Experimental and simulation study of the dynamics of an electro-mechanical landing gear actuator

This paper summarizes the testing and simulation activities carried out for the study of an electro-mechanical actuator for helicopter landing gear extension/retraction. The basic objective of the work was to obtain an experimentally-validated model of the actuator dynamics, to be used as support tool for the design enhancement as well as for the development of similar systems. The database for the model validation has been obtained by testing the actuator with a specifically developed real-time hardware-in-the-loop system, in which the actuator voltage supply is regulated by a programmable power unit, and its mechanical loading is controlled by a counteracting hydraulic servo. The test results in terms of actuator position, speed and motor currents, and related to different combinations of voltage supply and load factors, have been then used to tune the parameters of a model developed by the authors. The satisfactory matching between simulation predictions and experimental data allowed to highlight and discuss specific performance issues in the actuator speed response, which can be characterised by a limit-cycle behaviour when the landing gear is extended under high tensile loads.