Steering Control Device Gradual Force Restoration
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Solution Overview
Problem
Existing steering control systems cause discomfort to drivers due to a rapid increase in steering reaction force when the suppression of control amount is released during turn signal operations, leading to an uncomfortable driving experience.
Innovation Solution
A steering control device that sets a steering reaction force characteristic with self-aligning torque and steering reaction force coordinates, offsetting the steering reaction force characteristic as the vehicle approaches a white line, and gradually restoring it when the turn signal is ended, with a limiter processing unit controlling the offset to minimize the increase gradient when releasing suppression, thus reducing the rapid increase in steering reaction force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the suppression of control amount is released at the end of turn signal operation, then the lane maintenance control is restored, but the steering reaction force increases rapidly causing driver discomfort
Solution Approach 1:
The patent applies dynamics by making the steering reaction force characteristic adjustable and time-dependent. During turn signal operation, the system dynamically modifies the steering reaction force characteristic to be less steep, and upon release, gradually restores the original characteristic over a predetermined period rather than instantaneously. This dynamic adjustment ensures smooth transition and prevents sudden changes that would cause driver discomfort.
Solution Approach 2:
The patent implements beforehand cushioning by preparing a modified steering reaction force characteristic with a reduced increase gradient before the turn signal operation ends. The system stores this cushioned characteristic and activates it during the transition period, preventing the rapid increase in steering reaction force that would otherwise occur. This preparatory modification acts as a cushion against the harmful sudden force change.
2Manufacturing precision
If the steering reaction force characteristic is offset more as the vehicle approaches the white line, then lane deviation control is improved, but the steering reaction force increases rapidly when suppression is released
Solution Approach 1:
The patent applies parameter changes by modifying the steering reaction force characteristic parameters based on lateral position relative to the white line. The system adjusts the increase gradient parameter of the steering reaction force characteristic according to the offset amount, which is determined by the lateral position. When the vehicle is close to the white line, the parameter modification is more significant, providing stronger lane deviation control. However, this parameter change is applied gradually over time during turn signal operation to prevent sudden force increases.
Solution Approach 2:
The system dynamically adjusts the steering reaction force characteristic parameters based on both lateral position and time. The offset amount is calculated based on lateral position to improve lane deviation control precision, while the restoration process is dynamically controlled over a predetermined period to prevent rapid force increases. This dual dynamic control reconciles the need for precise lane control with the need to avoid uncomfortable force changes.
Data Source
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AI summary
A steering reaction force characteristic is set to coordinates, of which the coordinate axes are self-aligning torque and steering reaction force, so that the self-aligning torque increases as the steering reaction force increases, and upon applying a steering reaction force corresponding to the self-aligning torque to a steering unit based on the steering reaction force characteristic to offset the steering reaction force characteristic at the coordinates more in a direction in which the absolute value of the steering reaction force increases as the lateral position of a host vehicle becomes closer to a white line, the offset of the steering reaction force characteristic is suppressed when a turn signal operation is started while the suppression of the offset of the steering reaction force characteristic is released when the turn signal operation is ended so that the absolute value of the increase gradient when releasing the suppression of the offset becomes smaller than the absolute value of the decrease gradient when suppressing the offset.