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  • A weighted cost function to deal with the muscle force sharing problem in injured subjects: A single case study

     Serrancoli Masferrer, Gil; Font Llagunes, Josep Maria; Barjau Condomines, Ana
    Proceedings of the Institution of Mechanical Engineers. Part K, journal of multi-body dynamics
    Vol. 228, num. 3, p. 241-11
    DOI: 10.1177/1464419314530110
    Date of publication: 2014-09-01
    Journal article

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    The human body is an over-actuated multi-body system, as each joint degree of freedom can be controlled by more than one muscle. Solving the force-sharing problem (i.e. finding out how the resultant joint torque is shared among the muscles actuating that joint) calls for an optimization process where a cost function, representing the strategy followed by the central nervous system to activate muscles, is minimized. The main contribution of the present study has been the particular formulation of that cost function for the case of the pathological gait of a single subject suffering from anterior cruciate ligament rupture. Our hypothesis was that the central nervous system does not weight equally the muscles when trying to compensate for a lower limb injury during gait (in contrast to what is the usual practice for healthy gait where all muscles are weighted equally). This hypothesis is supported by the fact that muscle activity in injured individuals differs from that of healthy subjects. Different functions were tested until we finally came out with a cost function that was consistent with experimental electromyography measurements and inverse dynamics results for a subject suffering this particular pathology.

  • Combining vibrational linear-by-part dynamics and kinetic-based decoupling of the dynamics for multiple smooth impacts with redundancy

     Barjau Condomines, Ana; Agullo Batlle, Joaquim; Font Llagunes, Josep Maria
    Multibody system dynamics
    Vol. 31, num. 4, p. 497-517
    DOI: 10.1007/s11044-013-9398-z
    Date of publication: 2014-04-01
    Journal article

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    This article proposes a simple linear-by-part approach for perfectly elastic 3D multiple-point impacts in multibody systems with perfect constraints and no friction, applicable both to nonredundant and redundant cases (where the normal velocities of the contact points are not independent). The approach is based on a vibrational dynamical model, and uses the so called "independent contact space." Two different time and space scales are used. At the macroscale, the impact interval is negligible, and the overall system configuration is assumed to be constant. Consequently, the inertia and Jacobian matrices appearing in the formulation are also constant. The dynamics at the contact points is simulated through stiff springs undergoing very small deformations and generating system vibrations at the microscale. The total impact interval is split into phases, each corresponding to a constant set of compressed springs responsible for an elastic potential energy. For each phase, a reduced inertia matrix associated with a set of contact points, and a reduced stiffness matrix obtained from the potential energy (associated with all contact points undergoing compression) are introduced. From these matrices, a modal analysis is performed yielding an all-analytical solution within each phase. The main difference between the redundant and nonredundant cases concerns the inertia and stiffness matrices for modal analysis. While in the former case, both are related to the total set of contact points (total contact space), in the latter one they are related to two subsets: a subset of independent points for the inertia matrix (independent contact space), and the total set for the stiffness matrix. A second difference concerns the calculation of the normal impulses generated at each contact point. For the nonredundant case, they can be directly obtained from the total incremental normal velocities of the contact points through the inertia and stiffness matrices. For the redundant one, they can be obtained by adding up their incremental values at each impact phase. This requires an updating of a new effective stiffness matrix depending on the contact points undergoing compression at each phase. Four planar application cases are presented involving a single body and a multibody system colliding with a smooth ground.

  • Formulation to predict lower limb muscle forces during gait

     Serrancoli Masferrer, Gil; Walter, Jonathan P.; Kinney, Allison L.; Barjau Condomines, Ana; Fregly, Benjamin J.; Font Llagunes, Josep Maria
    Reunión del Capítulo Español de la Sociedad Europea de Biomecánica
    p. 1
    Presentation's date: 2013-10-24
    Presentation of work at congresses

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    The human body has more muscles than Degrees of Freedom (DoF), and that leads to indeterminacy in the muscle force calculation. This study proposes the formulation of an optimization problem to estimate the lower-limb muscle forces during a gait cycle of a patient wearing an instrumented knee prosthesis. The originality of that formulation consists of simulating muscle excitations in a physiological way while muscle parameters are calibrated. Two approaches have been considered. In Approach A, measured contact forces are applied to the model and all inverse dynamics loads are matched in order to get a physiological calibration of muscle parameters. In Approach B, only the inverse dynamics loads not affected by the knee contact loads are matched. With that approach, contact forces can be predicted and validated by comparison with the experimental ones. Approach B is a test of the optimization method and it can be used for cases where no knee contact forces are available

