Road Surface State Classification via Velocity-Compensated Suspension Vibration Analysis
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Solution Overview
Problem
Existing methods for determining the state of a road surface on which a vehicle has traveled, such as those described in EP556070, fail to accurately differentiate between high-speed travel on a smooth surface and low-speed travel on a rough surface, and require significant computational resources due to the need for frequent FFT transformations.
Innovation Solution
A method that retrieves a signal representing the distance between the wheel axle and the vehicle body, filters this signal to obtain components, calculates excitation values, compensates these values for vehicle velocity, and compares them with stored data to classify the road surface state, allowing for accurate differentiation between high-speed smooth and low-speed rough surface scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If FFT transform is used to analyze road surface state, then measurement precision is improved, but processor capacity requirements increase significantly
Solution Approach 1:
The patent extracts only the necessary frequency information from the vibration signal by identifying specific resonance frequencies of the wheel suspension system, rather than performing a complete FFT analysis. This allows the system to determine road surface state by comparing measured frequencies with predetermined reference frequencies, significantly reducing computational requirements while maintaining classification accuracy.
Solution Approach 2:
The patent uses simple frequency counters and comparators instead of complex FFT processing algorithms. The system counts zero-crossings or peaks in the acceleration signal within specific frequency bands and compares these counts with threshold values, providing a computationally inexpensive method for road surface evaluation.
2Speed
If frequent FFT transformations are performed for real-time road condition monitoring, then responsiveness is improved, but processor capacity requirements increase
Solution Approach 1:
The patent extracts only the essential frequency characteristics needed for road surface classification by monitoring specific resonance frequencies of the wheel suspension. Instead of performing full spectral analysis at each update interval, the system tracks frequency content in predetermined bands, enabling rapid updates with minimal processing.
Solution Approach 2:
The patent replaces complex computational processing with simpler electronic counting and comparison operations. The system uses frequency counters to measure vibrations in specific bands and comparators to evaluate whether measured values exceed thresholds, providing a computationally lightweight approach to real-time monitoring.
3Loss of information
If relative movement between wheel and vehicle body is measured for road condition determination, then measurement capability is improved, but inability to separate velocity effects from road surface state occurs
Solution Approach 1:
The patent segments the vibration signal analysis into specific frequency bands corresponding to the resonance frequencies of the wheel suspension system. By analyzing frequency content in these predetermined bands rather than examining overall relative movement, the system can distinguish between vibrations caused by road surface irregularities and those caused by vehicle velocity, enabling accurate road surface state determination independent of speed.
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
This approach enables precise classification of road surface states, reducing computational demands and providing accurate data for maintenance optimization, ride comfort estimation, and component dimensioning by effectively accounting for the influence of velocity on road surface assessment.
Implementation Method 1
measuring a relative movement between a wheel and a vehicle body generating an input signal
Implementation Method 2
Uneven road surfaces will result in vibrations being transmitted through the wheels and suspension to the suspended mass of the vehicle
Implementation Method 3
Filtering technologies can be used to separate the random noise from the transient components
Data Source
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AI summary
A method for determining the state of a road surface on which a vehicle has travelled comprising the steps of: a) retrieving a signal (S) representative of the distance (D) between the wheel axle (12) and the vehicle body (14); b) providing, from said retrieved signal (S), a band pass filtered first component (S1); c) calculating a first value (V1) representative of an excitation degree of the first component (S1).