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International audience; In this paper, we will perform a comparison between two approaches of dimensional synthesis of parallel robots. The first one concerns the single-objective optimization approach; in this case, the dimensional synthesis is expressed by taking into account only one performance criterion but enables to get a final solution if it exists. The second one concerns the multi-objective optimization approach; it enables to simultaneously take into account several performance criteria. However, this approach appears to provide a set of solutions instead of a single expected final solution which should directly enable to carry out the structural synthesis. In fact, the search of a single final solution is postponed to a further step where the designers have to impose and/or restrict certain parameters. And we will establish if it is really necessary to make a multi-objective optimization approach or if a single-objective is sufficient to reach the objectives set in the specifications (user requirements). A discussion is proposed concerning the arising questions related to each approach and leading to the optimal dimensional synthesis. The PAR2 robot with two degree-of-freedom is used to exemplify the analysis and the comparison of the two approaches. The proposed comparison can be applied to any classes of parallel robots.

This paper presents a geometrical model of a constrained robot of three degrees of freedom (d.o.f) added to a PPP passive central segment. This structure provides a pure translation motion. We will also determine the relations between generalized and articular velocities by using the inverse Jacobian matrix. Further, we determine the reciprocal relations between cartesian and angular velocities of the end-effector via articular velocities by simple derivation of the direct geometrical model expressions. A determination of the workspace based on the geometrical model analysis is derived followed by a numerical calculation of all the atteignables points enabling a graphical visualisation of such a workspace. Moreover, the analysis of the Jacobian matrix has permitted to ensure that there are no singularities of type 1 and 2 in such a structure. A prototype of a parallel robot has been built up in our laboratory in order to validate the proposed models.Este trabajo presenta el modelo geométrico de un robot paralelo con tres grados de libertad (d.o.f) agregados a un segmento central pasivo del PPP. Esta estructura proporciona un movimiento de translación pura. También determinaremos las relaciones entre las velocidades generalizadas y articulares usando la matriz Jacobiana inversa. Además, determinamos las relaciones recíprocas entre las velocidades cartesianas y angulares del end-effector vía velocidades articulares por la derivación simple de las expresiones del modelo geométrico directo. Una determinación del espacio de trabajo basado en el análisis del modelo geométrico es derivado seguido por un cálculo numérico de todos los puntos que deben alcanzarse permitiendo una visualización gráfica de tal espacio de trabajo. Por otra parte, el análisis de los coeficientes de la matriz Jacobiana permite asegurar que no haya singularidades del tipo 1 y 2 en tal estructura. Se ha realizado un prototipo de robot paralelo en nuestro laboratorio para validar los modelos propuestos.

This paper presents a generic design and implementation of a multi-modal operator interface (MOI) which has been dedicated for supervisory control systems. A presentation followed by an evaluation of some interactions and control modes, that have been so far integrated to built our experimental system, are given. These control modes are namely tele-manipulation, speech-based control, vision-based control, and model-based control. More emphasis is stressed on the vision-based control and tele-manipulation we have originally developed. Next, the combination of these control modes, through this MOI, is used to achieve some complex robotics tasks. Moreover, by incorporating some intelligent functions and fusing different sensors, the MOI enables a multi-modal interaction ranging from shared mode to superimposed mode, passing through traded mode. This entails a multi-level robot control and an adaptive automation. Robotics-oriented applications consisting of inserting a square (circular)-in-peg are described using tele-manipulation control mode and vision-based control. Importance of the multi-interaction mode versus unimodal mode is highlighted. Finally, improvement of the developed MOI system is investigated through incorporating an anticipatory system that protects against possible catastrophic errors of the operator.

The dense-pack grid is commonly used to get a synoptic view of the sub-photospheric dynamics when using ring diagram analysis (Haber et al 2002). This grid is based on a fixed distribution of patches in central meridian distance (cmd) at all latitudes. A shortcoming of the dense-pack grid is that the true motion of tracked areas at slower rotating latitudes is not handled correctly. For instance, a 15° × 15° area, centered at a cmd of 0° and a latitude of 60°, that rotates only 12° in 1664 minutes (ring day), is considered tobe centered at cmd = 15° in the subsequent ring day. In order to avoid this issue, another distribution is suggested where the grid point in central meridian distance is latitude dependant (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

International audience; In this article, we propose an optimization process able to generate optimal kinematic configuration for spatial hyper-redundant manipulators with multiple rigid parallel modules. The proposed method uses a deterministic optimization scheme that evaluates the score of trial kinematic configurations while accounting for various geometric constraints. This versatile method is based on a simultaneous search for both the best curve capturing the overall kinematic robot posture and the platform distribution along this curve. This process is carried out using the powerful sequential quadra-tic programming technique. Numerical results are presented to illustrate the efficiency of the proposed approach. Finally, this model was validated by real measurements obtained with the continuum bionic handling arm of a mobile robot called Robotino-XT.

