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On the existence of nonsmooth control-Lyapunov functions in the sense of generalized gradients

Ludovic Rifford — 2001

ESAIM: Control, Optimisation and Calculus of Variations

Let x ˙ = f ( x , u ) be a general control system; the existence of a smooth control-Lyapunov function does not imply the existence of a continuous stabilizing feedback. However, we show that it allows us to design a stabilizing feedback in the Krasovskii (or Filippov) sense. Moreover, we recall a definition of a control-Lyapunov function in the case of a nonsmooth function; it is based on Clarke’s generalized gradient. Finally, with an inedite proof we prove that the existence of this type of control-Lyapunov...

On the existence of nonsmooth control-Lyapunov functions in the sense of generalized gradients

Ludovic Rifford — 2010

ESAIM: Control, Optimisation and Calculus of Variations

Let x ˙ = f ( x , u ) be a general control system; the existence of a smooth control-Lyapunov function does not imply the existence of a continuous stabilizing feedback. However, we show that it allows us to design a stabilizing feedback in the Krasovskii (or Filippov) sense. Moreover, we recall a definition of a control-Lyapunov function in the case of a nonsmooth function; it is based on Clarke's generalized gradient. Finally, with an inedite proof we prove that the existence of this type of control-Lyapunov...

On the stabilization problem for nonholonomic distributions

Ludovic RiffordEmmanuel Trélat — 2009

Journal of the European Mathematical Society

Let M be a smooth connected complete manifold of dimension n , and Δ be a smooth nonholonomic distribution of rank m n on M . We prove that if there exists a smooth Riemannian metric on1for which no nontrivial singular path is minimizing, then there exists a smooth repulsive stabilizing section of Δ on M . Moreover, in dimension three, the assumption of the absence of singular minimizing horizontal paths can be dropped in the Martinet case. The proofs are based on the study, using specific results of...

Regularity properties of the distance functions to conjugate and cut loci for viscosity solutions of Hamilton-Jacobi equations and applications in Riemannian geometry

Marco CastelpietraLudovic Rifford — 2010

ESAIM: Control, Optimisation and Calculus of Variations

Given a continuous viscosity solution of a Dirichlet-type Hamilton-Jacobi equation, we show that the distance function to the conjugate locus which is associated to this problem is locally semiconcave on its domain. It allows us to provide a simple proof of the fact that the distance function to the cut locus associated to this problem is locally Lipschitz on its domain. This result, which was already an improvement of a previous one by Itoh and Tanaka [  (2001) 21–40], is due to Li and Nirenberg...

Feedback in state constrained optimal control

Francis H. ClarkeLudovic RiffordR. J. Stern — 2002

ESAIM: Control, Optimisation and Calculus of Variations

An optimal control problem is studied, in which the state is required to remain in a compact set S . A control feedback law is constructed which, for given ε > 0 , produces ε -optimal trajectories that satisfy the state constraint universally with respect to all initial conditions in S . The construction relies upon a constraint removal technique which utilizes geometric properties of inner approximations of S and a related trajectory tracking result. The control feedback is shown to possess a robustness...

Feedback in state constrained optimal control

Francis H. ClarkeLudovic RiffordR. J. Stern — 2010

ESAIM: Control, Optimisation and Calculus of Variations

An optimal control problem is studied, in which the state is required to remain in a compact set . A control feedback law is constructed which, for given ε > 0, produces -optimal trajectories that satisfy the state constraint universally with respect to all initial conditions in . The construction relies upon a constraint removal technique which utilizes geometric properties of inner approximations of and a related trajectory tracking result. The control feedback is shown to possess a robustness...

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