Road Surface State Estimation Using 1/N Octave Sound Analysis
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Solution Overview
Problem
Existing methods for estimating road surface states using sound detection signals are unreliable, particularly when distinguishing between finely classified states like wet, dry, frozen, and slushy/snowy conditions, due to limitations in frequency analysis and the need for manual visual inspection.
Innovation Solution
A method that calculates a wave profile of frequency dispersion using 1/N octave analysis of sound detection signals from a ground contact surface sound detection unit, applying predetermined determination conditions to classify road surface states, including resonance caused by a container housing the microphone, to accurately estimate road surface states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If only one frequency region is used to determine road surface state, then the measurement system is simple, but the measurement precision is insufficient to distinguish between similar states like smooth asphalt and slightly wet road surfaces
Solution Approach 1:
The patent divides the frequency spectrum into multiple frequency regions (first frequency region with lower frequencies and second frequency region with higher frequencies) to analyze sound signals. By segmenting the frequency analysis into multiple regions, the system can capture different acoustic characteristics of road surface contact, enabling distinction between similar road states that cannot be differentiated using a single frequency region.
2Adaptability or versatility
If multiple road surface states are to be determined, then the classification capability is enhanced, but the determination system becomes overly complex with limited practical utility
Solution Approach 1:
The patent applies different determination conditions to different frequency regions. The first determination condition compares sound pressure levels in the first frequency region against reference values to identify specific road states (wet, dry, frozen, slushy/snowy). This localized approach to determination allows the system to handle multiple road surface states without requiring an overly complex unified determination system.
3Reliability
If sound detection is performed without container protection, then the detection sensitivity is maximized, but the microphone is exposed to environmental hazards like water and debris
Solution Approach 1:
The patent introduces a container as an intermediary structure that houses the microphone. This container serves as a protective barrier between the microphone and environmental hazards such as water, debris, and other road conditions. The container design allows sound transmission to the microphone while providing physical protection, thus improving reliability without completely isolating the sensor from the acoustic environment.
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 precise classification of road surface states with high accuracy, reducing reliance on manual inspection and improving safety by distinguishing between wet, dry, frozen, and slushy/snowy conditions, with a robust determination system that minimizes resonance effects and protects the microphone from environmental hazards.
Implementation Method 1
a ground contact surface sound detection unit for detecting a sound in the vicinity of the ground contact surface of the tire
Implementation Method 2
said determining step is adapted to apply said determination conditions to said measured wave profile including a resonance caused by the container
Data Source
AI summary
There is provided a method for determining a road surface state which can accurately estimate the road surface state on which a vehicle is running at one of finely classified road surface states based on a sound detection signal from a ground contact surface sound detection unit for detecting a sound in the vicinity of the ground contact surface of the tire of the running vehicle.The method calculates a wave profile of frequency dispersion by executing a 1/N octave analysis of a detected sound signal from a sound detection unit 20 for estimating a road surface state. The state of the road surface on which the vehicle is running is determined whether the calculated wave profile of frequency dispersion satisfies predetermined determination conditions of the respective road surface states. A microphone housed in a container is used to detect said sound, and the determining step is adapted to apply the determination conditions to the measured wave profile including a resonance caused by the container.