SBW Steering Torque Control Using a Torsion Bar Feedback Unit

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Solution Overview

Problem

Conventional SBW systems require multiple motors, electronic control devices, and steering angle sensors, leading to increased material costs and structural complexity due to the need for mechanical connections and feedback mechanisms.

Innovation Solution

A steering control apparatus that utilizes a torsion bar and torsion sensor to detect steering torque, determining steering angles and motor torques based on vehicle speed, simplifying the system by removing redundant components and relying on the rigidity of the torsion bar for torque generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple motors, electronic control devices, and steering angle sensors are used to implement conventional SFA system, then steering feedback and redundancy are improved, but material cost and device complexity increase

Engineering Contradiction:

Improvesteering feedback reliabilityVSAvoidsystem component quantity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the steering feedback actuator and road-wheel steering actuator into a single integrated system. The steering feedback unit (including torsion bar and torsion sensor) is merged with the road-wheel steering unit, eliminating the need for separate motors and sensors in each actuator. This integration maintains steering feedback reliability while significantly reducing the quantity of components required in the system.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The steering feedback unit serves multiple functions: it detects steering torque through the torsion sensor, provides structural support through the torsion bar, and transmits steering commands to the road-wheel steering unit. This multi-functionality reduces the need for dedicated components for each function, thereby reducing overall system complexity while maintaining reliability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If multiple motors and steering angle sensors are installed to satisfy system redundancy, then steering control reliability is improved, but material cost increases

Engineering Contradiction:

Improvesystem redundancyVSAvoidmaterial cost

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

By merging the steering feedback and road-wheel steering functions into a single integrated unit, the system achieves redundancy through functional integration rather than through multiple separate components. The torsion bar and torsion sensor work together as a unified feedback mechanism that provides reliable steering control without requiring duplicate hardware, thereby reducing material costs while maintaining system redundancy.

Inventive Principle:

Principle #5Merging (Combining)

3Device complexity

If mechanical connection devices such as steering column and pinion shaft are removed, then system simplicity is improved, but steering feedback generation becomes difficult

Engineering Contradiction:

Improvemechanical connection structureVSAvoidsteering feedback generation

Core Design Contradiction:

Device complexityVSEase of manufacture

Solution Approach 1:

The patent replaces traditional mechanical connection devices (steering column, pinion shaft) with an electronic control system. The torsion bar and torsion sensor detect steering torque electronically, and the control unit processes this information to generate steering feedback. This substitution eliminates complex mechanical connections while providing a reliable method for generating steering feedback through electronic sensing and control.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Improves steering feel and secures hand-covered stability while reducing material costs and structural complexity by eliminating unnecessary motors and sensors, enhancing the overall efficiency and cost-effectiveness of the SBW system.

Implementation Method 1

a torsion bar connected to the steering wheel, and configured to measure a torsion displacement

Methodology Applied

Scientific EffectTorsion: Torsion Spring

Implementation Method 2

a torsion sensor including the torsion bar inserted therein, and configured to output the steering torque as corresponding to the torsion displacement

Methodology Applied

Scientific EffectTorsion sensing:

Implementation Method 3

the motor is connected to the steering wheel and configured to generate a force in an opposite direction to the rotation of the steering wheel

Methodology Applied

Scientific EffectElectromagnetic force: Lorentz Force

Data Source

PatentUS12485961B2Steering control apparatus of SBW system

Publication Date: 2025.12.02 HYUNDAI MOTOR CO LTD

AI summary

A steering feedback unit detects a steering torque generated according to an operation of a steering wheel, a road-wheel steering unit connected to the steering feedback unit to allow a steering of a wheel to be performed according to a steering angle or the steering torque transmitted from the steering feedback unit, and a control unit determines the steering torque detected in the steering feedback unit as a steering angle selectively according to a preset standard vehicle speed and standard steering speed to transmit the determined steering angle to the road-wheel steering unit, and controls the steering of the wheel according to the steering angle to be performed, or transmits the steering torque detected in the steering feedback unit to the road-wheel steering unit and control the amount of motor torque for the steering of the wheel to be determined.