Sizing and study of the regulation system of an electro-hydrostatic actuator for primary flight controls in a regional transport aircraft

Nowadays in the aeronautic field, the majority of civil aircraft are equipped with many electro-hydraulic actuation systems (EHSA) for primary flight controls. The only exceptions are the Airbus A380 and A350, which use an electro-hydrostatic actuation system but only as a backup in case of failure of the electro-hydraulic actuator. The purpose of this thesis work is to identify an alternative system for primary flight controls for the reference regional aircraft, within the wider framework of more-electric configuration. In particular, this work is aimed at integrating the models created within the Leonardo Labs Digital Flight Lab platform for aircraft-level architectural simulation of the interaction between the various on-board systems. In recent years, the research trend of the aeronautical industry has been oriented towards the replacement of the hydraulic lines in the primary flight controls with an electrical distribution of energy to the various actuation units. The choice of considering an electro-hydrostatic actuator as a possible alternative to traditional systems is part of the framework defined by this constructive criterion. The following design technique of such actuators can be scaled to any flight control surface of the reference aircraft. As a starting point, the aileron was taken into account. In the following thesis the context within which actuators for primary flight controls operates was initially presented; resorting to some fundamental concepts of flight mechanics. An overview of the current technologies available for actuation was then provided, analyzing their strengths and weaknesses. Following this general overview, the operation of an electro-hydrostatic actuator was specifically analyzed and a preliminary sizing in the static field was performed. The actuator regulation system was then designed, defining gains and strategies for each of the three control loops (current, speed, position). Firstly, this passage was performed in the linear field in order to identify the values for an approximate setting of the gains of the different control loops and to obtain an indication of the system stability margins. Secondly, one was made “high-fidelity” modeling of the system by implementing the equations available in the literature within the Matlab-Simulink ® simulation platform. This model was then used for analyze the behavior of the system in the non-linear field in order to verify compliance with the dynamic requirements within the entire operating range of the servo control.