【作者】 王益群； 孙孟辉； 陈春明； 杨阳；

【Author】 WANG Yiqun SUN Menghui CHEN Chunming YANG Yang (College of Mechanical Engineering, Yanshan University, Qinhuangdao, 066004)

【机构】 燕山大学机械工程学院；

【摘要】 由于对冷轧薄板质量的要求越来越高,液压AGC系统已经成为提高冷轧带钢成品精度必不可少的手段。但目前广泛应用于现场液压AGC系统的PID控制策略,由于其鲁棒性较差,已经难于满足进一步提高冷带轧机液压AGC系统控制精度的要求。广义预测控制是预测控制算法的一种,模型参数少,并采用多步预测、滚动优化、在线辨识与校正的策略,减少了控制算法的计算量,故探索该方法在冷带轧机液压AGC系统中的应用是一种有效实用的解决方案。本文首先针对冷带轧机液压AGC压下伺服系统,应用广义预测控制理论直接算法,采用随机梯度估计法在线估计控制器参数,避免了在线求解Diophantine方程,减少了在线计算时间,该控制算法基于离散CARIMA模型,吸取了自适应控制的优点,使控制系统具有较好的鲁棒性并具有智能性。同时,借鉴串级控制的思想,把广义预测控制结合到串级结构中,在液压AGC系统厚度环采用PID控制,而在压下伺服系统采用广义预测控制,形成串级预测控制。试验结果表明,本文采用的串级预测控制算法,综合了传统的PID控制器算法简单、参数调整方便的优点和广义预测控制跟踪特性好、对模型失配有较强鲁棒性的特点,使得液压AGC系统的动态品质有了较大的改善,压下伺服系统响应时间减少,带钢厚度精度进一步提高。更多还原

【Abstract】 Because request to quality of cold rolling sheet strips is higher and higher, the hydraulic AGC (Automatic Gauge Control) has been a requisite means for improving quality of cold rolling strips’ finished products. But the PID control strategy, being comprehensively used in the locale, is difficult to satisfy request of improving control precision of cold rolling mill, because its robustness is not very strong. The generalized predictive control is one of predictive control theories. It needs few parameters, and adopts strategies of multi-step prediction, receding-horizon optimization and feedback correction, which has good tracking characteristic and reduces on-line calculations of control algorithm. So it’s a kind of indispensable and practical strategy for exploring the application method of generalized predictive control. First, the direct algorithm of generalized predictive control was applied in the electro-hydraulic servo system of cold rolling mill, which adopted the stochastic gradient estimate algorithm to estimate parameters of controller on-line. It avoided on-line solving the Diophantine equation and reduced the on-line calculation time. Based on the discrete controlled autoregressive integrated moving average (CARIMA) model, the control algorithm was combined with merits of adaptive control, which made the control system possess of excellent robust and intelligent capability. At the same time, in this article, using for reference the thought of cascade control, the generalized predictive control is combined in cascade structure. In the thickness loop of hydraulic AGC, it adopts PID control. And in the inner loop of screw-down servo system, it adopts generalized predictive control. It synthesizes merits of PID control, which possesses of easy algorithm, adjusting parameters conveniently and characteristic of generalized predictive control including of good tracking characteristic and strong robustness. The experimental result shows that adopted control strategies make the system dynamic quality improved largely. The response time and control precision of screw-down servo system are improved. And the thickness precision of cold rolling strip is improved too.更多还原