Steering Control Device Managing Reaction Force Fluctuations
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Solution Overview
Problem
Existing steering control systems, particularly those employing steer-by-wire technology, often cause discomfort to drivers due to fluctuations in steering reaction force characteristics related to self-aligning torque, especially during turns and when handling external disturbances.
Innovation Solution
A steering control device that calculates and offsets the steering reaction force characteristic in the same direction as the self-aligning torque, with increased offset amounts as curvature increases, and suppresses offset changes during hands-off states, using a system that includes a steering unit, turning unit, and a controller that adjusts steering reaction force torque based on vehicle speed and lane position data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the steering reaction force characteristic is adjusted to match self-aligning torque during turns, then steering smoothness is improved, but driver discomfort increases due to excessive steering reaction force
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the steering reaction force characteristic based on curvature. Specifically, the steering reaction force is modified using a curvature-dependent gain factor, where the reaction force characteristic is scaled down during high-curvature turns to prevent excessive forces that cause driver discomfort, while maintaining smooth steering behavior
Solution Approach 2:
The patent implements dynamics by making the steering reaction force characteristic adaptive rather than fixed. The system continuously monitors curvature and adjusts the reaction force parameter in real-time, transitioning between different reaction force characteristics depending on the turning condition, thereby optimizing both smoothness and comfort across varying operational states
2Stability of the object's composition
If the steering reaction force is changed to maintain consistent characteristic, then steering stability is improved, but the system complexity increases
Solution Approach 1:
The patent employs feedback by continuously measuring the curvature of the road and using this information to adjust the steering reaction force characteristic. The curvature data feeds back to the control system, which then modulates the reaction force to maintain consistent steering characteristics, creating a closed-loop control mechanism that achieves stability through information feedback
Solution Approach 2:
The patent replaces complex mechanical steering systems with an electronic control system that uses sensors and actuators to achieve the same steering function. By substituting mechanical linkages with electronic control, the system maintains steering stability through software-based reaction force adjustment rather than complex mechanical mechanisms
Data Source
AI summary
The present invention comprises: a steering unit 1 that receives steering input from a driver and that is mechanically separated from a turning unit 2 that turns left and a right front wheels 5FL, 5FR; a steering reaction force control unit 20 that sets a steering reaction force characteristic to coordinates, of which the coordinate axes are the self-aligning torque and the steering reaction force, so that the self-aligning torque increases as the steering reaction force increases, and the control unit applies the steering reaction force to the steering unit 1 based on the steering reaction force characteristic; a curvature calculation unit 34a that detects the curvature of a white line; a limiter processing unit 34e that calculates an offset amount that increases as the detected curvature increases and calculates a lateral force offset amount that limits the change amount of the offset amount in a normal limiter 342; a lateral force offset unit 34 that offsets the steering reaction force characteristic at the coordinates in the same coding direction as the self-aligning torque only by the lateral force offset amount; a steering reaction force torque offset unit 36 that applies a steering reaction force that increases as the distance to the white line decreases to the steering unit 1; and a previous value reading unit 346 that suppresses an increase in the lateral force offset amount when a steering torque is opposite of the curve direction of the detected curvature and a determination is made that a hands-off state exists.