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http://hdl.handle.net/10985/17395
Instability Mechanism of Roll/Lateral Biodynamic Rotorcraft–Pilot Couplings
MUSCARELLO, Vincenzo; MASARATI, Pierangelo; QUARANTA, Giuseppe; TOD, Georges; PAVEL, Marilena; GOMAND, Julien; MALBURET, François
The paper investigates the basic mechanism of aeroservoelastic pilot-assisted oscillation about the roll axis due to the interaction with pilot's arm biomechanics. The motivation stems from the observation that a rotor imbalance may occur as a consequence of rotor cyclic lead–lag modes excitation. The work shows that the instability mechanism is analogous to air resonance, in which the pilot's involuntary action plays the role of the automatic flight control system. Using robust stability analysis, the paper shows how the pilot's biodynamics may involuntarily lead to a roll/lateral instability. The mechanism of instability proves that the pilot biodynamics is participating in the destabilization of the system by transferring energy, i.e., by producing forces that do work for the energetically conjugated displacement, directly into the flapping mode. This destabilizes the airframe roll motion, which, in turn, causes lead–lag motion imbalance. It is found that, depending on the value of the time delay involved in the lateral cyclic control, the body couples with rotor motion in a different way. In the presence of small or no time delays, body roll couples with the rotor through the lead–lag degrees of freedom. The increase of the time delay above a certain threshold modifies this coupling: The body no longer couples with the rotor through lead–lag but directly through flap motion.
Mon, 01 Jan 2018 00:00:00 GMThttp://hdl.handle.net/10985/173952018-01-01T00:00:00ZMUSCARELLO, VincenzoMASARATI, PierangeloQUARANTA, GiuseppeTOD, GeorgesPAVEL, MarilenaGOMAND, JulienMALBURET, FrançoisThe paper investigates the basic mechanism of aeroservoelastic pilot-assisted oscillation about the roll axis due to the interaction with pilot's arm biomechanics. The motivation stems from the observation that a rotor imbalance may occur as a consequence of rotor cyclic lead–lag modes excitation. The work shows that the instability mechanism is analogous to air resonance, in which the pilot's involuntary action plays the role of the automatic flight control system. Using robust stability analysis, the paper shows how the pilot's biodynamics may involuntarily lead to a roll/lateral instability. The mechanism of instability proves that the pilot biodynamics is participating in the destabilization of the system by transferring energy, i.e., by producing forces that do work for the energetically conjugated displacement, directly into the flapping mode. This destabilizes the airframe roll motion, which, in turn, causes lead–lag motion imbalance. It is found that, depending on the value of the time delay involved in the lateral cyclic control, the body couples with rotor motion in a different way. In the presence of small or no time delays, body roll couples with the rotor through the lead–lag degrees of freedom. The increase of the time delay above a certain threshold modifies this coupling: The body no longer couples with the rotor through lead–lag but directly through flap motion.An Energetic Approach to Aeroelastic Rotorcraft-Pilot Couplings Analysis
http://hdl.handle.net/10985/9458
An Energetic Approach to Aeroelastic Rotorcraft-Pilot Couplings Analysis
TOD, Georges; BARRE, Pierre-Jean; BOUDON, Benjamin; GOMAND, Julien; MALBURET, François
This paper describes an energetic method using multibond graphs to model multi-physical systems. Its potential in building physical meaningful graphs that represent equivalent mathematical models of classic analytical approaches is shown. An application to the study of an aeroelastic rotorcraft-pilot coupling is studied by analyzing the passive pilot behavior in the cyclic control loop. A rotorcraft in hover flight is simulated and perturbed on its rolling motion axis. Depending on the rotorcraft characteristics air resonance may occur, and the pilot may involuntarily excite the cyclic lever, increasing the rolling motion of the fuselage to an unstable point. Future work will explore eventual alternative solutions to notch filters to avoid passive pilot reinjection at low fuselage frequency modes by controlling for example the actuators of the swashplate through model inversion using the bond graph method