A vision-based control system has been developed. It enables a human operator to remotely direct a robot, equipped with a camera, towards targets in 3D space by simply pointing on their images with a pointing device. This paper presents an anticipatory system, which has been designed for improving the safety and the effectiveness of the vision-based commands. It simulates these commands in a virtual environment. It attempts to detect hard contacts that may occur between the robot and its environment, which can be caused by machine errors or operator errors as well.

Research on the modeling of continuum robots, focused on ways to constrain the geometrical models, while maintaining maximum specificities and mechanical properties of the robot. In this paper we propose a new numerical solution for solving the inverse geometric model of a planar flexible continuum robot, we assuming that each section is curved in an arc of a circle, while having the central axis of the inextensible structure. The inverse geometric model for one section is calculated geometrically, whereas the extreme points, of each section, used in calculating the inverse geometric model for multi-section is calculated numerically using a particle swarm optimization (PSO) method. Simulation examples of this method are carried to validate the proposed approach.

Fourier-Legendre decomposition (FLD) of solar Doppler imaging data is a promising method to estimate the sub-surface solar meridional flow. FLD is sensible to low-degree oscillation modes and thus has the potential to probe the deep meridional flow. We present a newly developed code to be used for large scale FLD analysis of helioseismic data as provided by the Global Oscillation Network Group (GONG), the Michelson Doppler Imager (MDI) instrument, and the upcoming Helioseismic and Magnetic Imager (HMI) instrument. First results obtained with the new code are qualitatively comparable to those obtained from ring-diagram analyis of the same time series., 4 pages, 2 figures, 4th HELAS International Conference "Seismological Challenges for Stellar Structure", 1-5 February 2010, Arrecife, Lanzarote (Canary Islands)

Die-to-Model (D2M) inspection is an innovative approach to running inspection based on a mask design layout data. The D2M concept takes inspection from the traditional domain of mask pattern to the preferred domain of the wafer aerial image. To achieve this, D2M transforms the mask layout database into a resist plane aerial image, which in turn is compared to the aerial image of the mask, captured by the inspection optics. D2M detection algorithms work similarly to an Aerial D2D (die-to-die) inspection, but instead of comparing a die to another die it is compared to the aerial image model. D2M is used whenever D2D inspection is not practical (e.g., single die) or when a validation of mask conformity to design is needed, i.e., for printed pattern fidelity. D2M is of particular importance for inspection of logic single die masks, where no simplifying assumption of pattern periodicity may be done. The application can tailor the sensitivity to meet the needs at different locations, such as device area, scribe lines and periphery. In this paper we present first test results of the D2M mask inspection application at a mask shop. We describe the methodology of using D2M, and review the practical aspects of the D2M mask inspection.

With each new process technology node, chip designs increase in complexity and size, leading to a steady increase in data volumes. As a result, mask data prep flows require more computing resources to maintain the desired turn-around time (TAT) at a low cost. The effect is aggravated by the fact that a mask house operates a variety of equipment for mask writing, inspection and metrology - all of which, until now, require specific data formatting. An industry initiative sponsored by SEMI® has established new public formats - OASIS® (P39) for general layouts and OASIS.MASK (P44) for mask manufacturing equipment - that allow for the smallest possible representation of data for various applications. This paper will review a mask data preparation process for mask inspection based on the OASIS formats that also reads OASIS.MASK files directly in real time into the inspection tool. An implementation based on standard parallelized computer hardware will be described and characterized as demonstrating throughputs required for the 45nm and 32nm technology nodes. An inspection test case will also be reviewed.

