Tire Load Estimation from Strain and Deflection at Low Speeds
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Solution Overview
Problem
Conventional tire load prediction methods experience high errors due to varying ground contact length with tire wear and struggle with accuracy at low speeds, where centrifugal force is minimal.
Innovation Solution
A tire load prediction system employing a strain sensor inside the tire, with a sensor unit, strain data acquisition, linear transformation, and multiple estimation units to estimate velocities and deflection, enabling accurate load prediction by processing strain data through specific formulas and coordinate transformations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If acceleration sensors are used for load prediction, then the system can operate at high speeds, but the prediction accuracy deteriorates at low speeds due to small centrifugal force
Solution Approach 1:
The patent replaces acceleration sensors (which rely on centrifugal force) with strain sensors that directly measure mechanical deformation of the tire. This substitution allows the system to operate accurately across the full speed range, including low speeds where centrifugal force is insufficient for acceleration-based measurement.
2Ease of manufacture
If ground contact length is used for load estimation, then the system is simple to implement, but prediction accuracy deteriorates due to tire wear variations
Solution Approach 1:
The patent changes the measurement parameter from ground contact length (which varies with tire wear) to strain distribution patterns on the tire inner surface. Strain measurements remain consistent regardless of tire wear because they reflect the actual mechanical deformation caused by load, providing accurate predictions throughout the tire's service life.
3Measurement precision
If multiple velocity components and deflection are estimated through complex calculations, then load prediction accuracy improves, but the computational complexity increases
Solution Approach 1:
The patent performs preliminary calculations by pre-establishing the relationships between strain measurements and velocity components. The system calculates tangential velocity and radial velocity from strain data using predetermined formulas, then uses these velocities to determine tire deflection. This structured approach breaks down the complex problem into manageable sequential steps, improving accuracy while controlling computational complexity.
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
The system significantly increases load prediction accuracy and can predict tire loads for vehicles traveling at low speeds, independent of tire wear conditions.
Implementation Method 1
a sensor unit that is provided inside a tire and has a strain sensor that detects strain of the tire
Data Source
AI summary
A tire load prediction system of the present invention includes: a sensor unit; a strain data acquisition unit; a linear transformation unit that performs a linear transformation on the strain data; a first estimation unit that estimates a velocity and angular velocity in the tire tangential direction; a second estimation unit that estimates a velocity in a tire radial direction from values of the velocity and angular velocity in the tire tangential direction; a third estimation unit that estimates a velocity in a θ-angle direction from values of an acceleration and angular velocity in the tire tangential direction; a fourth estimation unit that estimates deflection of the tire, the velocity in the tire radial direction, and the velocity in the θ-angle direction; and a load prediction unit that predicts a load applied to the tire.