  • Determinació de les variables crítiques que defineixen el confort en un calçat

     Barjau Condomines, Ana; Font Llagunes, Josep Maria; Pamies Vila, Rosa; Serrancoli Masferrer, Gil
    Date: 2013-07-15
    Report

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  • Determination of the strategy for solving the muscle force sharing problem in patients suffering ACL rupture

     Serrancoli Masferrer, Gil; Font Llagunes, Josep Maria; Barjau Condomines, Ana
    Congreso de Métodos Numéricos en Ingeniería
    p. 1
    Presentation's date: 2013-06-26
    Presentation of work at congresses

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  • Dynamic analysis of impact in swing-through crutch gait using impulsive and continuous contact models

     Font Llagunes, Josep Maria; Barjau Condomines, Ana; Pamies Vila, Rosa; Kövecses, József
    Multibody system dynamics
    Vol. 28, num. 3, p. 257-282
    DOI: 10.1007/s11044-011-9300-9
    Date of publication: 2012-09-01
    Journal article

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    The dynamics associated with the impact of the crutch with the ground is an important topic of research, since this is known to be the main cause of mechanical energy loss during swing-through gait. In this work, a multibody system representing a subject walking with crutches is used to investigate the behavior of two different contact models, impulsive and continuous, used for impact analysis. In the impulsive (discrete) approach, the impact interval is considered to be negligible and, therefore, the system configuration is constant. The postimpact state is directly obtained from the preimpact one through algebraic equations. In the continuous approach, the stiffness and dissipation characteristics of the contact surfaces are modeled through nonlinear springs and dampers. The equations of motion are integrated during the impact time interval to obtain the postimpact state, which, in principle, can differ from that obtained by means of the impulsive approach. Although both approaches have been widely used in the field of biomechanics, we have not found any comparative study in the existing literature justifying the model chosen for impact analysis. In this work, we present detailed numerical results and discussions to investigate several dynamic and energetic features associated with crutch impact. Based on the results, we compare the implications of using one contact model or the other.

  • On the force sharing problem in patients suffering joint pain

     Serrancoli Masferrer, Gil; Font Llagunes, Josep Maria; Barjau Condomines, Ana
    Congress of the European Society of Biomechanics
    Presentation's date: 2012-07-03
    Presentation of work at congresses

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    A linear-by-part approach for dissipative multiple-point collisions in smooth multibody systems with perfect constraints  Open access

     Barjau Condomines, Ana; Agullo Batlle, Joaquim; Font Llagunes, Josep Maria
    Joint International Conference on Multibody System Dynamics
    p. 105-106
    Presentation's date: 2012-05-30
    Presentation of work at congresses

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    A linear approach for multiple-point impact in multibody systems  Open access

     Agullo Batlle, Joaquim; Barjau Condomines, Ana; Font Llagunes, Josep Maria
    European Congress on Computational Methods in Applied Sciences and Engineering
    p. 1-12
    Presentation's date: 2011-07-06
    Presentation of work at congresses

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  • Two approaches for the dynamic analysis of impact in biomechanical systems

     Font Llagunes, Josep Maria; Barjau Condomines, Ana; Pamies Vila, Rosa; Kövecses, József
    Symposium on Brain, Body and Machine
    p. 1-4
    Presentation's date: 2010-11-11
    Presentation of work at congresses

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    Two main approaches are used when studying impact problems involving rigid bodies: impulsive and compliant. In an impulsive approach, the impact time interval is considered to be negligible, and so the system configuration is assumed to be constant. The final mechanical state can be obtained directly from the initial one by means of algebraic equations and energy dissipation assumptions. In a compliant approach, the colliding surfaces are modeled through nonlinear springs and dampers, and the differential equations of motion are integrated to solve the forward dynamics. In this paper, the performance of the two approaches is compared in two biomechanical application examples.

