Physically based bead topology model coupled with electro-mechanical power source model applied for wire and arc additive manufacturing

The present work is carried out in the framework of the WAS project [1] which deals with WAAM process. The process relies on an automatized welding process in which a part is built by successively deposed metal bead. We propose a physically based bead topology model using the equilibrium between the hydrostatic pressure and the capillarity force, under twodimensional hypothesis. This equilibrium can be described by the Laplace equation [2]. The proposed model is used to estimate a bead topology which is deposed on an inclined support. Moreover, a deposed melted metal volume is necessary for the bead topology model. By modelling a gas metal arc welding (GMAW) power source system [3], the volume can be estimated and be used as a physical parameter for the bead topology model. Combining the topology and the power source models, the coupling model allows to simulate the topology of a weld bead through WAAM. In addition to the modelling, experimental profiles of the beads are used to validate the model

Observer normal forms : extended, partial and reduced

L'observateur est un outil essentiel pour accéder à l'information, non mesurable directement, d'un système dynamique. Dans le cas des systèmes non linéaires, il y a une grande carence concernant la synthèse d'observateur. Motivée par l'absence d'une solution générique, cette thèse élargit la classe des systèmes non linéaires pour lesquels on peut appliquer les observateurs connus. Dans l'approche adoptée, le système non linéaire est transformé à travers un changement de coordonnées sous forme normale d'observabilité qui a une structure adéquate à la synthèse d'observateurs. Les difficultés liées aux conditions d'existence d'un changement de coordonnées sont mises en évidence et des solutions sont proposées. Par conséquent, la classe des systèmes non linéaires qui peuvent se mettre sous une forme normale d'observabilité est élargie. Dans un premier temps, nous avons proposé une forme normale d'observabilité étendue dépendante de la sortie en augmentant l'espace d'état par des variables auxiliaires. Ainsi, nous avons établi les conditions nécessaires et suffisantes à l'existence d’un changement de coordonnées permettant d’obtenir une telle forme. En outre, nous avons proposé, pour certains modèles, des procédures heuristiques pour la mise sous forme normale d'observabilité étendue dépendante de la sortie. Dans un deuxième temps, nous avons traité la mise sous forme normale d'observabilité d'un système non linéaire partiellement observable. Enfin, nous avons abordé la transformation d'une classe spéciale de systèmes non linéaires sous la forme normale d'observabilité réduite. L'efficacité et l'intérêt des méthodes développées sont établis au travers de plusieurs applications.Observer is an essential means to access to no-measurable information of a dynamical system. In the case of nonlinear systems, there is a great deficiency concerning the observer design theory. Motivated by the lack of a generic solution to observer design, this thesis enlarges the class of nonlinear systems which admit a standard observer. Using a geometrical approach, the considered nonlinear systems are transformed through a change of coordinates into observer form, which has an adequate structure to the observer design. The difficulties related to the conditions on the existence of such a change of coordinates are highlighted and solutions are proposed. Therefore, the class of nonlinear systems which can be transformed under an observer form is expanded. Firstly, we proposed an extended output depending observer form which does not preserve the size of the original state space and we established the sufficient conditions for the existence of a change of coordinates enabling to construct the proposed form. Moreover, we proposed a heuristic procedure to construct the extended output depending observer form of some models. Secondly, we dealt with the observer form for some partially observable nonlinear systems. Finally, we discussed the transformation into the reduced observer form for a class of nonlinear systems. The efficiency and interest of the developed methods is established through several applications

Observer normal forms : extended, partial and reduced

L'observateur est un outil essentiel pour accéder à l'information, non mesurable directement, d'un système dynamique. Dans le cas des systèmes non linéaires, il y a une grande carence concernant la synthèse d'observateur. Motivée par l'absence d'une solution générique, cette thèse élargit la classe des systèmes non linéaires pour lesquels on peut appliquer les observateurs connus. Dans l'approche adoptée, le système non linéaire est transformé à travers un changement de coordonnées sous forme normale d'observabilité qui a une structure adéquate à la synthèse d'observateurs. Les difficultés liées aux conditions d'existence d'un changement de coordonnées sont mises en évidence et des solutions sont proposées. Par conséquent, la classe des systèmes non linéaires qui peuvent se mettre sous une forme normale d'observabilité est élargie. Dans un premier temps, nous avons proposé une forme normale d'observabilité étendue dépendante de la sortie en augmentant l'espace d'état par des variables auxiliaires. Ainsi, nous avons établi les conditions nécessaires et suffisantes à l'existence d’un changement de coordonnées permettant d’obtenir une telle forme. En outre, nous avons proposé, pour certains modèles, des procédures heuristiques pour la mise sous forme normale d'observabilité étendue dépendante de la sortie. Dans un deuxième temps, nous avons traité la mise sous forme normale d'observabilité d'un système non linéaire partiellement observable. Enfin, nous avons abordé la transformation d'une classe spéciale de systèmes non linéaires sous la forme normale d'observabilité réduite. L'efficacité et l'intérêt des méthodes développées sont établis au travers de plusieurs applications.Observer is an essential means to access to no-measurable information of a dynamical system. In the case of nonlinear systems, there is a great deficiency concerning the observer design theory. Motivated by the lack of a generic solution to observer design, this thesis enlarges the class of nonlinear systems which admit a standard observer. Using a geometrical approach, the considered nonlinear systems are transformed through a change of coordinates into observer form, which has an adequate structure to the observer design. The difficulties related to the conditions on the existence of such a change of coordinates are highlighted and solutions are proposed. Therefore, the class of nonlinear systems which can be transformed under an observer form is expanded. Firstly, we proposed an extended output depending observer form which does not preserve the size of the original state space and we established the sufficient conditions for the existence of a change of coordinates enabling to construct the proposed form. Moreover, we proposed a heuristic procedure to construct the extended output depending observer form of some models. Secondly, we dealt with the observer form for some partially observable nonlinear systems. Finally, we discussed the transformation into the reduced observer form for a class of nonlinear systems. The efficiency and interest of the developed methods is established through several applications

