Weakly Calibrated Stereoscopic Visual Servoing for Laser Steering: Application to Phonomicrosurgery.

International audienceThis paper deals with the study of a weakly calibrated multiview visual servoing control law for microrobotic laser phonomicrosurgery of the vocal folds. It consists of the development of an endoluminal surgery system for laserablation and resection of cancerous tissues. More specifically, this paper focuses on the part concerning the control of the laser spot displacement during surgical interventions. To perform this, a visual control law based on trifocal geometry is designed using two cameras and a laser source (virtual camera). The method is validated on a realistic testbench and the straight point-to-point trajectories are demonstrated

Control of a team of micro-robots for non-invasive medical applications

National audienceThis paper deals with the control and the synchronisation of a team of micro-robots that performs a non-invasive surgical act into a human body. These micro-robots are very small sized (from ten to some hundred microns). A single unit embeds the minimum of computing power and memory (minimalist electronics) to run a very light program, such as a finite-state machine. The mass effect of the joined micro-robots will allow to achieve the mission through a satisfactory way. The originality of this work being to consider a micro-robot as a disposable unit, which has to be as simple as possible, we need to combine reduced computing power with recent architectures. Some kinds of mission are described and the most promising is detailed. Preliminary simulations support our approach

Quoi de neuf en asservissement visuel depuis les JNRR'03 ?

National audienceCet article de synthèse présente les avancées réalisées en France au cours de ces quatre dernières années dans le domaine de l'asservissement visuel

Vision-based self-calibration and control of parallel kinematic mechanisms without proprioceptive sensing

International audienceThis work is a synthesis of our experience over parallel kinematic machine control, which aims at changing the standard conceptual approach to this problem. Indeed, since the task space, the state space and the measurement space can coincide in this class of mechanism, we came to redefine the complete modeling, identification and control methodology. Thus, it is shown in this paper that, generically and with the help of sensor-based control, this methodology does not require any joint measurement, thus opening a path to simplified mechanical design and reducing the number of kinematic parameters to identify. This novel approach was validated on the reference parallel kinematic mechanism (the Gough-Stewart platform) with vision as the exteroceptive sensor

Economic model of a professional football club in France

The economic model of football clubs is a revenue model, but also a cost model in relation to their objective. It can be defined as the search for balance between revenues, costs and objective, and the latter can vary: profit maximization, sporting maximization under strict constraint (“hard” constraint) or “soft” budget constraint (Andreff, 2009). In France, the revenue model of football clubs has evolved with time. This mutation fits in the switch from an SSSL (Spectators-Subventions-Sponsors-Local) model to an MMMMG (Media-Magnats-Merchandising-Markets-Global) model at the European level (Andreff and Staudohar, 2000). Before 1914, sport financing came mainly from practitioners (Bourg and Gouguet, 2001, p. 19). Thereafter, with competitions being a spectacle, spectators have become the primary source of revenue, ahead of the subsidies granted by the local authorities and industry patrons. Advertising revenues have gradually become more and more important, and in the 1960s and 1970s, sponsorship increased significantly as firms were seeking a more direct identification in terms of audience, image, reputation and sales (Andreff and Staudohar, 2000, p. 259). In France, during the 1970s, operating revenues of first division football clubs came mainly from the spectators, supplemented by subsidies and sponsorship. The SSSL model was at its peak, with its “L” finding its justification in the fact that the revenues were generated from local or national residents

Asservissement visuel d'un bras robotique en l'absence d'informations géométriques

National audienceCet article étend les résultats classiques d'asservissement visuel au cas non calibre. Ces extensions sont l'utilisation de paramètres physiques de caméra approximativement connus, l'hypothèse que la structure de la scène observée est inconnue et que l'on est capable de donner une estimation de la norme de la translation pince/caméra. La méthode utilisée pour la commande du robot est la régulation par fonction de tâche, la tâche a effectuer étant le déplacement d'une caméra vis-à-vis d'un objet cible. Cette méthode utilise le Jacobien de l'image qui dépend de la distance entre la camera et la cible ainsi que de la structure euclidienne de cette dernière. Jusqu'a présent, seules étaient utilisées des approximations de ce Jacobien. Le principal apport du travail effectué est l'inclusion du calcul du Jacobien par reconstruction euclidienne et de la transformation pince/camera dans la structure de contrôle. La méthode adoptée pour la reconstruction est une méthode itérative par approximations affines du modèle projectif de camera

Micromechanisms for Laser Phonosurgery : A Review of Actuators and Compliants Parts.

International audiencePhonosurgery has to do with a surgical procedure, performed with an aim to enhance the voice. Common anomalies of the vocal fold includes a wide variety of pathologies such as nodules, polyps, cysts, and cancer. The method most commonly used of phonosurgery is done using a laser beam. The laser beam source is located approximately fourty centimeters away from the vocal cords. With this long distance, a small accuracy error would strongly impact the quality of the intervention. Recent advances in the area of micromechanisms used in medicine have increased the potential for an early detection and a better treatment against vocal folds diseases Using microdevices, micromechanisms can be designed to guide the laser beam nearest to the vocal fold, for an accurate treatment and for minimizing the risk of detriment of the delicate vocal fold structures

Linear Dynamic Modeling of Parallel Kinematic Manipulators from Observable Kinematic Elements.

International audienceThis paper presents a linear method for kinematic and dynamic modeling of parallel kinematic manipulators. This method is simple, compact and clear. One can write all the equations from the beginning till the end with pen and paper. It is thus well suited to mechanical understanding and computer implementation. We can apply it to many parallel robots. This method relies on a body-oriented representation of observable rectilinear kinematic structures (kinematic elements) which form the robot legs

On the adequation of dynamic modelling and control of parallel kinematic manipulators.

International audienceThis paper addresses the problem of controlling the dynamics of parallel kinematic manipulators from a global point of view, where modeling, sensing and control are considered simultaneously. The methodology is presented through the examples of the Gough-Stewart manipulator and the Quattro robot

Vector-based dynamic modeling and control of the quattro parallel robot by means of leg orientations.

International audienceOne of the key steps in high-speed control of a parallel robot is to define an efficient dynamic model. It is usually not easy to have such a model for parallel robots, since many of them have complex structures. Here, we propose a vector-based approach, which employs the robot leg orientations, to obtain a simplified inverse dynamic model. At the least, this vector-based methodology is pioneering, when combined with the observation of orientations by a calibrated camera, in the sense of solving the entire control-oriented (hard) modeling problem, both kinematics and dynamics, in an almost algebraic manner through the knowledge of only a nominal set of image features: the edges of the robot legs and their time derivatives. Proposed method is verified on a simulator of the Quattro robot with a computed torque control where the leg orientations are steered