Pneumatic Tire Load Estimation Using Crown Acceleration Signals
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Solution Overview
Problem
Measurement signals from sensors on terrestrial vehicles are disrupted by rotation, making it difficult to accurately determine the static load on a tyre casing due to noise from surface roughness and external forces, which affects sensitive physical variables.
Innovation Solution
A method involving fastening sensors to the tyre casing to capture acceleration signals, normalizing them using a reference speed, angularly resampling, and analyzing energy density or spectral variables to isolate tyre casing deformation, allowing for the determination of static load through a bijective function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensors are mounted on the tyre casing to measure fine variables, then measurement sensitivity is improved, but measurement precision deteriorates due to noise from rotation and surface roughness
Solution Approach 1:
The patent segments the measurement signal into discrete wheel turns (NTDR >= 1), processing each turn separately to isolate the deformation signal from rotational noise. By delimiting the signal over multiple wheel turns and processing them individually, the method separates useful information from harmful rotational interference.
Solution Approach 2:
The patent utilizes the periodic nature of wheel rotation by normalizing the signal over multiple wheel turns (NTDR >= 1). The periodic repetition of the wheel turn cycle allows for averaging and filtering of noise while preserving the consistent deformation pattern caused by static load across multiple rotation periods.
2Reliability
If general variables such as inflation pressure are measured, then measurement reliability is improved, but measurement precision deteriorates due to insensitivity to load variations
Solution Approach 1:
The patent transitions from measuring general variables (inflation pressure) to measuring local fine variables (acceleration at specific sensor positions on the tyre casing). By placing sensors at specific locations and measuring local acceleration, the system captures load-specific deformation patterns that general variables miss, while maintaining reliability through robust signal processing.
3Measurement precision
If signal processing is performed to remove noise, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent employs self-service principles by using the wheel-turn signal itself as the normalization reference. The system normalizes each wheel turn signal by its own reference speed and energy characteristics, eliminating the need for external calibration equipment or complex reference systems. The processing leverages the inherent periodicity and structure of the measurement signal.
Solution Approach 2:
The patent transforms the raw acceleration signal through parameter changes including normalization by reference speed, energy density calculation, and spectral analysis. These parameter transformations convert the noisy time-domain signal into frequency-domain characteristics that reveal load information while filtering out rotational noise.
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 method effectively filters out noise and provides a precise scalar value for static load on the tyre casing, improving measurement accuracy and reducing interference from rotation and external forces.
Implementation Method 1
Fastening at least one sensor to the tyre casing at the crown of the tyre casing so as to generate at least one output signal sensitive to the acceleration, in the direction normal to the crown, applied to said sensor in the tyre casing
Data Source
AI summary
Ascertaining the load applied to a pneumatic tyre, comprising the following steps:Fastening a sensor to the tyre so as to generate an acceleration along the normal to the crown;Acquiring (201) a temporal signal SigTDR (101) comprising the amplitude of the acceleration while rolling;Determining a speed Wreference (202) associated with a portion of the signal SigTDR;Normalizing (203) the portion of the signal SigTDR by a variable which is a function F proportional to the square of Wreference.Angularly resampling (204) the portion of the signal SigTDR;Defining (205) an energy density S, by means of a threshold A or a spectral variable B, by spectral analysis, from the resampled normalized signal SigTDR;Identifying (206) the deformation Def % as a function G of S or of β;Identifying (207) the load Z by the function H of Def %.