Braking Capacity Decrease Determining Device Using Wheel Speed Cross-Validation

Solution Overview

Problem

Existing braking capacity decrease determining devices inaccurately assess whether a vehicle's braking capacity has decreased due to their reliance on a fade determination condition that is not specific to braking capacity reduction, leading to potential false alarms, especially on low friction road surfaces.

Innovation Solution

A braking capacity decrease determining device that uses wheel speed sensors and a control unit to perform first and second determination processes, considering factors like required deceleration, slip index values, and estimated road surface friction coefficients to accurately assess braking capacity reduction across multiple wheels, and adjusts frictional braking forces through antilock brake control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a fade determination condition is used to determine braking capacity decrease, then the device can detect potential brake fade, but it may produce false alarms on low friction road surfaces

Engineering Contradiction:

Improvebraking capacity determination accuracyVSAvoidfalse alarm rate

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The determination process is divided into two independent stages: a temporary braking decrease determination that identifies potential issues, and a final determination that cross-validates across multiple wheels. This segmentation prevents false alarms by requiring consistent conditions across all wheels before confirming brake fade.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system continuously monitors wheel speeds, slip indices, and deceleration patterns to provide real-time feedback on braking performance. This feedback mechanism allows the system to distinguish between actual brake capacity loss and temporary variations caused by road surface conditions.

Inventive Principle:

Principle #23Feedback

2Device complexity

If the device determines braking capacity decrease based on deceleration difference alone, then the determination process is simple, but accuracy is reduced due to road surface friction variations

Engineering Contradiction:

Improvedetermination process complexityVSAvoidbraking capacity assessment accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The determination process is divided into two independent stages: a temporary braking decrease determination that identifies potential issues, and a final determination that cross-validates across multiple wheels. This segmentation prevents false alarms by requiring consistent conditions across all wheels before confirming brake fade.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system incorporates multiple parameters beyond simple deceleration difference, including wheel speed, slip index, and their rates of change. By monitoring changes in these parameters over time, the system achieves higher accuracy without significantly increasing complexity.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the device monitors all wheels for braking capacity decrease, then comprehensive assessment is achieved, but computational load increases

Engineering Contradiction:

Improveassessment comprehensivenessVSAvoidprocessing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The determination process is divided into two independent stages: a temporary braking decrease determination that identifies potential issues, and a final determination that cross-validates across multiple wheels. This segmentation prevents false alarms by requiring consistent conditions across all wheels before confirming brake fade.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system performs preliminary assessment on individual wheels first, then only conducts full cross-validation when temporary braking decrease is detected. This partial action approach reduces computational load by avoiding unnecessary comprehensive analysis during normal braking conditions.

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

Enhances the accuracy of determining braking capacity decrease by differentiating between wheels with sufficient and insufficient frictional braking forces, thereby reducing false alarms and improving the reliability of braking capacity assessments.

Implementation Method 1

wheel speed sensors configured to generate signals corresponding to wheel speeds

Methodology Applied

Scientific EffectElectromagnetic sensing:

Implementation Method 2

frictional brake devices that are provided in the plurality of wheels and that are able to adjust a frictional braking force which is applied to the corresponding wheel

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 3

a slip index value (SPi, Smi) indicating a degree of slip of each wheel which is calculated based on the wheel speeds of the plurality of wheels

Methodology Applied

Scientific EffectKinematic calculation:

Data Source

PatentUS11603083B2Braking capacity decrease determining device

Publication Date: 2023.03.14 TOYOTA JIDOSHA KK

AI summary

A braking capacity decrease determining device including a brake ECU is applied to a vehicle including wheel speed sensors and a brake device. The brake ECU performs a first determination process of determining whether a temporary braking decrease determination condition is satisfied for each of a plurality of wheels provided on the vehicle. The brake ECU additionally performs a second determination process of determining whether there are both a wheel for which the temporary braking decrease determination condition is satisfied and a wheel for which the temporary braking decrease determination condition is not satisfied out of the plurality of wheels and determining that a braking capacity of the brake device has decreased when it is determined that there are both a wheel for which the temporary braking decrease determination condition is satisfied and a wheel for which the temporary braking decrease determination condition is not satisfied.