References of "Bruls, Olivier"
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See detailProgramme d'étirement appliqué à l'épaule raide : conséquences fonctionnelles
Forthomme, Bénédicte ULg; Croisier, Jean-Louis ULg; COLLIGNON, Pierre ULg et al

Conference (2015, October 09)

Les athlètes de lancer présentent une mobilité passive gléno-humérale de l’épaule dominante spécifique avec une majoration de la rotation externe et une limitation de la rotation interne. La limitation ... [more ▼]

Les athlètes de lancer présentent une mobilité passive gléno-humérale de l’épaule dominante spécifique avec une majoration de la rotation externe et une limitation de la rotation interne. La limitation interne semble liée à une raideur capsulo-musculaire postérieure, favorisant les pathologies de l’épaule sportive. Matériel et méthodes Vingt hommes, sportifs d’armer / lancer (volley-ball, handball) et pratiquant au moins 6 heures d’entraînement depuis plus de 5 années ont participé à cette étude. Ils présentaient tous une raideur des structures postérieures évaluée en clinique. Lors de l’inclusion dans l’étude, 10 athlètes (22,5 ± 4 ans) étaient asymptomatiques, 10 (24,8 ± 4 ans) présentaient une épaule dominante symptomatique (≥ 3/10 sur l’EVA). Les athlètes ont étiré chaque jour leur épaule dominante (sleeper stretch et cross body arm) pendant 4 semaines (5 x 30’'). Avant et après le programme d’étirement des structures postérieures, ils ont subi un test isocinétique de force maximale des rotateurs internes et externes ainsi qu’une analyse tridimensionnelle définissant la cinématique scapulaire. Résultats Après 4 semaines d’étirement des structures postérieures, tous les athlètes ont montré un gain significatif de mobilité en rotation interne passive. Nous n’observons aucune modification de la cinétique scapulaire lors de l’analyse 3D après les étirements chez les athlètes asymptomatiques ; les athlètes symptomatiques présentent une diminution du tilt antérieur scapulaire au repos après les 4 semaines. L’évaluation isocinétique des rotateurs d’épaules après les étirements montrent uniquement une légère réduction (- 4% ; p < 0,05) de la force des rotateurs internes à 60°/s en concentrique chez les athlètes asymptomatiques. Les sportifs qui décrivaient des douleurs avant les étirements sont significativement améliorés après le programme de 4 semaines ; cette diminution de la douleur est corrélée au gain en rotation interne passive. Discussion L’étirement pendant 4 semaines des structures postérieures de l’épaule raide sportive permet une augmentation de la mobilité passive. Ce gain de mobilité est corrélé à la diminution de la douleur chez les athlètes symptomatiques. [less ▲]

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See detailBiomechanical Analysis of Abdominal Injury in Tennis Serves. A Case Report
Tubez, François ULg; Forthomme, Bénédicte ULg; Croisier, Jean-Louis ULg et al

in Journal of Sports Science & Medicine (2015), 14

The serve is an important stroke in any high level tennis game. A well-mastered serve is a substantial advantage for players. However, because of its repeatability and its intensity, this stroke is ... [more ▼]

The serve is an important stroke in any high level tennis game. A well-mastered serve is a substantial advantage for players. However, because of its repeatability and its intensity, this stroke is potentially deleterious for upper limbs, lower limbs and trunk. The trunk is a vital link in the production and transfer of energy from the lower limbs to the upper limbs; therefore, kin-ematic disorder could be a potential source of risk for trunk injury in tennis. This research studies the case of a professional tennis player who has suffered from a medical tear on the left rectus abdominis muscle after tennis serve. The goal of the study is to understand whether the injury could be explained by an inappropriate technique. For this purpose, we analyzed in three dimensions the kinematic and kinetic aspects of the serve. We also performed isokinetic tests of the player’s knees. We then compared the player to five other professional players as refer-ence. We observed a possible deficit of energy transfer because of an important anterior pelvis tilt. Some compensation made by the player during the serve could be a possible higher abdominal contraction and a larger shoulder external rotation. These partic-ularities could induce an abdominal overwork that could explain the first injury and may provoke further injuries. [less ▲]

