Dynamic characteristic analysis for an electro-mechanical actuator based on planetary roller screw mechanism

Aiming at an electro-mechanical actuator (EMA) in an actuator loop, a model of EMA based on a planetary roller screw mechanism (PRSM) was developed to investigate the effects of nonlinearities associated with structural stiffness, friction and clearance on the dynamic characteristics of the EMA system. Anchorage compliance and transmission compliance related to aerodynamic force were considered. The simulation analysis results with AMESim showed that the improvement of anchorage compliance has a more important influence on the system's transient response than that of transmission compliance does; the fluctuation of the system's step response becomes more obvious with a bigger clearance in the PRSM; besides, under a certain input command, the maximum displacement output error of EMA is 1.8mm and the relative error is 1.2%. The nonlinear model was proved to be an effective one which provided a theoretical foundation for the further structural optimization and control of EMA.