and collision avoidance capability
Solution Approach 2:
The patent changes the steering control parameter (steering direction) based on the rate of change of steering angle. When the steering angle changes rapidly, the system switches to opposite-direction rear wheel steering to enhance responsiveness, while maintaining same-direction steering during normal operation
3Device complexity
If the conventional rear wheel steering system uses fixed control strategies based on vehicle speed, then control simplicity is maintained, but the ability to quickly identify avoidance steering intention and prevent collisions is reduced
Solution Approach 1:
The patent introduces feedback control by continuously monitoring the rate of change of steering angle and using this information to adjust rear wheel steering behavior. The control unit receives real-time steering angle data, calculates its rate of change, and uses this feedback to determine whether emergency avoidance maneuvering is occurring, enabling the system to respond appropriately to driver intent
Solution Approach 2:
The system performs preliminary identification of avoidance steering intention by detecting rapid changes in steering angle before the vehicle trajectory actually changes. This allows the rear wheel steering system to be pre-positioned for optimal collision avoidance performance before the emergency maneuver is fully executed
Data Source
AI summary
An apparatus for controlling rear wheel steering includes a steering angle sensor detecting a steering angle of a steering wheel; a vehicle speed sensor detecting a vehicle speed of a vehicle; a steering torque sensor detecting a steering torque applied to a steering shaft; and a control unit calculating a front wheel angle and a steering angle velocity from the steering angle detected by the steering angle sensor, calculating a rear wheel angle compensation factor for improving rear wheel steering responsiveness based on at least one of the steering torque detected by the steering torque sensor and the calculated steering angle velocity and a same/opposite phase gain depending on the vehicle speed detected by the vehicle speed sensor, and calculating a target rear wheel angle based on the front wheel angle, the rear wheel angle compensation factor and the same/opposite phase gain.