针对在高炉和连铸机等重工业恶劣工况下，采用传统液压伺服系统，抗油液污染能力低、可靠性差等问题，依据直接位移反馈闭环控制原理，结合数字化控制方式，开发了步进式电液控制液压缸。阐述了电液步进缸的工作机理，并对其进行数学建模和理论分析，建立了系统传递函数方框图。在试验台上对电液步进缸的内泄漏流量、十脉冲精度、一步精度、重复位置精度和频率响应等静动态性能进行测试，结果表明，电液步进缸在开环状态下也具有较高的控制精度和响应速度，可靠性高、抗油液污染能力强。

Aimed at the problems of poor ability of resistance to oil pollution and low reliability with the hydraulic servo systems used under the harsh conditions in heavy industry such as the blast furnaces and continuous casting machines, an electrohydraulic stepping cylinder is developed based on the principle of direct displacement feedback closedloop control and combined with digital control mode. The working principle of the electrohydraulic stepping cylinder is elaborated, and the mathematical modeling and theoretical analysis of the system are also involved. Then the transfer function block diagram of the system is established. Finally, the main static and dynamic characteristics of the cylinder such as internal leakage flow rate, tenpulse accuracy, onestep precision, position repeatability and frequency response are tested on a test bed. Experimental results show that the electrohydraulic stepping cylinder with openloop control is of high control accuracy and response speed, high reliability and ability of resistance to oil pollution.