A simple system for helicopter individual-blade-control and its application to gust alleviation

A new, advanced type of active control for helicopters and its application to gust alleviation is described. Each blade is individually controlled in the rotating frame over a wide range of frequencies up to the sixth harmonic of rotor speed. Considerable system simplification is achieved by means of modal decomposition. It is shown both analytically and experimentally that by utilizing a tip-mounted accelerometer as a sensor in the feedback path, significant reductions in blade flapping response to a sinusoidal gust can be achieved at the gust excitation frequency as well as at super- and subharmonics of rotor speed.