Rotor-state feedback control design to improve helicopter turbulence alleviation in hover

Abstract

A helicopter flight control system with rotor-state feedback to improve turbulence alleviation in hover is presented. First, a flight dynamic model coupled with turbulence model is developed and validated. Then, an integrated control strategy with a rotor-state feedback control law is proposed based on the baseline control system. The feedback gains of body and rotor states are designed in synergy to improve turbulence alleviation in the interested frequency range of handling qualities. Subsequently, the effects of the rotor-state feedback gains on both the stability of rotor dynamics and helicopter turbulence alleviation are analyzed in detail. Finally, the effectiveness of the integrated control system is evaluated with linear analysis in frequency domain and nonlinear simulation in time domain. The results indicate that with the rotor-state feedback control law integrated into the control system, the helicopter turbulence alleviation in the interested frequency range is improved with less degradation in helicopter stability margins, and the roll and pitch rate responses of helicopter to turbulence, measured with Root-Mean-Square (RMS) values, are reduced by more than 50% and 35% respectively.

Large-Sized Multirotor Design: Accurate Modeling with Aerodynamics and Optimization for Rotor Tilt Angle

“…in which R is the rotor radius; b is the number of blades; e is the offset of the blade flapping hinge; r is the radial length from the blade profile to the flapping hinge; κ is the tip loss coefficient; m b is the blade mass; M β is the moment of inertia of the blade about the flapping hinge; K β is the spring stiffness of the flapping hinge; and I MR is the moment of inertia of the rotor. In addition, the details of F 1 ϕ i , F 2 ϕ i , and F 3 ϕ i are described in [27,28].…”

“…The simplified mathematical model of aerodynamics is adopted in [26]. In [27,28], an accurate model of the aerodynamics of a rotor is derived in detail. In addition, blade flapping and coaxial effects are analyzed in [29] and [30], respectively.…”