Research On Position Servo Control Of A Dual Magnetostrictive Radial Plunger Pumps-based Electro-Hydrostatic Actuator

Electro-hydrostatic actuator（EHA）based on smart materials has the advantages of compact structure,high integration,and power density.EHA has important applications prospects in the field of aircraft operation such as more electric aircraft or all electric aircraft where power by wire is one of the most core technology.However,most of the researches on actuators driven by smart materials focus on the model theory,output characteristics,and structural optimization currently.Furthermore,most actuators can output motion in only one direction so that the position of actuator can not be controlled which reduced the practical application value of the actuator.In this paper,a dual magnetostrictive radial plunger pumps-based electro-hydrostatic actuator（DMREHA）with active ratory valve is researched.Based on the actuator’s working principle,an electronic commutation direction control strategy is proposed which enables the actuator to achieve bi-directional movement without using any reversing device.Combined with the velocity regulation strategy,the theoretical and experimental research on the servo position control of the actuator’s movement is carried out.Firstly,based on frequency modulation,phase angle modulation,amplitude modulation and the working principle of the DMREHA,three velocity regulation strategies and one direction control strategy are proposed.After the comparative analysis,the position control strategy of the DMREHA is established by a combination of amplitude modulation velocity regulation and phase modulation direction control.Secondly,on the basis of the the DMREHA’s working process,the DMREHA system is divided into four parts for mathematical modeling:magnetostrictive pump and the driving model,active rotary valve model,tube model and kinetic model of the cylinder.And the complete simulation model of the DMREHA is built in MATLAB/Simulink.The relationship between the input and output flow of the magnetostrictive pump and the flow area of the active rotary valve under the conditions of compensation,over compensation,and best match between the driving signals’s phase angle of the magnetostrictive pump and control signal’s phase angle of the active ratory valve is resesrched.The output flow characteristics of the actuator under different driving conditions are analyzed through simulation,which verifies the feasibility of the position control strategy theoretically.Also the influence of valve spool’s factors such as different structures and sizes on the output flow characteristics of the actuator is studied.Further,in order to achieve the test requirements,the hardware controller and software program are designed.Hardware controller is developed based on DSP chip which realizes signal acquisition,signal output and data communication.Software program consists of two parts:the upper and the lower computer program.The upper computer program develops a human-computer interaction interface based on Lab VIEW;the lower computer program realizes real-time measurement and control,also the output signals are tested.Then the controller is designed in Simulink,and the simulation model of actuator position control is established to verify the rationality of position control strategy.Finally,the experimental test platforms are built.The output flow characteristics of the DMREHA are tested.The results indicate that when the driving frequency is 200Hz,the maximum no-load output flow of the DMREHA reaches 3.39L·min^-1 with an input current of 6A.In addtion,the position control characteristics of DMREHA are tested and PD algorithm is used to adjust the output flow of the DMREHA.The results show that the step response time is about 0.143s,and the steady-state error can be controlled at 0.05mm.While tracking a sinusoidal displacement desired signal with peak-to-peak value of 6mm and frequency of 4Hz,DMREHA can still achieve quite well effect.The main innovation in this thesis are as the following:In order to realize the position servo control of a dual magnetostrictive radial plunger pumps-based electro-hydrostatic actuator,a position servo control strategy based on the combination of amplitude modulation velocity regulation and phase angle modulation direction control was proposed,and a simulation model was established to theoretically verify the control strategy.The hardware controller and software modules were designed to satisfied the test requirments,and the experimental platform was established.The experimental results show that the movement position of DRMEHA can be controlled with the designed strategy,and the displacement error is 0.05 mm.