Robustness Analysis of the Model-Predictive Position Control of an Electro-Mechanical Actuator for Primary Flight Surfaces

This paper deals with the design and the robustness analysis of a Model Predictive Control (MPC) for the position tracking of primary flight movables driven by elec-tro-mechanical actuators. The study is in particular focused on a rotary Elec-tro-Mechanical Actuator (EMA) by UMBRAGROUP, employing a patented mechanical transmission based on differential ball-screw mechanism characterized by huge gear ratio. To obtain a baseline reference, conventional PID regulators have been initially optimized by using multi-objective cost functions based on tracking accuracy, load disturbance rejection and power consumption. The position regulator has been then replaced by an MPC regulator, designed to balance performance, computational re-sources and safety constraints. A nonlinear physics-based simulation model of the EMA, entirely developed in the Matlab-Simulink environment and validated with ex-periments, has been used to compare the two control strategies. Simulation results in both time and frequency domains highlight that the MPC solution provides faster and more accurate position tracking, improved dynamic stiffness and reduced power ab-sorption. Finally, the robustness against model uncertainties of the MPC is addressed, by imposing random and combined deviations of model parameters from the nominal values (via Monte Carlo analysis). The results demonstrate that the implementation of MPC control laws could enhance the stability and the reliability of EMAs, thus sup-porting their application for safety-critical flight control functions.