Steering Reaction Force Control for Vehicle Stability
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Solution Overview
Problem
Existing stability control systems in vehicles cause discomfort to drivers by applying steering reaction forces that promote turning for disturbance suppression, leading to fluctuations in steering reaction force and discomfort during disturbances like crosswinds.
Innovation Solution
A stability control device that controls the turning amount of the turning unit based on a steer-by-wire turning amount and suppression turning amount, and adjusts the steering reaction force applied to the steering unit, increasing the suppression turning amount as the vehicle approaches a white line, thereby reducing the need for a steering reaction force component that promotes turning and minimizing steering reaction force fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a steering reaction force component that promotes turning for disturbance suppression is applied to the steering wheel, then the disturbance suppression effect is improved, but the driver experiences discomfort due to steering reaction force fluctuations
Solution Approach 1:
The patent segments the steering reaction force control into two independent parts: one that follows the steering operation (normal feedback) and another that would promote disturbance suppression. By separating these functions, the system can apply disturbance suppression turning to the wheels without necessarily applying the corresponding reaction force to the steering wheel, thus reducing discomfort while maintaining suppression effectiveness through other means.
Solution Approach 2:
The patent introduces an intermediary control mechanism that decouples the steering reaction force from the disturbance suppression turning amount. Instead of directly coupling the suppression turning with reaction force application to the steering wheel, the system uses an intermediate control layer that can selectively apply suppression effects to the wheels while managing the reaction force separately, thereby reducing the harmful fluctuations in steering reaction force.
2Stability of the object's composition
If the suppression turning amount is increased to improve disturbance suppression, then the vehicle stability is improved, but the steering reaction force fluctuates more causing driver discomfort
Solution Approach 1:
The patent applies local quality by differentiating the treatment of steering reaction force based on its source. Normal steering operations receive full feedback, while disturbance suppression operations receive reduced or modified feedback. This localized differentiation allows the system to maintain vehicle stability through suppression turning while preventing the associated reaction force fluctuations from reaching the driver, thus resolving the contradiction between stability and comfort.
3Adaptability or versatility
If a steer-by-wire system is used to mechanically detach the steering wheel from the turning wheels, then the control flexibility is improved, but the steering reaction force becomes less natural causing driver discomfort
Solution Approach 1:
The patent makes the steering reaction force control system universal by designing it to handle multiple functions: normal steering feedback, disturbance suppression, and comfort optimization. The reaction force control unit can adaptively adjust the feedback characteristics based on the operating mode, providing natural feedback during normal steering while suppressing unnecessary fluctuations during disturbance correction, thus maintaining driver comfort across different operating conditions.
Data Source
AI summary
The turning angle of the left and right front wheels 5L, 5R is controlled based on an SBW command turning angle corresponding to the steering angle of a steering wheel 6 that is mechanically detached from the left and right front wheels 5L, 5R and on a disturbance suppression command turning angle for suppressing the yaw angle that is generated to a vehicle by a disturbance; on the other hand, when controlling the steering reaction force that is applied to the column shaft 7 based on the steering angle of the steering wheel 6, the suppression turning amount is corrected to increase as the lateral position of a host vehicle becomes closer to a white line that intersects with the host vehicle traveling direction.