Controller design of uncertain nonlinear systems based on T-S fuzzy model

A robust control for uncertain nonlinear systems based on T-S fuzzy model is discussed in this paper. First, a T-S fuzzy system is adopted to model the uncertain nonlinear systems. Then, for the system with input variables adopting standard fuzzy partitions, the efficient maximal overlapped-rules group （EMORG） is presented, and a new sufficient condition to check the stability of T-S fuzzy system with uncertainty is derived, which is expressed in terms of Linear Matrix Inequalities. The derived stability condition, which only requires a local common positive definite matrix in each EMORG, can reduce the conservatism and difficulty in existing stability conditions. Finally, a simulation example shows the proposed approach is effective.

Fuzzy Adaptive Tracking Control of Uncertain Strict-Feedback Nonlinear Systems with Disturbances Based on Generalized Fuzzy Hyperbolic Model

In this paper, a fuzzy adaptive tracking control for uncertain strict-feedback nonlinear systems with unknown bounded disturbances is proposed. The generalized fuzzy hyperbolic model (GFHM) with better approximation performance is used to approximate the unknown nonlinear function in the system. The dynamic surface control (DSC) is used to design the controller, which not only avoids the “explosion of complexity” problem in the process of repeated derivation, but also makes the control system simpler in structure and lower in computational cost because only one adaptive law is designed in the controller design process. Through the Lyapunov stability analysis, all signals in the closed loop system designed in this paper are semi-globally uniformly ultimately bounded (SGUUB). Finally, the effectiveness of the method is verified by a simulation example.

Stability analysis and control synthesis of uncertain Roesser-type discrete-time two-dimensional systems

We study the stability analysis and control synthesis of uncertain discrete-time two-dimensional（2D） systems.The mathematical model of the discrete-time 2D system is established upon the well-known Roesser model,and the uncertainty phenomenon,which appears typically in practical environments,is modeled by a convex bounded（polytope type） uncertain domain.The stability analysis and control synthesis of uncertain discrete-time 2D systems are then developed by applying the Lyapunov stability theory.In the processes of stability analysis and control synthesis,the obtained stability/stabilzaition conditions become less conservative by applying some novel relaxed techniques.Moreover,the obtained results are formulated in the form of linear matrix inequalities,which can be easily solved via standard numerical software.Finally,numerical examples are given to demonstrate the effectiveness of the obtained results.

LMI Approach to Suboptimal Guaranteed Cost Control for 2-D Discrete Uncertain Systems

This paper studies the problem of the guaranteed cost control via static-state feedback controllers for a class of two-dimensional (2-D) discrete systems described by the Fornasini-Marchesini second local state-space (FMSLSS) model with norm bounded uncertainties. A convex optimization problem with linear matrix inequality (LMI) constraints is formulated to design the suboptimal guaranteed cost controller which ensures the quadratic stability of the closed-loop system and minimizes the associated closed-loop cost function. Application of the proposed controller design method is illustrated with the help of one example.

不确定转子系统动力学降阶模型构建与模型散度参数辨识

在航空、航天、船舶等领域的实际工程转子系统中,广泛存在高维复杂的非线性系统。在航空发动机转子系统、燃气轮机转子系统等重点研究领域,通常还难以对高维复杂非线性系统进行直接的数据处理和分析统计。针对不确定性转子系统的模型维度较高等问题,提出了一种模型不确定性动力学降阶计算模型构建和模型散度参数辨识方法。首先,根据确定性动力学模型和静态矩阵降阶方法,完善了确定性动力学降阶模型;然后,基于随机矩阵理论和非参数动力学建模方法,提出了不确定性动力学降阶模型;最后,利用系统确定性模型的一阶临界转速、振型和实验数据,对不确定性动力学模型的散度参数进行了辨识;为了验证散度参数辨识方法的有效性,笔者又在转子实验平台上进行了实验验证。研究结果表明:实验结果与降阶之后振动响应均值的差异性较小,且与不确定性动力学模型相差不超过10%,表明所采用的理论模型在描述转子系统行为方面具备了较高的准确性和可靠性,该模型可以为深入研究模型不确定性转子系统提供参考。

无穷时间不确定线性二次最优控制的乐观值模型

基于不确定性理论,研究了在乐观值准则下连续不确定系统具有折扣因子的无穷时间最优控制模型。首先,利用动态规划方法,给出了求解该模型的最优性方程。然后,基于最优性方程,得到了不确定线性二次最优控制模型的最优状态反馈控制和最优值。最后,将所得的结果,应用到乐观值准则下的不确定广告投放问题。

