Vehicle Control Unit for Active Steering and Yaw Rate Optimization

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Solution Overview

Problem

Existing vehicle control systems face challenges in simultaneously improving ride comfort and turning performance, as excessive steering angle increases vehicle roll, degrading comfort while emphasizing steering performance.

Innovation Solution

A control unit for vehicles with an active steering system that adjusts steering gear ratio and independently controls driving forces of electric drive wheels to optimize yaw rate and roll, using a steering turning assist controller and left-right driving force controller to manage roll conditions and generate target yaw rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the tire steering angle is excessively increased to improve turning performance, then the steering performance is improved, but the roll of the vehicle increases and ride comfort is degraded

Engineering Contradiction:

Improveturning performanceVSAvoidvehicle roll

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The steering gear ratio is made dynamically adjustable through the active steering system, allowing it to change based on vehicle conditions. This enables the system to optimize the balance between turning performance and ride comfort by adapting the steering ratio in real-time rather than using a fixed ratio

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the steering gear ratio parameter according to vehicle roll conditions. When roll exceeds a predetermined threshold, the ratio is adjusted to reduce the additional tire steering angle, thereby controlling the roll while maintaining acceptable turning performance

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If the steering gear ratio is adjusted to reduce vehicle roll, then ride comfort is improved, but turning performance may be compromised

Engineering Contradiction:

Improvevehicle rollVSAvoidturning performance

Core Design Contradiction:

Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The active steering system acts as an intermediary between the driver's steering input and the actual tire steering angle. It mediates by adjusting the steering gear ratio to achieve a compromise that satisfies both ride comfort requirements and turning performance needs

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system applies partial steering assist by controlling the additional tire steering angle rather than fully transmitting the driver's steering input. This partial action allows roll reduction while maintaining sufficient turning performance

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS10272943B2Control unit for vehicle and control method for vehicle

Publication Date: 2019.04.30 SUBARU CORP

AI summary

A control unit for a vehicle having an active steering system capable of changing a steering gear ratio between a steering angle of a steering wheel and a tire steering angle includes a steering turning assist controller and a left-right driving force controller. The steering turning assist controller controls the steering gear ratio so that a yaw rate generated by the vehicle becomes a target yaw rate to assist a turning of the vehicle. The left-right driving force controller controls, in the left and right electric drive wheels which each add a yaw moment to a vehicle body independently of a steering system and are able to be independently driven, driving forces of the electric drive wheels so that the yaw rate generated by the vehicle becomes the target yaw rate based on a roll of the vehicle.