Vehicle Braking System Yawing Moment Torque Compensation

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Solution Overview

Problem

Existing vehicle control systems fail to effectively improve agility and steering behavior, particularly when the coefficient of friction exceeds a threshold, leading to undesirable tendencies like understeering or oversteering, and often result in vehicle acceleration or stability issues.

Innovation Solution

A method that involves a driver-independent braking action generating a yawing moment and increasing drive torque on specific wheels to compensate braking deceleration, using a control system that estimates the instantaneous coefficient of friction and adjusts braking torque based on transverse acceleration and steering angle deviations to assist steering and prevent unstable driving situations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a braking action is applied to generate a yawing moment for assisting steering, then the steering behavior is improved, but the vehicle experiences braking deceleration which affects driving dynamics

Engineering Contradiction:

Improvesteering behaviorVSAvoidvehicle speed

Core Design Contradiction:

Ease of operationVSSpeed

Solution Approach 1:

The system applies a counteracting drive torque to compensate for the braking deceleration. When a braking action is applied to generate a yawing moment for steering assistance, the control device simultaneously increases the drive torque on the driven wheels to counterbalance the decelerating effect, thereby maintaining the vehicle's longitudinal speed while achieving the desired steering behavior.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The system merges the braking function and drive torque function into a coordinated control strategy. The control device integrates the braking action for yawing moment generation with the drive torque application for deceleration compensation, allowing both functions to work together harmoniously to achieve improved steering behavior without significant speed loss.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If the coefficient of friction exceeds a threshold value, then the braking effectiveness is improved, but the vehicle develops unstable tendencies like understeering or oversteering

Engineering Contradiction:

Improvebraking effectivenessVSAvoidvehicle stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The control device continuously monitors the coefficient of friction between the tires and road surface, and based on this feedback, dynamically adjusts the braking torque and drive torque. When the coefficient of friction exceeds a threshold value, the system modulates the braking and drive forces to prevent unstable tendencies like understeering or oversteering, thereby maintaining both braking effectiveness and vehicle stability.

Inventive Principle:

Principle #23Feedback

3Stability of the object's composition

If driver-independent braking action is applied to stabilize the vehicle, then the driving stability is improved, but the driver's steering control is interfered with

Engineering Contradiction:

Improvedriving stabilityVSAvoiddriver control

Core Design Contradiction:

Stability of the object's compositionVSEase of operation

Solution Approach 1:

The control device applies only the necessary amount of braking torque and drive torque to achieve stability without excessive intervention. The system monitors driving conditions and applies partial braking and drive actions only when needed to correct unstable tendencies, thereby maintaining driving stability while minimizing interference with the driver's steering control.

Inventive Principle:

Principle #16Partial or excessive action

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

This approach enhances the vehicle's steering behavior by harmoniously following the driver's instructions with reduced time delay, avoiding understeering and oversteering, and maintaining driving stability by dynamically adjusting braking and drive torque according to changing friction conditions.

Implementation Method 1

a driver-independent braking action generating a yawing moment which assists the steering

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

a driver-independent increase in the drive torque being caused on at least one wheel, in order at least partially to compensate the braking deceleration

Methodology Applied

Scientific EffectTorque: Torque

Data Source

PatentUS9020699B2Method and braking system for influencing driving dynamics by means of braking and driving operations

Publication Date: 2015.04.28 DR ING H C F PORSCHE AG

AI summary

A method and a braking system are provided, in which the driving dynamics of a motor vehicle are influenced, a driver-independent braking action generating a yawing moment which assists a steering in or steering round of the motor vehicle, and a driver-independent increase in the drive torque being caused on at least one wheel, in order at least partially to compensate the braking deceleration of the motor vehicle, a braking action being required when the ratio of the instantaneously used coefficient of friction and of the possible utilizable coefficient of friction overshoots a stipulated threshold value.