Vehicle Turning Control via Differential Drive and Braking Force

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Solution Overview

Problem

Conventional techniques struggle to effectively suppress over-steering and under-steering in vehicles during turning, leading to reduced traction and increased risk of wheel slip, which affects the vehicle's stability and acceleration performance.

Innovation Solution

A device that adjusts drive force and braking force distribution between the front and rear wheels using a combination of differential gear mechanisms and hydraulic control systems, with a motion controller that dynamically adjusts ratios to enhance or suppress yawing based on the vehicle's turning state.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If drive force control is executed only on the inner turning wheel to suppress over-steering, then the drive force to inner wheel is increased, but the inner wheel slips due to reduced traction from decreased load

Engineering Contradiction:

Improvevehicle stabilityVSAvoidacceleration performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent divides the drive force control into separate controls for inner and outer turning wheels. The inner wheel receives increased drive force to suppress over-steering, while the outer wheel simultaneously receives increased drive force to maintain traction and acceleration performance, resolving the contradiction between stability and productivity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent combines multiple control mechanisms (inner wheel drive force control, outer wheel drive force control, and braking force control) into a composite control system that achieves both over-steering suppression and maintained acceleration performance

Inventive Principle:

Principle #40Composite materials

2Ease of operation

If differential limitation between front and rear wheels is weakened to suppress under-steering, then turning property is enhanced, but traction of the entire vehicle is decreased

Engineering Contradiction:

Improveturning propertyVSAvoidacceleration performance

Core Design Contradiction:

Ease of operationVSProductivity

Solution Approach 1:

The patent applies local quality by providing enhanced drive force specifically to the outer wheel, which has reduced traction during under-steering conditions. This localized compensation maintains overall vehicle traction and acceleration performance while allowing the differential limitation to be weakened for better turning property

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent dynamically adjusts drive force parameters based on vehicle state (under-steering detection). When under-steering is detected, the system increases drive force to the outer wheel while reducing or maintaining differential limitation, changing operational parameters to simultaneously improve turning property and maintain acceleration performance

Inventive Principle:

Principle #35Parameter changes

3Reliability

If braking force is applied to suppress over-steering during acceleration, then over-steering is reduced, but the feeling of speed reduction becomes remarkable and accelerates over-steering

Engineering Contradiction:

Improvevehicle stabilityVSAvoidfeeling of speed reduction

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful effect of braking-induced speed reduction feeling into a benefit by simultaneously applying drive force to the outer wheel. This compensates for the speed reduction sensation and prevents secondary over-steering, while still achieving over-steering suppression through coordinated braking and drive force control

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

4Force

If drive force is increased to the inner turning wheel to suppress over-steering, then moment for suppressing over-steering is generated, but traction of the inner wheel is lowered due to reduced load

Engineering Contradiction:

Improvemoment for suppressing over-steeringVSAvoidtraction of inner wheel

Core Design Contradiction:

ForceVSStrength

Solution Approach 1:

The patent applies counterweight principle by providing compensatory drive force to the outer wheel, which counterbalances the loss of traction on the inner wheel. This allows the inner wheel to generate sufficient moment for over-steering suppression while the outer wheel compensates for the overall traction loss

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Data Source

PatentUS7761215B2Device operable to control turning of vehicle using driving and braking force for understeering and oversteering

Publication Date: 2010.07.20 MITSUBISHI MOTORS CORP

AI summary

A device operable to control a turning of a vehicle, includes: a motion controller operable to: control a first adjuster so as to increase the drive force applied to at least one of front wheels and rear wheels situated in an inner side of the turning, and control a second adjuster so as to increase the braking force applied to at least one of the front wheels and the rear wheels situated in an outer side of the turning; and control the first adjuster so as to increase the drive force applied to at least one of the front wheels and the rear wheels situated in an outer side of the turning, and control the second adjuster so as to increase the braking force applied to at least one of the front wheels and the rear wheels situated in an inner side of the turning.