Active Noise Reduction Controller Disturbance Detection
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Solution Overview
Problem
Active noise reduction systems in vehicles often generate abnormal sounds due to disturbances like wind from air conditioners or open windows, which can cause the canceling sound to diverge, leading to ineffective noise cancellation.
Innovation Solution
An active noise reduction system that includes a canceling sound output device, a noise signal generator, and a controller that acquires and processes buffer data to detect disturbances by calculating correlation values and switching control accordingly, ensuring accurate detection and prevention of abnormal sound generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the speaker is controlled based on the canceling error sound, then the noise cancellation function is improved, but disturbance may be mixed into the canceling error sound causing abnormal sound generation
Solution Approach 1:
The patent introduces an intermediary detection mechanism between the microphone and the controller. The disturbance detection unit acts as a mediator that analyzes the canceling error sound to identify disturbance components before they can affect the speaker control. This intermediary layer filters out harmful disturbances while preserving the useful noise cancellation signal.
Solution Approach 2:
The system implements a feedback loop where the canceling error sound is continuously monitored and analyzed. The disturbance detection unit provides feedback about the presence of disturbances to the controller, which then adjusts the speaker control accordingly. This feedback mechanism enables the system to adapt to changing conditions and prevent abnormal sound generation.
2Measurement precision
If the controller continuously monitors and processes buffer data to detect disturbances, then the detection accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent segments the buffer data into multiple divided data portions for analysis. Instead of processing the entire buffer at once, the system divides it into smaller segments and calculates correlation values for each segment. This segmentation approach improves detection accuracy by enabling more granular analysis while reducing the computational complexity of processing large data sets.
Solution Approach 2:
The system performs partial processing of the buffer data by focusing on specific segments and correlation calculations rather than analyzing every aspect of the data. This partial action approach achieves sufficient detection accuracy without the excessive computational burden of complete data analysis, balancing precision and complexity.
Data Source
AI summary
An active noise reduction system includes a canceling sound output device configured to output a canceling sound for canceling a noise, a noise signal generator configured to generate noise signals based on the noise, and a controller configured to control the canceling sound output device based on the noise signals, wherein the controller is configured to acquire buffer data in which the noise signals are stored in a time series, generate a plurality of divided data by dividing the buffer data, calculate a correlation value of the buffer data based on the plurality of divided data, detect presence/absence of disturbance mixed in the buffer data based on the correlation value, and switch control over the canceling sound output device according to the presence/absence of the disturbance mixed in the buffer data.