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See detailEffect of a stretching program on overhead athletes with a stiff and painful shoulder
Schwartz, Cédric ULg; Croisier, Jean-Louis ULg; Bruls, Olivier ULg et al

Conference (2015, July 01)

Overhead athletes are more at risk of suffering shoulder injuries or/and developing shoulder pain. Stretching programs have been shown to successfully reduce pain for this population. However no study has ... [more ▼]

Overhead athletes are more at risk of suffering shoulder injuries or/and developing shoulder pain. Stretching programs have been shown to successfully reduce pain for this population. However no study has provided a global overview of the effects of stretching. The present study evaluated the evolution of the pain, the strength of the shoulder muscles, potential instabilities or lesion of the shoulder as well as the 3D scapular kinematics of 10 overhead athletes having a painful and stiff dominant shoulder. Our results show a significant decrease of the pain and of the positive impingement syndrome tests. The kinematics of the scapula reveals a more upward rotation of the scapula after the stretching, which may reduce the risk of sub-acromial conflicts. The strength of the internal and external rotators of the shoulder is not modified by the program. [less ▲]

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See detailHow biomechanical analysis may help to identify abdominal injury causes in high level tennis
Tubez, François ULg; Forthomme, Bénédicte ULg; Croisier, Jean-Louis ULg et al

Conference (2015, July)

This research studies the case of a professional tennis player who has suffered from a medical tear on the left rectus abdominis muscle after a tennis serve. The goal of the study is to understand whether ... [more ▼]

This research studies the case of a professional tennis player who has suffered from a medical tear on the left rectus abdominis muscle after a tennis serve. The goal of the study is to understand whether the injury could be explained by an inappropriate technique. For this purpose, we analyzed the three dimensions kinematic and kinetic of the serve. We also performed isokinetic tests of the knees. We compared the player to five other professional players. We observed a possible deficit of energy transfer because of an important anterior pelvis tilt. Some compensations of the player during serve could be a possible higher abdominal contraction and a larger shoulder external rotation. These particularities could induce an abdominal overwork that would explain the first injury and may provoke a new injury. [less ▲]

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See detailStructural optimization of multibody system components described using level set techniques
Tromme, Emmanuel ULg; Tortorelli, Daniel; Bruls, Olivier ULg et al

in Structural and Multidisciplinary Optimization (2015)

The structural optimization of the components in multibody systems is performed using a fully coupled optimization method. The design’s predicted response is obtained from a flexible multibody system ... [more ▼]

The structural optimization of the components in multibody systems is performed using a fully coupled optimization method. The design’s predicted response is obtained from a flexible multibody system simulation under various service conditions. In this way, the resulting optimization process enhances most existing studies which are limited to weakly coupled (quasi-) static or frequency domain loading conditions. A level set description of the component geometry is used to formulate a generalized shape optimization problem which is solved via efficient gradient-based optimization methods. Gradients of cost and constraint functions are obtained from a sensitivity analysis which is revisited in order to facilitate its implementation and retain its computational efficiency. The optimizations of a slider-crank mechanism and a 2-dof robot are provided to exemplify the procedure. [less ▲]

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See detailSimulation of multibody systems and granular media using the non-smooth contact dynamic approach
Docquier, Nicolas; Dubois, Frédéric; Bruls, Olivier ULg

Conference (2015, July)

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See detailTrajectory optimization for 3D robots with elastic links
Lismonde, Arthur ULg; Sonneville, Valentin ULg; Bruls, Olivier ULg

Scientific conference (2015, June 29)

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See detailA level set approach for the structural optimization of flexible mechanisms
Tromme, Emmanuel ULg; Tortorelli, Daniel; Bruls, Olivier ULg et al

Conference (2015, June 08)

With the evolution of virtual prototyping, mechanical systems are commonly analyzed using a multibody system (MBS) approach to study the behavior of the entire system and notably the dynamic interactions ... [more ▼]

