Tire Load Prediction Using Strain Sensing at Low Speeds

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Solution Overview

Problem

Conventional tire load prediction methods face inaccuracies due to varying ground contact length with tire wear and difficulties in low-speed vehicle predictions, especially with acceleration sensors having limited centrifugal force at low speeds.

Innovation Solution

A tire load prediction system utilizing a strain sensor inside the tire, which includes a sensor unit, strain data acquisition, linear transformation, estimation units for velocity and angular velocity, and a load prediction unit to estimate deflection and predict tire load, allowing for improved accuracy and low-speed predictions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If ground contact length is used for load prediction, then load prediction can be performed, but prediction accuracy deteriorates due to tire wear variations

Engineering Contradiction:

Improveload prediction accuracyVSAvoidsensitivity to tire wear condition

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent changes the measurement parameter from ground contact length to strain in the tire tangential direction. This parameter change makes the measurement less sensitive to tire wear conditions while maintaining load prediction capability, thereby resolving the contradiction between prediction accuracy and adaptability to tire wear.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If acceleration sensor is used for load prediction, then load prediction can be performed, but prediction accuracy deteriorates at low speeds due to small centrifugal force

Engineering Contradiction:

Improveload prediction accuracyVSAvoidvehicle speed

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The patent replaces the acceleration sensor-based mechanical measurement system with a strain sensor-based measurement system. The strain sensor measures strain in the tire tangential direction, which remains effective at low speeds unlike centrifugal force measurement, thereby resolving the contradiction between prediction accuracy and speed range.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 enhances load prediction accuracy and enables reliable predictions for vehicles traveling at low speeds by using strain data to estimate tire deflection and load, independent of tire wear conditions.

Implementation Method 1

a strain sensor that detects strain of the tire

Methodology Applied

Scientific EffectStrain detection: Deformation

Data Source

PatentEP4246112B1Tire load prediction system, tire load prediction program, and tire load prediction method

Publication Date: 2025.03.26 BRIDGESTONE CORP

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AI summary

A tire load prediction system of the present invention includes: a sensor unit SU; a strain data acquisition unit 202; a linear transformation unit 251 that performs a linear transformation on the strain data; a first estimation unit 252 that estimates a velocity and angular velocity in the tire tangential direction; a second estimation unit 253 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 254 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 255 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 256 that predicts a load applied to the tire.