中文摘要：

极低速大型等温模锻压机是强非线性机电液耦合系统，由于摩擦是不可避免的，在极低速运行条件下易出现速度不稳定、抖动、甚至爬行，致使系统的控制效果恶化。压机系统摩擦在低速下具有强非线性静态、动态交替作用的特性，且与其他非线性因素强烈耦合，导致建模与参数辨识变得异常困难。为此，设计大型模锻压机极低速空载运行实验，使非线性摩擦免受其他因素的耦合影响，从而降低摩擦建模的难度和复杂度；在此基础上，采用LuGre模型作为系统的摩擦模型结构，并提出使用粒子群优化算法（PSO）对复杂非线性摩擦参数进行辨识。实验结果表明：该方法能有效的获得实际大型模锻压机极低速下的系统模型。

英文摘要：

The large die-forging hydraulic press is a nonlinear system of electro-hydraulic coupling. Because friction is inevitable, it will cause the speed fluctuation and instability, even creeping phenomenon under extremely low speed, so that the control performance gets deteriorated. The friction of the press is nolinear, and has both dynamic and static characteristic, and couples with other disturbance factors, so friction modeling and parameter identification get very complicated. Because of this, a no-load test was designed for the press, which could make the nonlinear friction decoupled with the others, enabling friction parameters become easier to identificate. Then, LuGre model was selected and used the particle swarm optimization （PSO） was used for identification friction parameters. The experimental results show that the system model of the large die-forging hydraulic press of extremely low speed can be obtained by the proposed method.