Generalized Active Control of Vibrations in Helicopters

Abstract

The problem of active control of vibrations in the main rotor of helicopters is dealt with in the individual blade control framework. We propose a controller valid for a generic e ight condition by resorting to a linear parametrically varying (LPV)controltechniquecoupled with theso-called internalmodelcontrol (IMC)principle. The problem can be reformulated as the one of rejecting a periodic disturbance having known frequency acting on the output of a suitable linear time-varying dynamic model. The main advantage of our control technique is the e exibility of the LPV ‐IMC approach: It not only can be used with the generic e ight condition, but it also can be adapted to comply with a rotor blade model having a complex structure. We obtain a unique controller that automatically gets adapted to the measured advance ratio. An alternative to this control rationale would be to resort to the gain scheduling of periodic controllers, one for each forward e ight condition. However, as indicated by our previous research, this would require keeping memory of a large number of control laws in the onboard computer. Furthermore, an H1 control strategy is considered to take into account the effects of both unmodeled dynamics and unmodeled disturbances.