On uniform global attainability of two-dimensional linear systems with locally integrable coefficients

A. A. Kozlov ; I. V. Ints

Vestnik Udmurtskogo universiteta. Matematika, mehanika, kompʹûternye nauki, Tome 27 (2017) no. 2, pp. 178-192

Résumé

We consider a linear time-varying control system with locally integrable and integrally bounded coefficients \begin{equation} \dot x =A(t)x+ B(t)u, \quad x\in\mathbb{R}^n,\quad u\in\mathbb{R}^m,\quad t\geqslant 0. \tag{1} \end{equation} We construct control of the system $(1)$ as a linear feedback $u=U(t)x$ with measurable and bounded function $U(t)$, $t\geqslant 0$. For the closed-loop system \begin{equation} \dot x =(A(t)+B(t)U(t))x, \quad x\in\mathbb{R}^n, \quad t\geqslant 0, \tag{2} \end{equation} we study a question about the conditions for its uniform global attainability. The last property of the system (2) means existence of a matrix $U(t)$, $t\geqslant 0$, that ensure equalities $X_U((k+1)T,kT)=H_k$ for the state-transition matrix $X_U(t,s)$ of the system (2) with fixed $T>0$ and arbitrary $k\in\mathbb N$, $\det H_k>0$. The problem is solved under the assumption of uniform complete controllability of the system (1), corresponding to the closed-loop system (2), i.e. assuming the existence of such $\sigma>0$ and $\gamma>0,$ that for any initial time $t_0\geqslant 0$ and initial condition $x(t_0)=x_0\in \mathbb{R}^n$ of the system (1) on the segment $[t_0,t_0+\sigma]$ there exists a measurable and bounded vector control $u=u(t),$ $\|u(t)\|\leqslant\gamma\|x_0\|,$ $t\in[t_0,t_0+\sigma],$ that transforms a vector of the initial state of the system into zero on that segment. It is proved that in two-dimensional case, i.e. when $n=2,$ the property of uniform complete controllability of the system (1) is a sufficient condition of uniform global attainability of the corresponding system (2).

Détail

Keywords: linear control system, uniform complete controllability, uniform global attainability.