  • Comparison of impulsive and compliant contact models for impact analysis in biomechanical multibody systems

     Font Llagunes, Josep Maria; Kövecses, József; Pamies Vila, Rosa; Barjau Condomines, Ana
    International Conference on Multibody System Dynamics
    p. 1-11
    Presentation's date: 2010-05-25
    Presentation of work at congresses

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    Two approaches are used when studying impact problems: impulsive ones and compliant ones. In an impulsive approach, the time interval where the collision takes place is considered to be negligible, and so the system configuration is assumed to be constant. The final mechanical state of the colliding system is obtained directly from the initial one through algebraic equations and energy dissipation assumptions. In a compliant approach, the colliding surfaces are modelled through springs and dampers (usually nonlinear), and the equations of motion are integrated during the impact time interval to obtain the final state. Though both approaches have been widely used in the field of biomechanics, no comparative study can be found in the literature that could justify choosing one or another. In this paper, we present both approaches and compare them when applied to two examples related to gait problems: a passive walker and a simple model of crutch locomotion. We will show that the results are really close whenever nonsliding conditions are assumed at the impact points.

  • Calibration for mobile robots with an invariant Jacobian

     Agullo Batlle, Joaquim; Font Llagunes, Josep Maria; Barjau Condomines, Ana
    Robotics and autonomous systems
    Vol. 58, num. 1, p. 10-15
    DOI: 10.1016/j.robot.2009.09.002
    Date of publication: 2010-01
    Journal article

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  • APLICACIÓN DE TÉCNICAS DE DINÁMICA MULTICUERPO AL DISEÑO DE ORTESIS ACTIVAS PARA LA AYUDA A LA MARCHA

     Agullo Batlle, Joaquim; Pamies Vila, Rosa; Barjau Condomines, Ana; Serrancoli Masferrer, Gil; Font Llagunes, Josep Maria
    Competitive project

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  • Holonomy in mobile robots

     Agullo Batlle, Joaquim; Barjau Condomines, Ana
    Robotics and autonomous systems
    Vol. 57, num. 4, p. 433-440
    Date of publication: 2009-04
    Journal article

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  • On the one-dimensional acoustic propagation in conical ducts with stationary mean flow

     Barjau Condomines, Ana
    Journal of the Acoustical Society of America
    Vol. 122, num. 6, p. 3242-3251
    DOI: 10.1121/1.2799478
    Date of publication: 2007-12
    Journal article

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  • Optimal design of a tenora

     Agullo Batlle, Joaquim; Barjau Condomines, Ana
    International Symposium on Musical Acoustics
    Presentation's date: 2007-07
    Presentation of work at congresses

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  • Exploring a Van der Pol woodwind

     Barjau Condomines, Ana
    147th meeting of the Acoustical Society of America
    Presentation's date: 2004-05-25
    Presentation of work at congresses

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  • Calculation of impulse responses with a cellular automata algorithm

     Barjau Condomines, Ana
    147th meeting of the Acoustical Society of America
    Presentation's date: 2004-05-25
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  • Calculation of impulse responses with a cellular automata algorithm

     Barjau Condomines, Ana
    147th meeting of the Acoustical Society of America
    p. 2451
    Presentation of work at congresses

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  • Exploring a Van der Pol woodwind

     Barjau Condomines, Ana; Genesca Francitorra, Meritxell
    147th meeting of the Acoustical Society of America
    p. 2452
    Presentation of work at congresses

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  • Delayed models for simplified musical instruments

     Barjau Condomines, Ana; Vincent, Gibiat
    Journal of the Acoustical Society of America
    Vol. 114, num. 1, p. 496-504
    DOI: 10.1121/1.1577558
    Date of publication: 2003-07
    Journal article

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  • Conceptes d'acústica musical

     Barjau Condomines, Ana
    Date of publication: 2003-06-30
    Book chapter

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  • Acoustical propagation in a prefractal waveguide

     Vincent, Gibiat; Barjau Condomines, Ana; Kaelig, Castor; Etienne, Bertaud Du Chazaud
    Physical review E, statistical physics, plasmas, fluids, and related interdisciplinary topics
    Vol. 67, p. 006660-9
    DOI: 10.1103/PhysRevE.67.066609
    Date of publication: 2003-06
    Journal article

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  • Les instruments à vent Renaissance de la cathédrale de Salamanque

     Barjau Condomines, Ana
    Date of publication: 2003-02-28
    Book chapter

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  • The acoustical impedance or how ti guess the sound of a silent instrument

     Barjau Condomines, Ana
    International Symposium on Musical Acoustics
    Presentation's date: 2002-12-09
    Presentation of work at congresses

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  • Ware propagation in self-similar structures

     Barjau Condomines, Ana
    FORUM ACUSTICUM Sevilla 2002. 3rd. European Congress on Acoustics XXXIII SPANISH CONGRESS ON ACOUSTICS-Tecniacústica 2002
    Presentation's date: 2002-09-19
    Presentation of work at congresses

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  • Delay lines, finite differences and cellular automata: three close but different schemes for simulating acoustical propagation in 1D systems

     Barjau Condomines, Ana; Gibiat, V
    Acustica united with acta acustica
    Vol. 88, p. 554-566
    Date of publication: 2002-05
    Journal article

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  • L'archet du vidon: une non-linéarité et une discontinuité dans un système à retards multiples

     Barjau Condomines, Ana
    6ème Congrès Français d'Acoustique
    Presentation's date: 2002-04-08
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  • Un témoignage historique, musicologique et acoustique: les hautbois de la cathédrale de Salamanque.

