Steer-By-Wire Rack Position Correction for Driver Comfort

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Solution Overview

Problem

Steer-by-wire steering systems experience rapid wheel movement in response to quick steering operations, causing driver discomfort.

Innovation Solution

A steering system with a controller that corrects the target position of the rack based on steering angular velocity and acceleration to delay wheel movement, incorporating a target position correction control mechanism.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the steering member and steering mechanism are mechanically connected via a shaft, then the structure is simple and reliable, but the rack movement is delayed relative to the steering operation due to shaft twisting

Engineering Contradiction:

Improvemechanical connection reliabilityVSAvoidrack movement delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces the mechanical shaft connection with an electric signal transmission system. The steering member is mechanically separated from the steering mechanism, and torque is transmitted via electric signals from the steering actuator, eliminating the shaft twisting delay while maintaining control reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Loss of time

If the steering system uses electric signal transmission (steer-by-wire), then the rack movement responsiveness is improved, but rapid wheel steering occurs immediately after quick steering operations causing driver discomfort

Engineering Contradiction:

Improverack movement responsivenessVSAvoiddriver discomfort from rapid wheel steering

Core Design Contradiction:

Loss of timeVSObject-affected harmful factors

Solution Approach 1:

The controller executes preliminary action by detecting quick steering operations through steering angle sensors and rack position sensors, then proactively controlling the steering actuator to delay rack movement before the driver experiences discomfort from rapid wheel steering.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from steering angle sensors and rack position sensors to continuously monitor the steering operation and rack position. The controller adjusts the steering actuator based on this feedback, delaying rack movement when quick steering operations are detected to prevent driver discomfort.

Inventive Principle:

Principle #23Feedback

3Object-affected harmful factors

If the rack movement is delayed to prevent driver discomfort, then the harmful effect of rapid wheel steering is reduced, but the steering responsiveness is degraded

Engineering Contradiction:

Improvedriver discomfort suppressionVSAvoidsteering responsiveness

Core Design Contradiction:

Object-affected harmful factorsVSSpeed

Solution Approach 1:

The system dynamically adjusts the rack movement delay based on the steering operation conditions. The controller determines whether to apply delay based on detected steering angular velocity and acceleration, allowing normal responsiveness during steady steering while suppressing rapid movements only when necessary to prevent driver discomfort.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12552450B2Steering system for vehicle

Publication Date: 2026.02.17 HONDA MOTOR CO LTD

AI summary

The steering system for the vehicle includes: a steering mechanism mechanically separated from a steering member and configured to steer wheels by moving a rack; a steering actuator configured to apply a driving force to the steering mechanism; and a controller configured to calculate a target position of the rack and to control the steering actuator such that a position of the rack matches the target position thereof. The controller is configured to execute target position correction control in which the controller corrects the target position of the rack according to a steering angular velocity and/or a steering angular acceleration of the steering member.