Tire Pressure Detection via Resonant Frequency Estimation
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Solution Overview
Problem
Existing methods for detecting a decrease in tire air pressure using resonant frequency analysis are hindered by the need for high-capacity memory and computational costs, and struggle to accurately estimate resonant frequencies without being influenced by external factors like vehicle velocity and road surface vibrations, leading to inaccurate results.
Innovation Solution
An apparatus and method that estimate the frequency characteristic of a wheel rotation signal using a high-order linear model, followed by a second-order model to identify parameters and estimate the resonant frequency of the tire in the torsional direction, allowing for stable and accurate detection of air pressure decreases without correcting for vehicle velocity or road surface influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency analysis (Fourier transform) is used to estimate resonant frequency, then measurement precision is improved, but device complexity and cost increase due to requiring high-capacity memory
Solution Approach 1:
The patent extracts only the necessary resonant frequency information from the wheel rotation signal using a simplified linear model approach, rather than performing complete frequency analysis. This extraction method obtains the essential resonant frequency data without requiring high-capacity memory for full spectrum analysis.
Solution Approach 2:
The patent changes the estimation approach from frequency domain analysis (Fourier transform) to time domain analysis using linear prediction models. By changing the parameter estimation method and mathematical domain, the system achieves resonant frequency estimation with reduced memory requirements while maintaining accuracy.
2Device complexity
If second-order linear prediction model is used to estimate resonant frequency, then device complexity is reduced, but measurement precision deteriorates due to inability to accurately estimate resonance points
Solution Approach 1:
The patent segments the resonant frequency estimation process into distinct stages: first estimating the input signal to the linear model, then using this estimated input signal to identify model parameters, and finally calculating the resonant frequency. This segmentation allows accurate resonance point identification through a systematic multi-step approach.
Solution Approach 2:
The patent performs preliminary estimation of the input signal to the linear model before identifying the model parameters. This preliminary action provides accurate reference data for subsequent parameter identification, ensuring that the resonant frequency calculation is based on precise input signal characteristics rather than raw, unprocessed data.
3Measurement precision
If correction for external factors (vehicle velocity, road surface vibration) is applied, then measurement precision is improved, but device complexity increases due to additional correction processes
Solution Approach 1:
The patent converts the potentially harmful influence of external factors into a beneficial reference signal. By treating the estimated input signal to the linear model as a reference that already contains the necessary correction information, the system automatically compensates for external influences without requiring separate correction algorithms or additional sensors.
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 accurate and stable estimation of tire air pressure decreases by simplifying the calculation of resonance points and improving computation accuracy, reducing the load on computer resources and avoiding skewing of signals, even when external factors like vehicle velocity and road surface vibrations are present.
Implementation Method 1
a resonant frequency of a tire in a torsional direction is generally known to be influenced by the outside air temperature. However, the vehicle velocity and the magnitude of the vibration given to a tire from a road surface have substantially little influence on the resonant frequency
Implementation Method 2
the resonant frequency of a tire in the torsional direction is a tire-specific vibration mode and is caused due to the torsional rigidity of the tire
Data Source
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AI summary
An apparatus for detecting a decrease in a tire air pressure includes: a rotation velocity information detection means for periodically detecting tire rotation velocity information for the respective wheels of a vehicle; a frequency characteristic estimate means for estimating, based on this rotation velocity information, a frequency characteristic of the rotation velocity information; and a judgment means for judging, based on the estimated frequency characteristic, a decrease in the air pressure of the tire.