摘要
冷带轧机液压伺服系统是具有非线性特性、参数不确定性和未知外部扰动的复杂系统，这给系统的控制带来了一定的困难。为了尽量削弱这些不确定干扰对系统性能的影响，设计鲁棒性较强的控制器，满足冷带轧机生产的要求，本文对冷带轧机液压伺服系统进行了鲁棒变结构控制方法的研究。
本文首先根据冷带轧机液压伺服系统的结构和工作原理，建立了内环轧机液压伺服位置系统数学模型，进一步，结合冷带轧机厚度检测过程中存在的测量延时，建立了外环轧机液压厚度控制系统的数学模型。
其次，介绍了反步控制的基本设计方法，然后针对轧机液压伺服位置系统设计了反步位置控制器，进一步，将反步递推方法和动态滑模方法相结合，设计了轧机液压伺服位置系统的反步动态滑模控制器，使系统的位置输出快速准确跟踪位置给定信号，动态滑模方法可得到连续的动态滑模控制律，削弱了应用传统的滑模控制方法造成的抖振现象。
然后，针对轧机液压伺服位置系统存在的非线性特性、参数不确定性，以及控制输入前具有不确定系数的问题，提出了一种自适应反步滑模控制方法，有效解决了由于控制输入前具有不确定系数导致的所设计的控制量与自适应律互相嵌套的难题。把自适应反步法和滑模控制方法相结合，给出了不确定参数的自适应律，并对系统跟踪误差的收敛性进行了证明，仿真结果表明该方法有效的克服了系统非线性与参数不确定性的影响，实现了快速准确的位置跟踪。
最后，针对冷带轧机液压厚控系统存在的参数不确定性、外部扰动、测量延时问题，提出了一种鲁棒保性能控制方法。利用Lyapunov稳定性理论，以线性矩阵不等式的形式，给出了使闭环系统渐近稳定及鲁棒保性能控制器存在的条件及控制器的设计方法，同时也保证系统的性能指标不超过某个确定的上界。通过仿真证明了该方法能实现板带出口厚度的有效控制。
Hydraulic servo system of cold strip rolling mill is a complex system which containsnonlinear characteristic, parameter uncertainty and unknown external disturbance, and itmakes the system difficult to control. In order to eliminate the uncertain disturbances anddesign the controller with strong robustness to meet the requirements of cold strip millproduction, robust variable structure control methods are researched in this paper.
Firstly, a mathematical model is established for the hydraulic servo position systemaccording to its structure and working principle. Then the model of hydraulic gaugecontrol system is erected based on the time delay process of gauge detect device.
Secondly, backstepping control method is introduced, and then the backsteppingposition controller is designed for the hydraulic servo position system of rolling mill.Further more, the backstepping control method and the dynamic sliding mode controlmethod is combined and the backstepping dynamic sliding mode controller is designed,which makes the position output of the system track the given signal rapidly andaccurately. The dynamic sliding mode method can obtain the continuous control law andovercome the chattering phenomenon caused by the application of the traditional slidingmode control method.
Then, an adaptive backstepping sliding mode control method is proposed for thehydraulic servo position system of rolling mill, which contains nonlinear characteristics,parametric uncertainty and the control input with uncertain coefficient. By combining theadaptive backstepping and the sliding mode method, it can improve the robustness of thesystem. In the adaptive backstepping sliding mode controller design, adaptive law of theuncertain parameters is given and the stability of the system tracking is also proved.Simulation results show that the designed controller can effectively overcome theinfluence caused by the nonlinear characteristics and parametric uncertainty and achievefast and accurate tracking.
Finally, an robust guaranteed-cost control method is proposed for the thicknesscontrol system , which contains parametric uncertainty, external disturbance and the detection delay. By using Lyapunov stability theory, the condition to make the closed-loopsystem asymptotically stable and robust guaranteed-cost controller exist is given in theform of LMI, and it also make sure that the system performance does not exceed a definedupper. Furthermore, the design method of robust optimal guaranteed-cost controller isgiven by solving a linear matrix inequality constrained convex optimization problem. Asimulation example is given to illustrate the efficacy of the proposed method.
引文
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