Rear-Wheel Steering Neutral Control for Sharp Steering Stability
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Solution Overview
Problem
Rear-wheel steering systems experience instability due to sudden changes in control methods during abrupt direction changes, particularly during transitions between reverse-phase and in-phase control, affecting vehicle responsiveness and safety.
Innovation Solution
A control apparatus and method that utilizes sensors to detect vehicle status, calculates a target understeer ratio based on side-slip angle and speed, and adjusts control modes (reverse-phase, in-phase, or neutral) to enhance stability and safety by switching to neutral control in sharp steering situations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If reverse-phase control is used to reduce turning radius, then maneuverability is improved, but vehicle stability deteriorates during abrupt direction changes
Solution Approach 1:
The control system dynamically switches between reverse-phase control and neutral control based on driving conditions. Reverse-phase control is applied during normal maneuvering to reduce turning radius, while neutral control is activated during abrupt direction changes to maintain stability. This dynamic adaptation resolves the contradiction by adjusting the control mode according to the specific driving situation.
Solution Approach 2:
The system changes the control parameter (control mode) from reverse-phase to neutral based on detected steering angle rate and vehicle speed. When the absolute value of the steering angle rate exceeds a threshold during reverse-phase control, the system transitions to neutral control, effectively changing the operational parameters to maintain both maneuverability and stability.
2Speed
If control mode transitions are implemented to improve responsiveness, then vehicle responsiveness is enhanced, but control stability worsens due to sudden switches between reverse-phase and in-phase control
Solution Approach 1:
The system preemptively switches to neutral control when detecting conditions that may lead to instability (high steering angle rate during reverse-phase control). This preliminary anti-action prevents the instability from occurring in the first place, rather than reacting after the problem arises, thus maintaining both responsiveness and control stability.
Solution Approach 2:
The control system continuously monitors steering angle rate and vehicle speed to determine when to switch between control modes. This feedback mechanism ensures that control mode transitions occur only when necessary, improving responsiveness while avoiding unnecessary switches that would degrade control stability.
Data Source
AI summary
The present disclosure relates to a control apparatus and method of a rear-wheel steering system. The control apparatus of a rear-wheel steering system includes: a plurality of sensors configured to detect information on a vehicle status; and a processor configured to: check the vehicle status in response to signals input from the plurality of sensors and determine a control mode for a rear-wheel steering (RWS) system as one of reverse-phase control, in-phase control, and neutral control; and, in the event of a sharp steering situation, change the control mode for the RWS system and perform control. The control apparatus and method of a rear-wheel steering system may improve responsiveness through reverse-phase control in the RWS system and enhance safety by performing neutral control in a sharp steering situation, thereby enhancing steering performance of the RWS system.