Improving rotation behaviour of robotic structures for micro-assembly.

International audienceSerial micro-assembly requires high precision robots able to produce translations and rotations to position and orient objects during assembly. In micro-scale, the translation ranges required are typically up to the millimeter and can be obtained with smart devices (piezomotor, etc...). In the other hand, the rotation ranges stay identical to the macroscale (eg. 90°) and require standard guidings like ball bearings which induce disturbances on the linear position. Thus, the ability to produce high precision robots where translations and rotations are découpled is currently one of the major stake in microassembly. This paper deals with an original modeling of the coupling between rotation and linear position. The geometrical model is presented and two calibration methods are discussed. Our method were tested on a 3 DOF planar robotic systems and the coupling was reduced by 93 %

L’Atlas des nouveaux mondes. Territoires d’exploration et de découverte

International audienc

L’Atlas des nouveaux mondes. Territoires d’exploration et de découverte

International audienc

Bubble nucleation process in a metal tritide modeled using a cellular automaton

International audienceThe modeling of the He-3 bubble nucleation phase that occurs during the aging of metal tritides such as palladium tritide is undertaken using a cellular automaton describing the material at the atomic scale. In that model, using simple rules of cell state change, the physical phenomena involved in the bubble nucleation, namely tritium diffusion, formation of He-3 by radioactive tritium decay, He-3 diffusion, He-3 self-trapping, bubble growth, influence of pre-existing trapping sites such as vacancies, are taken into consideration. Calculations steps are related to physical time through the decay of tritium atoms into He-3 atoms which is characterized by a half-life of 12.32 years. That work has shown that the bubble density and distribution are almost stable within a few days of aging - typically 5-10 -, whatever the input parameters, the system making created bubbles to grow thereafter instead of creating new ones. The reached bubble density is very dependent on the He-3 mobility - related to temperature for instance - during the first days of aging. The smaller it is, the higher the density. With a larger density of trapping sites, bubbles appear earlier and their density is higher. These results are discussed and compared to available experimental and theoretical works on palladium tritide

Synthesis and characterization of regioselectively monoderivatized maltooligosaccharides through a combination of tandem mass spectrometry and enzymatic hydrolysis studies

International audienceRecently, we have designed chemical strategies leading to C-6 perfunctionalized linear maltoheptaose derivatives via the acetolysis of persubstituted β-cyclodextrin (β-CD) at the 6-positions. This approach has now been extended to the synthesis of monofunctionalized maltoheptaose derivatives. This report deals with the regioselectivity of the ring opening of monosubstituted β-CD and the use of electrospray ionization tandem mass spectrometry (ESIMS/MS) to identify the substituted unit. In order to confirm our results, a controlled enzymatic degradation of the resulting derivatives, using the glucoamylase of Aspergillus niger, was performed and monitored by liquid chromatography / electrospray ionization mass spectrometry (LC/ESI-MS). ©ARKAT-USA, Inc