输入受限非线性系统的鲁棒广义逐点最小范数控制

面向具有输入约束的非线性不确定系统,根据输入输出有限增益$L_2$稳定的概念,提出了一种新的鲁棒控制Lyapunov函数.根据此概念,在前期研究的广义逐点最小范数控制的基础上,提出了一种对参数不确定性及外部干扰均具有抑制作用的鲁棒广义逐点最小范数控制器设计方法,并研究了其解析形式的求解方法.通过引入``引导函数",新的算法能够在保证鲁棒稳定性的同时更加灵活的考虑各种控制性能指标.最后,通过将新方法与状态相关Riccati方程非线性控制方法相结合验证该方法可用于提高原有控制器的闭环性能,并通过仿真实验验证了方法的可行性及有效性.     

智能空间刚架的模糊自抗扰振动抑制研究

智能空间刚架作为太空望远镜支撑架是一种新型智能空间结构.为抑制刚架系统在运动过程中产生的振动,"文章提出了一种基于自抗扰控制的非线性模糊自抗扰控制理论,并设计出模糊自抗扰控制器.首先采用有限元方法计算出空间刚架的质量矩阵、阻尼矩阵和刚度矩阵,进而建立系统模型并设计出自抗扰控制器以实现对系统振动的抑制.基于普通自抗扰控制器,利用模糊推理在线整定控制器中非线性状态误差反馈的参数.该控制器不依赖于被控对象的精确数学模型,具有良好的控制性能,同时参数的在线自整定简化了调参难度.仿真实验验证了所提方法的有效性.     

基于生物适应对策的间接自适应模糊控制

针对一类不确定非线性系统,提出了一种基于生物适应对策的间接自适应模糊控制方法.方法在控制器的设计中,将生态位态势理论函数作为模糊规则的后件构造模糊系统,给出了基于生物适应对策的自适应控制器.控制器的设计既体现了生物对环境的适应性,又体现了生物开发和利用环境的能力.通过实例仿真说明,控制器与常规控制器相比,具有更好的控制效果,而且具有良好的抗干扰性.     

离散时间线性切换系统的事件触发控制

提出了离散时间线性切换系统的事件发生器和混杂控制器的联合设计问题,利用分段Lyapunov函数方法和平均驻留时间技术分析了离散时间线性切换系统指数稳定性,并通过线性矩阵不等式建立了事件发生器和混杂控制器共同存在的充分条件.结果扩展到了自触发控制技术,即下一次控制律的刷新是由当前触发时刻系统状态决定的.最后,通过仿真说明了结果的可行性和有效性.     

基于分层变论域模糊控制方法的倒车控制

为了解决一些模糊控制中的维数爆炸与精确控制问题,提出一种将分层控制思想和变论域控制思想结合起来的分层变论域模糊控制方法,并将这种模糊控制器应用于拖车倒车控制,其中下层变论域模糊控制器控制小车的方位角,上层变论域模糊控制器控制小车前轮转角.仿真实验结果与未采用分层方法的普通模糊控制器和变论域模糊控制器的控制结果作了比较,说明了新的控制方法计算量小,调整时间短且几乎无超调,具有较好的可行性与有效性.     

基于一种半间歇控制的忆阻超混沌电路的同步（英文）

就一种由蔡氏超混沌电路衍生而来的电路的基本特征进行了分析;并且就一种包含两种不同类型的子控制器的具有三明治结构的半间歇控制方法进行了研究与讨论.基于线性矩阵不等式(LMIs),李雅普诺夫稳定性理论以及本文中的半间歇控制方法,在实现两个忆阻(分段线性模型的忆阻器)超混沌电路的同步过程中的参数不匹配问题得以解决,并且还给出了实现这两个忆阻超混沌电路同步的指数稳定条件.最后的仿真实验还进一步验证了该方法的高效及可行性.     

具有外部干扰的连续时间线性系统鲁棒最优开环解耦控制

针对具有外部干扰的一类连续时间线性系统,将开环解耦控制和无限时间最优跟踪控制相结合,提出了一种鲁棒最优开环解耦控制方法.首先,通过引入中间虚拟变量,对系统进行开环解耦;其次,将解耦后的系统看做被控对象的广义系统,针对标称广义系统设计了无限时间最优跟踪控制方法;最后分析了该最优跟踪控制器与具有外部干扰的广义系统组成的闭环广义系统的鲁棒性.仿真结果表明所提方法的有效性以及与经典的无限时间最优跟踪控制控制方法相比的优越性.     

非脆弱离散重复控制的二维模型方法

针对一类线性离散系统,提出一种基于二维模型的非脆弱离散重复控制设计方法.通过独立地考虑重复控制系统的控制与学习行为,建立离散重复控制系统的二维模型. 在此基础上,针对重复控制器和反馈控制器具有不确定性的离散重复控制系统,给出了基于线性矩阵不等式的系统稳定性条件和重复控制律. 最后,数值仿真实例验证了所提方法的有效性.     

