Matching design rules of linear-driven electro-hydrostatic actuator

Electro-hydrostatic actuator (EHA) is a highly integrated pump controlled transmission system, and it has been successfully applied to A380 and F35 to drive main flight control surface. However, the traditional EHA composed by rotary motor and axial piston pump has limited dynamic response. This paper introduces a novel linear-driven electro-hydrostatic actuator (LEHA) with fast dynamic response, and studies the parameter design rules of LEHA. The key feature of LEHA is the novel linear pump with collaborative rectification principle. Pistons and valve spools in collaborative rectification pump are directly driven by linear motor. The parameter design rules of LEHA are firstly considered from the static index matching rules, and the constraint conditions of the maximum no-load speed, the constraint condition of the maximum static output force and the constraint condition of the maximum pressure of the system are deduced. According to LEHA's mathematic model, the influence of each parameter on the bandwidth of the LEHA is analyzed, and the dynamic performance design rule of LEHA is obtained, which is the constraint condition of the LEHA bandwidth index to the resonance frequency of the linear motor. The power constraint condition of LEHA is analyzed finally, and the power envelope condition of LEHA for inertial load, elastic load and viscous damping load is given in the output force-velocity coordinates, from which the power matching design rule of the LEHA is obtained. In conclusion, the 6 matching design constraints of LEHA parameter design rule can provide a theoretical basis for the design process of LEHA.