基于扰动观测器的动态供应链系统模型预测控制

针对不确定市场需求供应链系统(supply chain system)的生产-库存预测控制问题,设计了一种模型预测控制(model predictive control,MPC)和扰动观测器(disturbance observer,DOB)结合的供应链系统生产控制策略。首先,对三级供应链系统进行分析,构建三级动态供应链的生产-库存数学模型;其次,设计基于扰动观测器的前馈补偿机制,补偿不确定性需求对供应链系统的影响;最后,考虑供应链系统存在的实际约束条件,设计模型预测控制方案,并证明系统的渐进稳定性。算例仿真验证了该方法的有效性。

基于综合集成评价方法的矿井通风系统安全评价分析

将未确知理论与层次分析法相结合,以此为基础介绍一种矿井通风系统评估的综合集成评价方法。该方法主要包括矿井通风系统安全评价指标体系构建、矿井通风系统安全评价指标确定、未确知测度评价模型构建3个环节。为确定方法的应用效果,以A煤矿为研究案例,介绍了矿井通风系统安全评价方法的工程应用情况,确认矿井通风系统安全评价方法具备较好的分析效果。

ROBUST STABILITY ANALYSIS FOR RAILWAY VEHICLE SYSTEMS

The lateral stability for railway vehicle dynamic system with uncertainparameters and nonlinear uncertain force vector is studied by using the Lyapunov stability theory. Arobust stability condition for the considered system is derived, and the obtained stability boundsare not necessarily symmetric with respect to the origin in the parameter space. The lateralstability analysis for a railway bogie model is analyzed by using the proposed approach. Thesymmetric and asymmetric results are both given and the influence of the adjustable parameter betaon the stability bounds is also discussed. With the help of the proposed method, the robuststability analysis can provide a reference for the design of the railway vehicle systems.

一类不确定分数阶Rucklidge系统的自适应滑模同步

根据自适应滑模方法研究不确定Rucklidge分数阶混沌系统的同步,获得实现不确定系统Rucklidge同步的充分条件,研究得出结论:设计适当的滑模面,选取合适的控制器,不确定Rucklidge分数阶混沌系统是可取得自适应滑模同步的.

基于最近邻聚类的光伏-制氢系统运行备用容量需求预估模型

在预估光伏-制氢系统运行备用容量需求时,受光伏-制氢系统运行数据不确定性的影响,预估结果的误差偏大,为此,提出基于最近邻聚类的光伏-制氢系统运行备用容量需求预估模型。引入最近邻聚类中的不确定自然最近邻机制,以近邻数数量为基础,按稠密点、稀疏点、噪声点的分类标准,将数据集中的不确定光伏-制氢系统运行数据对象进行划分处理;在使用不确定自然邻域搜索算法获取到不确定的自然稳定状态输出结果后,根据特征值的差异性去除噪声点,借助不确定自然邻域密度因子对光伏-制氢系统运行数据进行聚类;在预估模型构建阶段,将径向对称的高斯径向基函数(radial basis function, RBF)作为核函数,并将所有的RBF输出结果映射到同一个空间中,得到光伏-制氢系统运行备用容量需求结果。测试结果表明,所提方法对最大备用容量需求预估结果的偏差始终稳定在250 MW以内,对最小备用容量需求预估结果的偏差始终稳定在150 MW以内,有效降低了能量管理的成本开销。

不确定性源荷下电气互联系统两阶段鲁棒调度优化

针对电气互联系统中风电大量接入的背景下,传统风电区间预测模型的“最恶劣场景”过于保守的问题,提出了基于0-1规划的多区间预测方法。以电力网络、天然气网络和耦合元件为核心,考虑天然气传输中的动态管存模型及负荷侧的不确定性,构建了电气综合能源系统三层两阶段调度优化模型,利用NC&CG算法求解优化模型。结果表明,与传统风电区间预测模型相比,提出的风电预测模型之后,“最恶劣场景下”相邻时刻的最大峰谷差值从104 MW降低到72 MW,降低了28.8%。该研究证明了所提0-1规划的多区间预测模型能够有效降低风电预测的保守性。

