Steer-by-Wire Reaction Torque Control for Realistic Road Feel

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Solution Overview

Problem

Electronic steering systems based on the SBW system struggle to provide real-time reaction forces that accurately mimic road conditions, leading to undesired steering feel and a lack of transfer of tire self-alignment or kickback to the driver.

Innovation Solution

An electronic steering apparatus that includes a reaction torque generator and a reaction torque controller, which tunes road sensitivity by applying a band-pass filter to the rack force based on vehicle speed, setting gains for steering angular velocity and column torque to generate a final reaction torque that reflects road characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If an SBW system is used to eliminate mechanical connections, then vehicle weight is reduced and safety is improved, but road reaction feel cannot be transferred to the steering wheel

Engineering Contradiction:

Improvevehicle weightVSAvoidroad reaction feel transfer

Core Design Contradiction:

Weight of moving objectVSEase of operation

Solution Approach 1:

The patent introduces a reaction force generator as an intermediary device that creates artificial reaction forces to simulate road conditions. This mediator transfers road-like feedback to the driver through the steering wheel, resolving the contradiction by providing the missing sensory connection without mechanical linkages.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces mechanical connection-based force transfer with an electronic control system that generates reaction forces using a motor. This substitution eliminates mechanical connections while maintaining the functional capability of transferring road reaction feel through electronic actuation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If reaction force is generated based on steering angular velocity and vehicle speed, then basic steering control is achieved, but real-time road reaction feel cannot be provided

Engineering Contradiction:

Improvesteering control responseVSAvoidroad reaction feel accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent implements a feedback mechanism where the reaction force generator continuously adjusts the steering wheel torque based on detected steering state and road condition information. This closed-loop feedback enables real-time adaptation to provide accurate road reaction feel while maintaining responsive steering control.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent makes the reaction force generation dynamic by adjusting the magnitude and characteristics of the reaction force based on real-time steering conditions, vehicle speed, and detected road states. This dynamic adjustment allows the system to accurately simulate varying road conditions while maintaining responsive control.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12459564B2Electronic steering apparatus of vehicle and control method thereof

Publication Date: 2025.11.04 HYUNDAI MOBIS CO LTD

AI summary

An electronic steering apparatus of a vehicle may include a reaction torque generator configured to generate command reaction torque based on a steering condition, and a reaction torque controller configured to receive a rack force and vehicle speed, to tune road sensitivity according to the vehicle speed, to set road sensitive torque by applying a gain according to a reaction sensitivity, to reflect the road sensitive torque into the command reaction torque to generate a final reaction torque, and to output the final reaction torque to a driving motor.