Model and experimental research of a hybrid self-contained electro-hydrostatic actuator using piezoelectric stack

Smart material–based electro-hydrostatic actuators are a potential alternative to traditional hydraulic actuators. Piezoelectric materials are a type of smart materials that can deliver large blocked forces. In this article, a piezoelectric stack–based electro-hydrostatic actuator is first introduced by presenting the schematic diagrams of its structure and work principle. Next, according to the research of the piezoelectric stack–based electro-hydrostatic actuator working principle, a mathematical model that can describe the dynamic characteristics of piezoelectric stack–based electro-hydrostatic actuator was established. The output displacement model of the piezoelectric stack–based actuator was established based on the improved asymmetric Bouc–Wen model. The simulation model was built in MATLAB/Simulink. Finally, experiments under different working conditions were conducted, as well as the corresponding simulations. The experimental results demonstrate that the prototype no-load output flow reaches its maximum at 275 Hz and the output flow peak is close to 1.6 L/min. Moreover, the load capacity is more than 20 kg and the maximum load is more than 50 kg according to the trend forecast. The simulation results exhibit good agreement with the experimental results, which means that the piezoelectric stack–based electro-hydrostatic actuator model is feasible.