Dynamic Characteristics Analysis And Experimental Study Of Large Radio Telescope FAST Hydraulic Actuator

This subject is derived from the manufacture of the hydraulic actuator for the major national science and technology infrastructure project Five-hundred-meter Aperture Spherical radio Telescope(FAST). A design scheme with simple principle and various operational mode is chosen according to the functions and design requirements of FAST based on investigate and survey. Several implementation methods of different operational modes are detailed discussed and the actuator prototype is developed.A new modeling approach which uses leakage features of gear pump and opening characteristic of pilot operated check valve to form a closed loop control is proposed to analyze the dynamic characteristic of FAST hydraulic actuator. The parameter identification experiment of the mathematical model is designed and testing equipment is invented to obtain the flow-pressure coefficient Kq and the opening characteristic Kf. Simulation model is established based on Matlab/Simulink to analyze the motion performance both in open and closed loop mode based on the mathematical model. And the dynamic characteristic is analyzed based on AMESim. Lastly, the simulation results are validated by the testing data of prototype experiments.The results indicate that the mathematical model can describe the working principle of the actuator and the simulation results have a good consistency with the experiment data. The actuator speed arises with the increase of input pulses in open loop and also can achieve stable track with changing load in closed loop. The maximum tracking errors of simulation and experiment are 0.15 mm and 0.2 mm respectively and which can fulfill the designing accuracy. And the minimum force to pull the piston rod out is 160 N when outage.The theoretical analysis, simulation research and prototype experiment of FAST hydraulic actuator are completed is this paper. Due to the differences between protraction and retraction, the working principle of the FAST actuator can’t be described accurately. And the problem is solved in this paper to provide a basis for the maintenance and upgrade of hydraulic actuator. The mathematical model can not only be used as the theoretical basis in subsequent research about FAST actuator but also as the reference of similar operating condition with major differences between protraction and retraction.