Research On Variable Arm Length Electro-hydraulic Load Simulator And Its Control Strategy

The electro-hydraulic load simulator is a semi-physical simulation equipment for theoretical research and experimental verification under ground conditions.It can simulate various aerodynamic(torque)or hydrodynamic(torque)load spectra of the load deck of aircraft or ships under different environments in the normal process of travel under laboratory conditions.To realize the dynamic and static performance test of aircraft or ship servo control mechanism.When the loading system simulates the force(moment)load spectrum under different environments,in addition to the loading force applied to the steering gear system,it will also be subjected to strong position disturbance caused by the active motion of the steering gear system,which is a typical passive loading system.If the loading system can not respond to the strong position disturbance in time and effectively eliminate the disturbance,the loading force will contain the extra force,which will work with the normal loading force to the steering gear system,seriously affecting the loading accuracy.Therefore,the key to obtain a high-performance electro-hydraulic load simulator is to minimize this excess force.In this dissertation,a variable arm length electro-hydraulic load simulator is designed according to the load simulation project of aircraft steering gear in a certain institute of the Chinese Academy of Astronautics,based on the classical electrohydraulic load simulator,and attempts to improve the physical connection mechanism of its simulation steering gear system and loading system.The improved loading force mechanism and steering gear force mechanism are respectively hinged at both ends of the rocker lever with adjustable fulcrum.The two mechanisms are connected through the rocker lever and buffer spring.By calculating and adjusting the fulcrum position of the rocker lever,the force displacement disturbance brought by the steering gear system to the loading system can be weakened.In order to reduce the extra force of the loading system from the structural principle;The compound control strategy based on FUZZY PID is designed for the steering gear system and the loading system respectively,and it is analyzed and verified by MATLAB simulation and MATLAB and AMESim co-simulation.The following is the main content of this dissertation:The structure composition and working principle of the electro-hydraulic load simulator with variable arm length are introduced.The position of the lever fulcrum of the rocker arm is preliminarily determined on the basis of theoretical analysis,which provides early preparation for the subsequent simulation analysis.At the same time,the mathematical model of the electro-hydraulic load simulator with variable arm length is established to prepare for the subsequent simulation analysis of the dynamic characteristics and overall performance of the system.The open-loop frequency characteristics of the steering gear system and the loading system are analyzed,and the time-domain simulation analysis of the two systems is carried out under the traditional PID controller,and the simulation model of the variable arm length electro-hydraulic load simulator is built under the AMESim platform.The simulation focuses on the analysis of different buffer spring stiffness and different rocker arm lever fulcrum position conditions.Influence on the performance and spare force of loading system.A FUZZY PID controller optimized by PSO algorithm was designed for the steering gear system.Aiming at the disadvantage that the standard particle swarm optimization algorithm is easy to fall into the local optimal solution,a FUZZY PID controller optimized by the improved PSO algorithm was designed for the loading system.The response performance of the two subsystems under the action of the traditional PID controller is compared with the simulation to verify the effectiveness of the designed controller and improve the dynamic loading accuracy of the system.The co-simulation model of variable arm length load simulator is built based on Matlab and AMESim,and the effectiveness of the designed controller is verified by using Matlab’s powerful data analysis ability and co-simulation.On the basis of structural improvement,the electro-hydraulic load simulator with variable arm length is improved.The controller is further used to improve the loading performance of the loading system and the ability to resist strong position interference.