Adaptive Filter Transfer-Function Phase Correction for Stability

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Solution Overview

Problem

Active noise control systems face challenges in dynamically adapting to changes in the environment, leading to instability and reduced noise cancellation efficiency, particularly in dynamic settings like vehicles where acoustic changes occur frequently.

Innovation Solution

The method involves identifying phase errors in the adaptive filter's transfer function by analyzing the trajectory of its coefficients over time, adjusting the phase to reduce these errors, and updating the filter coefficients based on the adjusted transfer function to ensure stability and effective noise cancellation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the adaptive filter uses fixed transfer function parameters, then the system is simpler to implement, but it cannot adapt to environmental changes leading to reduced noise cancellation efficiency

Engineering Contradiction:
Improveadaptability to environmental changesVSAvoidcomplexity of phase adjustment mechanism
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system automatically identifies and corrects its own phase errors through self-diagnosis of coefficient trajectories, eliminating the need for external manual tuning and achieving self-adaptation to environmental changes

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system uses feedback from the adaptive filter coefficient trajectories to detect phase errors and automatically adjusts the transfer function phase accordingly, creating a closed-loop control system that adapts to environmental changes

Inventive Principle:
Principle #23Feedback

2Productivity

If the adaptive filter coefficients are frequently updated to track environmental changes, then noise cancellation efficiency improves, but system stability deteriorates

Engineering Contradiction:
Improvenoise cancellation efficiencyVSAvoidsystem stability
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The system dynamically adjusts the transfer function phase based on real-time analysis of coefficient trajectories, allowing the filter to adapt to environmental changes while maintaining stability through controlled, data-driven adjustments rather than frequent arbitrary updates

Inventive Principle:
Principle #15Dynamics

3Measurement precision

If manual tuning is performed to optimize noise cancellation, then performance improves, but time consumption and operational complexity increase

Engineering Contradiction:
Improvenoise cancellation precisionVSAvoidtime for manual tuning
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The system performs self-tuning by automatically analyzing its own coefficient trajectories to identify phase errors and adjusting the transfer function accordingly, completely eliminating the need for manual intervention and time-consuming manual tuning processes

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system replaces manual tuning operations with automated computational analysis of coefficient trajectories and algorithmic phase adjustment, substituting human operators with automated signal processing methods

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS9485035B2Self-tuning transfer function for adaptive filtering
Publication Date: 2016.11.01 BOSE CORP
  • US9485035B2 patent drawing
  • US9485035B2 patent drawing
  • US9485035B2 patent drawing

AI summary

The technology described in this document can be embodied in a computer-implemented method that includes receiving, at one or more processing devices, a plurality of values representing a set of coefficients of an adaptive filter over a period of time, and identifying, by the one or more processing devices based on the plurality of values, a phase error associated with a transfer function of the adaptive filter. The method also includes adjusting, based on the identified phase error, a phase associated with the transfer function of the adaptive filter such that coefficients calculated using the adjusted transfer o function reduce the phase error. The method further includes determining a set of coefficients for the adaptive filter based on the adjusted transfer function, and programming the adaptive filter with the determined set of coefficients to enable operation of the adaptive filter.