Steer-by-Wire Handwheel Resynchronization Module

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Solution Overview

Problem

Steer by wire (SbW) systems face synchronization challenges between the handwheel and roadwheel, leading to uncomfortable jolts and self-steering issues due to the lack of mechanical connection, causing desynchronization when the vehicle is switched off or during autonomous driving.

Innovation Solution

A resynchronization module dynamically adjusts the handwheel position to calculate the rack position reference, using a desynchronization amount based on the difference between actual and synchronized handwheel positions, vehicle speed, and handwheel speed, ensuring continuous adjustment until synchronization is achieved, preventing sudden jolts and self-steering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the handwheel and roadwheel are mechanically disconnected in an SbW system, then the system achieves electronic control flexibility and safety, but synchronization errors occur leading to uncomfortable jolts and self-steering issues

Engineering Contradiction:

Improveelectronic control flexibilityVSAvoidsynchronization accuracy

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the actual handwheel position is continuously monitored and compared with the expected position derived from roadwheel position. The desynchronization amount is calculated as the difference between these positions, and this feedback is used to dynamically adjust the rack position reference, ensuring continuous correction of synchronization errors without mechanical connection.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces the mechanical connection between handwheel and roadwheel with an electronic control system using CAN interface communication. The mechanical linkage is substituted with digital signal transmission and software-based position reference calculation, allowing flexible electronic control while maintaining steering functionality through computational methods rather than physical connection.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If the rack position reference is directly calculated from handwheel position without dynamic adjustment, then the calculation is simple, but desynchronization causes uncomfortable jolts during steering

Engineering Contradiction:

Improvecalculation simplicityVSAvoiduncomfortable jolts

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent transforms the static rack position reference calculation into a dynamic adjustment process. Instead of using a fixed calculation method, the system continuously adjusts the rack position reference based on the desynchronization amount, vehicle speed, and handwheel speed. This dynamic approach adapts to changing steering conditions, preventing uncomfortable jolts while maintaining computational efficiency through iterative refinement.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent performs preliminary adjustment of the rack position reference by computing the desynchronization amount before executing the final position command. The system proactively calculates the correction needed based on current synchronization status and applies this correction in advance, preventing synchronization errors from manifesting as uncomfortable jolts during actual steering operations.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If the handwheel position is adjusted dynamically using desynchronization amount, vehicle speed, and handwheel speed, then synchronization accuracy is improved, but the computational complexity increases

Engineering Contradiction:

Improvesynchronization accuracyVSAvoidcomputational complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies partial adjustment by focusing computational resources on the most critical synchronization parameters. Instead of recalculating all steering parameters, the system specifically adjusts the rack position reference using only the necessary components: desynchronization amount, vehicle speed, and handwheel speed. This selective approach achieves effective synchronization while minimizing unnecessary computational complexity.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS11414122B2Handwheel-roadwheel resynchronization in steer-by-wire systems

Publication Date: 2022.08.16 STEERING SOLUTIONS IP HOLDING CORP

AI summary

According to one or more embodiments, a steer by wire steering system includes a handwheel actuator, a roadwheel actuator, and a resynchronization module to dynamically adjust handwheel position that is used for rack position reference calculation. The dynamic adjustment includes determining a desynchronization amount based on a difference in an actual handwheel position and a synchronized handwheel position. The dynamic adjustment further includes computing a handwheel adjustment using the desynchronization amount, a vehicle speed, and a handwheel speed. The dynamic adjustment further includes computing an adjusted handwheel position based on the handwheel adjustment and the actual handwheel position. The dynamic adjustment further includes updating the reference rack position based on the adjusted handwheel position. The dynamic adjustment is continuously repeated until the handwheel adjustment is substantially equal to zero.