针对国家重大科技基础设施项目500 m口径球面射电望远镜(Five-hundred-meter aperture spherical radio telescope， FAST)液压促动器进行分析研究。提出利用齿轮泵泄漏特性及液控单向阀开启特性实现流量闭环的建模方法可使数学模型更准确。设计样机试验并研发试验设备以获取齿轮泵流量压力系数K_q及液控单向阀开启特性K_f两参数。利用Matlab/Simulink软件搭建系统模型分析了促动器在开环外伸及闭环跟踪两模式下的运动特性，并通过试验对系统模型进行对比验证。结果表明：建立的模型能够描述液压促动器的工作原理，参数K_q及K_f与试验结果一致性较好。开环时促动器的速度随输入脉冲频率增加而增大，闭环时促动器在变载荷下可实现稳定跟踪。仿真与试验最大跟踪误差分别为0.15 mm和0.2 mm，满足设计精度要求。该系统模型为FAST液压促动器奠定理论基础，同时可为伸缩回路差异较大的液压系统提供参考。

Analysis and research are made for the major national science and technology infrastructure project five-hundred-meter aperture spherical radio telescope(FAST). 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 make the mathematical model more accurate. The prototype testing and testing equipment are designed to obtain flow-pressure coefficientK_q and opening characteristicK_f. Simulation model is established based on Matlab/Simulink to analyze the motion performance both in open and closed loop mode. And the mathematical model is validated by experiment. The results indicate that the mathematical model can describe the working principle of the actuator.K_qandK_fhave a good consistency with the experiment results,the actuator speed arises with the increase of input pulse in open loop and also can achieve stable track with changing load in closed loop. The maximum tracking errors of simulation and testing are 0.15 mm and 0.2 mm respectively and which can fulfill the designing accuracy. The system model can be used as the theoretical basis in subsequent research about FAST actuator and meanwhile as the reference of similar operating condition with major differences between protraction and retraction.