Research On Bidirectional Piezoelectric Stack Based Electro-Hydrostatic Actuator Rectified By Wheel-type Valve

Smart material based electro-hydrostatic actuator was extensive researched,due toits advantage of simple structure,small volume,Light-weight,highly integrated and the prospect to be used in the aircraft actuation system of “More Electric Airplane” and “Morphing Aircraft”.However,research of the smart material based electro-hydrostatic actuator mainly focused on its structure,mathematic model and the actuator could only move one way.Bidirectional movement and speed regulation of the actuator were publiclittle.In future,speed regulation and displacement control was a key technology and we must solve it.Thus,this dissertation based on bidirectional piezoelectric stack based electro-hydrostatic actuator,analyzing its output performance and coming up withcapacity speed governing with changing frequency of input voltage and analyzing its displacement control.To begin with,based on the principle of bidirectional piezoelectric stack based electro-hydrostatic actuator,the structure of actuator was designed in detail and wheel type one way valve of actuator was analyzed by fluid-structure interaction simulation and getting the result of movement of wheel type one way valve in fluid and its flow characteristics to optimize the structure of actuator.The parameters of the model was identified by particle swarm optimization arithmetic.Then,as the driver of bidirectional piezoelectric stack based electro-hydrostatic actuator,piezoelectric stack actuator's displacement determines the output flow of bidirectional piezoelectric stack based electro-hydrostatic actuator.Thus,to improve the output flow of bidirectional piezoelectric stack based electro-hydrostatic actuator,it is necessary to analyze the output displacement of piezoelectric stack actuator.AsymmetricBouc-Wen dynamic model of piezoelectric stack acatuor was built to simulink output displacement of piezoelectric stack acatuor to describe the hysteresis characteristics of piezoelectric stack acatuorand the parameters of the model was identified by particle swarm optimizationarithmetic.Experiment and simulation results show that the model can well fit and forecast output displacement of piezoelectric stackactuator when the frequency of input sinusoidal voltage within 600 Hz.To improve the precision of its output displacement,The feedforward compensation of based on inverse was used and error of its output displacement of piezoelectric stack acatuor was declined about 1?m and nonlinearity declined about 3%.Based on the research of piezoelectric stack actuator,mathematical model of bidirectional piezoelectric stack based electro-hydrostatic actuator was built and simulation model of piezoelectric stack pump,pipeline,directional valve,hydraulic cylinder,accumulatorwas built by simscape in Matlab/Simulink.The experiment and simulation result both show that the output flow of bidirectional piezoelectric stack based electro-hydrostatic actuator is linear with frequency of input sinusoidal voltage with 225 Hz.Its highest output flow and output power of the actuator can reach 0.48L/min and 0.71 W respectively when the frequency of input voltage is 225 Hz,peak to peak voltage is 120 Vpp.Finally,Based on the performance of bidirectional piezoelectric stack based electro-hydrostatic actuator.Because of the linear relation between frequency of input sinusoidal voltage and its output flow,the control way of volumetric speed control by changing input frequency and switchingworking direction by directional valve was used to control the movement of bidirectional piezoelectric stack based electro-hydrostatic actuator.Besides,the controller based DSP-FPGA was used.Experiment results prove the princle of closed-loop control scheme.Experiment results show that the error of step output displacement of actuator can be controlled within 0.1mm,the output displacement of bidirectional piezoelectric stack based electro-hydrostatic actuator can follow sinusoidal displacement when frequency of sinusoidal displacement less than 0.1Hz.