Dynamic in-vehicle noise cancellation divergence control

Patent metadata

Field	Value
Publication number	US-11205413-B2
Application number	US-202016859396-A
Country	US
Kind code	B2
Filing date	Apr 27, 2020
Priority date	May 7, 2019
Publication date	Dec 21, 2021
Grant date	Dec 21, 2021

Abstract

An active noise cancellation (ANC) system may include an adaptive filter divergence detector for detecting divergence of the one or more controllable filters as they adapt, based on dynamically adapted thresholds. Upon detection of a controllable filter divergence, the ANC system may be deactivated, or certain speakers may be muted. Alternatively, the ANC system may modify the diverged controllable filters to restore proper operation of the noise cancelling system.

First claim

What is claimed is:

1. A method for controlling stability in an active noise cancellation (ANC) system, the method comprising:
receiving, from a vehicle sensor, sensor signals indicative of current vehicle operating conditions affecting an interior soundscape of a vehicle cabin;
retrieving a threshold adjustment value from a look-up table based on the sensor signals;
modifying a nominal threshold for detecting ANC system divergence by the threshold adjustment value to obtain an adjusted threshold;
receiving an error signal output from a microphone located in the vehicle cabin;
computing a parameter based on an analysis of at least a portion of the error signal; and
modifying properties of a controllable filter in response to the parameter exceeding the adjusted threshold, the controllable filter configured to generate an anti-noise signal based on an adaptive transfer characteristic and a noise signal.

2. The method of claim 1 , wherein the parameter is an amplitude of the error signal at one or more frequencies.

3. The method of claim 1 , wherein the nominal threshold is a predetermined static threshold programmed for the ANC system under nominal operating conditions.

4. The method of claim 1 , wherein the sensor signals received from the vehicle sensor includes the noise signal received from a vibration sensor.

5. The method of claim 1 , wherein the sensor signals received from the vehicle sensor include engine torque signals.

6. The method of claim 1 , wherein the sensor signals received from the vehicle sensor are indicative of at least one of vehicle speed, engine rotational speed, and accelerator pedal position.

7. The method of claim 1 , wherein modifying properties of the controllable filter comprises resetting filter coefficients of the controllable filter to a set of filter coefficient values stored in memory.

8. The method of claim 1 , wherein modifying properties of the controllable filter comprises increasing a leakage value of an adaptive filter controller.

9. The method of claim 8 , further comprising:
decreasing the leakage value of the adaptive filter controller when the parameter falls below the adjusted threshold.

10. The method of claim 1 , wherein modifying the nominal threshold by the threshold adjustment value includes adding the threshold adjustment value to the nominal threshold to obtain the adjusted threshold.

11. The method of claim 1 , wherein modifying the nominal threshold by the threshold adjustment value includes multiplying the threshold adjustment value by the nominal threshold to obtain the adjusted threshold.

12. An active noise cancellation (ANC) system comprising:
at least one controllable filter configured to generate an anti-noise signal based on an adaptive transfer characteristic and a noise signal, the adaptive transfer characteristic of the at least one controllable filter characterized by a set of filter coefficients;
an adaptive filter controller, including a processor and memory, programmed to adapt the set of filter coefficients based on the noise signal and an error signal received from a microphone located in a cabin of a vehicle; and
a divergence controller in communication with at least the adaptive filter controller, the divergence controller including a processor and memory programmed to:
receive, from a vehicle sensor, sensor signals indicative of current vehicle operating conditions affecting an interior soundscape of the cabin;
retrieve a threshold adjustment value from a look-up table based on the sensor signals;
retrieve a dynamic threshold for detecting ANC system divergence based on the sensor signals;
modify the dynamic threshold for detecting ANC system divergence by the threshold adjustment value to obtain an adjust dynamic threshold;
receive the anti-noise signal from the controllable filter and compute a parameter based on an analysis of at least a portion of the anti-noise signal; and
modify properties of the at least one controllable filter in response to the parameter exceeding the adjusted dynamic threshold.

13. The ANC system of claim 12 , wherein the parameter is an amplitude of the anti-noise signal at one or more frequencies.

14. The ANC system of claim 12 , wherein the sensor signals received from the vehicle sensor includes at least one of the noise signal and an engine torque signal.

15. The ANC system of claim 12 , wherein the properties of the at least one controllable filter is modified by the divergence controller by resetting the set of filter coefficients of the at least one controllable filter to a known state using a different set of filter coefficients stored in memory.

16. The ANC system of claim 12 , wherein the properties of the at least one controllable filter is modified by the divergence controller by increasing a leakage value of the adaptive filter controller.

17. A computer-program product embodied in a non-transitory computer readable medium that is programmed for active noise cancellation (ANC), the computer-program product comprising instructions for:
receiving an anti-noise signal output from a controllable filter and an error signal output from a microphone located in a vehicle cabin, the anti-noise signal being indicative of anti-noise to be radiated from a speaker into the vehicle cabin;
receiving, from a vehicle sensor, sensor signals indicative of current vehicle operating conditions affecting an interior soundscape of the vehicle cabin;
adjusting a nominal anti-noise threshold for detecting ANC system divergence based on the sensor signals to obtain an adjusted anti-noise threshold;
adjusting a nominal microphone-level threshold for detecting ANC system divergence based on the sensor signals to obtain an adjusted microphone-level threshold;
computing a first parameter based on an analysis of the anti-noise signal;
computing a second parameter based on an analysis of the error signal; and
modifying an adaptive transfer characteristic of the controllable filter in response to at least one of the first parameter exceeding the adjusted anti-noise threshold and the second parameter exceeding the adjusted microphone-level threshold.

18. The computer-program product of claim 17 , wherein the instructions for modifying an adaptive transfer characteristic of the controllable filter includes:
detecting diverged frequencies of the controllable filter; and
resetting the diverged frequencies of the controllable filter to zero, attenuating filter coefficients at the diverged frequencies, or increasing a leakage value of an adaptive filter controller at the diverged frequencies.

19. The computer-program product of claim 17 further comprising instructions for:
retrieving an effort value component from a corresponding look-up table for each sensor signal indicative of the current vehicle operating conditions affecting the interior soundscape of the vehicle cabin;
calculating an overall effort value from a combination of the respective effort value components;
retrieving a first adjustment value from a first threshold adjustment table based on the overall effort value; and
retrieving a second adjustment value from a second threshold adjustment table based on the overall effort value;
wherein the nominal anti-noise threshold is adjusted based on the first adjustment value to obtain the adjusted anti-noise threshold and the nominal microphone-level threshold is adjusted based on the second adjustment value to obtain the adjusted microphone-level threshold.

Assignees

• Harman Int Ind

Inventors

• Bastyr Kevin J
• May James
• Trumpy David

Classifications

• G10K11/17835

  using detection of abnormal input signals · CPC title

• G10K11/1781 Primary

  characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions · CPC title

• G10K11/17879

  using both a reference signal and an error signal · CPC title

• G10K11/178 Primary

  by electro-acoustically regenerating the original acoustic waves in anti-phase · CPC title

• G10K11/17833

  by using a self-diagnostic function or a malfunction prevention function, e.g. detecting abnormal output levels · CPC title