Tue, 01 Jan 2013 00:00:00 GMThttp://hdl.handle.net/10985/94582013-01-01T00:00:00ZTOD, GeorgesBARRE, Pierre-JeanBOUDON, BenjaminGOMAND, JulienMALBURET, FrançoisThis paper describes an energetic method using multibond graphs to model multi-physical systems. Its potential in building physical meaningful graphs that represent equivalent mathematical models of classic analytical approaches is shown. An application to the study of an aeroelastic rotorcraft-pilot coupling is studied by analyzing the passive pilot behavior in the cyclic control loop. A rotorcraft in hover flight is simulated and perturbed on its rolling motion axis. Depending on the rotorcraft characteristics air resonance may occur, and the pilot may involuntarily excite the cyclic lever, increasing the rolling motion of the fuselage to an unstable point. Future work will explore eventual alternative solutions to notch filters to avoid passive pilot reinjection at low fuselage frequency modes by controlling for example the actuators of the swashplate through model inversion using the bond graph methodModeling Stiffness and Damping in Rotational Degrees of Freedom Using Multibond Graphs
http://hdl.handle.net/10985/9227
Modeling Stiffness and Damping in Rotational Degrees of Freedom Using Multibond Graphs
TOD, Georges; BARRE, Pierre-Jean; GOMAND, Julien; MALBURET, François
A contribution is proposed for the modeling of mechanical systems using multibond graphs. When modeling a physical system, it may be needed to catch the dynamic behavior contribution of the joints between bodies of the system and therefore to characterize the stiffness and damping of the links between them. The visibility of where dissipative or capacitive elements need to be implemented to represent stiffness and damping in multibond graphs is not obvious and will be explained. A multibond graph architecture is then proposed to add stiffness and damping in hree rotational degrees of freedom. The resulting joint combines the spherical joint multibond graph relaxed causal constraints while physically representing three concatenated revolute joints. The mathematical foundations are presented, and then illustrated through the modeling and simulation of an inertial navigation system; in which stiffness and damping between the gimbals are taken into account. This method is particularly useful when modeling and simulating multibody systems using Newton-Euler formalism in multibond graphs. Future work will show how this method can be extended to more complex systems such as rotorcraft blades' connections with its rotor hub.
Tue, 01 Jan 2013 00:00:00 GMThttp://hdl.handle.net/10985/92272013-01-01T00:00:00ZTOD, GeorgesBARRE, Pierre-JeanGOMAND, JulienMALBURET, FrançoisA contribution is proposed for the modeling of mechanical systems using multibond graphs. When modeling a physical system, it may be needed to catch the dynamic behavior contribution of the joints between bodies of the system and therefore to characterize the stiffness and damping of the links between them. The visibility of where dissipative or capacitive elements need to be implemented to represent stiffness and damping in multibond graphs is not obvious and will be explained. A multibond graph architecture is then proposed to add stiffness and damping in hree rotational degrees of freedom. The resulting joint combines the spherical joint multibond graph relaxed causal constraints while physically representing three concatenated revolute joints. The mathematical foundations are presented, and then illustrated through the modeling and simulation of an inertial navigation system; in which stiffness and damping between the gimbals are taken into account. This method is particularly useful when modeling and simulating multibody systems using Newton-Euler formalism in multibond graphs. Future work will show how this method can be extended to more complex systems such as rotorcraft blades' connections with its rotor hub.An upper limb musculoskeletal model using bond graphs for rotorcraft-pilot couplings analysis
http://hdl.handle.net/10985/9042
An upper limb musculoskeletal model using bond graphs for rotorcraft-pilot couplings analysis
TOD, Georges; BARRE, Pierre-Jean; GOMAND, Julien; MALBURET, François
Under certain flight conditions, a rotorcraft fuselage motions and vibrations might interact with its pilot voluntary and involuntary actions leading to potentially dangerous dynamic instabilities known as rotorcraft-pilot couplings (RPCs). A better understanding of this phenomenon could be achieved by being able to reproduce the phenomenon during simulations. Design guidelines could be then obtained at an early stage of development of rotorcrafts improving flight safety for pilots and passengers. In this work, an upper limb musculoskeletal model using bond graphs is presented. It is then integrated in a larger aeroelastic rotorcraft bond graph model that allows simulating pilot-rotor-fuselage couplings under several flight conditions. Simulations are performed and compared to literature’s models and experimental data.
