Finite-time adaptive fuzzy control for a class of output constrained nonlinear systems with dead-zone

The article investigates the finite-time adaptive fuzzy control for a class of nonlinear systems with output constraint and input dead-zone. First, by skillfully combining the barrier Lyapunov function, backstepping design method, and finite-time control theory, a novel adaptive state-feedback tracking controller is constructed, and the output constraint of the nonlinear system is not violated. Second, the fuzzy logic system is used to approximate unknown function in the nonlinear system. Third, the finite-time command filter is introduced to avoid the problem of “complexity explosion” caused by repeated differentiations of the virtual control signal in conventional backstepping control schemes. Meanwhile, a new saturation function is added in the compensating signal for filter error to improve control accuracy. Finally, based on Lyapunov stability analysis, all the signals of the closed-loop are proved to be semi-globally uniformly ultimately bounded, and the tracking error converges to a small neighborhood region of the origin in a finite time. A simulation example is presented to demonstrate the effectiveness for the proposed control scheme.     

Robot control and parameter estimation with only joint position measurements

Most adaptive control schemes for rigid robots assume velocities measurements to be available. Although it is possible to measure velocities by using tachometers, this increases costs and the signals delivered may be contaminated with noise. Since the use of encoders allows to read joint position pretty accurately, it is desirable to estimate joint velocities through an observer. This paper presents an adaptive scheme designed in conjunction with a linear observer. Boundedness of the estimated parameters and uniform ultimate boundedness for the tracking and observation errors are guaranteed. Experimental results are included to support the developed theory.     

基于受扰动的PMSM系统动力学研究及模拟

借助Lyapunov函数稳定性理论和最优化理论研究了永磁同步电动机系统解的界,得到了它的界估计。通过计算机模拟,数值模拟验证了计算理论的可行性。     

Finite-time consensus of multiple second-order dynamic agents without velocity measurements

This article considers the finite-time consensus of multiple second-order dynamic agents without velocity measurements. A feasible protocol under which each agent can only obtain the measurements of its position relative to its neighbours is proposed. By applying the graph theory, Lyapunov theory and the homogeneous domination method, some sufficient conditions for finite-time consensus of second-order multi-agent systems are established under the different kinds of communication topologies. Some examples are presented to illustrate the effectiveness of the theoretical results.     

直接侧向力与气动力复合控制导弹脱靶量分析

大气层内姿控式直接侧向力控制导弹末制导系统存在气动力控制与复合控制之间的切换,在这种特殊情形下引入有限时间广义H2方法进行脱靶量分析.根据复合控制导弹末制导系统数学模型,研究了切换情形下的零效脱靶量与制导系统关键参数之间的关系,分析了直接侧向力启控时间、有效导航比、修正比例导引系数以及目标估计环节时间常数对零效脱靶量的影响.分析结果为制导末端直接侧向力启控时间的确定和修正比例导引律参数的选择提供了有力依据.     

NSG系统和分数阶金融系统的有界性及其同步

研究了两个混沌系统的有界性及其同步问题,解决了NSG系统和分数阶金融系统的有界性问题,在这两个混沌系统有界的条件下,用线性反馈控制实现有界混沌系统的同步,数值模拟的结果证明了这个方法的有效性．     

具有随机扰动的时滞竞争系统

在21世纪,有关生物数学的研究显得越发重要,生物数学与其他学科的交叉领域将成为主要的研究对象.与确定性生物数学模型相比较,在现实生活中,种群生态系统经常会遇到环境白噪声的干扰,研究环境白噪声的存在是否影响种群生态系统,以及是否会使已有的结果发生变化已受到广泛关注.讨论具有随机扰动的n-种群时滞竞争系统在其具有正解的前提下,证明该系统解矩有界,并证明解的一致连续性。     

从Zygmund空间到Bloch-type空间的加权复合算子

令φ,u分别是复平面C上的单位开圆盘D中的解析自映射和解析函数.加权复合算子定义为（uCφ）（f）（z）=u（z）f（φ（z））,z∈D,f∈H（D）.主要讨论了从Zygmund空间到Bloch-type空间的加权复合算子的有界性和紧性.     

Finite‐time H ∞ control for discrete‐time switched nonlinear systems with time delay

In this paper, the problem of finite‐time H _∞ control is addressed for a class of discrete‐time switched nonlinear systems with time delay. The concept of H _∞ finite‐time boundedness is first introduced for discrete‐time switched delay systems. Next, a set of switching signals are designed by using the average dwell time approach, under which some delay‐dependent sufficient conditions are derived to guarantee the H _∞ finite‐time boundedness of the closed‐loop system. Then, a finite‐time H _∞ state feedback controller is also designed by solving such conditions. Furthermore, the problem of uniform finite‐time H _∞ stabilization is also resolved. All the conditions are cast into linear matrix inequalities, which can be easily checked by using recently developed algorithms for solving linear matrix inequalities. A numerical example and a water‐quality control system are provided to demonstrate the effectiveness of the main results. Copyright © 2013 John Wiley & Sons, Ltd.     

Output feedback control of discrete‐time systems with self‐triggered controllers

This paper is concerned with the self‐triggered output feedback control for discrete‐time systems, where an updating instants scheduler is implemented to determine when the controller is updated. For both the full‐order and reduced‐order observer cases, the updating instants are determined, respectively, where only the information of the estimated state at the current updating instant is required to obtain the next updating instant. It is shown that, with the proposed self‐triggered control schemes, not only the updating frequency is significantly reduced, but also the uniform ultimate boundedness of the closed‐loop system is guaranteed. Finally, a numerical example is used to verify the effectiveness and the merits of the proposed approaches. Copyright © 2014 John Wiley & Sons, Ltd.