Citation: Maré, J.-C. A Preliminary Top-Down Parametric Design of Electromechanical Actuator Position Control. Aerospace 2022, 9, 314. https://doi.org/10.3390/ aerospace9060314 Academic Editor: Gianpietro Di Rito Received: 28 March 2022 Accepted: 6 June 2022 Published: 9 June 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the author. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). aerospace Article A Preliminary Top-Down Parametric Design of Electromechanical Actuator Position Control Jean-Charles Maré INSA-Institut Clément Ader (CNRS UMR 5312), 31400 Toulouse, France; jean-charles.mare@insa-toulouse.fr Abstract: A top-down process is proposed and virtually validated for the position control of elec- tromechanical actuators (EMA) that use conventional cascade controllers. It aims at facilitating the early design phases of a project by providing a straightforward mean that requires simple algebraic calculations only, from the specified performance and the top-level EMA design parameters. This makes it possible to include realistic control considerations in the preliminary sizing and optimisa- tion phase. The position, speed and current controllers are addressed in sequence. This top-down process is based on the generation and use of charts that define the optimal position gain, speed loop second-order damping factor and natural frequency with respect to the specified performance of the position loop. For each loop, the control design formally specifies the required dynamics and the digital implementation of the following inner loop. A noncausal flow chart summarises the equations used and the interdependencies between data. This potentially allows changing which ones are used as inputs. The process is virtually validated using the example of a flight control actuator. This is achieved with resort to the simulation of a realistic lumped-parameter model, which includes any significant functional and parasitic effects. The virtual tests are run following a bottom–up approach to highlight the pursuit and rejection performance. Using low-, medium- and high-excitation mag- nitudes, they show the robustness of the controllers against nonlinearities. Finally, the simulation results confirm the soundness of the proposed process. Keywords: actuator; aerospace; electromechanical; flight control; friction; modelling; position control; preliminary design; simulation; validation 1. Introduction The last decade has seen significant progress in electromechanical technology for actu- ation. In the range of some kilowatts or some tens of kilonewtons, they provide attractive solutions compared with the servohydraulic (or so-called conventional) technology [1]. This evolution is particularly observed in aerospace, which is looking for greener actuation for flight controls, landing gears and engines. For many applications, electromechanical actuators (EMAs) have already reached the highest technology readiness level, TRL9, which enables them to be put into service. However, it appears that EMAs for aerospace cannot be standardised easily, as opposed to those devoted to industrial applications. This mainly comes from the specificity of requirements and constraints that concern the geometrical integration, the reliability, the mission profiles (including four-quadrant operation with numerous and rapid changes between quadrants) and the certifiability and development assurance level (DAL). The EMA control design itself is driven by these considerations. Although commercially off-the-shelf drives for industrial applications include effi- cient self-tuning features [2], each aerospace actuation project requires a specific activity for control design, which must suit the application constraints and development timing in a systems-engineering (SE) frame [3]. There are potentially many candidate types of controllers that today offer extended possibilities: for example, R-S-T digital poly- nomial controllers (combining parallel R, series S and feedforward T corrections), state Aerospace 2022, 9, 314. https://doi.org/10.3390/aerospace9060314 https://www.mdpi.com/journal/aerospace