Tire Cavity Resonance Cancellation via RPM-Based EOC Algorithm

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Solution Overview

Problem

Current road noise cancellation (RNC) technologies face challenges in effectively addressing tire cavity resonance noise, which contributes significantly to unwanted noise in vehicles, due to the complexity and computational power requirements of existing systems that rely on accelerometers and broadband noise cancellation methods.

Innovation Solution

A modified Engine Order Cancellation (EOC) algorithm utilizing an RPM sensor and a lookup table to generate antinoise signals that cancel tire cavity resonance noise, which does not require accelerometers and can be adapted using a single-channel or dual-channel feedforward active noise cancellation system with a Least Mean Squares (LMS) adaptive algorithm.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If traditional RNC systems use accelerometers and broadband noise cancellation methods, then they can address general road noise, but they require high computational power and complex system architecture

Engineering Contradiction:

Improveroad noise cancellation effectivenessVSAvoidsystem complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent extracts and isolates the tire cavity resonance component from the overall road noise spectrum. By using an RPM sensor to identify the specific rotational frequency and its harmonics, the system targets only the tonal TCR noise rather than processing the entire broadband road noise signal, thereby simplifying the system architecture while maintaining effectiveness for this specific noise source

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the accelerometer-based mechanical vibration sensing system with an RPM sensor-based rotational speed detection system. This substitution leverages the existing rotational information from the wheel/tire to directly calculate TCR frequencies, eliminating the need for complex accelerometer arrays and associated signal processing infrastructure

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Object-affected harmful factors

If traditional RNC systems use accelerometers and broadband noise cancellation methods, then they can address general road noise, but they require high computational power

Engineering Contradiction:

Improveroad noise cancellation effectivenessVSAvoidcomputational power consumption

Core Design Contradiction:

Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies partial action by focusing computational resources only on canceling the specific TCR frequency components identified from RPM data, rather than attempting to cancel all road noise frequencies. This selective approach significantly reduces computational power requirements while effectively addressing the most problematic tonal resonance noises

Inventive Principle:

Principle #16Partial or excessive action

3Device complexity

If EOC systems use RPM sensor data, then they do not require accelerometers, but they traditionally target engine noise rather than tire cavity resonance

Engineering Contradiction:

Improvesensor system complexityVSAvoidnoise cancellation applicability

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent extends the EOC algorithm's functionality from its traditional engine noise cancellation application to also handle tire cavity resonance noise. By using the same RPM sensor input to generate both engine order cancellation and TCR cancellation signals, the system achieves multi-functionality without adding sensors or increasing complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent dynamically adapts the EOC algorithm to generate antinoise signals for TCR frequencies based on real-time RPM data. The system calculates the fundamental TCR frequency and its harmonics dynamically from the measured rotational speed, allowing the cancellation frequencies to adjust automatically as tire rotation speed changes

Inventive Principle:

Principle #15Dynamics

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 achieves 6-10 dB of noise cancellation in the tire noise frequency range (190-250 Hz), improving upon traditional RNC systems by reducing computational power needs and enhancing cancellation depth without the need for accelerometers.

Implementation Method 1

an RPM sensor that provides a signal indicative of a rotational speed of the tire

Methodology Applied

Scientific EffectRotational speed sensing:

Implementation Method 2

an adaptive filter that generates an antinoise signal from the reference signal

Methodology Applied

Scientific EffectActive noise control:

Implementation Method 3

which reduces tire cavity resonance noise at a listening position

Methodology Applied

Scientific EffectDestructive interference: Interference

Data Source

PatentEP3537430B1Method and apparatus for a low cost, acoustic tire cavity resonance canellation

Publication Date: 2023.08.16 HARMAN INT IND INC

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AI summary

A sensor is configured to infer a rotational speed of a tire of a vehicle. A frequency generator is configured to synthesize frequencies of a tire cavity resonance according to the rotational speed of the tire to generate a sense signal. An active noise control filter is configured to generate an antinoise signal from the sense signal. A loudspeaker configured to convert the antinoise signal into antinoise and to radiate the antinoise to a listening position. The antinoise signal is configured so that the antinoise reduces sound of the tire cavity resonance at the listening position.