Road Noise Cancellation Filter Memory for Fast Vehicle Restart
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Solution Overview
Problem
Road noise-cancellation systems lose their adaptive filter coefficients during shutdown, requiring a lengthy re-adaptation period when restarted, and can become unstable or divergent, leading to suboptimal noise cancellation.
Innovation Solution
Implementing a system that stores the last state of noise-cancellation filter coefficients in non-volatile memory before shutdown and restores them upon startup, using a noise sensor, actuator, and controller with an adaptive processing module and divergence detector to ensure stability and convergence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the vehicle is shut down, then power consumption is reduced, but the adaptive filter coefficients are lost and re-adaptation time increases
Solution Approach 1:
The system performs preliminary action by storing the adaptive filter coefficients in non-volatile memory before shutdown occurs. This ensures that when the vehicle restarts, the coefficients are already preserved and ready for immediate use, eliminating the need for time-consuming re-adaptation while maintaining the power savings from shutdown.
2Productivity
If the adaptive filter coefficients are continuously updated, then noise cancellation performance is improved, but system stability may deteriorate due to divergence
Solution Approach 1:
The system implements feedback through the error sensor that continuously monitors the noise cancellation effectiveness and feeds this information back to the adaptive processing module. This feedback mechanism allows the system to adjust the filter coefficients in real-time based on actual performance, improving noise cancellation while maintaining stability through controlled adaptation.
Solution Approach 2:
The system applies dynamics by making the filter coefficients adaptive and time-varying rather than fixed. The adaptive processing module continuously adjusts the coefficients based on changing road conditions and vehicle dynamics, allowing the system to optimize performance for different operating conditions while maintaining stability through controlled adaptation rates.
3Reliability
If the filter coefficients are restored from default settings, then system stability is improved, but noise cancellation performance deteriorates due to loss of adapted coefficients
Solution Approach 1:
The system performs preliminary action by storing the adapted filter coefficients in non-volatile memory before shutdown. This preserves the learned coefficients that represent optimal noise cancellation settings, so when the system restarts, it can restore these performance-optimized coefficients rather than reverting to default settings, thereby maintaining both stability and performance.
Data Source
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AI summary
A road noise-cancellation system (100), comprising: an actuator (110) disposed in a vehicle cabin (104); a controller (112) programmed to: generate a noise-cancellation signal (118) with a noise-cancellation filter including a first plurality of coefficients, the noise-cancellation signal being based on the first plurality of coefficients, the noise- cancellation signal being transduced by the actuator to generate a noise-cancellation audio signal based on the noise-cancellation signal, the noise-cancellation audio signal destructively interfering with an undesired noise in a noise-cancellation zone (102); adjust the first plurality of coefficients of the noise-cancellation filter based on one or more input signals to provide a second plurality of coefficients; store the second plurality of coefficients in the non-volatile memory (122) during a shutdown sequence or at the end of an interval; and restore the second plurality of coefficients from non-volatile memory to the noise-cancellation filter after startup or other conditions.