Road Surface Detection via Radio Wave Polarization Ratio

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Solution Overview

Problem

Existing road surface condition detection devices struggle to accurately detect road conditions under unsettled weather conditions due to unstabilized temperature baselines.

Innovation Solution

A road surface condition detection device installed in vehicles that uses a radio waves receiving unit to calculate polarization ratios of horizontally and vertically polarized waves, determining refractive indices based on these ratios to recognize road surface conditions, regardless of weather, by employing a refractive index calculation unit and storage unit to exclude incorrect determinations based on ambient temperature.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If road surface condition detection is performed based on radiation temperature of the sky, then road surface conditions can be detected, but the temperature baseline is not stabilized when the weather is unsettled

Engineering Contradiction:
Improveroad surface condition detection accuracyVSAvoidtemperature baseline stability
Core Design Contradiction:
Measurement precisionVSStability of the object's composition

Solution Approach 1:

The patent introduces radio waves as an intermediary medium to detect road surface conditions. Instead of directly measuring temperature, the system measures the polarization ratio of radio waves reflected from the road surface, which serves as a stable intermediary indicator that is not affected by weather conditions. This mediator allows accurate detection while maintaining baseline stability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the detection parameter from radiation temperature to polarization ratio of radio waves. By measuring the polarization ratio (ratio of horizontally polarized to vertically polarized radio wave components) instead of temperature, the system achieves weather-independent detection. The refractive index calculation unit then converts this polarization ratio into road surface condition information.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If radiation temperature measurement is used for road surface detection, then detection capability is provided, but incorrect determinations occur under unsettled weather conditions

Engineering Contradiction:
Improvedetection reliabilityVSAvoidroad surface condition accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

Radio waves serve as a reliable intermediary that reflects off the road surface with characteristics dependent on surface conditions but independent of weather. The polarization ratio of these reflected radio waves provides a stable measurement basis that prevents incorrect determinations while maintaining high detection reliability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the thermal measurement system (radiation temperature sensing) with an electromagnetic wave-based system (radio wave polarization measurement). This substitution eliminates the weather-dependent thermal baseline issues while providing reliable and accurate road surface condition detection through electromagnetic interaction with the road surface.

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

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 accurate detection of road surface conditions, including dry, ice, and snow, by stabilizing refractive index calculations and reducing the risk of incorrect determinations, thereby improving vehicle operation and safety across varying weather conditions.

Implementation Method 1

a polarization ratio calculation unit (3) that calculates a polarization ratio of a horizontally polarized waves component to a vertically polarized waves component of the radio waves received by the radio waves receiving unit (1)

Methodology Applied
Scientific EffectPolarization: Polarisation

Implementation Method 2

a refractive index calculation unit (6) that calculates a refractive index of an object based on a ratio of the polarization ratios with regard to two radiation angles

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP2884311B1Road surface state detection device and road surface state detection method
Publication Date: 2017.07.19 NISSAN MOTOR CO LTD
  • EP2884311B1 patent drawingFigure 1
  • EP2884311B1 patent drawingFigure 2~3
  • EP2884311B1 patent drawingFigure 4~5

AI summary

A radio waves receiving unit 1 receives horizontally polarized waves and vertically polarized waves of radio waves radiated from an object at a radiation angle. An image generation unit 2 generates a horizontally polarized waves image and a vertically polarized waves image based on the horizontally polarized waves and the vertically polarized waves, respectively. A polarization ratio calculation unit 3 calculates, for each radiation angle, a polarization ratio which is a ratio of intensity of the horizontally polarized waves to the vertically polarized waves based on the horizontally polarized waves image and the vertically polarized waves image. A refractive index calculation unit 6 calculates a refractive index of the object based on a change between polarization ratios of two different radiation angles. A road surface condition recognition unit 8 recognizes a condition of a road surface based on the refractive index.