Sikorsky Aircraft Corporation

Thomas A Millott

Douglas G MacMartin

Christopher G Park

William Arthur Welsh

James W Fuller

Donald Joseph Butts

Stuart K Drost

Robert K Goodman

A noise-suppression assembly of a mechanical drive system having a rotational frequency includes an audio filter unit configured to receive a first audio signal and a timing signal of the mechanical drive system. The audio filter unit generates a noise-cancellation signal based on a frequency of the timing signal to suppress a noise generated by the mechanical drive system and to apply the noise-cancellation signal to the first audio signal to produce a filtered first audio signal. The frequency of the timing signal is based on the rotational frequency of the mechanical drive system.

Noise suppression device, system, and method

A system and method reduces undesired noise or vibration in a vehicle. The ambient vibration is measured and command signals are generated over time. The command signals are generated based upon the measured vibration and based upon a control weighting. By varying the control weighting over time, the maximum possible performance is always obtained subject to the saturation constraints.

Computationally efficient means for optimal control with control constraints

A noise or vibration control system improves the quality of adaptation estimates by filtering the input signals to the adaptation, selectively implementing a 'dead-zone' during which adaptation does not occur and by selectively adding a dither signal to the control commands. The dead-zone is based on the magnitude of the changes in the control commands, which are responding to the changes in the sensor signals. The dead-zone can be applied to all actuators simultaneously, or can be applied to the adaptation of each actuator channel independently. To maintain identifiability, a 'dither signal' is added to the control commands to &#x201c;ping&#x201d; the system to increase the amount of information available to the adaptive algorithm. The dither signal is preferably implemented on only one actuator channel at a time. Also, the dither amplitude for each channel is preferably set to be proportional to the current control amplitude. The quality of the adaptation estimates is also improved by filtering the input signals to the adaptation circuit, y=&#x394;z, and v=&#x394;u. Among other things, the filter matches the filtering applied by the harmonic estimator.

Adaptation performance improvements for active control of sound or vibration

A noise or vibration control system improves the quality of adaptation estimates by filtering the input signals to the adaptation, selectively implementing a &ldquo;dead-zone&rdquo; during which adaptation does not occur and by selectively adding a dither signal to the control commands. The dead-zone is based on the magnitude of the changes in the control commands, which are responding to the changes in the sensor signals. The dead-zone can be applied to all actuators simultaneously, or can be applied to the adaptation of each actuator channel independently. To maintain identifiability, a &ldquo;dither signal&rdquo; is added to the control commands to &ldquo;ping&rdquo; the system to increase the amount of information available to the adaptive algorithm. The dither signal is preferably implemented on only one actuator channel at a time. Also, the dither amplitude for each channel is preferably set to be proportional to the current control amplitude. The quality of the adaptation estimates is also improved by filtering the input signals to the adaptation circuit, y &equals;&Dgr;z , and v &equals;&Dgr;u . Among other things, the filter matches the filtering applied by the harmonic estimator.

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Milford, CT, United States of America

Thomas A Millott