【作者】 李建雄；

【导师】 方一鸣；

【作者基本信息】 燕山大学 ， 控制科学与工程， 2012， 博士

【摘要】 对于电液伺服系统的高精度控制问题，目前已经取得了较为丰富的研究成果，然而，这些成果绝大部分是在假设所有状态可测量的情况下，采用状态反馈取得的，输出反馈的成果却很少。在电液伺服系统的许多应用场合都存在不可测状态，如柱塞速度信号、加速度信号，因此，研究电液伺服系统的输出反馈控制是非常必要的。本课题结合河北省自然科学基金“液压伺服驱动的冷带轧机厚控系统自适应鲁棒控制研究”和国家自然科学基金“考虑输入受限的轧机液压伺服系统多模型切换自适应控制研究”，以轧机电液伺服系统为研究对象，针对系统中普遍存在的状态不可测、参数不确定、非线性、外负载力未知、输入饱和，以及轧机厚控系统存在的测量延时等问题进行了鲁棒自适应输出反馈控制方面的研究。本文主要做了以下几方面工作：首先，针对轧机电液伺服位置系统中存在不确定参数和未知外负载力，提出了一种基于未知输入降维观测器的鲁棒输出反馈控制算法。将包含未知外负载力的干扰项视为系统的未知输入，构造未知输入降维观测器用于估计系统的不可测状态和未知干扰项，进而，基于所得到的估计值设计输出反馈控制器。与传统的输出反馈控制算法相比较，本文提出的算法具有更好的暂态性能和更小的稳态误差。其次，针对轧机电液伺服位置系统中存在不确定参数，在假设不确定参数上界已知的情况下，提出了一种基于高增益观测器和参数估计器的自适应输出反馈控制算法。通过选取适当的设计参数，该算法能够保证闭环系统的所有信号最终有界，系统状态及其估计值最终收敛到原点的一个由高增益决定的邻域内；对于不确定参数上界未知的情况，并考虑一些未建模动态，可将电液伺服位置系统视为具有未知控制系数和未知线性增长率的非线性系统。对这样一类系统，提出了一种基于动态高增益观测器的自适应输出反馈控制算法。在该算法中，利用线性组合变换，使得变换后的广义误差的动态不再依赖于控制输入，以便于输出反馈控制器设计；通过引入动态高增益，解决了系统线性增长率未知的问题。该算法能够保证闭环系统所有信号有界，且系统状态和估计误差最终收敛到零。进而，将该算法应用到电液伺服位置系统中，并通过实例仿真验证了该算法的有效性。第三，考虑到轧机电液伺服位置系统中存在的输入饱和，给出了一种抗饱和鲁棒动态输出反馈控制算法。首先在不考虑输入饱和情况下设计鲁棒动态输出反馈控制器，利用Finsler引理将保证闭环系统稳定的充分条件转化为线性矩阵不等式(LMI)条件，通过求解LMI可得到控制器参数矩阵。然后基于anti-windup方法设计了抗饱和鲁棒动态输出反馈控制器。所设计的控制器能够保证闭环系统有界稳定，并具有鲁棒H∞性能。最后，考虑到轧机厚控系统的输出测量存在延时，给出了一种基于观测器的输出反馈鲁棒预测控制算法。首先，将具有测量延时的厚控系统变换为无输出测量延时的系统，再基于变换后的系统构造观测器重构系统状态，然后，基于状态估计设计鲁棒预测控制器。为减小在线计算负担，采用了离线、在线相结合的算法，最后通过实例仿真验证了所提出控制算法的有效性。更多还原

【Abstract】 The problem of high accuracy hydraulic servo control was investigated quiteintensively in recent years, especially for state feedback control under the assumptionthat all the states are measurable. However, these studies do not provide much attentionto output feedback control. In most cases, there exists unmeasurable state in theelectro-hydraulic servo system (EHSS), such as the speed and acceleration of plunger.Therefore, the research on output feedback control for EHSS is very necessary. Thisresearch originates from the project of National Natural Science Foundation (NNSF) ofHebei Province “Research on adaptive robust control for cold-strip rolling mill AGCsystem driven by EHSS” and NNSF of China “Research on multi-model switch adaptivecontrol for EHSS of rolling mill with input saturation”. Focusing on the EHSS of rollingmill, this thesis concerns the development of robust adaptive output-feedback control forthe EHSS with unmeasurable state, uncertain parameters, nonlinearities, unknownexternal load force, input saturation, and delayed measurement. The main contents of thisthesis are as follows:First, focusing on the uncertain parameters and unknown load force in EHSSposition control of rolling mill, a reduced-order unknown input observer based robustoutput-feedback control (UIOROFC) algorithm is proposed. A reduced-order unknowninput observer is first constructed to estimate unmeasurable state and unknownperturbation, in which the perturbation containing unknown external force is regarded asan unknown input. Then, a robust output feedback controller is developed. In comparisonwith traditional observer based robust output-feedback controller (OROFC), the proposedUIOROFC algorithm has better transient performance and smaller steady state error.Second, a high gain observer (HGO) and parameter estimator based adaptive outputfeedback control algorithm is proposed for the EHSS of rolling mill with the assumptionthat the upper bounds of uncertain parameters are known. By choosing the appropriatehigh gain and design parameters, the proposed algorithm can guarantee that all signals ofthe closed loop system are ultimately bounded, the system state and its estimation error converge to a neighbourhood determined by the high gain of the origin. On the otherhand, if the upper bounds of the uncertain parameters are unknown, the EHSS can beregarded as an uncertain nonlinear system with unknown control coefficient andunknown linear growth rate. A dynamic HGO based adaptive output feedback controlalgorithm is proposed for this class of systems. By means of a linear combination, thedynamics of the resulting generalized error does not depend on the control input, and byintroducing a dynamic high gain, the unknown linear growth rate as a difficult issue issolved. It can be proved that all the signals of the closed-loop system are bounded, andthe system state and estimation errors ultimately converge to zero. Moreover, theproposed controller is applied to the EHSS, the effectiveness of the algorithm is validatedby example simulations.Third, an anti-windup robust dynamic output feedback (DOF) control algorithm isproposed to solve the input saturation problem in EHSS. Without consideration of inputsaturation, a robust DOF controller is first designed for a class of uncertain nonlinearsystems. By using Finsler’s lemma, a sufficient condition of stability of the closed-loopsystem is transferred into a linear matrix inequality (LMI) condition, and the controllerparameter matrices are obtained by solving the LMI. Then, a static anti-saturation robustDOF controller, based on anti-windup method, is designed. It can be proved that theclosed-loop is robust stable and has robust H∞performance.Finally, an observer based output-feedback robust predictive control algorithm isproposed to solve the delayed output measurement problem in hydraulic automatic gaugecontrol (HAGC) of rolling mill. Through proper transformation, a system withoutdelayed output measurement is obtained, and an observer is constructed to reconstruct thesystem state. Then, a robust predictive controller via output-feedback is developed. Toreduce on-line computational burden, an off/on-line algorithm is adopted. Theeffectiveness of the proposed algorithm is validated by simulations.更多还原