Context. We compare solar differential rotation of subphotospheric layers derived from local helioseismology analysis of GONG++ dopplergrams and the one derived from tracing small bright coronal structures (SBCS) using EIT/SOHO images for the period August 2001 - December 2006, which correspond to the declining phase of solar cycle 23. Aims. The study aims to find a relationship between the rotation of the SBCS and the subphotospheric angular velocity. The northsouth asymmetries of both rotation velocity measurements are also investigated. Methods. Subphotospheric differential rotation was derived using ring-diagram analysis of GONG++ full-disk dopplergrams of 1 min cadence. The coronal rotation was derived by using an automatic method to identify and track the small bright coronal structures in EIT full-disk images of 6 hours cadence. Results. We find that the SBCS rotate faster than the considered upper subphotospheric layer (3Mm) by about 0.5 deg/day at the equator. This result joins the results of several other magnetic features (sunspots, plages, faculae, etc.) with a higher rotation than the solar plasma. The rotation rate latitudinal gradients of the SBCS and the subphotospheric layers are very similar. The SBCS motion shows an acceleration of about 0.005 deg/day/month during the declining phase of solar cycle 23, whereas the angular velocity of subsurface layers does not display any evident variation with time, except for the well known torsional oscillation pattern. Finally, both subphotospheric and coronal rotations of the southern hemisphere are predominantly larger than those of the northern hemisphere. At latitudes where the north-south asymmetry of the angular velocity increases (decreases) with activity for the SBCS, it decreases (increases) for subphotospheric layers., 6pages, 8 figures, Accepted for publication in Astronomy and Astrophysics

International audience; We have estimated the radial gradient of angular velocity in the near subsurface layers of the sun for the period 07/2001-07/2007 which covers 80 Carrington rotations, starts at the maximum of cycle 23 and ends at its minimum. This analysis confirms that, on average, the radial gradient of angular velocity remains negative and roughly constant between 0.980 and 0.991 Rsun below 40° of latitude. The extension of ring analysis up to 60° over two periods covering three Carrington rotations each shows a positive gradient at this latitude which tends to confirm the sign reversal revealed by the analysis of MDI f modes (Corbard & Thompson 2002). Finally, we report an enhancement of the radial gradient around 35° and 0.990 Rsun at the beginning of 2007 which corresponds to the beginning of the new cycle 24.

In this paper, we propose a new approach for computing force-closure grasps of two-dimensional and three-dimensional objects. Assuming n hard-finger contact with Coulomb friction model and based on central axes of the grasp wrench (i.e., force and torque), we develop a new necessary and sufficient condition for n-finger grasps to achieve force-closure. We demonstrate that a grasp is force-closure if and only if, its wrench can generate any arbitrary central axis. According to this condition, we reformulate the force-closure test as a linear programming problem without computing the convex hull of the primitive contact wrenches. Therefore, we present an efficient algorithm for computing n-finger force-closure grasps. Finally, we have implemented the proposed algorithm and verified its efficiency through some examples.

Colloque avec actes et comité de lecture. Internationale.; International audience; Nous présentons dans cet article une nouvelle approche pour le calcul des prises dites de types force-closure pour les objets bidimensionnels (2D). Cela concerne les mains artificielles munies de doigts rigides. Le contact avec l'objet est modélisé en considérant le frottement de Coulomb. Une nouvelle condition nécessaire et suffisante d'équilibre et de force-closure pour les prises d'objets 2D est alors proposée. Elle est basée sur la distribution des axes centraux des torseurs des forces de contact dans le plan de la prise. Ainsi, un algorithme pour tester la force-closure des prises 2D est développé. Cet algorithme nécessite peu de calcul géométrique. Sa validité est démontrée par des exemples.

Journal of Physics Conference Series, 118, p. 2090, http://dx.doi.org./10.1088/1742-6596/118/1/012090; International audience; Mapping the solar surface is a crucial step in any local helioseismology technique. Because the acoustic waves propagate along great circles at the solar surface, it has been shown that these circles need to be used in the geometrical construction of the plane grid. We study different types of projections based on great circles for the calculation of sub-surface flows from ring diagram analysis of GONG data. Azimuthal equidistant projection, transverse cylindrical projection, gnomonic projection and stereographic projection produce almost the same velocity fields with standard patch sizes (15°x 15°). The difference between the four projections is more noticeable when larger patches (30° x 30°) are used.

