Tire Load Detection via Acceleration Signal Difference

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Solution Overview

Problem

Existing methods for determining vehicle load require additional information about tire pressure and temperature, making them less efficient for load change detection.

Innovation Solution

A method that determines a change in the tire contact patch based on an acceleration signal, using a difference between recorded and reference acceleration signals, and converts the signal into a pulse width modulated signal to detect changes in tire contact area, which can be attributed to load changes or tread depth variations, utilizing piezoelectric or micro-electro-mechanical sensors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If acceleration signal, tire pressure and temperature are used to determine load changes, then measurement precision is improved, but device complexity increases due to requiring multiple sensors

Engineering Contradiction:
Improveload change detection precisionVSAvoidsensor system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts only the necessary information (load changes) from the acceleration signal by comparing amplitude profiles, eliminating the need for additional tire pressure and temperature sensors. This reduces device complexity while maintaining measurement precision for load detection.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The acceleration sensor serves multiple functions: it detects both vehicle load changes and tire rotation information. By making the acceleration sensor multi-functional, the patent eliminates the need for separate pressure and temperature sensors, thereby reducing device complexity while maintaining measurement capabilities.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Loss of information

If acceleration signal processing with Fourier analysis is used, then information content is retained, but calculation complexity increases

Engineering Contradiction:
Improvesignal information retentionVSAvoidsignal processing complexity
Core Design Contradiction:
Loss of informationVSDevice complexity

Solution Approach 1:

The patent extracts specific frequency components from the acceleration signal using Fourier analysis that are most relevant to load detection. By focusing on particular frequency bands rather than processing the entire spectrum, the method retains essential information while reducing computational complexity.

Inventive Principle:
Principle #2Taking out (Extraction)

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

Enables accurate detection of load changes and tread depth variations without needing tire pressure and temperature data, retaining the full information content of the acceleration signal through Fourier analysis, and allowing for real-time monitoring of tire contact length.

Implementation Method 1

In a piezoelectric acceleration sensor, pressure fluctuations are converted into electrical signals by a piezoceramic sensor plate

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

Due to the deflection during acceleration, a change in capacitance can be measured between the springs and the mass, which is proportional to the acceleration

Methodology Applied
Scientific EffectCapacitance: Capacitance

Data Source

PatentEP2250037B1Method for determining the loading of a vehicle
Publication Date: 2019.05.22 ROBERT BOSCH GMBH
  • EP2250037B1 patent drawingFigure 1
  • EP2250037B1 patent drawingFigure 2
  • EP2250037B1 patent drawingFigure 3

AI summary

The invention relates to a method for determining a change in contact surface of a tire, using a signal that corresponds to an acceleration and that can be associated with a rotation of the tire. The method comprises the following steps: acquiring at least one acceleration signal g1 that can be associated with the rotation of the tire; reading out a stored reference acquisition signal g0 that can be associated with the rotation of the tire; forming the difference between the acceleration signal g1 and the reference signal g0; and determining the change in contact surface of the tire using the formed difference of the acceleration signals.