106 research outputs found
Modeling and Motion Control of Serial Robots with Flexible Joints
No full textISBN: 978-1-84821-520-7International audienceThis chapter presents the modeling, identification and the motion control of serial robot manipulators with rigid and flexible joints. The perfectly rigid joint assumption, often at the basis of the study of manufacturing robots, can be insufficient in many situations. Flexible joint robots raise specific control issues, both in terms of static (deflections) and dynamic (vibrations) behavior. The chapter highlights the major differences compared to the perfectly rigid case and the characteristics related to flexibilities in modeling, identification and design of control laws. The reduced dynamic model of flexible joint robots is first recalled with its remarkable properties. Several identification approaches of this model are then presented and analyzed in terms of their implementation complexity and the instrumentation required by the experimental protocol. Finally, the chapter describes the main theoretical concepts and their application in several practical control strategies
Conception d'un capteur de force / couple résonnant multi-axes pour la robotique
No full textLes capteurs de force / couple au poignet utilisés dans les applications robotiques augmentent les performances et la flexibilité des tâches automatisées. Ils offrent également de nouvelles possibilités dans le processus de fabrication, où un contact physique entre la pièce et l'environnement est requis. La large diffusion de ces capteurs est pour le moment limitée par leurs caractéristiques. En guise d'alternative aux capteurs de force existants dans le jeu de contraintes, notre travail présente une structure composite résonante, sensible aux multiples composantes de la force prises en compte via l'effet de précontrainte. Des patchs piézoélectriques liés structurellement sont utilisés pour amener la structure à sa résonance, qui est décalée en fonction des forces appliquées. La relation entre la force et le décalage de fréquence est modélisée en tenant compte de la multi-physique de cette structure intelligente. Un prototype a été testé et validé.Wrist force/torque sensors used in robotic applications increase the performances and flexibility of the automated tasks. They also offer new possibilities in the manufacturing process, where physical contact between the work-piece and environment is required. The wide spreading of these sensors is for now restricted by their features. As an alternative to the existing straingauges force sensors, our work presents a resonant composite structure, which is sensitive to multiple components of force that are considered via the pre-stress effect. Structurally bonded piezoelectric patches are used to bring the structure to its resonance, which is shifted according to applied forces. The relationship between force and frequency shift is modelled considering the multi-physics of this smart structure. A prototype was tested and validated
Design of integrated flexible structures for Micromanipulation.
No full textInternational audienceThe design of robotic micromanipulators relies on flexible mechanical structures. These are increasingly being used due to their integration of actuator and measuring functions. The general design context for these integrated systems has resulted in a complex and multi-disciplinary approach to the problem. This design exploits structures flexibility to respond to the challenges of robotic manipulation on a microworld scale. The design analysis approach is used in fields ranging from material sciences to advanced automatic control and topological structural optimization. In this chapter, the need for optimal design aid tools for these systems will be clearly highlighted and a range of existing optimization strategies will be examined. Finally, an illustrative example that focuses on the development of an optimal design software tool for flexible monolithic structures, will conclude the chapter. The structures are capable of maintaining actuator and sensor functions in a distributed and integrated form using piezoelectric materials
Flexures for High-Precision Manipulation Robots
No full textINSTANT-LABChapter 7. Flexures for High-Precision Manipulation Robots 243 7.1. High-precision industrial robots background 243 7.2. Kinematic analysis of simple flexures 248 7.3. Design method of parallel modular kinematics for flexures 260 7.4. Example of the Legolas 5 robot design 264 7.5. Bibliography 27
Non-linear modeling and control of a robotic actuator. Application to object manipulation
No full textLa réalisation de tâches de manipulation dextres requiert une complexité aussi bien dans la conception de préhenseur robotique que dans la synthèse de leurs lois de commande. Une optimisation de la mécatronique de ces systèmes permet de répondre aux contraintes d'intégration fonctionnelle en se passant de capteurs de force terminaux. L'utilisation de mécanismes réversibles rend alors possible la détermination du positionnement du système dans l'espace libre et la détection de son interaction avec les objets manipulés, grâce aux mesures proprioceptives inhérentes aux actionneurs électriques. L'objectif de cette thèse est de parvenir synthétiser, dans le contexte articulaire (un degré-de-liberté), une commande adaptée à la manipulation en tenant compte de ces particularités mécaniques. La méthode proposée est basée sur une commande robuste par rapport aux non-linéarités structurelles dues aux effets gravitationnels et aux frottements secs d'une part et par rapport aux rigidités variables des objets manipulés. L'approche choisie nécessite la connaissance précise de la configuration du système étudié à chaque instant. Une représentation dynamique de son comportement permet de synthétiser un capteur logiciel pour l'estimation des grandeurs indispensables à la commande. Ces différentes étapes sont validées par des essais expérimentaux pour justifier la démarche choisie menant à une commande adaptée à la manipulation d'objets.The realization of dexterous manipulation tasks requires a complexity in robotic hands design as well as in their control laws synthesis. A mecatronical optimization of these systems helps to answer for functional integration constraints by avoiding external force sensors. Back-drivable mechanics allows the free-space positioning determination of such system as far as the detection of its interaction with a manipulated object thanks to proprioceptives measures at electric actuator level. The objective of this thesis is to synthesize a control law adapted to object manipulation by taking into account these mechanical properties in a one degree-of-freedom case. The proposed method is based on a robust control according to structural non-linearities due to gravitational effects and dry frictions on the one hand and with regard to a variable rigidity of manipulated objects on the other hand. The chosen approach requires a precise knowledge of the system configuration at all time. A dynamic representation of its behavior enables a software sensor synthesis for the exteroceptives variables estimation in a control law application purpose. The different steps are experimentally validated in order to justify the chosen approach leading to object manipulation
Contribution à la conception optimale et la commande de systèmes mécatroniques flexibles à actionnement piézoélectrique intégré. Application en microrobotique.
