欠驱动水面机器人变周期全局渐近镇定控制

为了实现欠驱动水面机器人的全局渐近镇定,首先借助微分同胚变换,将欠驱动水面机器人的镇定问题转化成对由两个串级子系统构成的二阶欠驱动系统的镇定问题.针对转换后的系统,本文提出一种光滑的变周期控制方法,以实现对该系统的全局渐近镇定.与已有文献中控制律使用常数周期的方法相比,本文方法根据系统状态实时调整控制律周期,从而提高系统在原点附近的收敛速率.随后,基于上述方法,给出了水面机器人变周期控制算法,实现原系统的全局渐近镇定.最后,仿真对比结果验证所提变周期控制方法的有效性.     

一类非完整约束系统的镇定与能控性

考虑非完整约束系统的镇定与能控性问题. 文中首先证明了虽然一般地说这类系统不能由光滑反馈镇定, 但它的存在性依赖于初值. 当初值在一个零测集外时, 这种反馈镇定确实存在. 然后我们证明了这类系统在分段光滑控制下全局可控. 由于证明是构造性的, 它给出了相应的控制.     

非完整链式系统的时变光滑指数镇定

针对非完整链式系统,导出了一种时变光滑反馈控制律,该控制律可以保证系统状态 全局指数收敛到原点,克服了以往控制律非光滑或虽光滑但却只能渐近镇定系统的缺陷.所得 控制律应用于移动机器人系统的镇定.     

鲁棒镇定区间系统族的一个充分条件

讨论了区间系统族的鲁棒镇定问题,给出存在控制器鲁棒镇定区间系统族的一个充分条 件,并且当这个条件成立时,得到了鲁棒镇定区间系统族的控制器的参数化公式.     

控制李雅普诺夫承数的镇定应用

指出控制李雅普诺夫承数(源于松弛控制)正是零状态可检测性的一种刻面,并由此区别 两类镇定控制;无源性控制和Sontag型控制.然后考察一类典型的级联系统,基于一定条件下的控 制李雅普诺夫函数,给出了不同于无源性控制的Sontag型镇定设计;考察这类系统的扰动情形,基 于一定条件下的输入到状态稳定控制李雅普诺夫承数,给出了Sontag型输入到状态镇定设计.     

无源性原理在鲁棒镇定中的应用

研究自由动态临界稳定仿射系统的输入到状态镇定,通过零状态可探测假设,减弱了 通常的前提条件:自由动态全局渐近稳定;运用无源性原理研究扰动抑制,给出了输出负反馈解 扰动抑制问题的简明条件.分析中用到Legendre-Fenchel变换.     

双线性系统的全局可镇定性1)

讨论了多输入多输出双线性系统的全局可镇定问题.利用Lyapunov方法,分别通过静态状态反馈和动态输出反馈得到双线性系统全局可镇定的充分条件,并且给出了相应控制器的设计方法.     

双线性系统的全局可镇定性

讨论了多输入多输出双线性系统的全局可镇定问题.利用Lyapunov方法,分别通 过静态状态反馈和动态输出反馈得到双线性系统全局可镇定的充分条件,并且给出了相应控 制器的设计方法.     

一类高阶次随机非线性系统的状态反馈镇定

针对一类高阶次随机非线性系统,研究其状态反馈镇定问题.基于最近发展起来的增加幂次积分器技术,通过适当地选取Lyapunov函数和设计参数,给出了一个光滑的状态反馈反推控制器的设计过程,所设计的控制器保证了闭环系统在原点处的平衡点是概率意义下全局渐近稳定的.     

一类二阶非完整系统的镇定

研究一类二阶非完整系统的镇定问题. 通过状态和输入反馈变换将系统模型转换为二阶链式标准型, 并对标准型给出一种时变光滑指数镇定控制律. 所得结果应用于欠驱动平面刚体的镇定.     

Global stabilization of a class of cascaded systems with upper‐triangular structures

In this paper, the global stabilization problem of a class of cascaded systems with upper‐triangular structures is considered. On the basis of the forwarding technique, a series of virtual controllers are recursively constructed for the driving subsystem. According to the mild assumption imposed on the driven subsystem, a partial‐state feedback controller is obtained for the entire cascaded nonlinear system by developing a delicate design fashion. It is shown that the obtained state feedback controller will render the entire cascaded nonlinear system globally asymptotically stable. Numerical examples are conducted to validate the proposed control scheme.     

Nonsmooth stabilization of a class of nonlinear cascaded systems

A global nonsmooth stabilization scheme is presented for a class of nonlinear cascaded systems with uncontrollable linearization. A stepwise constructive control methodology is proposed for the driving subsystem by using the adding a power integrator technique. Under suitable conditions and based on homogeneous properties, it is proved that the stabilization of the driving subsystem implies the stabilization of the overall cascaded system. Due to the versatility of the adding a power integrator technique and homogeneous properties, the proposed controller not only can be used to stabilize the cascaded system asymptotically, but also is able to lead to an interesting result of finite-time stabilization under appropriate conditions.     