船舶推进轴系振动的不确定性分析

[目的]针对传统的船舶推进轴系确定性振动分析存在安全性与可靠性不足的问题,开展轴系在不确定性激励下的振动响应分析。[方法]采用基于非概率凸模型过程的非随机振动分析方法,以区间上下界的形式描述不确定性激励和振动响应,降低对大量激励样本数据的依赖。与相关文献的计算结果对比,验证所编求解二自由度系统响应边界程序的正确性,并基于在此,探究轴系的不确定振动问题。[结果]当轴系受到螺旋桨[-30 N,30 N]的横向激励力激励时,在轴承处产生了量级约为10-6m的位移响应,表明轴系受到某一区间的激励,则必会产生某一区间的响应。[结论]将基于非概率凸模型过程的非随机振动分析方法应用于船舶推进轴系不确定性振动分析领域,可求得轴系受到不确定性激励时的振动位移响应边界,并可在激励样本较少的情况下为提高轴系系统动态响应预测的稳健性提供有益参考。

A Sliding Mode Observer for Uncertain Nonlinear Systems Based on Multiple Models Approach

This paper presents a method of state estimation for uncertain nonlinear systems described by multiple models approach. The uncertainties, supposed as norm bounded type, are caused by some parameters＇ variations of the nonlinear system. Linear matri~ inequalities （LMIs） have been established in order to ensure the stability conditions of the multiple observer which lead to determine the estimation gains. A sliding mode gain has been added in order to compensate the uncertainties. Numerical simulations through a state space model of a real process have been realized to show the robustness of the synthesized observer.

Grey Qualitative Modeling and Control Method for Subjective Uncertain Systems

A new approach to model and control an unknown system using subjective uncertain rules is proposed. This method is established by combining the grey system theory and the qualitative simulation method. The proposed approach mainly contains three steps. In the first step, subjective uncertain rules are accumulated gradually during cognizing the system; the mapping relations between the system inputs and outputs are built and represented using the grey qualitative matrix in the second step; in the third step,the generalized whitening function is defined to realize the transformation between qualitative and quantitative information. Besides the theoretical results, two sets of simulations based on a water level control system are conducted comparatively to demonstrate the effectiveness of the proposed method. The water level expectation is set to be constant in the first set, while it changes in the second set. The simulation results show that the proposed method tracks the water level expectation well. By combining the proposed method with proportional-integral-derivative(PID) or fuzzy logic controller(FLC), it can be concluded that the system can reach the stable state more quickly and the overshoot can also be reduced compared to using PID or FLC alone.

基于盲数BM模型的电网灵活规划方法

介绍了盲数BM模型及其特点,采用了盲数描述电网规划中各种不确定性信息,提出了基于盲数BM模型的电网规划模型,并利用成本效益分析方法求得具有最佳经济性和可靠性的电网灵活规划方案.算例分析表明,基于盲数BM模型描述和处理不确定性信息获得的电网灵活规划方案具有更好的灵活性、适应性.

汽车驾驶智能型防碰撞系统

汽车行驶与安全驾驶构成了一个多变量、具有不确定性、响应延迟的控制系统。把汽车自身和周围环境作为一个整体 ,作者提出了一种基于汽车 -环境特征模型来描述驾驶过程中出现的各种状态的知识表达方法 ,讨论了汽车驾驶辅助操作专家系统的构成。仿真说明了所讨论的知识表示方法和系统构成法的可行性以及正确性。

粗集理论在电力系统负荷预测中的应用

电力负荷预测的准确性对于电力系统的合理规划与建设意义重大。影响负荷预测准确性的最主要因素是原始数据的不确定性。文章应用粗集理论研究了历史数据不确定性影响下的电力系统中长期负荷预测问题。在结合具体实例的基础上,应用粗集理论给出了从负荷预测建模、缺失数据补齐、有效数据筛选到决策规则生成、最终得出负荷预测结果的一完整的预测过程。算例分析表明,应用粗集理论解决数据不确定性影响下的电力负荷预测是可行的。

一种开放网络环境中的不确定信任模型

开放网络环境中的信任关系是一种不确定关系 ,所以在建立信任模型时 ,需要对信任的不确定性进行建模 .为此 ,提出了一种新的基于云模型的信任模型 .通过用一维正态云来对实体之间的信任关系进行描述 ,本模型将实体之间的信任程度和信任的不确定性统一起来 .在此基础上 ,还提出了基于云的信任关系的传播和合并算法 ;并通过仿真实验说明 ,该模型在开放网络环境中具有良好的效果 .