Four-Wheel Steering Feedback Control for Straight-Line Stability
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Solution Overview
Problem
Existing controllers for four-wheel independently steering vehicles face challenges in maintaining stability during straight traveling while avoiding vehicle deflection and overshoot during sudden steering due to independent wheel control, which conventional technologies cannot effectively address.
Innovation Solution
A turning control device with a controller that performs feedback control on four-wheel independently steering vehicles, adjusting responsiveness based on vehicle state to minimize turning angle deviation during straight travel and prevent instability during sudden maneuvers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feedback control responsiveness is increased to reduce turning angle deviation, then steering accuracy is improved, but vehicle deflection and overshoot occur during sudden steering
Solution Approach 1:
The patent applies dynamics by making the feedback control responsiveness adjustable rather than fixed. The controller dynamically changes the responsiveness based on vehicle state detection - using high responsiveness for steering accuracy during normal operation, and switching to low responsiveness to prevent deflection and overshoot during sudden steering maneuvers. This resolves the contradiction by allowing the system to adapt its control characteristics to different operational conditions.
Solution Approach 2:
The patent implements parameter changes by modifying the feedback control responsiveness parameter according to vehicle state. The controller detects whether the vehicle is in a normal state or sudden steering state, and accordingly adjusts the responsiveness parameter - maintaining high responsiveness for accurate steering control during normal travel, and reducing responsiveness to prevent vehicle deflection and overshoot during sudden steering events.
2Stability of the object's composition
If feedback control responsiveness is decreased to prevent vehicle deflection, then vehicle stability is improved, but steering accuracy deteriorates
Solution Approach 1:
The system uses dynamic adjustment of feedback control responsiveness to resolve this contradiction. During normal vehicle operation, high responsiveness is maintained for accurate steering control. When sudden steering is detected, the controller dynamically switches to low responsiveness to prevent vehicle deflection and maintain stability, thus achieving both high steering accuracy and vehicle stability under different conditions.
Solution Approach 2:
The controller changes the responsiveness parameter based on detected vehicle state. In normal operating conditions, the parameter is set to provide high steering accuracy. When sudden steering maneuvers are detected, the parameter is adjusted to prioritize vehicle stability and prevent deflection, thereby resolving the contradiction between steering precision and vehicle stability.
3Adaptability or versatility
If independent wheel control is implemented for four-wheel steering, then steering versatility is improved, but control complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the control system into separate independent control units for each wheel. Each wheel has its own steering actuator and control logic, allowing independent control of all four wheels. This segmentation enables versatile steering modes (front-wheel steering, rear-wheel steering, four-wheel independent steering) while managing complexity through modular architecture where each wheel's control can be handled independently by the controller.
Data Source
AI summary
A turning control device is for a vehicle having four wheels that are mechanically separated and steered independently. The four wheels are left and right wheels of a front row and a rear row. The turning control device controls four steering actuators corresponding to the four wheels. The turning control device includes a controller that performs feedback control of the four steering actuators to reduce a deviation for each of the four wheels. The deviation is a difference between a state parameter convertible into a turning angle and a target value of the state parameter set according to steering of a steering wheel. The controller executes a responsiveness changing process of changing a responsiveness of the feedback control so that the deviation is likely to be smaller in a vehicle straight traveling state than in a vehicle non-straight traveling state.