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Arcese L.,University of Orleans | Fruchard M.,University of Orleans | Ferreira A.,INSA Val de Loire
IEEE Transactions on Biomedical Engineering | Year: 2012

This paper deals with the benefits of using a nonlinear model-based approach for controlling magnetically guided therapeutic microrobots in the cardiovascular system. Such robots used for minimally invasive interventions consist of a polymer binded aggregate of nanosized ferromagnetic particles functionalized by drug-conjugated micelles. The proposed modeling addresses wall effects (blood velocity in minor and major vessels' bifurcations, pulsatile blood flow and vessel walls, and effect of robot-to-vessel diameter ratio), wall interactions (contact, van der Waals, electrostatic, and steric forces), non-Newtonian behavior of blood, and different driving designs as well. Despite nonlinear and thorough, the resulting model can both be exploited to improve the targeting ability and be controlled in closed-loop using nonlinear control theory tools. In particular, we infer from the model an optimization of both the designs and the reference trajectory to minimize the control efforts. Efficiency and robustness to noise and model parameter's uncertainties are then illustrated through simulations results for a bead pulled robot of radius 250 μm in a small artery. © 2006 IEEE. Source

Boutat D.,INSA Val de Loire | Boutat-Baddas L.,Nancy Research Center for Automatic Control | Darouach M.,Nancy Research Center for Automatic Control
Systems and Control Letters | Year: 2012

This paper presents a new observability normal form for discrete-time nonlinear systems. This form enables us to design a reduced-order observer. Necessary and sufficient geometrical conditions for the existence of a coordinate change to transform a discrete-time nonlinear system into such normal form are given. An illustrative example is given to show the effectiveness of our approach. © 2012 Elsevier B.V. All rights reserved. Source

Joy J.,INSA Val de Loire
AI and Society | Year: 2012

This article presents a sample of references issuing directly from the existing NMSAT database. The method employed-that of systematically probing the database-reveals forms of sonification, but also hypothetical premises of sonification, covering the period from ancient times to the beginning of the twentieth century. The following are some of the categories of sonification that have emerged as a result of this search: Natural phenomenon & meteorology to sound (autophones); Image to sound; Text & communication to sound; Human & machine activities to sound (auditing); Localisation to sound (sonar); Architecture & geometry & abstract proportions to sound (scalization, transcription, & spatialization); Energy to sound; Human body to sound; Distance to sound (distance listening); Movement to sound (holophony, kynophony); and Interpreted observations to sound (naturalist music, transpositions & analogies, paraphrasing). The search also uncovered other principals and practices in the vicinity of sonification including: audification, auditing, auscultation, auralization, soniculation, transduction, mapping, earcons, auditory icons, sympathy, echometry, etc. It has been decided to summarise the results of « What NMSAT Says About Sonification » in this special issue of AI&Society, access to the unabridged version of article is available here: http://www. locusonus. org/sonification/. © 2011 Springer-Verlag London Limited. Source

Batailly A.,McGill University | Magnain B.,INSA Val de Loire | Chevaugeon N.,Ecole Centrale Nantes
Computational Mechanics | Year: 2013

The numerical simulation of contact problems is still a delicate matter especially when large transformations are involved. In that case, relative large slidings can occur between contact surfaces and the discretization error induced by usual finite elements may not be satisfactory. In particular, usual elements lead to a facetization of the contact surface, meaning an unavoidable discontinuity of the normal vector to this surface. Uncertainty over the precision of the results, irregularity of the displacement of the contact nodes and even numerical oscillations of contact reaction force may result of such discontinuity. Among the existing methods for tackling such issue, one may consider mortar elements (Fischer and Wriggers, Comput Methods Appl Mech Eng 195:5020-5036, 2006; McDevitt and Laursen, Int J Numer Methods Eng 48:1525-1547, 2000; Puso and Laursen, Comput Methods Appl Mech Eng 93:601-629, 2004), smoothing of the contact surfaces with additional geometrical entity (B-splines or NURBS) (Belytschko et al., Int J Numer Methods Eng 55:101-125, 2002; Kikuchi, Penalty/finite element approximations of a class of unilateral contact problems. Penalty method and finite element method, ASME, New York, 1982; Legrand, Modèles de prediction de l'interaction rotor/stator dans un moteur d'avion Thèse de doctorat. PhD thesis, École Centrale de Nantes, Nantes, 2005; Muñoz, Comput Methods Appl Mech Eng 197:979-993, 2008; Wriggers and Krstulovic-Opara, J Appl Math Mech (ZAMM) 80:77-80, 2000) and, the use of isogeometric analysis (Temizer et al., Comput Methods Appl Mech Eng 200:1100-1112, 2011; Hughes et al., Comput Methods Appl Mech Eng 194:4135-4195, 2005; de Lorenzis et al., Int J Numer Meth Eng, in press, 2011). In the present paper, we focus on these last two methods which are combined with a finite element code using the bi-potential method for contact management (Feng et al., Comput Mech 36:375-383, 2005). A comparative study focusing on the pros and cons of each method regarding geometrical precision and numerical stability for contact solution is proposed. The scope of this study is limited to 2D contact problems for which we consider several types of finite elements. Test cases are given in order to illustrate this comparative study. © 2012 Springer-Verlag. Source

Arcese L.,University of Reims Champagne Ardenne | Fruchard M.,University of Orleans | Ferreira A.,INSA Val de Loire
IEEE Transactions on Robotics | Year: 2013

This paper discusses the control design of a magnetically guided microrobotic system in blood vessels to perform minimally invasive medical procedures. Such microrobots consist of a polymer-bonded aggregate of nanosized ferromagnetic particles and a possible payload that can be propelled by the gradient coils of a magnetic device. A fine modeling is developed and used to define an optimal trajectory which minimizes the control efforts. We then synthesize an adaptive backstepping law that ensures a Lyapunov stable and fine tracking, despite modeling errors, and estimates some key uncertain parameters. As the controller synthesis uses the microrobot unmeasured velocity, the design of a high-gain observer is also addressed. Simulations and experiment illustrate the robustness to both noise measurement and some uncertain physiological parameters for a 250 μm radius microrobot that navigates in a fluidic environment. © 2004-2012 IEEE. Source

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