Research On Clearance Nonlinear Compensation Of Electro-hydraulic Servo Shaking Table

As the core equipment of vibration simulation experiment,electro-hydraulic servo shaking table is widely used in the reliability test of various equipment and test pieces.The clearance at the load connection of the shaking table will result in excessive overdraft,response delay,and severe distortion of the output waveform,which will seriously hinder the improvement of system performance.Therefore,the design of effective clearance compensation strategy has important academic research value and practical engineering application value to improve the control precision of the shaking table.In this paper,the nonlinearity of the clearance at the hinge of the shaking table is studied,the system model of the shaking table with clearance is established,and the influence of the clearance on the system output response is analyzed in detail.The improved genetic algorithm is used to accurately identify the system clearance,and the adaptive clearance inverse model based on the steepest descent method is used to compensate the system clearance.This article mainly completes the following work:The dynamic mechanism and frequency characteristics of the shaking analyzed in detail.The three-parameter control strategy is used to correct the shaking table.The experimental results show that the three-parameter control strategy can effectively improve the system performance without considering the system clearance.The appropriate clearance hysteresis nonlinear model is selected to describe the system.The method of describing function is used to analyze the shaking table system model with nonlinear clearance.The influence of clearance on system response of shaking table is analyzed under three typical excitations.On the basis of analyzing the principle of parameter estimation,based on the defects of the traditional genetic algorithm such as long search time and poor convergence,an improved genetic algorithm with the addition of regulatory factors is proposed to identify the clearance of the system,which lays a foundation for the clearance compensation of subsequent systems.In order to solve the problem that the fixed inverse model compensation can not adjust the system parameters in real time,a clearance dynamic inverse model compensation method based on the adaptive control of the steepest descent is designed.The unit step response,sine response and seismic wave response of the system before and after the control are analyzed.The simulation results show that the proposed algorithm can improve the accuracy of the system’s repetition of the input signal,basically eliminate the adverse effect of the clearance nonlinearity on the system,and the robust of the system is improved obviously.