     Barjau Condomines, Ana
    Colloque International "Les hautbois populaires en France et dans la Méditerranée"
    Presentation's date: 2002-04-06
    Presentation of work at congresses

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  • Ware propagation in self-similar structures

     Bertaud, Du Chazaud E; Gibiat, V; Barjau Condomines, Ana
    FORUM ACUSTICUM Sevilla 2002. 3rd. European Congress on Acoustics XXXIII SPANISH CONGRESS ON ACOUSTICS-Tecniacústica 2002
    Presentation of work at congresses

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  • Ware propagation in self-similar structures

     Bertrand, Du Chazand E; Gibiat, V; Barjau Condomines, Ana
    FORUM ACUSTICUM Sevilla 2002. 3rd. European Congress on Acoustics XXXIII SPANISH CONGRESS ON ACOUSTICS-Tecniacústica 2002
    p. 1-7
    Presentation of work at congresses

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  • L'archet du violon: une non-linéarité et une discontinuité dans un système à retards multiples

     Barjau Condomines, Ana
    6ème Congrès Français d'Acoustique
    p. 570-573
    Presentation of work at congresses

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  • The acoustical impedance or how to guess the sound of a silent instrument

     Barjau Condomines, Ana
    International Symposium on Musical Acoustics
    p. 116-126
    Presentation of work at congresses

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  • Unified modelling of simplified musical instruments in time domain

     Barjau Condomines, Ana; Gibiat, V; Chareyron, D
    FORUM ACUSTICUM Sevilla 2002. 3rd. European Congress on Acoustics XXXIII SPANISH CONGRESS ON ACOUSTICS-Tecniacústica 2002
    p. 1-6
    Presentation of work at congresses

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  • Conceptes d'acústica musical

     Barjau Condomines, Ana
    Date of publication: 2001-12-31
    Book chapter

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  • Phenomenological models for musical instruments

     Barjau Condomines, Ana
    17th International Congress on Acoustics
    Presentation's date: 2001-09-03
    Presentation of work at congresses

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  • Phenomenological models for musical instruments

     Barjau Condomines, Ana; Vincent, Gibiat
    Rivista italiana di acustica
    Vol. 25, num. 1-3/2001, p. 89
    Date of publication: 2001-09
    Journal article

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  • Simulación de los procesos de lacado plastificado y vendado de perfiles de aluminio.

     Santos Lopez, M. Antonia de Los; Barjau Condomines, Ana; Ferrer Marti, Laia
    Date: 2001-06
    Report

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  • Modèle hybride réduit pour la corde frottée

     Barjau Condomines, Ana
    "Instruments à corde: entre facture, acoustique et musique"
    Presentation's date: 2001-04-20
    Presentation of work at congresses

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  • Phenomenological models for musical instruments

     Barjau Condomines, Ana; Vincent, Gibiat
    17th International Congress on Acoustics
    Presentation of work at congresses

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  • Copie et tradition dans les chalemies: de la Renaissance aux instruments populaires du XXème siècle

     Barjau Condomines, Ana
    Fabrication artisanale d'instruments de musique: procédés, acoustique et perspectives
    Presentation's date: 2000-06-09
    Presentation of work at congresses

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  • A study of shawms: from the ancestors of the Renaissance to the survivors of the 20th century

     Barjau Condomines, Ana
    The Physics Congress
    Presentation's date: 2000-03-27
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  • Contribució a l'estudi de l'acústica dels tubs axisimètrics  Open access

     Jordi Nebot, Lluïsa
    Department of Mechanical Engineering, Universitat Politècnica de Catalunya
    Theses

