Research On Surplus Force Suppression And Nonlinear Control Strategy Of Electro-hydraulic Load Simulator

Electro-hydraulic load simulator is a kind of Hardware-in-the-loop simulation equipment on ground,which is used to simulate the dynamic load of steering gear systems such as aircraft and ships,and provide reliable performance tests for steering gear drive systems,so as to detect whether their performance meets the design requirements.Require.Since the force loading system of the load simulator is directly and rigidly connected to the tested steering gear system in structure,the active motion of the steering gear will cause external positional disturbance to the force loading system during its working process,resulting in surplus force,which seriously affects the loading accuracy of the system.Effectively suppressing surplus force and improving the loading performance of electro-hydraulic load simulator has always been the focus of load simulator research,and is also the focus of this paper.This paper took the electro-hydraulic load simulator as the research object,combined with the relevant knowledge of hydraulic control system and engineering fluid mechanics,respectively constructed mathematical models of electro-hydraulic load simulator position system,force loading system and other parts,finally gave the overall block diagram of the electro-hydraulic load simulator system.Based on this,It revealed the generation mechanism and characteristics of surplus force theoretically.Aiming at effect of noise in the actual situation,the velocity feedforward composite control strategy based on nonlinear tracking differentiator is proposed.The designed nonlinear tracking differentiator is used to filter out the system noise and obtain good output tracking signal and differential signal.The obtained tracking and differential signals,on the one hand,are used as the feedback term of the position system to construct a nonlinear PID controller to control the displacement output of the position system;on the other hand,it is used as the force-velocity feedforward compensation term of the force loading system,and is combined with the original control quantity to achieve the force control.The system model and controller model are built in MATLAB/Simulink,and the effectiveness of the control strategy is verified by simulation.Aiming at the inherent nonlinear problems of hydraulic system in the force loading system of electro-hydraulic load simulator and the existence of uncertain parameters in the working process,an adaptive backstepping control strategy was proposed.Furthermore,considering the uncertain nonlinear problems existing in the system,on the basis of the adaptive backstepping control strategy combined with sliding mode control,the adaptive backstepping sliding mode control strategy is proposed.The control strategy gives the adaptive update law of uncertain parameters and the control quantity of the system,and proves the stability of the system.The parameters of the controller are complex and the coupling is serious.In the simulation environment of MATLAB/Simulink,the influence of each parameter of the controller on the system response is discussed in detail.By selecting appropriate controller parameters,the uncertainty parameters can be well tracked and the force loading error can be controlled within a small precision range.The proposed velocity feedforward composite control strategy based on nonlinear tracking differentiator is experimentally verified.The load simulator test bench was built,and the selection of equipment hardware,the design of the human-computer interface of the control software and the writing of the underlying logic were carried out.The tracking and differentiation effect of the nonlinear tracking differentiator is tested by using the built experimental bench,and the control effect of the composite control strategy is experimentally verified on this basis.