Waveform Reproduction Control Of 2-Dof Electro Hydraulic Shaking Table

With the progress of society and the development of science and technology,as a kind of equipment used to test the reliability and seismic performance of products by simulating the vibration environment waveform,shaking table has been widely used in aerospace,engineering machinery and other industrial fields.However,due to the structural complexity and system nonlinearity of the electro-hydraulic servo shaking table,there are some problems such as mutual coupling effect and phase lag among the joint control channels,which seriously affect the overall waveform reproduction accuracy of the electro-hydraulic servo shaking table.Therefore,this paper takes the two degree of freedom electro-hydraulic shaking table as the research object,aiming at improving the waveform reproduction accuracy of electro-hydraulic servo shaking table,a compound control strategy of mode decoupling control and feedforward inverse control is proposed.The purpose is to effectively decouple the control channels of each joint in the physical space,and further reduce the amplitude attenuation and phase lag of the dynamic response of each joint control channel,so as to improve the waveform reproduction control accuracy of the electro-hydraulic servo shaking table.The main research work of this paper is as follows:(1)Establish the joint space control structure of the shaking table,establish the mathematical model of the hydraulic power mechanism,establish the kinematic model of the shaking table,establish the dynamic model of the shaking table by using Newton Euler method and Kane method.The reason of output coupling of each joint channel is analyzed.The simulation model of the system is built in MATLAB/Simulink software for simulation analysis.(2)Aiming at the coupling problem,the system is introduced into the modal space for control.Based on the vibration theory,the modal space of the shaking table system is constructed,the independent characteristics of each channel in the modal space are analyzed,the decoupling conditions of the physical space are deduced,the relationship between the modal space and the control performance of the physical space is analyzed,and the modal space decoupling controller is designed.(3)In order to further solve the problem of low tracking accuracy in the joint control channel after decoupling control,a compound control strategy based on feedforward inverse control and modal decoupling control is p roposed.The system identification method is used to identify the each joint control channel based on decoupling controller.Based on the identification model,a stable feedforward inverse controller is designed by using zero phase difference tracking cont rol theory.(4)Build an experimental control system to verify the theoretical analysis and control method.Firstly,the coupling effect between joint channels is verified,and then the decoupling effect of the decoupling controller is verified through the independent characteristic experiment of modal channel,the decoupling condition experiment of physical space and the dynamic response experiment of physical space and modal space.The control effect of feedforward inverse controller is verified by experi ments.Finally,the effectiveness of the composite control strategy based on modal decoupling controller and feedforward inverse controller to improve the waveform reproduction accuracy of shaking table is verified.