Wed, 01 Jan 2014 00:00:00 GMThttp://hdl.handle.net/10985/90422014-01-01T00:00:00ZTOD, GeorgesBARRE, Pierre-JeanGOMAND, JulienMALBURET, FrançoisUnder certain flight conditions, a rotorcraft fuselage motions and vibrations might interact with its pilot voluntary and involuntary actions leading to potentially dangerous dynamic instabilities known as rotorcraft-pilot couplings (RPCs). A better understanding of this phenomenon could be achieved by being able to reproduce the phenomenon during simulations. Design guidelines could be then obtained at an early stage of development of rotorcrafts improving flight safety for pilots and passengers. In this work, an upper limb musculoskeletal model using bond graphs is presented. It is then integrated in a larger aeroelastic rotorcraft bond graph model that allows simulating pilot-rotor-fuselage couplings under several flight conditions. Simulations are performed and compared to literature’s models and experimental data.Understanding pilot biodynamical feedthrough coupling in helicopter adverse roll axis instability via lateral cyclic feedback control
http://hdl.handle.net/10985/11326
Understanding pilot biodynamical feedthrough coupling in helicopter adverse roll axis instability via lateral cyclic feedback control
TOD, Georges; PAVEL, Marilena; BARRE, Pierre-Jean; GOMAND, Julien; MALBURET, François
The paper reassesses the mechanism of biodynamical feedthrough coupling to helicopter body motion in lateral-roll helicopter tasks. An analytical bio-aeroelastic pilot–vehicle model is first developed and tested for various pilot's neuromuscular adaptions in the lateral/roll axis helicopter tasks. The results demonstrate that pilot can destabilize the low-frequency regressing lead-lag rotor mode; however he/she is destabilizing also the high-frequency advancing lag rotor mode. The mechanism of pilot destabilization involves three vicious energy circles, i.e. lateral-roll, flap-roll and flap-lag motions, in a very similar manner as in the air resonance phenomenon. For both modes, the destabilization is very sensitive to an increase of the steady state rotor coning angle that increases the energy transfers from flap to lag motion through Coriolis forces. The analytical linear time-invariant model developed in this paper can be also used to investigate designs proneness to lateral/roll aeroelastic rotorcraft–pilot couplings.
The authors thank Joost Venrooij, Project Leader at the Max Planck Institute for Biological Cybernetics, for providing the experimental results obtained on SIMONA flight simulator (TU Delft).
Fri, 01 Jan 2016 00:00:00 GMThttp://hdl.handle.net/10985/113262016-01-01T00:00:00ZTOD, GeorgesPAVEL, MarilenaBARRE, Pierre-JeanGOMAND, JulienMALBURET, FrançoisThe paper reassesses the mechanism of biodynamical feedthrough coupling to helicopter body motion in lateral-roll helicopter tasks. An analytical bio-aeroelastic pilot–vehicle model is first developed and tested for various pilot's neuromuscular adaptions in the lateral/roll axis helicopter tasks. The results demonstrate that pilot can destabilize the low-frequency regressing lead-lag rotor mode; however he/she is destabilizing also the high-frequency advancing lag rotor mode. The mechanism of pilot destabilization involves three vicious energy circles, i.e. lateral-roll, flap-roll and flap-lag motions, in a very similar manner as in the air resonance phenomenon. For both modes, the destabilization is very sensitive to an increase of the steady state rotor coning angle that increases the energy transfers from flap to lag motion through Coriolis forces. The analytical linear time-invariant model developed in this paper can be also used to investigate designs proneness to lateral/roll aeroelastic rotorcraft–pilot couplings.