巨型模锻水压机液压位置保持系统迭代控制研究

巨型模锻水压机动梁同步精度是决定锻件成型精度的关键参数。由于该类型水压机一般具有加工过程重复性、初始加工精度要求高、批次加工数量小的特点,单纯采用PID控制仅能保证初始加工精度,无法确保加工精度的逐步提高,因此本文在分析动梁位置保持系统模型的基础上,采用开环迭代控制和PD控制相结合控制策略,并提出了直接采用PD控制输出作为迭代控制初始控制量的方法.试验结果表明该方法收敛速度快,且能保证初始加工精度,动梁的位置保持精度经过2~3次迭代运行后可提高40%,调整时间可缩短约1.8 s。

Hydraulic Position Holding System of a Huge Water Press Based on Iterative Learning Control

Synchronization precision of the moving beam in a huge water press is a very crucial parameter.Since the position holding system of the moving beam which merely adopts a proportional-integral-differential(PID) controller can only ensure the initial process precision of the forging pieces but can not improve its precision gradually,therefore,a new control strategy adopting open loop iterative learning control(ILC) combined with proportional-differential(PD) control is employed for such type of forging press.Analysis of the hydraulic position holding system of a 30,000 t huge water press shows that this controller has such characteristics as process repetition and strict initial process precision.Experimental results indicate that this system has high constringency speed and can ensure initial process precision,the position holding accuracy can be improved by 40% compared with the system only adopting a PD controller and the stabilization time can be shortened by 1.8 s after the water press runs only 2 or 3 forging processes.