Model And Experimental Research Of Electro-hydrostatic Actuator Driven By Piezoelectric Stack

Confronted with the development of the modern aircraft,conventional airborne hydraulic system develops to the distributed and miniaturization direction.Meantime,intelligent material-based electro-hydrostatic actuator has been developed to a potential development direction of the airborne actuator because of its advantages of compact structure.In this paper,an electro-hydrostatic actuator using a piezoelectric stack(PEHA)as its driving element is developed,the main work is conducted in order of experimental prototype development,experimental characteristic observation,theoretical modeling and simulation,prototype improvement research.Firstly,the mechanical structure of the electro-hydrostatic actuator driven by a piezoelectric stack is designed according to the general working principle of the intelligent material-based electro-hydrostatic actuator,the experimental prototype is developed and the experiments are conducted under different input voltage,bias pressure and load.The experimental results show that the prototype output flow reaches 1.6L/min with no-load and nearly 1.0L/min driving 20 kg at 275 Hz.Then,Based on the observation of experimental characteristics,the research work of actuator modeling,comparison of simulation and experiment is carried out.First,in view of the adverse effects of piezoelectric materials hysteresis nonlinearity on the actuator control performance,the hysteresis nonlinearity of the piezoelectric stack output displacement is modeled based on the asymmetric Bouc-Wen model.On this basis,the mathematical model and simulation model of the piezoelectric stack actuator(PSA)dynamic output displacement are established,and the simulation and experimental research are carried out.The results show that The PSA maximum output displacement is 37?m corresponds to 100 Vpp input voltage;And in the range of 0-100 Vpp excitation voltage and 0-600 Hz excitation frequency,the maximum error between the PSA output displacement hysteresis loop simulation results and the experimental results is not more than 4?m.Second,in order to build the whole system model of actuator,the mathematical model of the fluid transmission part is built based on the concept of the Mechanical-Electric-Hydraulic systems simulation.And the fluid structure coupling problem of the cantilever valve,which is a key part of the fluid transmission part,is studied through the finite element analysis,to identify the cantilever valve's equivalent mass,stiffness and other parameters.Based on the above work,the simulation model of the whole PEHA system is built in MATLAB/Simulink and the simulation of output flow under different conditions is carried out.According to the comparison between simulation results and experimental results,under the condition of no load and 0-20 kg load,excitation frequency in the 0-450 Hz range,100 Vpp,120Vpp and 140 Vpp input voltage,1.0MPa and 1.2MPa system bias,the PEHA simulation results can describe the experimental results accurately.And the correctness of the above theoretical model and simulation model is verified.Finally,the PEHA is studied from two aspects,the accumulator and the lightweight prototype.The influence of the accumulator stiffness on the PEHA output performance is found and studied through experiment.And a spring-loaded accumulator of small size and easy operation is designed and replaced the balloon-type accumulator original used in the experiment system successfully.Then a light-duty design of the prototype is carried out and related experiments are carried out.And the prototype mass reduces from 4.8kg to 2.7kg through structural optimization design.