With the evolution of virtual prototyping, mechanical systems are commonly analyzed using a multibody system (MBS) approach to study the behavior of the entire system and notably the dynamic interactions between the components. Modern structural optimization of mechanical systems considers the dynamic loading exerted on the individual flexible components. The consideration is an essential feature and can be implemented in two ways. Firstly, one can consider a strong coupling wherein the component’s optimization is performed using the time dependent loading conditions coming directly from the MBS simulation. Secondly, one can consider a weak coupling wherein the component’s optimization is performed using a series of static load cases that do not fully account for the interactions between the components of the MBS. Rather this approach performs a MBS simulation to evaluate the loads for the initial design and then optimizes the component assuming the loads do not change. The process of evaluating the loads and then performing the optimization is repeated until suitable convergence criteria is satisfied, assuming convergence is possible. The present paper focuses on the strong coupling method wherein the flexible MBS dynamic analysis is based on a nonlinear finite element formalism [1]. A level set (LS) description of the component geometry is used to enable a generalized shape optimization. The LS approach combines the advantages of shape and topology optimizations. Moreover, since the component boundaries are defined by CAD features, the manufacturing process is facilitated as no post-processing step of a rasterized design is required. The design sensitivity analysis for MBS is revisited in order to facilitate its implementation. The optimization of a slider-crank mechanism and a 2-dof robot is provided to exemplify the procedure. [1] Géradin M., Cardona A. (2001) Flexible Multibody Dynamics: A Finite Element Approach. John Wiley & Sons, New York. [less ▲]

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See detailNonlinear Interpolation on Manifold of Reduced Order Models in Magnetodynamic Problems
Paquay, Yannick ULg; Bruls, Olivier ULg; Geuzaine, Christophe ULg

Poster (2015, June)

Proper Orthogonal Decomposition (POD) is an efficient model order reduction technique for linear problems in computational sciences, recently gaining popularity in electromagnetics. However, its ... [more ▼]

Proper Orthogonal Decomposition (POD) is an efficient model order reduction technique for linear problems in computational sciences, recently gaining popularity in electromagnetics. However, its efficiency has been shown to considerably degrade for nonlinear problems. In this paper, we propose a reduced order model for nonlinear magnetodynamic problems by combining POD with an interpolation on manifolds, which interpolates the reduced bases to efficiently construct the desired solution. [less ▲]

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See detailNonsmooth generalized-alpha scheme for the simulation of flexible multibody systems with impacts
Cardona, Alberto; Cavalieri, Federico; Bruls, Olivier ULg et al

Conference (2015, April)

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See detailDevelopment and validation of an accelerometer-based method for quantifying gait events
Boutaayamou, Mohamed ULg; Schwartz, Cédric ULg; Stamatakis, Julien et al

in Medical Engineering & Physics (2015)

An original signal processing algorithm is presented to automatically extract, on a stride-by-stride basis, four consecutive fundamental events of walking, heel strike (HS), toe strike (TS), heel-off (HO ... [more ▼]

An original signal processing algorithm is presented to automatically extract, on a stride-by-stride basis, four consecutive fundamental events of walking, heel strike (HS), toe strike (TS), heel-off (HO), and toe-off (TO), from wireless accelerometers applied to the right and left foot. First, the signals recorded from heel and toe three-axis accelerometers are segmented providing heel and toe flat phases. Then, the four gait events are defined from these flat phases. The accelerometer-based event identification was validated in seven healthy volunteers and a total of 247 trials against reference data provided by a force plate, a kinematic 3D analysis system, and video camera. HS, TS, HO, and TO were detected with a temporal accuracy ± precision of 1.3 ms ± 7.2 ms, ‒4.2 ms ± 10.9 ms, ‒3.7 ms ± 14.5 ms, and ‒1.8 ms ± 11.8 ms, respectively, with the associated 95% confidence intervals ranging from ‒6.3 ms to 2.2 ms. It is concluded that the developed accelerometer-based method can accurately and precisely detect HS, TS, HO, and TO, and could thus be used for the ambulatory monitoring of gait features computed from these events when measured concurrently in both feet. [less ▲]

