Steering System Force Feedback With Dual-Phase Torque Switching

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Solution Overview

Problem

Steer-by-wire steering systems lack physical feedback, making it difficult for drivers to assess driving situations and perform appropriate maneuvers, compromising safety and comfort.

Innovation Solution

A method for operating a steering system with a force feedback actuator using dual phase systems, allowing seamless switching between them based on vehicle conditions and parameters to prevent torque jumps and extend component life.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single phase system is used to drive the electric machine in the force feedback actuator, then the device complexity is reduced, but the reliability decreases due to potential torque jumps and component overload

Engineering Contradiction:
Improveoperational reliabilityVSAvoidphase system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The single phase system is segmented into two separate phase systems (first phase system and second phase system), each capable of independently driving the electric machine. This segmentation allows the system to switch between phases, preventing overload and torque jumps while maintaining operational reliability without significantly increasing overall system complexity.

Inventive Principle:
Principle #1Segmentation

2Force

If the electric machine is continuously operated at high torque to provide sufficient force feedback, then the force feedback performance is improved, but the component life decreases due to increased stress

Engineering Contradiction:
Improveforce feedback torqueVSAvoidcomponent service life
Core Design Contradiction:
ForceVSDuration of action of stationary object

Solution Approach 1:

The system implements periodic action by switching between two phase systems in alternating intervals. Each phase system operates at high torque during its active period to provide sufficient force feedback, then rests during the other phase's operation. This periodic alternation maintains the required force feedback performance while reducing cumulative stress on individual components, thereby extending service life.

Inventive Principle:
Principle #19Periodic action

3Strength

If torque limits are imposed on the force feedback actuator to protect components, then the component stress is reduced, but the haptic feedback quality deteriorates due to torque jumps

Engineering Contradiction:
Improvecomponent stress resistanceVSAvoidtorque fluctuations
Core Design Contradiction:
StrengthVSObject-generated harmful factors

Solution Approach 1:

The system applies beforehand cushioning by pre-establishing torque limits and switching mechanisms before torque jumps can occur. The control device monitors torque levels and switches between phase systems proactively when approaching torque thresholds, preventing harmful torque fluctuations before they affect haptic feedback quality. This proactive approach protects components while maintaining smooth force feedback.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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

Ensures smooth and reliable haptic feedback without torque fluctuations, enhancing safety and comfort by reducing component stress and ensuring operational reliability.

Implementation Method 1

an electric machine drivable by at least a first phase system or second phase system

Methodology Applied
Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Data Source

PatentEP4098518B1Method for operating a steering system
Publication Date: 2025.09.10 VOLKSWAGEN AG
  • EP4098518B1 patent drawingFigure 1
  • EP4098518B1 patent drawingFigure 2
  • EP4098518B1 patent drawingFigure 3

AI summary

The invention relates to a method for operating a steering system (1) of a vehicle, with a force feedback actuator (2) which acts on a steering handle (3) to represent reaction forces of at least one steered wheel (4) of the steering system (1) depending on at least one road surface condition, a vehicle speed or a current steering angle of the steered wheel (4), wherein the force feedback actuator (2) comprises an electric machine (7) which can be driven by at least one first phase system (5) and a second phase system (6), wherein switching of the at least first phase system (5) and/or at least second phase system (6) is carried out by means of a control and/or regulating device (8) of the steering system (1).