Dependence of helicopter pilots’ biodynamic feedthrough on upper limbs’ muscular activation patterns

The involuntary interaction of pilots with vehicles is often an undesired consequence of the biodynamic feedthrough of cockpit vibrations into the control system in relation with the characteristics of the man–machine interface. This work presents a numerical study of how the estimated muscular activation patterns associated with performing basic helicopter piloting tasks may affect the variability of the pilot’s biodynamic feedthrough and admittance. The limbs’ motion is predicted using an inverse kinematics formulation for redundant manipulators imposing the motion of the hand from measurements. Articulation torques are then estimated by inverse dynamics. Activation of the involved muscles is estimated according to the ‘total activation’ paradigm. Equivalent pilot feedthrough is obtained by consistent linearization of the constitutive model of the muscles about the reference activation. The effect on equivalent feedthrough of non-optimal activation, resulting from the addition of torque-less activation modes to the optimal activation, is evaluated and discussed. The multibody model of the pilot’s biodynamic feedthrough is incorporated in a detailed multibody model of a helicopter, to perform coupled bioaeroservoelastic simulations.