Road Surface Sensor Using Polarized Light Detection
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Solution Overview
Problem
Existing road surface sensors are bulky, require multiple light sources and detectors that need alignment and calibration, and struggle to reliably differentiate between ice and water on the road surface, providing incomplete and often ignored warnings to drivers about road conditions.
Innovation Solution
A compact optical surface sensor design that integrates a light source unit, emitter optics, and polarizers on the optical axis of a focusing device, allowing for simultaneous collection and differentiation of specularly and diffusely reflected light using multiple wavelengths, enabling accurate detection of road conditions such as wet, dry, icy, or snow-covered surfaces within a single housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple light sources and detectors are used to detect road conditions, then detection accuracy is improved, but device size and complexity increase
Solution Approach 1:
The patent combines multiple light sources (first and second light sources emitting different wavelengths) and multiple detectors (first and second detectors) into a single integrated sensor unit. This merging approach allows simultaneous detection of both specular and diffuse reflected light at different wavelengths without requiring separate sensor assemblies, thereby improving detection accuracy while controlling device complexity through unified integration.
Solution Approach 2:
The sensor unit is designed to perform multiple detection functions simultaneously: detecting both specular and diffuse reflected light, measuring at multiple wavelengths, and determining various road conditions (wet, icy, snowy, dry). This multi-functionality allows a single device to replace what would traditionally require multiple separate sensors, improving measurement precision while avoiding proportional increases in device complexity.
2Measurement precision
If multiple light sources and detectors are used to detect road conditions, then detection accuracy is improved, but installation and maintenance complexity increase
Solution Approach 1:
By integrating all light sources, detectors, and optical components into a single compact sensor unit, the patent simplifies installation procedures. Instead of installing and aligning multiple separate sensors, only one unit needs to be mounted, reducing alignment complexity and maintenance requirements while preserving the multi-wavelength detection capabilities that ensure accurate road condition assessment.
3Adaptability or versatility
If visible light is used to detect road surface conditions, then detection capability is provided, but reliable differentiation between ice and water cannot be achieved
Solution Approach 1:
The patent changes the wavelength parameter by employing light sources that emit at different wavelengths (including infrared wavelengths). This parameter change enables the sensor to detect differences in light absorption and reflection characteristics between ice and water that are not visible to the human eye or detectable with visible light alone, thereby achieving reliable differentiation between these similar road conditions while maintaining broad detection capability.
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
The solution provides a space-saving, high-quality detection system that can be easily installed in vehicles, offering improved accuracy and reliability in determining road surface conditions, including type and roughness, and reducing the complexity of assembly and maintenance.
Implementation Method 1
surface sensors are known which emit light onto the roadway and measure the diffusely reflected light and the specularly reflected light on the roadway surface
Implementation Method 2
Water and ice can be detected with a reflection detector, since the light that hits it is reflected specularly
Implementation Method 3
the proportion of diffusely reflected light increases with increasing brightness of the road surface
Implementation Method 4
spectral surface sensors are also known, which use the effect that different wavelengths in the infrared range are absorbed differently by water and ice
Implementation Method 5
A comparison of the reflected light intensities of different wavelengths then indicates a dry, wet or icy road
Implementation Method 6
The device comprises a light source unit, two detectors and polarizers in order to split the light reflected diffusely and specularly from the roadway onto the first and second detector using a beam splitter
Data Source
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AI summary
The invention relates to a sensor (102; 202) for detecting the surface of a roadway for a motor vehicle. The sensor comprises at least one light source (112; 212), a first detector (122; 222) for measuring diffuse reflection, wherein a first polarizer (124; 224) is arranged in front of the first detector (122; 222), and a second detector (132, 232). The diffusely reflected light and the specularly reflected light are focused by means of a common focusing device (160; 162; 260) having an optical axis (A; B) and split onto the first detector (122; 222) and the second detector (132; 232) by means of a beam splitter (150; 250), wherein the at least one light source (112; 212) is arranged substantially on the optical axis (A; B) of the focusing device (160; 162; 260).