Researches on the hybrid electro-hydraulic actuators

The new generation of „more electric” actuators involve simpler, cheaper and lighter power generation and distribution architectures. To achieve this goal, the electro hydraulic servovalves controlled by electrical signals have to be eliminated in the frame of the new concept „Power-by-Wire”, which uses electric power to actuate flight control surfaces, robotic arms, steering systems, presses etc. These developments have generated two new types of actuators: electro-hydrostatic (hybrid) actuators (EHA) and electro mechanical actuators (EMA). This paper presents both the modeling and simulation of an original hybrid actuator, and the static and dynamic performances of a real one with similar electric, mechanic and hydraulic parameters. The simulations were performed for the control of an asymmetrical hydraulic cylinder. The validation experiments were performed on the original test bench. The new concept of the hybrid servosystems was validated by the good accuracy for different type of inputs. The time constant for a step type input signal is good enough for any industrial application.