Helicopter Vibratory Loads Alleviation through Combined Action of Trailing-Edge Flap and Variable-Stiffness Devices

摘要

The aim of this paper is the assessment of the capability ofcontrollers based on the combined actuation of flaps andvariable-stiffness devices to alleviate helicopter main rotorvibratory hub loads. Trailing-edge flaps are positioned at therotor blade tip region, whereas variable-stiffness devices arelocated at the pitch link and at the blade root. Control laws arederived by an optimal control procedure based on the besttrade-off between control effectiveness and control effort, underthe constraint of satisfaction of the equations governing rotorblade aeroelastic response. The numerical investigation concernsthe analysis of performance and robustness of the controltechniques developed, through application to a four-bladedhelicopter rotor in level flight. The identification of the mostefficient control configuration is also attempted.