Robust Stability Analysis: A Tool to Assess the Impact of Biodynamic Feedthrough on Rotorcraft

Biodynamic feedthrough (BDFT) may significantly affect the closed-loop behavior of rotorcraft, reducing the stability and increasing the proneness to Rotorcraft-Pilot Couplings (RPC). Leveraging robust stability analysis, the inherently uncertain pilot BDFT can be treated as the uncertain portion of a feedback system, allowing analytical, numerical or graphical determination of proneness to RPC by comparing robust stability margins of helicopter models with BDFT data. The application of the proposed approach to collective bounce is exemplified using simple analytical helicopter and pilot BDFT models and is applied to detailed helicopter models and BDFT measurement data.