Observateur non linéaire étendu

International audienceThis paper deals with the observer design for nonlinear dynamical system after trans-formation through change of coordinates into an observer normal form which supports a high gain observer. Moreover, the sufficient geometrical conditions that guarantee the existante of change of coordinates are given. The proposed approach is applied to estimate the states of SEIR model. RÉSUMÉ. Cet article étudie le problème de la recherche d'un changement de coordonnées per-mettant de transformer un système non-linéaire en forme normale d'observabilité, qui est une forme idéale pour l'estimation d'états. Des conditions géométriques suffisantes pour l'existence d'un changement de coordonnées d'un un système non linéaire mono sortie sont données

Extended output depending normal form

International audienceThis paper concerns the design of a nonlinear observer through a transformation of a nonlinear system into an observer form that supports a high gain observer. Sufficient geometrical condition is deduced to guarantee the existence of change of coordinates allowing the transformation of a nonlinear system into the proposed normal form. The result is highlighted by studying the Susceptible Exposed Infected and Recovered (SEIR) model

Optimization of mechanical part’s quality based on a manufacturing strategy in WAAM process

International audienceWire Arc Additive Manufacturing (WAAM) process recently attracted strong interest within different industrial fields because of its capabilities to produce large metal parts dedicated to aeronautics, automotive or energy domain. In WAAM process, a weld bead is deposed layer by layer by a robot. The weld bead is fed through a wire of which the tip is fused by power generator.The present work proposes a strategy to choose suitable welding process parameters (welding torch path and process parameters) to obtain an optimal topology quality. To do so, a numerical model fortopology simulation of deposited material is firstly used for 2D configuration. The model is based on the resolution of the Young-Laplace equation which allows to modelize the assembly of weld beads(superposition and juxtaposition). Geometrical meta models based on 3D scans of each layer of the manufactured specimens are used as inputs of the topological model.This work aims to find the best positions of the welding torch enabling to satisfy quality requirementsin a manufactured part. The part’s quality is based on the gap between its manufactured topology and the geometry specified in its associated CAD file. Such as in 2D configuration of topology simulation, we consider some quality criteria such as the size of the part, and the planarity of some specific layers. The height and width of the simulated part are those of the CAD geometry. An optimization strategy is to establish a number N of layers and a number M of weld beads per layer reaching the targetedheight and width respectively. Another criteria is also to minimize planarity defect at every K layer(which is smaller than N). A parallelepiped part is used as a test case for this study

Nonlinear observer normal form with output injection and extended dynamic

International audienceThis paper presents a new extended output depending nonlinear observer normal form. A sufficient geometrical conditions that guarantee a change of coordinates allowing the transformation of a given nonlinear dynamical system into the proposed observer form are given. Throughout this work, it will be showed that, unlike to the existing observer normal forms, this new form enables to design an observer for the Susceptible, Exposed, Infected, and Recovered (SEIR) model of population under an infectious disease

Nonlinear observer for the PM synchronous motor

International audience— This paper deals with nonlinear states and pa-rameters estimation of a permanent magnet synchronous motor (PMSM) without mechanical sensors. In the proposed method, a change of coordinates is established in order to transform the PMSM system into an observer form which enables us to apply an adaptive or a high gain observer. Then the load torque, rotor speed and some parameters can be estimated from both measurable currents and voltages. The efficiency of the proposed methods is illustrated by the simulation results

Nonlinear observer normal form with output injection and extended dynamic

International audienceThis paper presents a new extended output depending nonlinear observer normal form. A sufficient geometrical conditions that guarantee a change of coordinates allowing the transformation of a given nonlinear dynamical system into the proposed observer form are given. Throughout this work, it will be showed that, unlike to the existing observer normal forms, this new form enables to design an observer for the Susceptible, Exposed, Infected, and Recovered (SEIR) model of population under an infectious disease