毕业生知识库

高超声速飞行器因其在航空航天以及快速全球打击方面展现出的巨大价值，在近几十年内受到了越来越多的关注。为了实现飞行器的高速及高品质飞行，飞行器机体采用了一种特殊的机体发动机一体化结构，而超燃冲压发动机与机体的高度集成将会对系统造成强烈的耦合及机体结构弹性扰动。并且，由于高超声速飞行器飞行速度快、飞行包线大，变化的大气条件及未知的随机扰动将极大地恶化飞行器的飞行品质。上述所有因素使得高超声速飞行器的巡航控制设计成为一项困难且具有挑战性的工作。
区间二型模糊系统作为传统的一型模糊系统的扩展，在对不确定信息的建模方面具有更强的能力。依靠其对实连续函数的万能逼近特性，区间二型模糊系统被广泛地应用于复杂非线性系统的控制设计中。
本论文从高超声速飞行器巡航飞行阶段所面临的控制问题出发，综合考虑巡航飞行过程中多种不确定性影响，研究新型的基于区间二型模糊系统的高超声速飞行器自适应巡航控制方法。本文的主要工作和创新点归纳如下：
(1) 针对现有文献很少研究的高超声速飞行器输出通道传感器测量噪声的抑制问题，本文创新性地提出了一种基于状态估计器和区间二型模糊系统的鲁棒自适应巡航控制系统。该系统采用基于连续模型的状态估计器来重构被测量噪声所污染的速度和高度状态，同时基于理想的状态测量设计基于区间二型模糊系统的鲁棒自适应巡航控制器以实现飞行器的指令跟踪飞行。将状态估计器和鲁棒自适应巡航控制器相结合得到最终的巡航控制系统。对比仿真结果验证了该控制系统在测量噪声抑制方面的有效性和优越性。
(2) 针对高超声速飞行器输出通道传感器测量噪声与强未知气动扰动同时存在的高品质巡航飞行实现问题，本文进一步提出了一种新型的高超声速飞行器区间二型模糊增益自适应状态估计器，并以此构建新型的鲁棒自适应巡航控制系统。在分析固定增益状态估计器的稳定性之后，本文阐述了精确快速的状态重构与高频测量噪声的抑制之间的矛盾并归纳出期望的先验控制知识，进而设计两个基于知识的区间二型模糊系统在线调整状态估计器的增益值，以同时实现飞行器巡航飞行暂态过程的精确快速状态重构和稳态过程的高频测量噪声抑制。对比仿真结果展示了该新型的状态估计器在飞行器巡航飞行性能上的提升。
(3) 针对高超声速飞行器高品质鲁棒巡航飞行目标带来的区间二型模糊控制系统计算和存储载荷过高的问题，本文提出了一种新型的基于区间二型模糊系统和小增益理论的高超声速飞行器鲁棒自适应巡航控制系统。对于飞行器中的每一个未知子系统，本文采用TSK 型区间二型模糊系统在线估计未知模型信息，并通过构建一个新的自适应参数代替原有的学习参数向量以缓解系统的计算和存储载荷。利用小增益理论设计出最终的控制律，并通过严格的稳定性分析得出闭环系统内的所有状态均最终一致有界。对比仿真结果展示了该控制系统的鲁棒性和优越性。
总体而言，本文着眼于高超声速飞行器巡航飞行阶段的实际工程问题，致力于飞行器高品质巡航飞行的实现，开展一系列新型的基于区间二型模糊系统的自适应巡航控制方法研究，所得出的研究成果具有非常高的实际工程价值。

Hypersonic vehicle, which reveals significant values in space accessing and prompt global striking, has achieved more and more attention in the past decades. To realize a high-speed and high-quality flight performance, hypersonic vehicle takes a specific airframe-engine-integrated structure, with which strong couplings and structural flexibility disturbances will appear. Furthermore, due to the high-speed operation as well as large flight envelope, the varying atmospheric conditions and various random disturbances may significantly deteriorate the flight performance. All of the above factors make the cruise flight control design difficult and challenging.
As an extension of conventional type-1 fuzzy logic system, interval type-2 fuzzy logic system (IT2-FLS) shows a stronger capability of modeling uncertain information. Based on the universal approximation property for real continuous function, IT2-FLS has been widely applied in complex nonlinear control design.
Focusing on the control problems of the hypersonic vehicle in the cruise flight stage and taking various uncertainties into consideration, some novel adaptive control methods for hypersonic vehicle based on IT2-FLSs are investigated in this dissertation. The main contributions and highlights of this dissertation are summarized as follows:
(1) Considering the measurement noises in the output channels of the hypersonic vehicle, which is seldom investigated in the existing literature, a novel state-estimator-integrated robust adaptive control system based on IT2-FLSs is proposed. A continuous-model-based state estimator is applied to reconstruct the exact states of the velocity and altitude which are contaminated by the measurement noises, while a robust adaptive controller based on IT2-FLSs is designed to fulfil the tracking mission using the ideal state measurements. By combining the state estimator and the robust adaptive controller, the control system is finally developed. Comparative simulation results verify the effectivenss and superiority of the proposed control system on measurement noises suppression.
(2) Simultaneously taking the measurement noises in the output channels and the uncertain strong aerodynamic disturbances into consideration, a novel interval type-2 fuzzy gain adaptive state estimator together with a novel robust adaptive control system for hypersonic vehicle is further proposed. After analyzing the stability of the static gain state estimator, the contradiction between accurate and fast state reconstruction versus high-frequency measurement noise suppression is stated, and the prior control knowledge is summarized. Then, two knowledge-based IT2-FLSs are formulated to adapt the gains online, which can realize accurate and fast state reconstruction in the transition process as well as high-frequency noise suppression in the steady-state process. Comparative simulation results demonstrate the improvements of the cruise flight performances with this novel state estimator.
(3) To deal with the issue of the computation and storage costs in IT2-FLSs brought by high-quality flight objective, a novel robust adaptive control system for hypersonic vehicle based on IT2-FLSs and small gain theorem is proposed. For each uncertain subsystem in the vehicle, an IT2-TSK-FLS is adopted to approximate the unknown model information online. Moreover, a new adaptive parameter is developed to replace the original learning parameter vector, which can alleviate the computation and storage burden of the system. By applying the small gain theorem, the final control law is developed. Rigorous stability analysis shows that all the states in the closed-loop system are uniformly ultimately bounded. Comparative simulation results illustrate the robustness and superiority of this control system.
To sum up, this dissertation focuses on the real problems of hypersonic vehicle in the cruise flight stage, and aims to achieve a high-quality flight performance. Several novel adaptive control methods based on IT2-FLSs are brought out, and the results reveal great values in real engineering.