Tire Vibration Analysis for Road Surface Estimation
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Solution Overview
Problem
Existing methods for estimating road surface conditions under a traveling vehicle often inaccurately determine the positions of the leading and trailing end points of the tire contact patch due to excessive inputs, such as bumps or curbs, leading to incorrect estimations, and require additional sensors for monitoring.
Innovation Solution
A method that estimates the positions of the leading and trailing end points of the tire contact patch from peak positions in the time-series waveform of tire vibration, calculates contact time, extra-contact time, and revolution time, and determines if these positions match actual ones based on these calculations, canceling road surface condition estimation if they do not, thereby avoiding incorrect estimations without increasing the number of sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If peak positions in the time-series waveform are used to estimate leading end point and trailing end point positions, then the road surface condition estimation can be performed, but incorrect estimation occurs when excessive inputs (bumps, curbs) create conspicuous peaks
Solution Approach 1:
The patent uses feedback by comparing the estimated contact time and revolution time with expected values to verify whether the identified peak positions are correct. If the calculated contact time falls outside the predetermined range or the revolution time does not match expectations, the system determines that the peak identification is incorrect and excludes that data from road surface condition estimation, thereby preventing erroneous estimates caused by excessive inputs.
Solution Approach 2:
The system uses the vibration data itself to verify the correctness of peak identification without requiring external sensors. By calculating contact time and revolution time from the same vibration waveform and comparing these derived parameters against expected ranges, the system performs self-validation to ensure reliable peak position identification before proceeding with road surface condition estimation.
2Reliability
If an acceleration sensor for monitoring is installed on the suspension to detect excessive inputs, then large input detection accuracy is improved, but the number of sensors and device complexity increases
Solution Approach 1:
The patent makes the vibration detecting means perform multiple functions: it detects both the vibration signals needed for road surface condition estimation and the excessive inputs (large inputs) that could corrupt the estimation. By using the same sensor for both purposes and analyzing different aspects of the vibration data, the system eliminates the need for a separate monitoring sensor while maintaining reliable large input detection capability.
Solution Approach 2:
The system uses the vibration data collected for road surface condition estimation to also detect excessive inputs. By analyzing the same vibration waveform for both estimation purposes and validation purposes, the system performs self-monitoring without requiring additional sensors, thereby reducing device complexity while maintaining detection accuracy.
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 accurately determines excessive inputs to the tire and improves the accuracy of road surface condition estimation by ensuring that only correct peak positions are used for estimation, enhancing safety and reducing sensor requirements.
Implementation Method 1
a time-series waveform of tire vibration detected by a vibration detecting means
Data Source
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AI summary
A method is provided for estimating a road surface condition by accurately determining whether or not there has been any large input to a tire without increasing the number of sensors. An acceleration sensor is disposed on the tire to detect the vibration of the tire in motion. The positions of leading end point and trailing end point of tire contact patch are estimated from the peak positions appearing in the time-variable waveform of the vibration. At the same time, the contact time, extra- contact time, and revolution time of the tire are calculated from the estimated positions of leading end point and trailing end point. Then using one or more of the calculated data, it is determined whether or not the estimated positions of leading end point and trailing end point are equal to the actual positions of leading end point and trailing end point. And if the result of the leading and trailing position determination is "incorrect estimation", the estimation of a road surface condition is not performed.