Steering Apparatus Reaction Force Compensation
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Solution Overview
Problem
Steer-by-wire vehicles face challenges in maintaining an appropriate sense of steering due to inconsistent or decreased steering reaction forces, which can lead to a feeling of strangeness or loss of steering effort as the steering angle increases, unlike traditional vehicles with rack and pinion systems.
Innovation Solution
A steering apparatus with a first reaction force member applying a force opposite to the shaft rotation and a second reaction force member that can adjust and apply a force in the opposite direction when the first reaction force decreases, using a motor and controller to detect and respond to changes in steering angle and angular velocity to maintain a consistent steering experience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single reaction force member is used in a steer-by-wire system, then the structure is simple, but the steering reaction force becomes inconsistent and decreases at large steering angles
Solution Approach 1:
The reaction force application mechanism is divided into two independent parts: a first reaction force member (friction member) that provides initial reaction force, and a second reaction force member (motor) that provides additional reaction force. This segmentation allows each component to contribute differently to the overall steering feel, ensuring consistent reaction force across all steering angles while maintaining manageable structural complexity
Solution Approach 2:
The patent combines two different reaction force generation mechanisms (friction-based and motor-based) into a unified steering reaction force system. The first and second reaction force members work together synergistically, with the motor supplementing the friction member's output at large steering angles, achieving reliable and consistent steering feedback throughout the entire steering range
2Device complexity
If steering reaction force is not adjusted at large steering angles, then the control system is simple, but the driver experiences loss of steering effort and rotation loss
Solution Approach 1:
The control unit continuously monitors the steering angle and dynamically adjusts the reaction force output from the second reaction force member (motor) based on real-time steering conditions. This feedback mechanism ensures that the steering reaction force remains appropriate and proportional across all steering angles, preventing rotation loss and maintaining natural steering effort without requiring complex manual adjustments
Solution Approach 2:
The reaction force characteristics are made dynamic rather than static. The control unit varies the motor's reaction force output according to the steering angle, providing higher reaction force at large steering angles where the friction member alone becomes insufficient. This dynamic adjustment maintains consistent steering effort and prevents the driver from experiencing rotation loss or unnatural steering feel
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The apparatus ensures a consistent and appropriate sense of steering effort by adjusting the second reaction force to compensate for decreases in the first reaction force, preventing the feeling of light steering effort and rotation loss, thus mimicking the proportional steering experience of traditional vehicles.
Implementation Method 1
a motor that applies an electromagnetic force that serves as a second reaction force in a direction opposite to a direction of rotation of the shaft
Data Source
AI summary
A steering apparatus for use in a vehicle equipped with a steer-by-wire system includes a shaft, a first reaction force member, and a second reaction force member. The shaft is configured to be able to rotate with rotation of a steering wheel disposed in a vehicle compartment. The first reaction force member is configured to apply a first reaction force in a direction opposite to a direction of the rotation of the shaft. The second reaction force member is configured to be able to apply and stop applying a second reaction force to the shaft. The second reaction force is different from the first reaction force and applied in a direction opposite to the direction of the rotation of the shaft. The second reaction force member applies the second reaction force when there is a decrease in the first reaction force.