Contribution à l'agrandissement de l'espace de travail opérationnel des robots parallèles. Vérification du changement de mode d'assemblage et commande pour la traversée des singularités

Abstract : Compared to their serial counterparts, parallel robots have the edge in terms of rigidity,cycle time and positioning precision. However, the reduced size of their operationalworkspace is a drawback that limits their use in the industry. Kinematic analysis explainshow the workspace is divided in aspects, separated from each others by so-called Type 2singularities. Among existing solutions for workspace enlargement, which are evaluatedin this thesis, we chose to work on a method based on singularity crossing. This can beachieved thanks to dedicated trajectory generators and control strategies. Yet, failuresin crossing can still happen and crossing success cannot be certified.In consequence, the first part of the thesis consists in the development of an algorithmable to state on the results of a crossing attempt. Such a tool does not exist inthe literature, since solvers for the forward kinematics of parallel robots diverge aroundsingularities. Nonetheless, interval methods allow to bypass this problem by trackingend-effector velocity alongside with its pose. The ability of the algorithm to detect assemblymode change is proven in simulation, and its usefulness for reliable trajectoryplanning is shown.In a second part, we seek to improve trajectory tracking through the use of advancedcontrol techniques. A review on those techniques showed adaptive control and predictivecontrol methods to be well-fitted to our application. Linear synthesis of articularadaptive control is proposed and then derived in order to predict dynamic parametersthanks to the Predictive Functional Control method. Efficiency of the proposed controllaws is evaluated in simulation.1In order to validate both contributions, algorithms and control laws are implementedon a 2-degree of freedom planar parallel robot named DexTAR. As it is mandatory forassembly mode detection, the kinematic calibration of the robot is completed from whichcertified geometric parameters are derived. Assembly mode detection is performed onreal trajectories and results are compared to those obtained in simulation. Moreover,adaptive and predictive control laws are tested in realistic cases of singularity crossingand object manipulation.Overall, proposed contributions answer the problems that were stated previously andform an improvement to the workspace enlargement method based on Type 2 singularitycrossing.
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Adrien Koessler. Contribution à l'agrandissement de l'espace de travail opérationnel des robots parallèles. Vérification du changement de mode d'assemblage et commande pour la traversée des singularités. Automatique / Robotique. Université Clermont Auvergne, 2018. Français. ⟨NNT : 2018CLFAC075⟩. ⟨tel-02128890⟩

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