Este trabajo presenta el modelo geometrico de un robot paralelo con tres grados de libertad (d.o.f) agregados a un segmento central pasivo del PPP. Esta estructura proporciona un movimiento de translacion pura. Tambien determinaremos las relaciones entre las velocidades generalizadas y articulares usando la matriz Jacobiana inversa. Ademas, determinamos las relaciones reciprocas entre las velocidades cartesianas y angulares del end-effector via velocidades articulares por la derivacion simple de las expresiones del modelo geometrico directo. Una determinacion del espacio de trabajo basado en el analisis del modelo geometrico es derivado seguido por un calculo numerico de todos los puntos que deben alcanzarse permitiendo una visualizacion grafica de tal espacio de trabajo. Por otra parte, el analisis de los coeficientes de la matriz Jacobiana permite asegurar que no haya singularidades del tipo 1 y 2 en tal estructura. Se ha realizado un prototipo de robot paralelo en nuestro laboratorio para validar los modelos propuestos.

This paper presents a geometrical model of a constrained robot of three degrees of freedom (d.o.f) added to a PPP passive central segment. This structure provides a pure translation motion. We will also determine the relations between generalized and articular velocities by using the inverse Jacobian matrix. Further, we determine the reciprocal relations between cartesian and angular velocities of the end-effector via articular velocities by simple derivation of the direct geometrical model expressions. A determination of the workspace based on the geometrical model analysis is derived followed by a numerical calculation of all the atteignables points enabling a graphical visualisation of such a workspace. Moreover, the analysis of the Jacobian matrix has permitted to ensure that there are no singularities of type 1 and 2 in such a structure. A prototype of a parallel robot has been built up in our laboratory in order to validate the proposed models. Este trabajo presenta el modelo geométrico de un robot paralelo con tres grados de libertad (d.o.f) agregados a un segmento central pasivo del PPP. Esta estructura proporciona un movimiento de translación pura. También determinaremos las relaciones entre las velocidades generalizadas y articulares usando la matriz Jacobiana inversa. Además, determinamos las relaciones recíprocas entre las velocidades cartesianas y angulares del end-effector vía velocidades articulares por la derivación simple de las expresiones del modelo geométrico directo. Una determinación del espacio de trabajo basado en el análisis del modelo geométrico es derivado seguido por un cálculo numérico de todos los puntos que deben alcanzarse permitiendo una visualización gráfica de tal espacio de trabajo. Por otra parte, el análisis de los coeficientes de la matriz Jacobiana permite asegurar que no haya singularidades del tipo 1 y 2 en tal estructura. Se ha realizado un prototipo de robot paralelo en nuestro laboratorio para validar los modelos propuestos.

Context. The most recent determination of the solar chemical composition, using a time-dependent, 3D hydrodynamical model of the solar atmosphere, exhibits a significant decrease of C, N, O abundances compared to their previous values. Solar models that use these new abundances are not consistent with helioseismological determinations of the sound speed profile, the surface helium abundance and the convection zone depth. Aims. We investigate the effect of changes of solar abundances on low degree p-mode and g-mode characteristics which are strong constraints of the solar core. We consider particularly the increase of neon abundance in the new solar mixture in order to reduce the discrepancy between models using new abundances and helioseismology. Methods. The observational determinations of solar frequencies from the GOLF instrument are used to test solar models computed with different chemical compositions. We consider in particular the normalized small frequency spacings in the low degree p-mode frequency range. Results. Low-degree small frequency spacings are very sensitive to changes in the heavy-element abundances, notably neon. We show that by considering all the seismic constraints, including the small frequency spacings, a rather large increase of neon abundance by about (0.5 +/- 0.05)dex can be a good solution to the discrepancy between solar models that use new abundances and low degree helioseismology, subject to adjusting slightly the solar age and the highest abundances. We also show that the change in solar abundances, notably neon, considerably affects g-mode frequencies, with relative frequency differences between the old and the new models higher than 1.5%, 6 pages, 7 figures. Accepted for publication in Astronomy and Astrophysics on 11/04/2007

Mobile robot control architectures are gradually shifting from hierarchical towards behaviour-based. Hierarchical controllers lack flexibility; behaviour-based architectures, on the contrary, enable rapid response to environment changes and, moreover, they feature robustness in industrial environments. A behaviour-based mobile robot system is described enabling task execution in unstructured real-world environments. The behaviour model consists of a number of motion behaviours, including reflexes and voluntary motion behaviours, and knowledge acquisition modules providing task-oriented information about the robot environment. A blackboard model is introduced to overcome some shortcomings of existing systems, especially concerning modularity and task execution capabilities. Some realistic scenarios are described to show the versatility of the system.