Steer-by-Wire Electromagnetic Actuator Geometry Error Prevention

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Solution Overview

Problem

Conventional steer-by-wire systems face issues such as geometry errors and braking pull biasing problems, which affect the accuracy and responsiveness of steering, particularly during emergency situations, and fail to provide optimal steering conditions across varying vehicle speeds.

Innovation Solution

A steer-by-wire system utilizing an electromagnetic actuator located at the axle beam, which includes a fixed coil unit and a moving part with a permanent magnet, allows for precise control of the steering angle through a controller that calculates and adjusts the steering input based on sensor data from steering angle, torque, and displacement sensors, ensuring accurate and responsive steering without geometric errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a mechanical connection structure through a U-joint and a clutch is implemented to deliver steering force in emergency situations, then steering force can be delivered mechanically, but the advantageous functions of the steer-by-wire system such as responsiveness, variable steering gear ratio, and accurate steering do not work properly

Engineering Contradiction:

Improvesteering force delivery in emergencyVSAvoidsteering responsiveness and accuracy

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent replaces the conventional mechanical U-joint and clutch connection with an electromagnetic actuator system. The electromagnetic actuator receives steering input signals from the steering wheel sensor and directly actuates the wheel to achieve steering, eliminating the need for mechanical power transmission components while maintaining emergency steering capability through direct electromagnetic force application.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements variable steering gear ratio control by changing the electromagnetic actuator's output parameters based on vehicle speed and steering conditions. The ECU dynamically adjusts the steering ratio by modifying the electromagnetic actuator's response characteristics, enabling optimal steering performance across different driving conditions without mechanical gear changes.

Inventive Principle:

Principle #35Parameter changes

2Force

If a spring receives a load to be pressed during braking, then braking force is applied, but a geometry error occurs causing braking pull biasing

Engineering Contradiction:

Improvebraking forceVSAvoidsteering geometry accuracy

Core Design Contradiction:

ForceVSManufacturing precision

Solution Approach 1:

The patent introduces an electromagnetic actuator as an intermediary between the steering input and wheel actuation. This intermediary system decouples the steering control from the braking force transmission path, preventing the transfer of braking-induced geometric errors to the steering system while maintaining independent and accurate steering control during braking operations.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical spring-based force transmission system with an electromagnetic actuator system. This substitution eliminates the mechanical coupling that causes geometry errors during braking, as the electromagnetic actuator directly converts electrical signals to mechanical motion without relying on spring-loaded mechanical linkages that are sensitive to geometric changes.

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

The system effectively prevents geometry errors and braking biasing, providing accurate and responsive steering by using electromagnetic actuation to control the steering angle, ensuring optimal steering performance and safety across different driving conditions.

Implementation Method 1

Methodology Applied

Scientific EffectElectromagnetic force: Lorentz Force

Data Source

PatentUS11713069B2Steer-by-wire system

Publication Date: 2023.08.01 HYUNDAI MOTOR CO LTD

AI summary

A steer-by-wire system includes: a steering wheel to generate a steering input, a sensor part to measure the steering input of the steering wheel, a controller to calculate a steering angle of a wheel based on the steering input measured by the sensor part, an actuator assembly located at an axle beam and configured to provide a steering driving force to the wheel, and a tie rod engaged with the actuator assembly and configured to vary the steering angle of the wheel.