Rotorcraft-pilot coupling analysis through state-space aerodynamic modelling

The terminology ‘rotorcraft-pilot coupling’ denotes phenomena arising from interaction between pilot and rotorcraft. Among these, the present work deals with ‘pilot-assisted oscillations’ that derive from unintentional pilot actions on controls due to seat vibrations, and are strictly related to rotor-aeroelasticity/airframe-structural-dynamics coupling, with involvement of blade control actuator dynamics. Focusing the attention on helicopters, a comprehensive rotorcraft model is developed and applied, with main rotor unsteady aerodynamics described in state-space form. This makes it particularly suited for stability and frequency-response analysis, as well as control applications. Numerical investigations address two critical rotorcraft-pilot coupling aeroelastic issues: stability of vertical bouncing and gust response in hovering. Results from main rotor unsteady aerodynamics modelling are compared with widely-used quasi-steady aerodynamics predictions. These suggest that, for accurate RPC/PAO phenomena predictions, mathematical modelling should include the three-dimensional, unsteady-flow effects, and that the pilot-in-the-loop passive behaviour produces a beneficial effect on the load factor generated by gust encountering. AeronAuticAl JournAl September 2015 Volume 119 no 1219 1105 Paper No. 4274. Manuscript received 9 October 2014, revised version received 15 February 2015, second revised version received 21 April 2015, accepted 21 April 2015. Rotorcraft-pilot coupling analysis through state-space aerodynamic modelling J. Serafini serafini@uniroma3.it Roma Tre University Department of Engineering Rome Italy L. Greco CNR-INSEAN Marine Technology Research Institute Rome Italy

[1]  Massimo Gennaretti,et al.  Whirl flutter analysis of prop-rotors using unsteady aerodynamics reduced-order models , 2008, The Aeronautical Journal (1968).

[2]  Giuseppe Quaranta,et al.  Numerical Investigation of Aeroservoelastic Rotorcraft-Pilot Coupling , 2007 .

[3]  Frans C. T. van der Helm,et al.  A Biodynamic Feedthrough Model Based on Neuromuscular Principles , 2014, IEEE Transactions on Cybernetics.

[4]  Vincenzo Muscarello,et al.  Anatomy, modelling and prediction of aeroservoelastic rotorcraft pilot coupling , 2013 .

[5]  Giuseppe Quaranta,et al.  Effects of Biodynamic Feedthrough in Rotorcraft/Pilot Coupling: Collective Bounce Case , 2013 .

[6]  Joost Venrooij,et al.  Biodynamic Pilot Modelling for Aeroelastic A/RPC , 2013 .

[7]  L. Morino,et al.  Matrix fraction approach for finite-state aerodynamic modeling , 1995 .

[8]  Giuseppe Quaranta,et al.  Aeroservoelastic Investigation of Rotorcraft-Pilot Coupling (RPC) by Coupled BEM/Multibody Analysis , 2011 .

[9]  H. Ashley,et al.  Unsteady aerodynamic modeling for arbitrary motions , 1977 .

[10]  Massimo Gennaretti,et al.  A finite-state aeroelastic model for rotorcraft–pilot coupling analysis , 2014 .

[11]  Giovanni Bernardini,et al.  Aeroelastic response of helicopter rotors using a 3D unsteady aerodynamic solver , 2006, The Aeronautical Journal (1968).

[12]  Pedro Ferreira,et al.  An MDP Model-Based Reinforcement Learning Approach for Production Station Ramp-Up Optimization: Q-Learning Analysis , 2014, IEEE Transactions on Systems, Man, and Cybernetics: Systems.

[13]  Massimo Gennaretti,et al.  Finite-state aerodynamic modelling for gust load alleviation of wing–tail configurations , 1999, The Aeronautical Journal (1968).

[14]  Joost Venrooij,et al.  Impact of pilots’ biodynamic feedthrough on rotorcraft by robust stability , 2013 .

[15]  Mordechay Karpel.  Design for Active Flutter Suppression and Gust Alleviation Using State-Space Aeroelastic Modeling , 1982 .

[16]  Gareth D. Padfield,et al.  Helicopter Flight Dynamics , 2000 .

[17]  Massimo Gennaretti,et al.  Adverse rotorcraft-pilot coupling: Recent research activities in Europe , 2008 .

[18]  Andrea Zanoni,et al.  Dependence of helicopter pilots’ biodynamic feedthrough on upper limbs’ muscular activation patterns , 2013 .

[19]  Joachim Götz,et al.  Adverse Rotorcraft-Pilot Coupling , 2008 .

[20]  Vincenzo Muscarello,et al.  Rotorcraft aeroelastic stability using robust analysis , 2014 .

[21]  Giuseppe Quaranta,et al.  A closed loop experiment of collective bounce aeroelastic Rotorcraft–Pilot Coupling , 2014 .

[22]  Massimo Gennaretti,et al.  A finite-state aeroelastic model for rotorcraft pilot-assisted-oscillations analysis , 2012 .

[23]  Massimo Gennaretti,et al.  A comparison among some aeroelastic models for the stability analysis of a flap-lag-torsion helicopter rotor in hover , 2000 .

[24]  Frans C. T. van der Helm,et al.  Mathematical Biodynamic Feedthrough Model Applied to Rotorcraft , 2014, IEEE Transactions on Cybernetics.

[25]  Giovanni Bernardini,et al.  Analysis of a structural-aerodynamic fully-coupled formulation for aeroelastic response of rotorcraft , 2013 .

[26]  R. Vepa,et al.  On the use of Pade approximants to represent unsteady aerodynamic loads for arbitrarily small motions of wings , 1976 .

[27]  R. Loewy.  A Two-Dimensional Approximation to the Unsteady Aerodynamics of Rotary Wings , 1957 .

[28]  D. H. Roberta. Hodges,et al.  Stability of elastic bending and torsion of uniform cantilever rotor blades in hover with variable structural coupling , 1976 .

[29]  Massimo Gennaretti,et al.  An optimal control approach for alleviation of tiltrotor gust response , 2012, The Aeronautical Journal (1968).

[30]  K. L. Roger,et al.  Airplane Math Modeling Methods for Active Control Design , 1977 .

[31]  T. Theodorsen.  General Theory of Aerodynamic Instability and the Mechanism of Flutter , 1934 .

[32]  Giuseppe Quaranta,et al.  Experimental and numerical helicopter pilot characterization for aeroelastic rotorcraft–pilot coupling analysis , 2013 .

[33]  Massimo Gennaretti,et al.  Time-dependent coefficient reduced-order model for unsteady aerodynamics of proprotors , 2005 .

[34]  Earl H. Dowell,et al.  Nonlinear equations of motion for the elastic bending and torsion of twisted nonuniform rotor blades , 1974 .

[35]  Linghai Lu,et al.  Adverse Rotorcraft-Pilot Couplings - Modelling and Prediction of Rigid Body RPC. Sketches from the Work of European Project ARISTOTEL 2010-2013 , 2013 .

[36]  Satya N. Atluri,et al.  Computational nonlinear mechanics in aerospace engineering , 1992 .