Active Noise Control Performance Estimation via Signal Copying
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Solution Overview
Problem
Existing active noise control systems for vehicles cannot estimate noise reduction performance without turning off the system, which is always in the ON state after production.
Innovation Solution
A method and system that estimate noise reduction performance by generating an estimation signal for the original noise before active noise control and using a residual signal, without requiring the system to be turned off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the active noise control system is kept in the ON state for continuous operation, then noise reduction performance is maintained, but noise reduction performance cannot be measured or estimated
Solution Approach 1:
The patent creates a virtual copy of the original noise signal by using the residual noise and control signal to generate an estimated original noise signal. This allows measurement of noise reduction performance without actually turning off the ANC system, as the estimated signal replicates what the original noise would have been for comparison purposes
Solution Approach 2:
The patent introduces an intermediary estimation process that uses the residual noise and control signal as intermediate elements to reconstruct the original noise characteristics. This intermediary approach enables performance measurement while the system remains operational
2Measurement precision
If the active noise control system is turned off to measure noise reduction performance, then noise reduction performance can be measured, but continuous noise reduction protection is lost
Solution Approach 1:
Instead of turning off the system to measure performance, the patent creates a virtual copy of the original noise through signal processing of the residual noise and control signal. This copying method enables measurement while maintaining the protective noise reduction function active
Solution Approach 2:
The system uses its own operational outputs (residual noise and control signal) to perform self-diagnosis and performance measurement. This self-service capability allows the system to monitor its own effectiveness without external intervention or shutdown
3Productivity
If signal processing operations are performed to generate estimation signals during ANC operation, then noise reduction performance can be estimated in real-time, but computational complexity increases
Solution Approach 1:
The patent replaces complex physical measurement methods with signal processing operations. Instead of physically shutting down the system to measure noise levels, it uses mathematical operations on existing signals (residual noise and control signal) to estimate performance, substituting mechanical/physical measurement with computational analysis
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
Enables real-time estimation of noise reduction performance, monitors performance and stability deterioration, and provides historical data for maintenance and improvement of the active noise control system.
Implementation Method 1
ANC systems typically cancel or reduce unwanted noise by generating canceling sound waves for destructively interfering with unwanted audible noise. In canceling interference, noise and 'anti-noise' which is approximately equal in magnitude but opposite in phase reduce a sound pressure level (SPL) at a certain location.
Data Source
AI summary
A method of estimating active noise control performance of a vehicle includes performing ANC by reproducing an acoustic signal for reducing noise introduced from the outside to the inside of the vehicle through a speaker and receiving a residual signal remaining after noise reduction from a microphone, generating an estimation signal for a control signal for controlling output of the speaker such that the acoustic signal is reproduced during the ANC, generating an estimation signal for original noise before the ANC based on the residual signal and the estimation signal for the control signal, and estimating noise reduction performance based on the estimation signal for the original noise and the residual signal.