Adaptive Notch Filter for Active Vibratory Noise Control
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Solution Overview
Problem
Existing active vibratory noise control systems face challenges in efficiently canceling noise at rapid vehicle accelerations due to high processing loads and insufficient modeling of signal transfer characteristics, leading to inadequate noise control capabilities and increased costs.
Innovation Solution
The system employs adaptive notch filters with reference signals generated by subtracting and adding products of sine and cosine corrective values based on phase characteristics, optimizing filter coefficients without using FIR filters, thereby reducing computational requirements and improving noise cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If FIR filter is used to generate reference signal, then noise control capability is improved, but processing load increases and device cost increases
Solution Approach 1:
The patent extracts only the essential frequency and phase characteristics needed for noise control, discarding the complex convolutional calculation structure of FIR filters. By using simple sine wave generation with adaptive frequency and phase adjustment, it achieves noise control capability while eliminating excessive processing load.
Solution Approach 2:
The patent replaces expensive high-performance digital signal processors required for FIR filter calculations with inexpensive microcomputers that can handle simple sine wave generation and adaptive parameter adjustment, significantly reducing device cost while maintaining effective noise control.
2Reliability
If FIR filter is used to generate reference signal, then noise control capability is improved, but device cost increases
Solution Approach 1:
The patent replaces expensive high-performance digital signal processors required for FIR filter calculations with inexpensive microcomputers that can handle simple sine wave generation and adaptive parameter adjustment, significantly reducing device cost while maintaining effective noise control.
Solution Approach 2:
The patent substitutes complex digital signal processing mechanics with simpler trigonometric calculations and adaptive parameter adjustment, replacing the need for expensive specialized hardware with standard microcomputer components.
3Device complexity
If adaptive notch filter is used without proper signal transfer characteristics modeling, then processing load is reduced, but noise control capability deteriorates
Solution Approach 1:
The patent performs preliminary measurement and storage of signal transfer characteristics (gain and phase) before operation. During actual noise control, these pre-measured characteristics are used to guide adaptive parameter adjustment, ensuring effective noise control without requiring complex real-time calculations.
Solution Approach 2:
The patent implements feedback mechanisms where the measured signal transfer characteristics are continuously used to adjust the adaptive parameters of the sine wave generator, ensuring the reference signal remains synchronized with the actual noise characteristics and maintains effective noise control.
Data Source
AI summary
The filter coefficients of an adaptive notch filter are sequentially updated to minimize an error signal based on the error signal and a first reference signal which is produced by subtracting a signal which represents the product of a sine corrective value C1 and a reference sine signal, from a signal which represents the product of a cosine corrective value C0 and a reference cosine signal. The filter coefficients of an adaptive notch filter are sequentially updated to minimize the error signal based on the error signal and a second reference signal which is produced by adding a signal which represents the product of the reference sine signal and the cosine corrective value C0 and a signal which represents the product of the reference cosine signal and the sine corrective value C1 to each other.