有限时间控制问题综述

有限时间控制系统因具有良好的鲁棒性能和抗扰动性能而受到广泛关注.首先,回顾了有限时间控制方法的起源,并列举了有限时间控制系统的几种常用判据;然后,总结了有限时间控制系统的研究现状;最后,讨论了未来可能的研究方向.  

Geometric homogeneity with applications to finite-time stability

This paper studies properties of homogeneous systems in a geometric, coordinate-free setting. A key contribution of this paper is a result relating regularity properties of a homogeneous function to its degree of homogeneity and the local behavior of the dilation near the origin. This result makes it possible to extend previous results on homogeneous systems to the geometric framework. As an application of our results, we consider finite-time stability of homogeneous systems. The main result that links homogeneity and finite-time stability is that a homogeneous system is finite-time stable if and only if it is asymptotically stable and has a negative degree of homogeneity. We also show that the assumption of homogeneity leads to stronger properties for finite-time stable systems.  

Semi-global finite-time observers for nonlinear systems

It is well known that high gain observers exist for single output nonlinear systems that are uniformly observable and globally Lipschitzian. Under the same conditions, we show that these systems admit semi-global and finite-time converging observers. This is achieved with a derivation of a new sufficient condition for local finite-time stability, in conjunction with applications of geometric homogeneity and Lyapunov theories.  

一类连续级联系统的全局一致稳定性

针对一类非线性连续级联系统, 利用齐次系统的齐次性质给出了其全局一致稳定性分析结果. 假设级联系统中的驱动子系统和被驱动子系统分别满足全局一致渐近稳定且满足一定的齐次度, 若级联项也满足一给定齐次不等式, 则整个非线性级联系统为全局一致渐近稳定的. 若驱动子系统和被驱动子系统都具有负的齐次度, 则该非线性级联系统为全局一致有限时间稳定的. 与传统的ISS假设或级联项增长假设相比, 文中方法所给的齐次不等式条件更容易验证. 且文中方法不仅适用于Lipschitz连续的系统, 而且适用于非Lipschitz连续的系统. 两个例子验证了该方法的有效性.  

Global stabilization of discrete-time homogeneous systems

The feedback stabilization of continuous time Δ^r-homogeneous systems has been studied by several authors, see for instance (Dayawansa and Martin, Proceedings of the 28th C.D.C., Tampa, Florida, December, 1989, Hermes, J. Differential Equations 92 (1991) 76–89, Hermes, Systems Control Lett. 24 (1995) 7–11, Kawski, Proceedings of the 27th C.D.C., Texas, 1988, Texas, Kawski, Control Theory and Advanced Technology, vol. 6, MITA Press, Tokyo, 1996, pp. 497–516, Sepulchre and Aeyels, Math. Control Signal Systems 9 (1996) 34–58). In (Kawski, Analysis of Controlled Dynamical Systems, Birkhauser, Basel, 1991, Kawski, Proceedings of IFAC NOLCOS, 1995), Kawski gave an intrinsic concept of homogeneity with respect to general smooth dilations. In this note, we define the homogeneity of transition maps w.r.t. continuous dilations and we show how one can construct a global stabilizing feedback control for discrete-time homogeneous systems which are locally asymptotically stabilizable.  

齐次非线性系统H∞控制的输出反馈

研究了齐次系统Ｈ∞控制的输出反馈问题，首先给出齐次伫与二次型Ｌｙａｐｕｎｏｖ函数之间的关系，随后讨论了齐次系统Ｈ∞控制的输出反馈总理２，在适当条件下，给出了全局解，然后考虑李具有高阶扰动项的齐次系统，对此系统也得到与无扰动项时的相似结论。  

On the asymptotic stability of switched homogeneous systems

The stability of switched systems generated by the family of autonomous subsystems with homogeneous right-hand sides is investigated. It is assumed that for each subsystem the proper homogeneous Lyapunov function is constructed. The sufficient conditions of the existence of the common Lyapunov function providing global asymptotic stability of the zero solution for any admissible switching law are obtained. In the case where we can not guarantee the existence of a common Lyapunov function, the classes of switching signals are determined under which the zero solution is locally or globally asymptotically stable. It is proved that, for any given neighborhood of the origin, one can choose a number L>0 (dwell time) such that if intervals between consecutive switching times are not smaller than L then any solution of the considered system enters this neighborhood in finite time and remains within it thereafter.  

The invariants of the binary decimic

We consider the algebra of invariants of binary forms of degree 10 with complex coefficients, construct a system of parameters with degrees 2, 4, 6, 6, 8, 9, 10 and 14 and find the 106 basic invariants.  

The invariants of the binary nonic

We consider the algebra of invariants of binary forms of degree 9 with complex coefficients, find the 92 basic invariants, give an explicit system of parameters and show the existence of four more systems of parameters with different sets of degrees.  

Stabilization via homogeneous feedback controls

In this paper, we provide an explicit homogeneous feedback control with the requirement that a control Lyapunov function exists for an affine control system and satisfies an homogeneous condition. We use a modified version of the Sontag formula to achieve our main goal. Moreover, we prove that the existence of an homogeneous control Lyapunov function for an homogeneous affine system leads to an homogeneous closed-loop system by using the previous feedback control.