Uncertainty Modeling Analysis And Reliability Calculation Of Electro-Hydrostatic Actuator

With the development of more electric/all electric aircraft, the.power of flight is delivered by wire. Power-by-Wire (PBW) actuator is a key aircraft component of operation and control system. It’s very important to improve actuator’s reliability for ensuring flight safety. As a typical representative of current airborne PBW actuators, Electro-Hydrostatic Actuator (EHA) has caused the concern widely. The higher demands about robustness and reliability of EHA are proposed by new generation aircraft. Uncertainty is one of the main factors that affect the aircraft EHA reliability. The research on reliability of EHA has already made some breakthrough; however, the research on uncertainty of EHA is almost blank.In order to eliminate uncertainty effects and improve the reliability of the EHA, based on the probability theory, the uncertainty modeling and the reliability calculation method of the EHA are studied in this paper. The contents and results are as follows:1) EHA system consists of many disciplines, such as mechanic, electric, hydraulic and control. The uncertainty of EHA system is analyzed qualitatively. Comprehensive assessments on the uncertainty, which affects EHA reliability, are made;2) Based on the complex multi-disciplinary EHA system, different discipline’s linear mathematical model is established respectively, comprising motor model, hydraulic model and mechanical model;3) Based on the established linear mathematical model, an uncertainty modeling method is proposed; uncertain parameters of EHA system are extracted and classified. Considering influence of the single parameter and the multi-parameters of the model respectively, the uncertainty model and the reliability calculation method of the EHA are established;4) Important parameters, which affect EHA reliability greatly, are selected to check the correctness of reliability model;5) Based on subsystems and overall system, the simulation model of EHA is established. The actuator’s cross-sectional area is taken as an example to check the correctness of the uncertainty model. Uncertainty model and method are verified by comparing with MATLAB/Simulation results. The numerical results are consistent with the results obtained from the simulation model. Validation results show that the uncertainty of the uncertainty model and the reliability calculation of EHA system, established in this paper, are efficient, reliable and comprehensive. Therefore, except for the EHA system, reliability calculation model can also be applied to other complex systems to estimate the system reliability. Meanwhile through the promotion, this model can also be used to estimate the MDO system uncertainty, which comprises a plurality of coupling disciplines. And it provides a theoretical basis for the construction of robust multidisciplinary design optimization methods.