| 摘要 |
<p>An active noise control (ANC) system (10) for a helicopter that is operative to effectively nullify one or more high frequency vibrations emanating from the main transmission gearbox thereof at the gearbox/airframe interface, thereby significantly reducing the interior noise levels of the helicopter, that is design optimized to minimize the number of actuators required, and that is design optimized to minimize contamination forces arising from operation of the system actuators. The ANC system includes modified transmission beams (12) that are mechanically stiffened to function as rigid bodies with respect to the one or more of the high frequency vibrations, a plurality of actuators (20) disposed in combination with the modified transmission beams (12), a plurality of sensors (30) disposed in combination with the modified transmission beams (12) in a colinear, spaced apart functional correlation with respective actuators (20), and controllers (40) interconnecting individual actuators (20) with respective functionally correlated sensors (30). Each transmission beam (12) may be mechanically stiffened in its entirety or only at localized segments adjacent each mounting hardpoint (14) thereof. Each sensor (30) is operative to detect a single dimensional component of the one or more high frequency vibrations and to generate a signal representative thereof. Each controller (40) is operative in response to such signal to generate a command signal to control operation of the respective actuator (20). Each actuator (20) is operative in response to command signals to generate dimensional counterforces having a frequency, magnitude, and phase to effectively nullify the respective dimensional component of the one or more high frequency vibrations emanating from the transmission gearbox. Each actuator (20) is further operative in response to such command signals to generate cancelling forces to counteract contaminating forces arising from operation of the actuators (20).</p> |
