【作者】 王宇飞；

【导师】 姜长生；

【作者基本信息】 南京航空航天大学 ， 控制理论与控制工程， 2012， 博士

【摘要】 近空间飞行器(NSV: Near Space Vehicle)集传统航空器与航天器的优点于一身，在军事和民用方面具备重大的战略价值，已成为各军事强国关注和研究的焦点。近空间飞行器的飞行环境特殊、飞行包络极大，并且在飞行过程中存在着多工作模式、多工作状态等特点，使得飞行器系统呈现出非常复杂的特性，因而飞行控制系统的设计是一项极具挑战但又意义重大的研究课题。本文针对这一科学问题，分别在飞行运动数学建模、不确定非线性鲁棒自适应飞行控制等方面开展了一系列研究工作。首先，综合现有的文献资料以及本课题组的前期研究成果，结合近空间飞行器的大飞行包络、多飞行任务等特点，考虑具体的飞行环境，对带翼锥形体且机翼后掠角可变的近空间飞行器进行了系统的飞行力学以及动力学分析，在地球坐标轴系下建立了它的飞行运动数学模型，并对受到干扰和不确定等影响的系统开环特性进行了检验和分析，论证了该系统能够体现近空间飞行器的严重非线性、强烈状态耦合、激烈快时变以及存在不确定等特点，可以满足飞控系统设计研究的需要。而后，围绕所建立的复杂非线性飞行运动方程，提出了一种基于模糊多模型的鲁棒软切换控制方法。首先根据机翼后掠角将近空间飞行器的工作区域划分为多个模糊区域，然后利用广义系统的方法设计系统的局部鲁棒控制器，减少了计算量和复杂度，最后对局部控制器进行模糊加权从而实现了控制器的软切换。通过变气动外形近空间飞行器的飞行运动仿真验证说明了所设计方法的有效性。接着，为了降低系统模型集的复杂度，考虑近空间飞行器气动参数等未知以及受到外界干扰影响的条件下，提出了一种基于多非线性模型切换的鲁棒自适应控制策略。利用模糊系统来在线逼近系统中的未知函数，并设计鲁棒控制器来对逼近误差进行补偿，根据公共Lyapunov函数方法证明了闭环系统的稳定性。为了获得更好的逼近效果，在模糊系统中增加了变论域的思想，相当于在不改变系统复杂度的前提下增加了模糊规则，显著提高了模糊系统性能。仿真结果表明两种方法都能够很好地实现对近空间飞行器的鲁棒自适应控制。然后，针对近空间飞行器在飞行过程中存在的环境干扰以及系统本身的建模不确定，提出了一种基于模糊观测器的多模型切换控制算法。充分利用系统的已知信息，构造多模型模糊观测器来实现对包含复合干扰的未知函数的估计，并设计了系统的鲁棒控制器，利用公共Lyapunov函数方法推导出可以保证闭环系统所有信号最终一致有界的参数自适应调整律。进一步，为了避免模糊系统过度依赖专家经验并改善模糊系统的逼近性能，设计了一种全调节多模型模糊观测器，模糊系统的中心、宽度和模糊参数均可在线调节，并据此提出了基于全调节模糊观测器的多模型切换控制方法。将上述两种方法用于变机翼后掠角近空间飞行器的姿态跟踪控制，取得了理想的控制效果。最后，考虑近空间飞行器的实际飞行需要，设计了一种基于多模型切换的输入输出受限控制律。设定系统的跟踪误差运动范围，构造系统的输出约束环节，然后将理想控制输入经过控制指令滤波器进行滤波得到实际控制输入，利用切换模糊系统对理想控制与实际控制之间的差值以及复合干扰进行估计，并用以补偿理想控制器的输出。仿真结果说明当近空间飞行器存在复合干扰，且气动外形发生改变时，所设计方法能够实现高精度的稳定跟踪控制，并且控制输入和输出均在所限制的区域内。更多还原

【Abstract】 Near space vehicle (NSV) has great strategic value both in military and civilian area, whichcombines the advantages of traditional aircrafts and spacecrafts. It has become a focus of concern andresearch for many military powers. NSV has special characteristics, such as special flightenvironments, large flight envelop, multiple work modes and multiple flight states. These make NSVpossess some very complicated features. Therefore, the NSV control system design is a challengingand meaningful research project. The dissertation carries out a series of research work in NSVmodeling and robust adaptive flight control for nonlinear uncertain systems.First of all, on the basis of the published literatures and the contributions of our research group,the flight mechanics and dynamics of the NSV with variable sweep angle are systematically analyzed,and a set of equations are established to describe the flight motion in the earth coordinate system. Theopen-loop control dynamics with disturbances and uncertainties are studied. They demonstrate thatthe developed model can embody the characteristics of NSV, such as serious nonlinearity, intensestate-coupling, fast time variation and uncertainties and can meet the requirements of flight controlsystem design.Secondly, a robust soft-switching control method based on multiple fuzzy models is presentedfor the nonlinear flight motion equations. The work space of NSV is divided into multiple fuzzyregions according to the sweep angle. Then local robust controllers are designed by the descriptorsystem method, which can reduce the calculation and complexity. The soft switching is realizedthrough combining local controllers with fuzzy weights. Simulations of NSV with variable sweepwings demonstrate the effectiveness of the proposed method.Thirdly, to decrease the scale of the model set, a robust adaptive control strategy based on theswitched multiple nonlinear systems is considered in the presence of unknown aerodynamicparameters and external disturbances. Fuzzy systems are employed to approximate the unknownfunctions, and robust controllers are designed to compensate for the approximation errors. Then thestability of the closed-loop system is proved according to the common Lyapunov function theory.Furthermore, the variable universe method is introduced to get better approach results. The fuzzy rulescan be increased without more complexity. The simulation results show that the two control methodscan realize robust adaptive control on NSV.In the following, a multi-model switching controller based on multi-model fuzzy observer isinvestigated in consideration of the disturbances in the environment and the unmodeled uncertainties in the NSV flight. The multi-model fuzzy observers are constructed by using the known systeminformation to approximate the unknown functions with dynamic lumped disturbances. Then robustcontrollers are also designed. The adaptive laws of the fuzzy weights and robust gains are derived bythe common Lyapunov function theory and the closed-loop system can be ultimately uniformlybounded. Further more, a fully tuned fuzzy observer is introduced to avoid overly relying on expertiseand improve the fuzzy system performance. The centers, widths and fuzzy weights of the fuzzysystem can be adjusted on line. And a multi-model switching control method based on fully tunedfuzzy observer is proposed. At last, the two schemes are used to track the attitudes for the NSV andreach ideal control effects.Finally, considering the actual flight requirements, a multi-model switching control law withconstrained-input and constrained-output is presented. The constrained-output part is constructedaccording to the given error range. Then the command filter is applied to the designed controller to getactual input. The switched fuzzy system is introduced to approximate the difference between thedesigned and actual controller as well as lumped disturbances. The estimates can be used tocompensate for the controller. The simulation results show that the designed method can realizehigh-precision tracking control with appropriate input and output.更多还原