Four-Wheel Steering Rate Control for Synchronized Wheel Motion
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Solution Overview
Problem
Existing four-wheel steering systems face issues with wheels following commanded steering angles differently, leading to abnormal driving, wheel drag, and vibrations, which impair driving stability.
Innovation Solution
A four-wheel steering control device and method that independently controls the steering of each wheel by calculating and applying differential turning control rates to ensure synchronized wheel movements, using a commanded steering angle acquiring part, a four-wheel turning control rate calculating part, and a control part to manage residual angles and turning control rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If wheels directly follow commanded steering angles, then steering responsiveness is improved, but driving stability deteriorates due to wheel drag and vibrations
Solution Approach 1:
The patent implements dynamic control of wheel steering angles by calculating individual turning control rates for each wheel based on residual angles. The control rates are adjusted in real-time to synchronize wheel movements, transforming the static direct-following approach into a dynamic coordinated control system that maintains both responsiveness and stability
Solution Approach 2:
The patent changes the control parameter from direct commanded steering angles to turning control rates. By calculating residual angles (difference between commanded and current angles) and converting them to turning control rates through mapping information, the system optimizes the steering parameter to achieve synchronized wheel movement and eliminate vibrations
2Adaptability or versatility
If four wheels are independently controlled without mechanical connection, then steering flexibility is improved, but control complexity increases
Solution Approach 1:
The patent creates a universal control algorithm that handles all four wheels through a unified process: acquiring commanded angles, calculating residual angles, mapping to turning control rates, and executing control. This multi-functional approach manages the complexity of independent wheel control through a single versatile control framework
Solution Approach 2:
The patent applies local quality control by individually calculating turning control rates for each wheel based on its specific residual angle, while maintaining overall system coordination. Each wheel receives customized control parameters tailored to its current state, enabling flexible independent control within a unified system
3Measurement precision
If wheels have different residual angles, then individual wheel positioning accuracy is improved, but synchronized movement deteriorates
Solution Approach 1:
The patent implements feedback control by continuously calculating residual angles (the difference between commanded and current wheel angles) and using these residuals to determine turning control rates. This closed-loop feedback mechanism ensures that wheels with different residual angles are guided to synchronize their movement, maintaining both positioning accuracy and coordinated motion
Solution Approach 2:
The patent creates equipotential conditions for wheel synchronization by calculating turning control rates that equalize the time required for each wheel to reach its commanded angle. Through the mapping relationship between residual angles and turning control rates, the system balances the steering process across all wheels, eliminating asynchronous movement while preserving individual positioning precision
Data Source
AI summary
A four-wheel steering control device for independently controlling steering of each of first to fourth wheels disposed in a vehicle. A commanded steering angle acquiring part acquires first to fourth commanded steering angles for first to fourth wheels of a vehicle. A four-wheel turning control rate calculating part determines first to fourth residual angles, by which the first to fourth wheels realize the first to fourth commanded steering angles, from current steering angles and calculate first to fourth turning control rates of the first to fourth wheels on basis of the first to fourth residual angles determined. A control part independently controls steering of each of the first to fourth wheels using the first to fourth turning control rates calculated.