Research On System Refinement And Flat Control Of Small Amplitude Frictional Torque Loading Simulator

Electro-hydraulic load simulator has been used to reproduce the load and test performance of industrial products due to its high accuracy,strong reliability,wide frequency band,large torque,fast response and relatively durable characteristics.Based on the analysis of the development of electrohydraulic load simulator at home and abroad,this paper puts forward a friction load simulator.In order to realize small torque loading,the tracking performance of the friction electro-hydraulic load simulator is improved by system improvement and control strategy through theoretical analysis,simulation and experiment.Firstly,the load scheme with the valve controlled hydraulic cylinder and the friction disc as the core is selected,and the whole scheme of the friction electrohydraulic load simulator is designed and demonstrated.Through theoretical analysis and ANSYS finite element simulation,a friction torque model based on boundary lubrication was established,which directly described the influence of microscopic conditions of friction interface,load distribution and lubrication conditions on the friction coefficient.Static and dynamic analysis is carried out on the key parts such as the spindle and the power mechanism to optimize the components or determine the loading limit of the system.Secondly,a complete mathematical model of the frictional electro-hydraulic load simulator system is established,the stability of the steady-state linear system is analyzed,the influence of the system parameters on the tracking performance of the system is explored,and the static and dynamic tracking ability of the system is analyzed according to the simulation results.The physical model of the friction load simulator was established by AMESim and the simulation was carried out.The similarities and differences between the physical model and the mathematical model were compared.Then,in order to suppress the effects of system nonlinearity and parameter timevariation on the loading performance of the friction electro-hydraulic load simulator,a flat nonlinear controller based on online parameter identification was designed,and the controller parameters were self-tuning preliminarily.The co-simulation was carried out using the established AMESim physical model.Finally,a prototype of the bidirectional load simulator based on friction is developed.Through excess torque tests,the tracking ability of the load simulator under dry friction and boundary lubrication conditions is compared.The rationality of system optimization is verified by static loading.The effectiveness of the designed flat nonlinear controller is verified by dynamic loading.