Adaptive Bio-Inspired Control of Humanoid Robots — From Human Locomotion to an Artificial Biped Gait of High Performances

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Lower Limb Mechanical Properties: Significant References Omitted

International audienceWe read with attention the recent narrative literature review by Pearson and McMahon [1]. We were very surprised and quite disappointed by the amount of relevant literature omitted by the authors on lower limb mechanical properties and, specifically, how ‘limb stiffness’ could affect performance and risk of injury. Although this review focuses on muscle-tendon unit (MTU) stiffness, the more global vertical, leg and joint stiffness (i.e. referred to as limb stiffness, collectively) are also reviewed, as the authors assume that limb stiffness is primarily controlled by MTU stiffness

Measuring Foot Progression Angle during Walking Using Force-Plate Data

Foot progression angle (FPA) is a gait-related clinical measurement commonly used for assessing the rotational profile of the lower extremity. This study examined the accuracy of two methods based on force-plate data for estimating FPA during walking by comparing them with a reference method using a motion capture system. Ten healthy adults performed a series of overground walking trials at three different speeds: slow, preferred and fast. FPA was estimated from two methods using data on center of pressure—one method previously reported in the literature, and a novel method proposed here. The FPA estimated by each of these two force-plate methods were compared with the reference FPA determined from kinematic data. Results showed that the novel force-plate method was more accurate and precise when measuring the FPA in the three speed conditions than the force-plate method previously reported in the literature. The mean absolute error obtained with this novel method was 3.3° ± 2.1° at slow speed, 2.0° ± 1.2° at preferred speed and 2.0° ± 1.2° at fast speed, with no significant effect of gait speed (p > 0.05). These findings suggest that the novel force-plate method proposed here is valid for determining FPA during walking at various speeds. In the absence of kinematic data, this method constitutes an attractive alternative for measuring FPA

Force/velocity and power/velocity relationships in squat exercise

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Validity and Reliability of a Kinematic Device for Measuring the Force Developed during Squatting

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Quelles identités culturelles pour les jeunes de l’Océan Indien ?

Am Strand von Etang Salé (Réunion) wie am Strand von Flic en Flac (Mauritius) oder am Strand von Praslin (Seychellen) sowie an den riesengrossen Küstenstreifen in der Nähe von Tamatave (Madagascar) sind es anscheinend die gleichen Jugendlichen, die die gleichen Spiele haben und dabei die gleiche Musik hören. Alles trägt zu dieser Undifferenzierungswirkung bei, spricht man nicht übrigens von den «Schwesterinseln « ? Ziel dieses Artikels ist zuerst den Leser an einem «Spiel der fünf Irrtümer «teilnehmen zu lassen und zwar als Gegenmittel zur vereinheitlichenden Vision, die von den Klischees einer teuchenden Exotik hervorgerufen wird.On the Etang Salé beach (Reunion), on Flic en Flac beach (Mauritius), on Praslin beaches (Seychelles) or even on the large coastal stretches close to Tamatave (Madagascar), the same young people seem to be playing the sames games while listening to the same music. Everything contributes to this lack of differentiation, aren’t these island considered as «Sister islands ? The aim of this paper is to invite the reader to take part in an unusual game of «spot the differences «, as an antidote against the standardized vision projected by cliches of deceptive exotism.Cet article souhaite prendre de la distance avec deux types de regards ; d’une part, celui ne percevant que les similitudes chez les jeunes des îles du sud-ouest de l’Océan Indien et, d’autre part, celui suggérant au contraire qu’ils n’ont rien à partager. Ni naïvement apologétique, ni désespérément sceptique, il s’attache aux avancées d’un bassin culturel en train de se faire. Il analyse la place réservée aux consommations de loisirs pour ces jeunes. Enfin, il analyse le rôle tenu par les manifestations sportives dans le bassin culturel, qui à la fois joue dans la mise en place de relations fraternelles, mais rappelle aussi à chacun des pays son niveau de développement.En la playa de la Laguna Salada (Reunión), al igual que en la del «Flic en Flac» (Mauricio), como en las de Praslin (Seychelles), o también en las inmensas extensiones costeras cercanas a Tamatave (Madagascar), parece que veamos a los mismos jóvenes jugando a los mismos juegos y escuchando la misma música. Todo conspira a este efecto de falta de diferenciación, ¿ no se habla de «islas hermanas» ? El propósito de este artículo es, en primera instancia, invitar al lector a participar en un insólito «juego de los cinco errores», como antídoto a la visión uniformizante proyectada por los tópicos de un exotismo engañoso.Duret Pascal, Augustini Muriel, Dalleau Georges, Leroyer Pierre, Zattara Maurice. Quelles identités culturelles pour les jeunes de l’Océan Indien ?. In: Agora débats/jeunesses, 20, 2000. Résistances à l’uniformisation culturelle. pp. 13-22

Detection of swing heel-off event in gait initiation using force-plate data

International audienceThis study investigated the accuracy and reliability of four methods using force-plate data for detecting the swing heel-off (HO) time in gait initiation. Results of these methods were compared to those obtained by means of a reference method using a footswitch. Ten young healthy adults performed 18 forward gait initiation trials at self-selected speed and at maximal speed. Results showed that the method based on vertical impulse was the most accurate and reliable in determining HO in both speed conditions. The mean error obtained with this method was −8±10ms in the self-selected speed condition (−7±10ms in the maximal speed condition), with no significant effect of gait speed (P>0.05). These findings suggest that this method based on force-plate data is valid and reliable for detecting HO in forward gait initiation in the absence of additional hardware

Influence of gait speed on the control of mediolateral dynamic stability during gait initiation.

International audienceThis study investigated the influence of gait speed on the control of mediolateral dynamic stability during gait initiation. Thirteen healthy young adults initiated gait at three self-selected speeds: Slow, Normal and Fast. The results indicated that the duration of anticipatory postural adjustments (APA) decreased from Slow to Fast, i.e. the time allocated to propel the centre of mass (COM) towards the stance-leg side was shortened. Likely as an attempt at compensation, the peak of the anticipatory centre of pressure (COP) shift increased. However, COP compensation was not fully efficient since the results indicated that the mediolateral COM shift towards the stance-leg side at swing foot-off decreased with gait speed. Consequently, the COM shift towards the swing-leg side at swing heel-contact increased from Slow to Fast, indicating that the mediolateral COM fall during step execution increased as gait speed rose. However, this increased COM fall was compensated by greater step width so that the margin of stability (the distance between the base-of-support boundary and the mediolateral component of the "extrapolated centre of mass") at heel-contact remained unchanged across the speed conditions. Furthermore, a positive correlation between the mediolateral extrapolated COM position at heel-contact and step width was found, indicating that the greater the mediolateral COM fall, the greater the step width. Globally, these results suggest that mediolateral APA and step width are modulated with gait speed so as to maintain equivalent mediolateral dynamical stability at the time of swing heel-contact