Dispositif de plusieurs micros robots mobiles contrôlés par un projecteur

Le but de ce projet est de tester le principe du « friction drive » sur des micro-robots avec un minimum de composants « on board ». Le « friction drive » est une utilisation d’une vibration horizontale et d’un changement, par différents moyens, de la force de contact entre le robot et sa surface de guidage. Le but de ce projet est de développer un dispositif capable de tester ce principe en utilisant une table vibrante en XY pour la vibration horizontale et une force électrostatique pour varier la force de contact. La table réalise des translations dans le plan XY selon des cercles de 0,1 à 4 mm de rayon avec une fréquence de 15 Hz. Elle est montée sur des lames pour la maintenir dans un plan horizontal. La commande des robots est faite au travers d’un projecteur vidéo. Les robots sont munis d’électrodes pour le serrage électrostatique sur le dessous et de cellules solaires pour la mise sous tension de ces électrodes sur le dessus. Les tests ont montré que le principe fonctionne dans des conditions très précises. L’excentricité de la table, la propreté du support, l’humidité doit être très bien maîtrisé. La vitesse du robot est de l’ordre de 5 mm/s

Thermal Behavior of an Ultra High-Precision Linear Axis Operating in Industrial Environment

Thermal expansion is the major source of inaccuracy for ultra high-precision robots. In this paper we propose a strategy to model and compensate this effect. The experiment is run using a 1 DOF (degree-of-freedom) parallel robot equipped with ten temperature sensors; the displacements of the end-effector are measured using an interferometer. After a session of measurements the data collected has been processed using the stepwise regression algorithm. A model of the thermal robot behavior has been found and implemented in the robot controller. In this way it has been possible to compensate all the thermal effects, reaching an absolute accuracy of 10 nanometers

A new concept of modular kinematics to design ultra-high precision flexure-based robots

This work deals with the kinematic conception and the mechanical design of ultra-high precision robots, which are at present costly to develop, both in time and money. The aim of this paper is thus to introduce a new modular concept of kinematics which allows to significantly reduce the time-to-market and a new double-stage flexure-based pivot. Regarding the modular concept of kinematics, this ‘robotic Lego’ consists in a finite number of building bricks allowing to rapidly design a high precision machine and to easily modify its mobility. The realised mock-up of a 4-DOF (Degrees of Freedom) robot, transformable into a 5-DOF one, validates this concept and the mechanical design of its bricks. Flexure hinges are used to achieve the aimed sub-micrometer precision; however, existing flexure-based rotary joints are not able to fulfil the requirements of some applications, as they present a too low angular stroke and a parasitic motion of their centre of rotation. Thus, this paper also introduces a new double-stage pivot based on blades working in torsion; experiments performed on a prototype allow to validate its principle and the simulation model used for its development

Thermal Calibration of a 3 DOF Ultra High-Precision Robot Operating in Industrial Environment

While dealing with sub-micrometer precision robots, thermal expansion is the most significant source of inaccuracy. Thermal variations in the environment, in the robot parts and in the frame change the robot geometry, lowering the robot precision. In this article we propose a strategy to model and compensate such effects. The thermal behavior of a 3 DOF (Degree(s)-of-freedom) parallel robot has been studied using a high-precision measuring system. A model of the robot thermal behavior has been built and implemented in the controller. By using it, thermal deformations are compensated in real-time and an absolute accuracy of ±71 nm has been reached

Parallel robotics, from research to industry

New trends and impact of parallel robotics and machinery in industry

Modularity and parallel kinematics: an original design methodology applied to high precision

This paper introduces a new methodology to design modular industrial ultra-high precision robots; it aims at significantly reducing both the complexity of their design and their development time. This modular concept can be considered as a robotic Lego®, where a finite number of building bricks is used to quickly design the robot and to easily change its mobility. The core of the concept is the thorough conceptual solution catalogue, which is independent from any mechanical design. This paper will first present the methodology and the techniques to establish this solution catalogue. Then, its application to high precision will include the formulation of hypotheses and a practical example of a 5-degree of freedom ultra-high precision robot design

A Novel Verticalized Reeducation Device for Spinal Cord Injuries: the WalkTrainer, from Design to Clinical Trials

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Modeling and compensation of cutting-forces generated during the EDM process for ultra high-precision robots

This work deals with the calibration of industrial robots operating at sub-micrometric precision. We demonstrate that the cutting-forces generated by the robot manufacturing process cause a significant deformation of the robot geometry, lo- wering its absolute accuracy. Then, we propose a way of studying and modeling such deformations, in order to compen- sate them during the robot usage. We have taken the micro electro-discharge machining process on the robot Agietron micro-nano as a case study and we have used an ultra high-precision measuring system to evaluate the deformations due to cutting-forces. Finally, we have built a mathematical model of the robot physical behavior and we have implemented it in the robot controller, in order to compensate the deformations in real-time

Actionneur linéaire basé sur le principe du « Inchworm » inertiel

Le but de ce projet était de développer un actionneur linéaire haute résolution basé sur le principe du « Inchworm », dans lequel le blocage des pieds sera effectué par la force inertielle d’une vibration verticale. Les vibrations des pieds sont réalisées par des céramiques piézoélectriques. La vitesse maximum de l’actionneur réalisé est 1,2 mm/s, la force maximum est de 19 grammes, le mouvement a une très bonne linéarité et la résolution est meilleure que 25 nm