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See detailAn integrated control-structure design for manipulators with flexible links
Bastos Jr., Guaraci; Bruls, Olivier ULg

in IFAC-PapersOnLine (2015), 48(11), 156-161

Integrated optimization techniques for mechatronic systems aim at designing simultaneously the trajectory, the control system and the mechanical structure in order to minimize a performance index. The key ... [more ▼]

Integrated optimization techniques for mechatronic systems aim at designing simultaneously the trajectory, the control system and the mechanical structure in order to minimize a performance index. The key advantage of such an integrated approach is the capability to search in a wide design space, to account for many dynamic couplings in an early design stage and to avoid simplifying assumptions which would induce a suboptimal design. This work considers that technique for robotic manipulators with flexible links. It is known that a exible multibody system is often non-minimum phase, here, no restriction is imposed to avoid it. This allows a free choice of the optimization process to select a lighter weight controlled system. Furthermore, the amplitudes of the non-actuated degrees-of-freedom should be reduced in order to limit bodies deformation. The mechanical model is derived using a nonlinear finite element method, which is a useful approach to represent systems with elastic bodies. An optimal control problem is considered to perform that integrated analysis and its time dicretization relies the direct transcription method. [less ▲]

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See detailOrder reduction in time integration caused by velocity projection
Arnold, Martin; Cardona, Alberto; Bruls, Olivier ULg

in Journal of Mechanical Science and Technology (2015), 29(7), 2579-2585

Holonomic constraints restrict the configuration of a multibody system to a subset of the configuration space. They imply so called hidden constraints at the level of velocity coordinates that may ... [more ▼]

Holonomic constraints restrict the configuration of a multibody system to a subset of the configuration space. They imply so called hidden constraints at the level of velocity coordinates that may formally be obtained from time derivatives of the original holonomic constraints. A numerical solution that satisfies hidden constraints as well as the original constraint equations may be obtained considering both types of constraints simultaneously in each time step (Stabilized index-2 formulation) or using projection techniques. Both approaches are well established in the time integration of differential-algebraic equations. Recently, we have introduced a generalized-alpha Lie group time integration method for the stabilized index-2 formulation that achieves second order convergence for all solution components. In the present paper, we show that a separate velocity projection would be less favourable since it may result in an order reduction and in large transient errors after each projection step. This undesired numerical behaviour is analysed by a one-step error recursion that considers the coupled error propagation in differential and algebraic solution components. This one-step error recursion has been used before to prove second order convergence for the application of generalized-alpha methods to constrained systems. [less ▲]

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See detailSegmentation of gait cycles using foot-mounted 3D accelerometers
Boutaayamou, Mohamed ULg; Bruls, Olivier ULg; Denoël, Vincent ULg et al

in Proceedings of the IEEE International Conference on 3D Imaging 2015 (2015)

We describe a new gait segmentation method based on the continuous wavelet transform to identify stride-by-stride gait cycles from measurements of foot-mounted three-dimensional (3D) accelerometers. The ... [more ▼]

We describe a new gait segmentation method based on the continuous wavelet transform to identify stride-by-stride gait cycles from measurements of foot-mounted three-dimensional (3D) accelerometers. The detection of such gait cycles is indeed a crucial step for an accurate extraction of relevant gait events such as heel strike, toe strike, heel-off, and toe-off. We demonstrate the ability of this segmentation method, used in conjunction with a validated extraction algorithm, to calculate the following gait (duration) parameters for each gait cycle during the gait of a healthy young subject and of an elderly subject with Parkinson’s disease (PD) in OFF and ON states: durations of (1) loading response, (2) mid-stance, (3) push-off, (4) stance, (5) swing, (6) stride, (7) step, and (8) double support phases. The experimental results show that the proposed method can extract relevant refined gait parameters to quantify subtle gait disturbances in subjects with PD. [less ▲]

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