Active Vibration Noise Control Using Overall Correlation
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Solution Overview
Problem
Conventional active vibration noise control devices struggle to accurately detect disturbances in noise when periodic components are small, leading to unstable noise reduction and potential noise amplification.
Innovation Solution
An active vibration noise control device that includes a speaker for cancellation sounds, an error microphone for generating error signals, and a control filter that uses overall correlation calculations between reference signals and error signals to determine the presence of disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional active vibration noise control devices use correlation value detection to determine disturbance presence, then control can be switched based on disturbance detection, but the determination becomes inaccurate when periodic noise components are small
Solution Approach 1:
The patent changes the parameter used for disturbance detection from single-channel correlation value to multi-channel overall correlation. By summing correlation functions across multiple channels (reference signals and error signals), the system achieves more accurate disturbance detection that is not dependent on the strength of periodic noise components in individual channels.
2Reliability
If disturbance detection relies on correlation value decrease, then control switching can be implemented, but noise amplification occurs and noise reduction effect becomes unstable
Solution Approach 1:
The patent implements a feedback mechanism where the overall correlation value (calculated from multiple correlation functions) is continuously monitored and used to control the cancellation sound output. This feedback loop allows the system to adjust cancellation sound levels based on real-time disturbance detection, preventing noise amplification and ensuring stable noise reduction.
3Productivity
If cancellation sound output is adjusted based on disturbance detection, then noise reduction can be optimized, but the system becomes complex
Solution Approach 1:
The patent merges multiple correlation function calculations into a single overall correlation value by summing the correlation functions across all channels. This consolidation simplifies the control logic while maintaining the benefits of multi-channel analysis, reducing computational complexity without sacrificing noise reduction efficiency.
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
Accurately detects disturbances and stably reduces noise even when periodic noise components are small, preventing noise amplification and ensuring stable noise reduction.
Implementation Method 1
an error microphone for generating an error signal from the noise and the cancellation sound
Implementation Method 2
a speaker for outputting a cancellation sound for canceling a noise
Data Source
AI summary
An active vibration noise control device includes: a speaker for outputting a cancellation sound for canceling a noise; an error microphone for generating an error signal from the noise and the cancellation sound; a control filter configured to generate the cancellation sound based on a plurality of reference signals corresponding to the noise; and a disturbance determination part configured to make a determination as to whether a disturbance is present using the error signal and the plurality of reference signals. The disturbance determination part is configured to: calculate an overall correlation by summing a correlation function between each of the plurality of reference signals and the error signal, and make the determination as to whether the disturbance is present based on the overall correlation.