含齿隙非线性的双电机伺服系统最优控制

针对具有齿隙非线性的双电机伺服系统,提出了一种基于反步法的最优控制策略,实现了负载跟踪与电机同步问题.首先,引入了近似死区函数来描述齿隙模型,建立了系统的状态方程;然后,结合反步控制技术与二阶滤波器,设计了最优跟踪控制器;基于两个电机的位置差与速度差,设计了最优同步控制器;结合这两个控制器,分别得到了两个电机的控制输入.通过使用李亚普诺夫定理证明了系统的稳定性.最后,与PI控制及动态面控制的仿真结果进行对比,证明了文章提出的控制方法对双电机伺服系统具有较好的控制效果.     

桥式吊车系统信息融合跟踪控制器设计

针对桥式吊车的跟踪控制问题,提出了一种基于融合控制理论的控制方法.首先将控制问题转化为系统的性能指标函数,然后将其表示成非线性信息融合统一量测模型,最后利用非线性信息融合定理求取控制量的最优估计值.本文中的控制方法把实际关心的输出量和控制量用统一的二次型函数表示,通过求取其极小值,然后逆向迭代计算,估计出控制量的最优估计值,该方法具有统一的形式,易于向其它领域推广.随后的数学仿真实验,验证了算法的有效性.     

Selection of optimum design for conical segmented aluminum tubes as energy absorbers: Application of MULTIMOORA method

The optimum design for energy absorbers requires considering different criteria. Therefore, the design process can benefit from Multiple-Attribute Decision-Making (MADM) approach. Thin-walled structures can be particularly employed as energy absorbers in automobiles to dissipate energy and protect passengers from the peak crush load caused by severe collisions. The present study investigates a thin-walled conical segmented aluminum tube which consists of several circular sections with different thicknesses. To achieve the optimum design, a number of conical segmented tubes were modeled by finite element method. Energy absorption, initial peak load, crush force efficiency (the ratio of mean load to maximum load), mass of the structure and deformation type as the conflicting objective functions were defined as attributes/criteria. The numeric logic (NL) technique was applied to determine the weight of various criteria. Furthermore, the MULTIMOORA method, as a well-accepted MADM model, was utilized to obtain the optimum design for a conical segmented tube. The design variables included wall thickness, lengths of sections, and taper angle. Drawing a comparison between the top rank conical segmented tube and the top rank conical simple tube revealed that the conical segmented tube could increase the efficiency of the crush load up to 23.8% and reduce the initial peak load and mass of the tube up to 54% and 17.54%, respectively.     

Hybrid decentralized maximum entropy control for large-scale dynamical systems

In the analysis of complex, large-scale dynamical systems it is often essential to decompose the overall dynamical system into a collection of interacting subsystems. Because of implementation constraints, cost, and reliability considerations, a decentralized controller architecture is often required for controlling large-scale interconnected dynamical systems. In this paper, a novel class of fixed-order, energy-based hybrid decentralized controllers is proposed as a means for achieving enhanced energy dissipation in large-scale lossless and dissipative dynamical systems. These dynamic decentralized controllers combine a logical switching architecture with continuous dynamics to guarantee that the system plant energy is strictly decreasing across switchings. The general framework leads to hybrid closed-loop systems described by impulsive differential equations. In addition, we construct hybrid dynamic controllers that guarantee that each subsystem–subcontroller pair of the hybrid closed-loop system is consistent with basic thermodynamic principles. Special cases of energy-based hybrid controllers involving state-dependent switching are described, and an illustrative combustion control example is given to demonstrate the efficacy of the proposed approach.     

Optimal actuator locations and precision micro-control actions on free paraboloidal membrane shells

Flexible paraboloidal shells, as key components, are increasingly utilized in antennas, reflectors, optical systems, aerospace structures, etc. To explore precise shape and vibration control of the paraboloidal membrane shells, this study focuses on analysis of microscopic control actions of segmented actuator patches laminated on the surface of a free paraboloidal membrane shell. Governing equations of the membrane shell system and modal control forces of distributed actuator patches are presented first, and followed by the analysis of dominating micro-control actions based on various natural modes, actuator locations and geometrical parameters. Finally, according to the parametric analysis, simulation data reveal main factors significantly influencing active control behavior on smart free-floating paraboloidal membrane shell systems, thus providing design guidelines to achieve optimal control of paraboloidal shell systems.     

On the role of energy in chip formation

The implicit code ABAQUS/Standard is used to simulate the formation of continuous and segmented chips. Using the described model, the idealized process of friction‐less machining of an elastic ideally‐plastic material is studied. It is shown that Merchant's classical shear angle relation does not hold, as chip formation does not minimize the energy as assumed by Merchant. The model is also used to study segmented chip formation using a realistic material law for the Titanium alloy Ti6Al4V at high cutting speeds.     

