Active Noise Control Using Position-Based Adaptive Filter Updates
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Solution Overview
Problem
Adaptive filters in active noise control systems struggle to maintain stability when noise characteristics change rapidly, particularly in environments like moving vehicles where noise properties shift significantly, leading to unstable noise suppression performance.
Innovation Solution
A noise control apparatus that uses position information to adjust the cancellation signal generation, either by stopping the ANC operation or updating the adaptive filter coefficients based on pre-stored noise map information associated with specific positions, ensuring stable noise suppression even during rapid changes in noise characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an adaptive filter is used to generate cancellation signals in active noise control, then noise suppression is achieved under stable conditions, but suppression performance becomes unstable when noise characteristics change rapidly
Solution Approach 1:
The system performs preliminary actions by detecting rapid changes in noise characteristics before suppression performance deteriorates. When such changes are detected, the system pre-emptively updates the adaptive filter coefficients or switches to a different filter configuration, preventing the instability that would otherwise occur during rapid noise transitions.
Solution Approach 2:
The system dynamically adjusts its noise suppression strategy based on real-time noise characteristic analysis. By continuously monitoring noise properties and adapting filter coefficients accordingly, the system transitions from static adaptive filtering to dynamic noise suppression that responds appropriately to changing acoustic environments.
2Adaptability or versatility
If adaptive filter coefficients are continuously updated to track noise changes, then responsiveness to noise changes improves, but system complexity and computational load increase
Solution Approach 1:
Rather than continuously updating adaptive filter coefficients at maximum rate, the system applies partial updates only when necessary - specifically when rapid noise characteristic changes are detected. This selective updating approach maintains adequate tracking performance while significantly reducing computational load compared to continuous full-rate updates.
Solution Approach 2:
The system employs simpler, computationally less intensive filter structures that can be rapidly reconfigured or replaced when noise characteristics change, rather than relying on complex filters that require extensive computation to adapt. This allows for faster response with lower computational overhead.
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 stabilizes noise suppression operations by predicting changes in noise characteristics using position information, preventing unstable performance such as howling or excessive noise, and improving determination accuracy, especially in vehicles with fixed travel routes.
Implementation Method 1
A cancelling speaker 92 reproduces a cancellation signal generated by a suppression signal generation device 90, and emits a cancelling sound that cancels out the noise
Data Source
AI summary
To provide a noise control apparatus capable of stabilizing a noise suppression operation even when noise characteristics rapidly change in a manner that the noise control apparatus is controlled by correcting a coefficient of an adaptive filter, stopping a cancelling speaker, and the like in accordance with the current position of a vehicle such as a train. The noise control apparatus generates a cancellation signal to be reproduced by a cancelling speaker by performing an operation corresponding to position information m of a moving object in which the cancelling speaker used in active noise control is installed.