近空间飞行器的多模型切换控制

针对受到扰动的变机翼后掠角近空间飞行器,研究一类基于多模型切换的多输入多输出非线性系统的模糊自适应鲁棒控制器的设计问题.通过构造公共Lyapunov函数设计系统的控制器,采用动态面控制方法避免了控制器设计中的计算膨胀问题,利用自适应模糊系统和鲁棒控制项在线消除系统中的未知干扰影响.仿真结果表明了该方法的有效性.     

一类线性切换系统的非脆弱控制器设计方法

研究一类线性切换系统的非脆弱控制器的设计问题。分别考虑当系统的控制器增益存在加性摄动和乘性摄动时,利用公共Lyapunov函数法给出切换闭环系统混杂状态反馈控制器存在的条件,并通过变量替换和Schur补引理将非脆弱控制器的设计问题转换为线性矩阵不等式（LMI）的求解问题。通过仿真证实所提方法的有效性。     

变体飞行器链式平滑切换控制

针对变体飞行器在连续变形过程中的高度保持和姿态稳定问题,提出了一种平滑切换状态反馈控制器设计方法.建立了纵向运动的链式平滑切换系统模型,相比于传统的任意切换律和硬切换方案,所提出的模型能够更准确的反映变形过程的运动特性,且降低了设计的保守性.推导了链式平滑切换系统有限时间有界且具有鲁棒性能指标的充分条件,将增稳控制器设计转化为具有线性矩阵不等式组约束的优化问题.所设计的控制器虽然放宽了对系统渐近稳定性的要求,但能够保证系统状态在变形时间段内有界稳定,且兼顾了实际的舵偏响应.控制算例和非线性仿真验证了所提方法的有效性.     

基于参数依赖滚动时域H∞控制的高超声速飞行器控制

针对输入受限的高超声速飞行器强耦合、强非线性以及严重不确定性的特点,提出一种参数依赖滚动时域?∞控制(PD-RHHC)的方法.首先在考虑控制输入约束的条件下,引入参数依赖Lyapunov函数和松弛因子并提出了基于LMI优化的PD-RHHC;然后采用函数替换方法,结合张量积模型转换方法实现高超声速飞行器(HSV)纵向非线性弹性模型的LPV描述,并将PD-RHHC应用到高超声速飞行器纵向控制中,以实现HSV在大飞行包线内的机动飞行;最后通过仿真实验验证了所提出算法的有效性.     

约束非线性系统切换鲁棒预测控制

采用“分段蕴含”(PWE)方法, 用一组线性变参数模型(LPV)近似约束非线性系统, 降低模型近似的保守性. 对每个LPV模型引入参数Lyapunov函数, 得到稳定的控制律, 并施加于非线性系统. 当检测到LPV模型发生切换时, 根据可行域的离线设计方法确定适当的切换律, 使系统按照设定的规则切换, 保证切换后的初始状态可行. 在文章最后给出了基于切换策略的控制算法的可行性和稳定性. 与传统非线性预测控制相比, 基于切换策略的鲁棒预测 控制方法保守性更低, 计算量更小.     

一类线性不确定切换系统的非脆弱控制器设计方法

针对一类线性不确定切换系统,在控制器增益存在加性摄动的情况下,给出了非脆弱状态反馈控制器的两种设计方案：方案1是利用多Lyapunov函数方法,通过子系统之间的切换,使系统对所有可允许的不确定性保持渐近稳定;方案2是基于平均驻留时间方法,给出了非脆弱状态反馈控制器存在的一个充分条件．相应的结果都是以线性矩阵不等式的形式给出．最后以一个数值例子说明了上述两种方法的有效性.     

风力机的线性变参数主动容错控制

针对风力机具有非线性和参数的不确定性的特征,提出了基于线性变参数(linear parameter varying,LPV)增益调度的风力机主动容错控制方法,降低故障对机组动态特性的影响.基于LPV凸分解方法,将风力机的非线性模型转化为具有凸多面体结构LPV模型,利用线性矩阵不等式(linear matrix inequalities,LMIs)技术对凸多面体各个顶点分别设计满足性能要求的控制器,再利用各顶点设计的反馈控制器得到具有凸多面体结构LPV容错控制器.仿真结果表明,LPV增益调度技术可以成功地应用于风力机系统的容错控制.     

