Research On Magnetostrictive Materials-based Electro-hydrostatic Actuator Rectified By Cylindrical Rotary Valve

Compared with the passive flow rectification of smart material-based Electro-Hydrostatic Actuator,active flow rectification owns more rapid response and flexible control.Based on the characteristics,a new type of magnetostrictive materials-based electro-hydrostatic actuator?MEHA?rectified by cylindrical active rotary valve is put out and corresponding theoretical and experimental research is proceeded in this paper.Firstly,a new type of program with cylindrical rotary valve is proposed based on the valve spool rotation for rectification,and according to the rectification principles and structure,the design philosophy of several parts is discussed,which includes pressure-equalizing grooves,valve spool grooves and sealing clearance.Secondly,the flow field model of grooves and valve chamber is established based on the designed rotary valve structure and finite element simulation is analyzed with COMSOL software;based on the results,the simulation of system flow field model is analyzed and then find the best choices of the groove shape,the opening of valve port and parameters of the inside rotary valve to maximize the rotary valve output flow.For further study,the actuator system mathematic model is established based on the working principles of MEHA,which consists with four parts: Magnetostrictive Material-based Pump,cylindrical rotary valve,tubes and hydraulic cylinder;the corresponding simulation model is set up in Matlab/Simulink and the result shows: the phase of input voltage signal and the driving frequency are the key parameters which most influences the rectification effect of the cylindrical rotary valve and the output performance of MEHA.With the change from 0²? for the input phase,the hydraulic cylinder can realize the bidirectional flow output with adjustable ratio;with the driving frequency from 0⁴00Hz,the output flow of MEHA reaches peak flow of 1.28L?min^-1 at 175 Hz and then appears decrease until 1.5L?min^-1 at 400 Hz.Finally,the experimental prototype of MEHA is manufactured and the experimental test platform is set up.With DSP as controller,based on the realization of real-time measuring the angular displacement of valve spool and transforming into analog sine signal,the output performance of MEHA is on experimental study and the experiment result shows: the MEHA reaches the maximum load capacity of 25 kg with actuator mass of 6.5kg;the no-load flow rate reaches 1.28L?min^-1 with the driving frequency of 120 Hz,which achieves an increase of 70% more than 0.7L?min^-1 for the MEHA with passive cantilever valve.The above research shows: the new type MEHA can both realize fluid rectification with high frequency and bio-direction flow output at the same time based on the control for driving frequency and input phase,which shows the characteristics of simplized structure and flexible control.In addition,compared with the MEHA using traditional passive valve,the MEHA in this paper can reach larger output flow and output power density at the same driving conditions.