Steer-By-Wire Steering Angle Control for Stable Dynamic Response
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Solution Overview
Problem
Current motor vehicle steering systems require driver experience and skill to calibrate steering maneuvers for optimal dynamic response, making driving difficult, especially in sport or extreme conditions, and affecting vehicle stability.
Innovation Solution
A steer-by-wire system with a control unit that processes steering signals to adjust wheel angles based on dynamic response targets, using variable gain mappings to achieve desired kinematic relationships between yaw rate, lateral acceleration, and steering angle, enhancing stability and ease of driving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a traditional steering assembly with fixed gain is used, then the steering system is simple and reliable, but the driver must calibrate maneuvers to match vehicle dynamic response, increasing driving difficulty and reducing ease of operation
Solution Approach 1:
The patent implements a dynamic steering system where the gain between steering control member movement and wheel steering angle is no longer fixed but varies based on vehicle operating conditions (speed, lateral acceleration, yaw rate). The control unit continuously adjusts the steering ratio in real-time to optimize the relationship between driver input and vehicle response, making the system adaptive rather than static.
Solution Approach 2:
The system changes the steering gain parameter dynamically based on measured vehicle state parameters. The control unit modifies the steering ratio parameter according to speed, lateral acceleration, and yaw rate measurements, allowing the steering system to adapt its characteristics to different driving conditions without requiring driver recalibration.
2Speed
If the steering gain is increased to improve vehicle responsiveness, then the dynamic response is enhanced, but the vehicle stability deteriorates during extreme or sport driving conditions
Solution Approach 1:
The system dynamically adjusts the steering gain based on the current operating state. During normal driving, higher gain provides responsive steering, while during extreme conditions detected through sensors (high speed, high lateral acceleration), the gain is reduced to maintain stability. This dynamic adaptation resolves the contradiction between responsiveness and stability.
Solution Approach 2:
The steering gain parameter is changed according to vehicle state parameters. The control unit monitors speed, lateral acceleration, and yaw rate, and adjusts the steering ratio accordingly - increasing it for responsive handling in normal conditions, and decreasing it for stability in extreme conditions, thus optimizing both performance and safety.
3Productivity
If the steering assembly transmits movement with high gain, then the steering response is more responsive, but the driver must acquire experience and knowledge to calibrate maneuvers, increasing driving difficulty
Solution Approach 1:
The steering system performs self-calibration and self-adjustment based on vehicle state sensors. Instead of requiring the driver to learn and adapt to fixed steering characteristics, the system automatically adapts its gain to provide optimal responsiveness for each driving condition, serving itself to eliminate the need for driver calibration experience.
Solution Approach 2:
The system uses feedback from vehicle sensors (speed, lateral acceleration, yaw rate) to continuously adjust the steering gain. This closed-loop control ensures the steering response remains optimized across different conditions without requiring driver intervention or learning, as the system self-corrects based on real-time vehicle state feedback.
Data Source
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AI summary
A process to adjust the steering angle (γ) of a motor vehicle (1) includes providing a target relationship between a first variable and a second variable, defining a region of an algebraic space defined by the first variable and by a third variable, providing a mapping which associates each of pairs of values of the first and third variable in the region with a corresponding desirable value, such that the steering angle (γ) fulfils the target relationship, acquiring current values of the first and third variable, calculating the desirable value by means of the mapping based on the current values if defining one of the pairs of values in the region, determining a steering control signal (S2) as a function of the calculated desirable value, and controlling the actuator device (5) with the steering control signal (S2).