No full textWhen applying scale reduction to mechatronic systems that are usually encountered at the macroscale, the miniaturisation step necessarily implies functional integration of these systems. This general trend makes microsystems more and more functionally integrated, which makes them converging towards the adaptronic concept. The aim of this thesis is to develop a new optimal synthesis method of monolithic compliant structures to design integrated actuators. Our method is based on the optimal arrangement of flexible building blocks thanks to a multi-criteria genetic algorithm. These building blocks result from the assembly of beam elements and are described by a finite element method. They can be either passive or active by exploiting the inverse piezoelectric effect, thus making realistic the integration of the actuation principle inside the mechanical structure. In addition, a dynamic description of the input(s)-output(s) behavior of these flexible mechanisms can be taken into account in our optimization method. Thus, new fitness functions allow the optimal synthesis of devices within a wide schedule of conditions, which can guaranty some specific performances during the control process of these synthesized systems afterwards. Finally, a monolithic piezoelectric microgripper prototype is optimally designed using our developed software tool. The experimental tests made can validate all the different steps of our mechatronics design methodology, from the first designing step of the complete topology study to the final step of the robust control in close-loop form.Lorsqu'on applique une réduction d'échelle aux systèmes mécatroniques habituellement rencontr és dans le macromonde, la miniaturisation n'est possible que si elle est accompagnée d'une intégration fonctionnelle de ces systèmes. Cette tendance générale pousse les microsystèmes à posséder une densité fonctionnelle de plus en plus importante, qui les fait converger progressivement vers le concept d'adaptronique. L'objectif de cette thèse est de développer une nouvelle méthode de synthèse optimale de structures flexibles monolithiques, pour permettre la conception d'actionneurs intégrés. Notre méthode de synthèse est basée sur l'agencement optimal de blocs flexibles élémentaires grâce à un algorithme génétique multi-critères. Ces blocs flexibles sont de type treillis de poutres et décrits par une méthode aux éléments finis. Ils peuvent être passifs ou rendus actifs par effet piézoélectrique inverse, permettant ainsi l'intégration de la fonction d'actionnement au sein même de la structure du mécanisme. En outre, une représentation dynamique du comportement entrée(s)-sortie(s) de ces mécanismes flexibles permet la prise en compte dans la méthode d'optimisation, dès la phase amont de conception, de nouvelles spécifications permettant de garantir certaines performances lors de la commande ultérieure des systèmes ainsi synthétisés. Enfin, un prototype de micropince piézoélectrique monolithique est conçu de manière optimale grâce à l'outil logiciel développé : les tests expérimentaux effectués permettent de valider la démarche de conception mécatronique dans son ensemble, depuis l'étape amont de l'étude complète de sa topologie, jusqu'à l'étape finale de sa commande robuste en boucle fermée
Flexible structures' representation and notable properties in control.
No full textInternational audienceIn this chapter, we will examine a discrete representation of dynamic input/output behavior in flexible structures in relation to their control. The dynamic model's expression, a product of a discretized formulation of mechanical equations for vibratory systems, will be explored in the form of a state-space representation. The dual modal controllability and observability notations, which play and important role in the control authority of significant vibratory modes, will be introduced. In the case of flexible structures, modal Controllability and observability Gramians are characterized by relatively simple analytical expressions that render them an important factor in the design of compliant mechanisms. We will examine a range of properties related to model reduction and demonstrate the influence of actuator and sensor collocation on the control performance of flexible structures. Using a number of examples of robotic manipulators, we will illustrate how these properties can be used to optimally design prehension devices in micromanipulation
Contributions to the multifunctional integration for micromechatronic systems.
No full textMechatronics is the interdisciplinary area related to the integration of mechanical, electronic and control engineering, as well as information technology to design the best solution to a given technological problem. It implies that mechantronics relates to the design of systems, devices and products aimed at achieving an optimal balance between basic mechanics and its overall control. Rototic systems design has certainly been the pioneer field of mechatronic applications
High Resolution Actuators
No full textDriven by increasing societal, economic, and technological pressures, high-resolution actuators must achieve ever increasing accuracy requirements and functional integration into the system.[...
- …