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    La tesi "Contribució a l'estudi de l'acústica dels tubs axisimètrics" és un treball centrat en l'estudi del comportament acústic dels tubs dels instruments musicals de vent amb simetria de revolució en el qual es fa especial èmfasi en el comportament del pavelló (tub axisimètric de conicitat variable).L'estudi contempla tres aspectes: l'analític, el numèric i l' experimental, necessari per poder comparar els models proposats però que no ha estat realizat per l'autora de la tesi. Quant a l'estudi analític, s'analitza en profunditat el model uniparamètric proposat per Webster al qual se li han trobat els límits d'aplicabilitat, per al cas dels pavellons de tenores (instrument típic català), i es realitza una extensió d'aquest model en passar-lo al domini temporal.Seguint dins de l'estudi analític, s'estableix un model temporal bidimensional aproximat que inclou la propagació a l'interior de les lentilles presents a les discontinuïtats de conicitat i que simula, en primera aproximació, l'efecte dispersiu que es produeix en la propagació a l'interior dels pavellons.Quant al tractament numèric, es realitza un estudi d'un altre model uniparamètric existent, l'equació "Conical Horn", que s'aplica a un pavelló amb perfil exponencial. La comparació dels resultats experimentals amb els del model permet establir-ne la bondat. Seguint dins del tractament numèric, s'estableix un primer model bidimensional basat en la propagació de raigs impulsionals que permet l'obtenció del camp acústic a l'interior dels tubs axisimètrics.Per altra banda, s'estableix un algoritme de càlcul per a la integral de convolució que permet simular de manera completa el comportament d'un instrument musical en el domini temporal.

    La tesis "Contribució a l'estudi de l'acústica dels tubs axisimètrics" es un trabajo centrado en el estudio del comportamiento acústico de los tubos de los instrumentos musicales de viento con simetría de revolución en el que se hace especial énfasis al comportamiento del pabellón (tubo axisimétrico de conicidad variable).El estudio contempla tres aspectos: el analítico, el numérico y el experimental, necesario para poder comparar los modelos propuestos pero que no se ha realizado por la autora de la tesis.En cuanto al estudio analítico, se analiza en profundidad el modelo uniparamétrico propuesto por Webster al que se le han encontrado sus límites de aplicabilidad, para el caso de los pabellones de "tenoras" (instrumento típico catalán), y se realiza una extensión de este modelo al pasarlo al dominio temporal.Siguiendo dentro del estudio analítico, se establece un modelo temporal bidimensional aproximado que incluye la propagación en el interior de las lentillas presentes en las discontinuidades de conicidad y que simula en primera aproximación el efecto dispersivo que se produce en la propagación en el interior de los pabellones.En cuanto al tratamiento numérico, se realiza un estudio de otro modelo uniparamétrico existente, la ecuación "Conical Horn", que se aplica a un pabellón con perfil exponencial. La comparación de los resultados experimentales con los del modelo permiten establecer la bondad de éste.Siguiendo dentro del tratamiento numérico, se establece un primer modelo bidimensional basado en la propagación de rayos impulsionales que permite la obtención del campo acústico en el interior de los tubos axisimétricos.Por otro lado, se establece un algoritmo de cálculo para la integral de convolución que permite simular de manera completa el comportamiento de un instrumento musical en el dominio temporal.

    The doctoral thesis named "Contribució a l'estudi de l'acústica dels tubs axisimètrics" is a research project focused in the study of the acoustical behaviour of the musical wind instruments bores with revolute simmetry in which a special emphasis is done in the behaviour of the horn (axisymmetrical tube with varying taper).The study looks at three aspects: the analytical, the numerical an d the experimental one, necessary to compare the proposed models but which has not been done by the author of the thesis.With regard to the analytical study, the uniparametrical model proposed by Webster is deeply analyzed; its applicability limits has been found for the horns of "tenores" (Catalan tenor shawn, double-reed conical woodwind) and an extension of the model is done passing it to the time domain.Going on with the analytical study, an approximated bidimensional temporal model is stablished in which the propagation inside the little lents present in taper discontinuities is taken into account. This model permits to simulate, in a first approximation, the dispersive effect that takes place in the propagation inside the horns.As for the numerical treatment, a study about another uniparametrical actual model is done. It's the Conical horn equation which is applied to a horn with exponential profile.The comparison between the experimental results and those obtained with the model allows to stablish its validity.Keeping on the numerical treatment, a first bidimensional model is stablished based on the propagation of impulsional rays. It allows to obtain the acoustical field inside the axisymmetrical tubes.In other side, an algorithm to calculate the convolution integral is stablished. It permits to simulate completely the behaviour of a musical instrument in the time domain.