Adaptive Algorithms for Rotorcraft Active Vibration Control

Rotorcraft vibration suppression has traditionally relied on passive devices, such as vibration isolation systems and dynamic absorbers that are effective at a single rotor speed. However, modern rotorcraft designs are moving towards variable rotor speed configurations for improved performance and reduced noise initiatives. Thus, in recent years airframe manufacturers, including Bell Helicopter Textron Inc., have been developing advanced Active Vibration Control (AVC) systems. Adaptive AVC algorithms have been developed and tested at Bell Helicopter to address the challenges of multiple rotor speeds and other aircraft changes that influence the vibration environment. These AVC algorithms are developed around the gain scheduling, automated real-time transfer function identification, and adaptive reference model methods. Laboratory testing of the algorithms using full-scale hardware has demonstrated their effectiveness and robustness. These algorithms have also been flight tested successfully on a Bell Model 430 helicopter. A summary of the algorithms and the test results is presented.