基于飞行器网络控制系统的多速率控制器设计

为了减少网络环境中的时延和数据包丢失对飞行器网络控制器系统的影响,设计了一种具有多速率的保性能控制器设计方法;多速率是指在具有多通道数据传输的系统中,各通道所需控制输入的频率不完全相同;在存在时延和丢包的情况下,利用增广技术对飞行器控制系统在整个循环周期内建立离散模型,此时为了使多速率控制方法更加有效,先基于此模型在控制器输入端构造一个预测器,根据预测器的输出为整个系统设计一个具有多控制速率的动态输出反馈控制器;然后给出并证明保性能控制器的存在条件和求解方法;最后通过某飞行器网络控制系统的数值算例验证了所提方法的有效性。     

近空间飞行器变增益非线性切换控制器设计

针对变后掠翼近空间飞行器大包络、多工作模态和模型不确定的特点,研究其模态切换过程中姿态的鲁棒跟踪控制问题.首先建立含扰动项的飞行器非线性切换模型,基于反步滑模方法和非线性干扰观测器设计鲁棒控制器,通过公共Lyapunov函数理论证明所设计的控制律能够保证闭环切换系统的稳定性;采用变增益切换控制策略为不同飞行模态设计合适的控制增益,用以提高系统的动态性能.仿真结果验证了所提出方法的有效性和必要性.     

变体飞行器的非脆弱有限时间鲁棒控制器设计

针对存在有界干扰和控制器参数不确定性的变体飞行器,研究非脆弱有限时间鲁棒控制器的设计问题.首先建立变体飞行器纵向运动的切换系统模型.考虑到每个子系统具有不同的特性,基于多Lyapunov函数方法和模态依赖驻留时间方法分析了飞行器系统有限时间有界性能及满足$H_{\infty     

An adaptive inverse controller for explicit rate congestion control with guaranteed stability and fairness

This paper examines explicit rate congestion control for data networks. The available bit rate (ABR) service category of asynchronous transfer mode (ATM) networks serves as an example explicit rate system. However, the results of this paper are applicable to other systems as well. After a plant model is established, a control strategy based on approximate inverse concepts is introduced. The control process includes a linear digital filter (with a DC or drift tap) that uses normalized least mean square (NLMS) adaptation. The convergence, stability and fairness properties of this control scheme are discussed. This work differentiates itself from the other contributions in the area of rate-based congestion control in its balanced approach of retaining enough complexity as to afford attractive, analytically-proven performance properties, but not so much complexity as to make implementation prohibitively expensive.     

Improved results on stability analysis and controller synthesis for T-S fuzzy systems

This paper is concerned with the stability analysis and synthesis issues for T-S fuzzy systems. By fully using the properties of fuzzy weighting functions and matrix inequalities, two improved sufficient stability conditions are derived based on the common Lyapunov function and fuzzy Lyapunov function, respectively. It is not necessary to require every fuzzy subsystem to be stable in these conditions. Following the analysis, both parallel and non-parallel distributed compensation controllers are obtained by solving linear matrix inequalities. Finally, four examples are given to show the effectiveness of our proposed approach and the advantages of the approach over existing methods.     

变体飞行器平滑切换LPV 鲁棒控制

针对一类变体飞行器控制问题, 提出一种平滑切换线性变参数(LPV) 鲁棒控制器设计方法. 建立变体飞行器切换LPV 模型, 设计平滑切换控制器, 其中偶数子系统控制器由相邻两个子系统控制器线性插值得到. 给出保证切换LPV 系统指数稳定且具有一定鲁棒性能的充分条件, 由于考虑了调参变量的渐变特性, 所得切换律没有平均驻留时间的限制. 仿真结果表明, 所提出方法使得飞行器系统既具有良好的稳定性和鲁棒性, 又能实现平滑切换.

     

机翼伸展对低速飞行状态的影响

变翼飞行器在飞行过程中因机翼构型、面积等发生变化,引起质量分布、惯性及气动特性发生相应改变,飞行动力学因此受到影响.基于Lagrange方程,本文首先建立变形机翼飞行器的动力学模型,简化后得到伸展变翼的纵向运动方程,并通过气动仿真获得伸展机翼飞行器的低速气动特性.然后,借助线性插值确定气动参数随翼展的变化关系,研究了伸展变翼过程对于飞行器平飞、爬升、俯冲和盘旋的作用.结果表明,因变翼过程中升阻系数改变,飞行器将发生变速沉浮运动,此时为保持飞行状态的稳定,需对飞行器加以控制.     