Hybrid dynamical control based on consensus algorithms for current sharing in DC-bus microgrids

The main objective of this work is to propose a novel paradigm for the design of two layers of control laws for DC-bus microgrids in islanded mode. An intensive attention will be paid to the inner control level for the regulation of DC–DC electronic power converters, where the use of Hybrid Dynamical System theory will be crucial to formulate and exploit switching control signals in view of reducing the dissipated energy and improving system performance. Indeed, this recent theory is well suited for analysing power electronic converters, since they combine continuous (voltage and currents) and discrete (on–off state of switches) signals avoiding, in this way, the use of averaged models. Likewise, an outer control level for controlling DC-bus microgrids will be developed to provide a distributed strategy that makes the microgrid scalable and robust with respect to blackouts of sources and/or loads, as well as, to provide a balance in the system of charge of the batteries, following the principle of Multi-Agent System theory. In this distributed strategy, they are several crucial and innovative aspects to be regarded such as the different converter architectures, the hybrid and nonlinear nature of these converters. Stability properties are guaranteed by using singular perturbation analysis.     

Modal analysis and control of a rotating Euler-Bernoulli beam part II: Residual vibration control

The crucial control system characteristics and analysis for distributed parameter system is illustrated and a new control scheme is presented by application to feedback control of a Euler-Bernoulli beam. The present paper is a continuation of [1] and a input preshaping technique based on frequency domain analysis is applied for the flexible link. For the application areas of a flexible link, the overshoot may not be welcome in spray painting, arc welding, and assembly of mechanical parts. This shaped input technique together with the designed controller can yield the shortest actual system input that makes the corresponding closed-loop system of the flexible link time-optimal operation, high accuracy, and energy efficiency.     

基于分段策略评分的冲突主体偏好排序方法及其应用

冲突中各利益主体的偏好信息对冲突局势的演变和纠纷调解具有重要影响。现有的冲突偏好排序方法主要基于决策者对冲突局势或状态、策略权重和声明信息的主观判断和理解,缺乏科学的数据来源支撑。为准确获取冲突主体的偏好信息,本文提出了一种基于调查法的分段策略冲突偏好排序方法。首先,根据决策者类别将冲突策略集合进行分段,并通过问卷、调研等方法获取每个冲突主体对所有分段策略的重要度评分信息。在此基础上,计算决策者对各个冲突状态的综合偏好评分,进而得到状态偏好的排序结果。最后以医患纠纷为例,对比分析了传统策略权重法和分段策略评分法的偏好排序和稳定性分析结果,进一步验证了所提方法的有效性。     

Nonlinear similarity analysis for epileptic seizures prediction

The prediction of epileptic seizures can promise a new diagnostic application and a novel approach for seizure control. This paper proposes an improved dynamical similarity measure to predict epileptic seizures in electroencephalographic (EEG). First, mutual information and Cao's method are employed to reconstruct a phase space of preprocessed EEG recordings by using the positive zero crossing method. Second, a Gaussian function replaces the Heavyside function within correlation integral at calculating a similarity index. The crisp boundary of the Heavyside function is eliminated because of the Gaussian function's smooth boundary. Third, an adaptive detection method based on the similarity index is proposed to predict the epileptic seizures. In light of test results of EEG recordings of rats, it is found that the new dynamical similarity index is insensitive to the selection of the radius value of Gaussian function and the size of segmented EEG recordings. Comparing with the dynamical similarity index proposed by Le Van Quyen et al. [Anticipating epileptic seizures in real time by a non-linear analysis of similarity between EEG recordings, NeuroReport 10 (1999) 2149–2155], the tests of twelve rats show the new dynamical similarity index is better to predict the epileptic seizures.     

Novel design of adaptive neural network controller for a class of non-affine nonlinear systems

The tracking control problem is studied for a class of uncertain non-affine systems. Based on the principle of sliding mode control (SMC), using the neural networks (NNs) and the property of the basis function, a novel adaptive design scheme is proposed. A novel Lyapunov function, which depends on both system states and control input variable, is used for the development of the control law and the adaptive law. The approach overcomes the drawback in the literature. In addition, the lumped disturbances are taken in account. By theoretical analysis, it is proved that tracking errors asymptotically converge to zero. Finally, simulation results demonstrate the effectiveness of the proposed approach.     

功能梯度压电圆柱体的旋转分析及其应用——内压和热荷载作用下的力学传感器

对旋转的功能梯度压电(FGP)圆柱体,进行了精确的热弹性分析．圆柱体同时承受电、热和力学荷载的作用,这是一个旋转传感器或者调节器的简化模型．应用能量法得到系统的控制微分方程．为了正确地评估能量函数,引进了一个被称为“附加能量”的新项．在两种边界条件下:自由旋转的圆柱体和受内压作用的圆柱体,求解所得到的控制方程．研究角速度对各个物理量沿半径分布的影响．所研究的结构也可以认为是,在压力及热荷载作用下,测量圆柱体角速度的一个传感器．结果表明,电势与角速度成正比例关系．