CEAS 2015 paper no. 57 Page | 1 This work is licensed under the Creative Commons Attribution International License (CC BY). Copyright © 2015 by author(s). Preliminary Design Rules for Electromechanical Actuation Systems – Effects of Saturation and Compliances Jian FU, Ion HAZYUK, Jean-Charles MARÉ Institut Clément Ader, INSA-Toulouse, Université de Toulouse 135 Avenue du Rangueil, 31077, Toulouse Cedex 4, France jian.fu@insa-toulouse.fr, ion.hazyuk@insa-toulouse.fr, jean-charles.mare@insa-toulouse.fr ABSTRACT Electromechanical actuator (EMA) is a type of power-by-wire (PBW) actuator that is becoming widely implemented in aerospace industry. Given the application area, designing an EMA is highly constrained in weight, integration space, maintenance costs, dynamic performances, reliability, etc. In order to reduce the EMA’s design time, cost and effort, all these constraints should be considered in the preliminary design stages. The problem is that at such early design stages, system engineers need simple and explicit models. Thus, this communication is attempting to formulate simple relations that account for torque and velocity saturation of the EMA as well as compliances effects on its dynamic performance. The simple and parametric models predict the main impact of the sizing variables on performance. Keywords: Aerospace, EMA, Flight Control, Preliminary Design, Modeling and Simulation ABBREVIATIONS F e , F ex EMA out and aerodynamic action force [N] I s , I m DC supplied and motor current [A] J m Inertia of the rotor [kgm 2 ] K p Position controller gain [Nm/m] K’ p Position controller gain for speed limit control architecture [(rad/s)/m] K v , K’ v Classical and speed limited architecture velocity controller gain [Nm/(rad/s)] k a , k s , k t , k z Anchorage, nut-screw, transmission and structural compliance [N/m] k e EMA equivalent compliance [N/m] M t , M s , M m EMA rod, equivalent flight surface and equivalent motor mass [Kg] p Lead of roller screw [mm] T r , T m , T e , T lim EMA reference, output, electromagnetic and limit torque [Nm] t s , t su , t ss Ideal minimum, unsaturated and saturated response time [s] U s , U m Supplied DC and motor voltage [V] V e , V ex EMA output and aerodynamic linear velocity [m/s] x c , x e , x s EMA command, rod and flight surface position [m]   ,  T EMA rotation speed and torque saturation ratio [-]  p ,  d Static position and static disturbance tracking error [m]  p ,  pu ,  ps Ideal unsaturated and saturated overshoot [-]  r ,  m ,  lim Motor reference, actual and limit velocity [rad/s]  n Natural frequency [rad/s]  Damping factor [-] BLDC, PMSM Brushless Direct Current and Permanent Magnet Synchronous Motor SHA, EHA, EMA Servo-Hydraulic, Electro-Hydrostatic and Electromechanical Actuator LVDT Linear Variable Displacement Transducer PDE Power Drive Electronics