Switching in time-optimal problem
Switching in time-optimal problem
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发表时间:
2017-09
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通讯作者:
Carolina Biolo
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作者:
Carolina Biolo
The central object of this thesis is time-optimal problem on an affine control system of type q̇ = f0(q) + u1f1(q) + . . . + ukfk(q), q ∈ M (Σ) where f0, . . . , fk are k + 1 vector fields defined on the manifold M . We assume that f0, . . . , fk are smooth (C∞(M)) and u = (u1, . . . , uk) are L∞ admissible controls taking value in the k -dimensional closed unitary ball. We analyse the local regularity of system (Σ), with the classical methods of the optimal control theory: the Pontryagin maximum principle, the second order optimality conditions and other methods based on the relations between geometric local properties of (Σ) and algebraic structure, as the configurations on the Lie brackets of the system. We are interested in finding generic conditions on the vector fields of the system (Σ) in a point q̄ in M , such that each time-optimal trajectory of (Σ) close to q̄ is piece-wise smooth with a finite number of smooth components, called arcs. More precisely, we look for generic conditions that guaranties the absence of chattering phemonema, i.e. the existence of a convergent series of smooth arcs in finite time. We found this conditions in chapters 3 and 4. In particular, we show that in the case of k = n − 1 there are sufficient conditions in terms of Lie bracket relations for all optimal controls to be smooth or to have only isolated jump discontinuities; and we characterized the flow of Pontryagin’s extremals. In Chapter 5 we analyse the global number of singularities, called switchings, considering (Σ) as a linear system: with linear drift f0 , and constant controllable vector fields. We show that there will appear a unique or an infinity number of switchings at regular time intervals. Finally, in Chapter 6 we present the cases for which we were able to prove the optimality of the broken extremal trajectory, we found in the previous chapters. Here we list all the works collected in this thesis: Chapter 3: A. A. Agrachev, C. Biolo, Switching in time-optimal problem with control in a ball, arXiv:1610.06755 (2016), to appear on SIAM J. Control Optim. Chapter 4: A. A. Agrachev, C. Biolo, Switching in time-optimal problem: the 3-D case with 2-D control, J Dyn Control Syst, DOI 10.1007/s10883-016-9342-7, 2016. Chapter 6: A. A. Agrachev, C. Biolo, Optimality of a broken extremal, preprint 2017.