Laser Road Friction Sensor for Adhesion Classification

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Solution Overview

Problem

Current driver assistance and vehicle dynamics systems face challenges in accurately determining the coefficient of adhesion between the road surface and tires, particularly in uniform driving states, leading to inadequate warning and intervention times, which can result in premature or delayed reactions to road conditions.

Innovation Solution

A sensor arrangement and method utilizing a classifier unit to analyze radiation detection output signals from multiple radiation emitter units, which perform frequency analysis and energy distribution pattern detection to determine the coefficient of friction, incorporating quality information and reference criteria, and integrating with a central electronic control unit for precise adhesion estimation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If indirect determination of the coefficient of adhesion using mathematical methods from other variables measured in the vehicle is used, then the system can provide adhesion information, but the measurement precision deteriorates in uniform driving states with low acceleration

Engineering Contradiction:
Improveadhesion determination reliabilityVSAvoidcoefficient of adhesion measurement precision
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent replaces mechanical/mathematical estimation methods with optical measurement methods. Laser radiation emitter units illuminate the road surface, and sensor units detect reflected radiation to directly measure road surface properties, eliminating the need for mathematical inference from vehicle dynamics variables.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces laser radiation as an intermediary between the measurement system and the road surface. The radiation interacts with the road surface to provide direct information about its friction properties, serving as a mediator that enables precise measurement without relying on vehicle motion states.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If a fixed value for the coefficient of adhesion is assumed, then the system operation is simplified, but the adaptability to different road conditions deteriorates

Engineering Contradiction:
Improvesystem operation simplicityVSAvoidroad condition adaptability
Core Design Contradiction:
Ease of operationVSAdaptability or versatility

Solution Approach 1:

The patent dynamically changes the measurement parameters by using optical properties (reflection characteristics) of the road surface to determine the coefficient of adhesion. This allows the system to adapt to different road conditions (wet, dry, icy, snowy) by detecting changes in how the road surface interacts with laser radiation.

Inventive Principle:
Principle #35Parameter changes

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

Enables reliable and robust classification of adhesion even in non-dynamic driving situations, improving system performance by providing accurate friction information for better driver assistance and vehicle control.

Implementation Method 1

the at least one radiation emitter unit and/or the one or more additional sensor units detect reflected radiation

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

the classifier unit carries out a frequency analysis of the radiation detection output signals

Methodology Applied
Scientific EffectFrequency analysis:

Data Source

PatentEP2454137B1Laser-based method for the friction coefficient classification of motor vehicles
Publication Date: 2015.09.09 CONTINENTAL TEVES AG & CO OHG
  • EP2454137B1 patent drawingFigure 1~2
  • EP2454137B1 patent drawingFigure 3~5

AI summary

The invention relates to a sensor array for detecting a friction coefficient of a roadway surface, wherein the sensor array is disposed on a motor vehicle and comprises at least one radiation emitter unit and at least one electronic evaluation circuit, wherein the radiation emitter unit emits electromagnetic radiation toward the roadway surface, and the radiation is at least partially reflected and/or scattered by the roadway surface, and the reflected and/or scattered radiation is at least partially detected in the radiation emitter unit and/or in one or more additional sensor units, wherein the electronic evaluation circuit is designed such that it determines friction coefficient information of the roadway surface from the intensity of the reflected and/or scattered radiation or a variable dependent thereon.