Adhesion, Friction and Lubrication of Viscoelastic Materials

The mechanical behavior of viscoelastic materials is a key factor of many physical phenomena occurring at the interface of contacting bodies [...

Power Flows and Efficiency of Output Compound e-CVT

Hybridization is the most promising vehicular technology to get significant improvements of the vehicle efficiency and performance in the short-term. Mechanical transmissions for hybrid vehicles are very often multiple modes transmission, which permit improving the performance in different working conditions. In this context, optimal design and control of these transmissions are a key point to improve the performance of the vehicles, and mathematical models which supports the design can play an important role in this field. In this work, an approach for evaluating the performance of Output Compound Split e-CVT (electric Continuously Variable Transmission) in steady-state is proposed. This approach, in addition to a kinematic analysis of the device, leads to the calculation of the internal power circulation modes and the efficiency of the device in different working conditions

Manipulability Optimization of a Rehabilitative Collaborative Robotic System

The use of collaborative robots (or cobots) in rehabilitation therapies is aimed at assisting and shortening the patient's recovery after neurological injuries. Cobots are inherently safe when interacting with humans and can be programmed in different working modalities based on the patient's needs and the level of the injury. This study presents a design optimization of a robotic system for upper limb rehabilitation based on the manipulability ellipsoid method. The human-robot system is modeled as a closed kinematic chain in which the human hand grasps a handle attached to the robot's end effector. The manipulability ellipsoids are determined for both the human and the robotic arm and compared by calculating an index that quantifies the alignment of the principal axes. The optimal position of the robot base with respect to the patient is identified by a first global optimization and by a further local refinement, seeking the best alignment of the manipulability ellipsoids in a series of points uniformly distributed within the shared workspace

La revitalisation des cœurs de ville : la nouvelle approche de l'espace public dans les projets urbains. Le cas du centre ancien méditerranéen de la Seyne-sur-Mer

Desde que el conocimiento de las políticas urbanas, que los centros están degradan y que reúnen situaciones críticas y precarias que incluyen, en las habitaciones, la decadencia comercial, y la descalificación de los espacios públicos, las comunidades desarrollan proyectos urbanos globales para la revitalización de los centros. Los centros antiguos mediterráneo se ven también afectados por una concentración de problemas sociales, de pobreza y del aislamiento de su población, la edad de los edificios que ya no corresponde al estilo de vida actual y la falta de lugares para vivir. Además, estos pueblos se enfrentan a la competencia con los suburbios de prestigio que aprovechan los turistas. El centro histórico de La Seyne-sur-Mer, ha perdido su capacidad de centralización, y tiene fuertes rupturas urbanas. Con el proyecto urbano para revitalizar el centro, la ciudad consiguió un contrato con la SAGEM para el proyecto “corazón de la ciudad " para solucionar las disfunciones de las habitaciones con una OPAH RU y con un “Convention Publique d’Aménagement” para integrar el centro en las dinámicas urbanas y económicas de su territorio y de la aglomeración Toulon Provence Méditerranée.Depuis la prise de conscience des politiques urbaines, de la dégradation avérée des centres villes et des situations critiques et précaires qu’ils regroupent, tant sur l’habitat, sur le déclin commercial, que sur la déqualification des espaces publics, les collectivités interviennent dans le cadre de projets urbains globaux pour la revitalisation de leur cœur de ville. Les centres anciens méditerranéens sont également touchés par une forte concentration de difficultés sociales, marqués par une paupérisation et un isolement de leur population, de la vétusté du bâti qui ne correspond plus aux modes de vie actuels et d’un manque de lieux de vie. De plus, ces quartiers sont confrontés à une concurrence des quartiers périphériques prestigieux qui profitent des vagues touristiques saisonnières. C’est le cas du centre ancien de la Seyne-sur-Mer qui a perdu ses capacités centralisatrices, marqué par de fortes ruptures urbaines. Dans le cadre d’un projet global de redynamisation du centre-ville, la ville a contractualisé avec la SAGEM pour la réalisation du projet « coeur de ville » dans le but de résoudre les dysfonctionnements liés à l’habitat par le biais d’une OPAH-RU et plus généralement par le biais d’une Convention Publique d’aménagement pour intégrer le centre ancien dans la dynamique urbaine et économique de son territoire et de l’agglomération Toulon Provence Méditerranée

Power Flows and Efficiency of Output Compound e-CVT

Hybridization is the most promising vehicular technology to get significant improvements of the vehicle efficiency and performance in the short-term. Mechanical transmissions for hybrid vehicles are very often multiple modes transmission, which permit improving the performance in different working conditions. In this context, optimal design and control of these transmissions are a key point to improve the performance of the vehicles, and mathematical models which supports the design can play an important role in this field. In this work, an approach for evaluating the performance of Output Compound Split e-CVT (electric Continuously Variable Transmission) in steady-state is proposed. This approach, in addition to a kinematic analysis of the device, leads to the calculation of the internal power circulation modes and the efficiency of the device in different working conditions

Mechanical Hybrid KERS Based on Toroidal Traction Drives: An Example of Smart Tribological Design to Improve Terrestrial Vehicle Performance

We analyse in terms of efficiency and traction capabilities a recently patented traction drive, referred to as the double roller full-toroidal variator (DFTV). We compare its performance with the single roller full-toroidal variator (SFTV) and the single roller half-toroidal variator (SHTV). Modeling of these variators involves challenging tribological issues; the traction and efficiency performances depend on tribological phenomena occurring at the interface between rollers and disks, where the lubricant undergoes very severe elastohydrodynamic lubrication regimes. Interestingly, the DFTV shows an improvement of the mechanical efficiency over a wide range of transmission ratios and in particular at the unit speed ratio as in such conditions in which the DFTV allows for zero-spin, thus strongly enhancing its traction capabilities. The very high mechanical efficiency and traction performances of the DFTV are exploited to investigate the performance of a flywheel-based Kinetic Energy Recovery System (KERS), where the efficiency of the variator plays an important role in determining the overall energy recovery performance. The energy boost capabilities and the round-trip efficiency are calculated for the three different variators considered in this study. The results suggest that the energy recovery potential of the mechanical KERS can be improved with a proper choice of the variator

On nonlinear model predictive direct yaw moment control for trailer sway mitigation

In car–trailer combinations, the hitch angle is the relative yaw angle between towing car and trailer. The literature has shown that the inclusion of the hitch angle measurement for the feedback control of trailer oscillations can bring safety benefits, compared with conventional trailer sway mitigation algorithms based on the yaw rate of the car. Given the nonlinearity of the vehicle system in the typical conditions requiring the hitch angle control function intervention, nonlinear model-based controllers could be an effective solution. This paper presents four real-time implementable nonlinear model predictive control (NMPC) formulations, using the hitch angle measurement for the torque-vectoring (TV) control of an electric frontwheel drive car towing a trailer. The simulation results show that: (i) the active safety is enhanced by the proposed NMPC TV formulations, with respect to a benchmarking NMPC TV controller only based on the control of the towing car; (ii) the NMPC formulations that directly constrain the hitch angle error, or perform continuous hitch angle tracking, outperform those that modify the reference yaw rate or yaw rate error based on the hitch angle error; and (iii) the NMPC approaches including a dynamic model of the trailer are robust with respect to variations of trailer parameters