Stabilization of the PVTOL aircraft based on a sliding mode and a saturation function

This study presents a feedback control strategy for the regulation of a planar vertical takeoff and landing aircraft. To this end, two controllers that work simultaneously were designed. The first controller is devoted to stabilizing the vertical variable and is based on a simple feedback‐linearization procedure in combination with a saturation function. The second controller – based on a combination of the traditionally PD‐controller and a sliding mode controller – stabilizes both the horizontal and angular variables to the desired rest position. The performance of the closed‐loop system is demonstrated through simulation results. Copyright © 2016 John Wiley & Sons, Ltd.     

H∞ Tracking Control for Switched LPV Systems With an Application to Aero-Engines

This paper focuses on the H_∞ model reference tracking control for a switched linear parameter-varying (LPV) model representing an aero-engine. The switched LPV aero-engine model is built based on a family of linearized models. Multiple parameter-dependent Lyapunov functions technique is used to design a tracking control law for the desirable H_∞ tracking performance. A control synthesis condition is formulated in terms of the solvability of a matrix optimization problem. Simulation result on the aero-engine model shows the feasibility and validity of the switching tracking control scheme.      

Robust model-following controller design for LTI systems affected by parametric uncertainties: a design example for aircraft motion

This article addresses the design problem of a robust model-following controller (MFC) which minimises the error between plant controlled output and model output for a linear time-invariant (LTI) plant system affected by parametric uncertainties and an LTI target model. To design such an MFC, a previously proposed MFC scheme, whose applicability has already been demonstrated with flight controller design, is adopted in this article. Our design procedure is as follows: first, a basic MFC is designed using the nominal LTI plant model and the LTI target model while a structured free matrix in the MFC is not assigned; second, model-following performance of the MFC for appropriately defined disturbance input and model input for the parametric uncertain plant model and the LTI target model is minimised using the structured free matrix; and finally, a robust MFC is obtained using the basic MFC and the optimal structured matrix. In the second step, an iterative design method for robust H ₂ controllers for LTI parameter-dependent (LTIPD) systems using parameter-dependent Lyapunov functions (PDLFs), which is also proposed in this article, is applied. Two MFCs for the lateral-directional (L/D) motions of a research aircraft, which has been developed for an in-flight simulator, for two different real aircraft models, i.e. a Boeing 747 model and a Lockheed Jetstar model, are designed and their performance is confirmed via numerical simulations and flight tests.     

Multiple Lyapunov Functions with Blending for Induced L2‐norm Control of Switched LPV Systems and its Application to an F‐16 Aircraft Model

This paper studies the induced L₂‐norm problem for switched linear parameter varying (LPV) systems using a blending method. For a switched LPV system where the parameters are grouped into slow‐varying and fast‐varying parameters, the blending method is used to construct blended Lyapunov functions based on the multiple Lyapunov functions conditions in terms of linear matrix inequalities (LMIs). The proposed method is applied to an F‐16 aircraft longitudinal model and the simulation results demonstrate the effectiveness of the approach.     

Model and robust gain‐scheduled PID control of a bio‐inspired morphing UAV based on LPV method

In this paper, a linear parameter‐varying (LPV)‐based model and robust gain‐scheduled structural proportion integral and derivative (PID) control design solution are proposed and applied on a bio‐inspired morphing wing unmanned aerial vehicle (UAV) for the morphing process. In the LPV model method, the authors propose an improved modeling method for LPV systems. The method combines partial linearization and function substitution. Using the proposed method, we can choose the varying parameters simply, thus creating a model that is more flexible and applicable. Then, a robust gain‐scheduled structural PID control design method is given by introducing a structural matrix to design a structural PID controller, which is more consistent with the structure of the PID controller used in practice and has a simpler structure than representative ones in the existing literature. The simulation results show that the developed LPV morphing UAV model is able to catch the response of the original nonlinear model with a smaller error than the existing Jacobian linearization method and the designed controller can maintain stable flights in practice with satisfactory robustness and performance.