Controller design for nonlinear affine systems by control Lyapunov functions

This paper addresses the stabilization problems for nonlinear affine systems. First of all, the explicit feedback controller is developed for a nonlinear multiple-input affine system by assuming that there exists a control Lyapunov function. Next, based upon the homogeneous property, sufficient conditions for the continuity of the derived controller are developed. And then the developed control design methodology is applied to stabilize a class of nonlinear affine cascaded systems. It is shown that under some homogeneous assumptions on control Lyapunov functions and the interconnection term, the cascaded system can be globally stabilized. Finally, some interesting results of finite-time stabilization for nonlinear affine systems are also obtained.     

Cascaded feedback linearization and its application to stabilization of nonholonomic systems

In this paper, a new cascaded feedback linearization problem is formulated and a set of conditions on the cascaded feedback linearizability are established for a class of two-input affine nonlinear systems. The proposed cascaded feedback linearization method enlarges the classes of nonlinear systems which can be dealt with using the feedback linearization technique. In particular, the proposed design can be applied to address the feedback stabilization problem for a few classes of nonlinear systems which have uncontrollable linearization and do not satisfy the standard feedback linearization conditions. As an illustrative application, the proposed cascade feedback linearization concept is used to solve the feedback stabilization problem of nonholonomic systems within the framework of continuously differentiable state feedback control. Simulation results are provided to illustrate the proposed method.     

Nonsmooth stabilizability and feedback linearization of discrete-time nonlinear systems

We consider the problem of stabilizing a discrete-time nonlinear system using a feedback which is not necessarily smooth. A sufficient condition for global dynamical stabilizability of single-input triangular systems is given. We obtain conditions expressed in terms of distributions for the nonsmooth feedback triangularization and linearization of discrete-time systems. Relations between stabilization and linearization of discrete-time systems are given.     

Global uniform asymptotical stability of a class of nonlinear cascaded systems with application to a nonholonomic wheeled mobile robot

In this article, we consider the stability analysis problem for a class of nonlinear cascaded systems by using homogeneous properties. Assume that the driving subsystem and the driven subsystem are both homogeneous and locally uniformly asymptotically stable. If the cascaded term satisfies a given inequality, then the cascaded system is globally uniformly asymptotically stable. Furthermore, in the case that both degrees of homogeneity are negative, the cascaded system is globally uniformly finite-time stable. Compared with the existing methods, the conditions given in this article are much easier to verify. These stability results are applied to the global tracking control problem of a nonholonomic wheeled mobile robot. Simulation results are provided to show the effectiveness of the methods.     

不确定非线性环链系统的分散鲁棒控制

提出了环链系统和一类不确定非线性环链系统,利用线性代数理论,给出了实现环链系统的充要条件,运用李雅普诺夫稳定理论和矩阵理论研究了不确定非线性环链系统的鲁棒镇定,并给出了一种非线性鲁棒镇定控制器的设计,还考虑了一类非线性环链相似组合大系统,给出了分散鲁棒镇定条件,最后给出数值例子说明设计方法的有效性。     

Output feedback stabilization and approximate and restricted tracking for a class of cascaded systems

In this note, we discuss the problems of output feedback stabilization for a class of cascaded systems and of (approximate and restricted) output regulation for general nonlinear systems. It is shown that (global) output feedback stabilization for a class of systems in feedforward form can be achieved with a dynamic feedback law, yielding bounded control, and relying on the introduction of a reduced-order observer. The above result, together with standard tools borrowed from the output regulator theory, is instrumental to construct dynamic control laws achieving (approximate) disturbance rejection and output tracking in the presence of (small) disturbance/reference signals generated by a known exosystem.     

Global finite-time stabilization for a class of switched nonlinear systems via output feedback

This paper addresses the problem of global finite-time stabilization for a class of uncertain switched nonlinear systems via output feedback under arbitrary switchings. Based on the adding a power integrator approach, we design a homogeneous observer and controller for the nominal switched system without the perturbing nonlinearities. Then, a scaling gain is introduced into the proposed output feedback stabilizer to implement global finite-time stability of the closed-loop system. In addition, the proposed approach can be also extended to a class of switched nonlinear systems with upper-triangular growth condition. Two examples are given to illustrate the effectiveness of the proposed method.     

具有Markov跳跃参数的一类随机非线性系统逆最优增益设计

研究了一类随机非线性系统的逆最优增益设计问题,系统中除了方差未知的Wiener噪声之外,还含有Markov跳跃参数. 首先,给出此类系统逆最优增益设计问题可解的一个充分条件. 其次,针对一类具有严格反馈形式的随机非线性系统,利用积分反推法,给出了依概率全局渐近稳定和逆最优控制策略的设计方法. 其中,所设计的Lyapunov函数和控制策略与模态显式无关,克服了由于Markov跳跃模态引起的耦合项所带来的设计困难. 最后,通过仿真验证了控制策略的有效性.