Noise Control Device With Fixed Filter Coefficient Renewal
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Solution Overview
Problem
Conventional noise control devices in aircraft require frequent and labor-intensive recalibration of filter coefficients due to changes in seat positions and ambient environments, leading to potential noise level increases and passenger discomfort, especially when using adaptive filters that need real-time processing and strict processing capabilities.
Innovation Solution
A noise control device that operates with fixed filter coefficients, renewing them only under specific conditions such as changes in aircraft service, seat replacement, or engine state changes, using a filter coefficient calculator and renewing section to automatically adjust coefficients to optimize noise reduction based on seat position and ambient environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adaptive filters are used to control noise in real-time, then noise reduction effectiveness is improved, but device complexity and processing requirements increase
Solution Approach 1:
The system dynamically switches between adaptive filter mode (when noise characteristics change) and fixed filter mode (when noise characteristics are stable). This allows the system to maintain noise reduction effectiveness while reducing processing complexity during stable conditions, resolving the contradiction between reliability and device complexity.
Solution Approach 2:
The system changes the operational parameters of the filter by switching between adaptive and fixed modes based on noise characteristics. This parameter change allows the system to optimize performance for different noise conditions while managing processing requirements, thereby resolving the contradiction between noise reduction effectiveness and processing capability requirements.
2Measurement precision
If filter coefficients are frequently renewed to adapt to changes, then noise control accuracy is improved, but computational load and processing time increase
Solution Approach 1:
The system performs filter coefficient renewal periodically or event-driven (when noise characteristics change) rather than continuously. This periodic action maintains noise control accuracy while significantly reducing computational load and processing time compared to continuous renewal, resolving the contradiction between measurement precision and loss of time.
Solution Approach 2:
The system automatically detects when noise characteristics change and initiates filter coefficient renewal only when necessary. This self-service mechanism maintains accurate noise control without requiring continuous computational resources, thereby resolving the contradiction between noise control accuracy and processing time.
3Adaptability or versatility
If adaptive filters continuously renew coefficients, then adaptability to noise changes is improved, but risk of incorrect coefficients and unpleasant noise increases
Solution Approach 1:
The system performs preliminary detection of noise characteristic changes before initiating filter coefficient renewal. This preliminary action ensures that coefficient renewal is triggered only when actually needed, preventing incorrect coefficients from being generated during unnecessary updates, thereby resolving the contradiction between adaptability and harmful noise from incorrect coefficients.
Solution Approach 2:
The system uses feedback from noise characteristic analysis to determine when filter coefficient renewal is appropriate. This feedback mechanism prevents unnecessary or incorrect coefficient updates that could cause unpleasant noise, while still maintaining adaptability to genuine noise changes, thus resolving the contradiction between adaptability and harmful factors.
4Ease of operation
If fixed filters are used with pre-set coefficients, then processing simplicity is improved, but adaptability to changing noise conditions deteriorates
Solution Approach 1:
The system dynamically transitions between fixed filter mode (for simplicity during stable conditions) and adaptive filter mode (for adaptability during changing conditions). This dynamic operation allows the system to maintain processing simplicity while achieving necessary adaptability, resolving the contradiction between ease of operation and adaptability to noise conditions.
Solution Approach 2:
The system changes the filter operation mode between fixed and adaptive based on noise characteristic analysis. This parameter change enables the system to maintain processing simplicity during stable conditions while achieving adaptability when needed, thereby resolving the contradiction between ease of operation and adaptability to noise conditions.
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 reduces noise levels effectively and minimizes passenger discomfort by ensuring optimal noise reduction without the need for frequent recalibration, reducing computational load and labor, and preventing unpleasant noise levels from incorrect filter coefficients.
Implementation Method 1
reproduces a control sound having a reverse phase to that of a noise arriving at a control point, thereby reducing the noise
Data Source
AI summary
A noise control device includes the following structural elements. A signal memory records both of a noise signal supplied from a noise microphone and an error signal supplied from an error microphone. A filter coefficient calculator calculates a fixed filter coefficient of a control filter by using data recorded in the signal memory. A filter coefficient renewing section renews, at a given timing, a filter coefficient set at a fixed filter in a control filter to a filter coefficient read out from the filter coefficient calculator.