The Purcell Three-link swimmer: some geometric and numerical aspects related to periodic optimal controls

Piernicola Bettiol 1 Bernard Bonnard 2, 3 Laetitia Giraldi 4 Pierre Martinon 5, 6, 7 Jérémy Rouot 3
3 McTAO - Mathematics for Control, Transport and Applications
CRISAM - Inria Sophia Antipolis - Méditerranée
5 Commands - Control, Optimization, Models, Methods and Applications for Nonlinear Dynamical Systems
CMAP - Centre de Mathématiques Appliquées - Ecole Polytechnique, Inria Saclay - Ile de France, ENSTA ParisTech UMA - Unité de Mathématiques Appliquées, Univ. Paris-Saclay, ENSTA ParisTech - École Nationale Supérieure de Techniques Avancées, Polytechnique - X, CNRS - Centre National de la Recherche Scientifique : UMR7641
Abstract : The maximum principle combined with numerical methods is a powerful tool to compute solutions for optimal control problems. This approach turns out to be extremely useful in applications, including solving problems which require establishing periodic trajectories for Hamiltonian systems, optimizing the production of photobioreactors over a one-day period, finding the best periodic controls for locomotion models (e.g. walking, flying and swimming). In this article we investigate some geometric and numerical aspects related to optimal control problems for the so-called Purcell Three-link swimmer [20], in which the cost to minimize represents the energy consumed by the swimmer. More precisely, employing the maximum principle and shooting methods we derive optimal trajectories and controls, which have particular periodic features. Moreover, invoking a linearization procedure of the control system along a reference extremal, we estimate the conjugate points, which play a crucial role for the second order optimality conditions. We also show how, making use of techniques imported by the sub-Riemannian geometry, the nilpotent approximation of the system provides a model which is integrable, obtaining explicit expressions in terms of elliptic functions. This approximation allows to compute optimal periodic controls for small deformations of the body, allowing the swimmer to move minimizing its energy. Numerical simulations are presented using Hampath and Bocop codes.
Type de document :
Pré-publication, Document de travail
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Contributeur : Jérémy Rouot <>
Soumis le : lundi 5 octobre 2015 - 15:13:43
Dernière modification le : jeudi 5 janvier 2017 - 01:53:28


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  • HAL Id : hal-01143763, version 2



Piernicola Bettiol, Bernard Bonnard, Laetitia Giraldi, Pierre Martinon, Jérémy Rouot. The Purcell Three-link swimmer: some geometric and numerical aspects related to periodic optimal controls. 2015. <hal-01143763v2>



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