Stability and Transparency Analysis of a Teleoperation Chain For Microscale Interaction.

International audienceMicroscale teleoperation with haptic feedback requires scaling gains in the order of 104 107. These high gains impose a trade-off between stability and transparency. Due to the conservative approach used in most designs, transparency is reduced since damping is added to the system to guarantee stability. Starting from the fact that series, negative feedback and parallel connection of passive systems is a passive system, a new approach is addressed in this work. We propose here a complete teleoperation chain designed from the ground up for full transparency and stability, including a novel self-sensing probe and a high fidelity force-feedback haptic interface. By guaranteeing the passivity of each device and assuming that the human operator and the environment are passive systems, a homothetic direct coupling can be used without jeopardizing the stability and provides best transparency. The system is experimentally demonstrated in the complex case of a probe interacting with a water droplet under human control, while accurately transcribing the interaction back to operator

Modélisation et simulation à topologie variable des convertisseurs statiques et des entraînements électromécaniques

Nous proposons une approche pour synthétiser automatiquement le modèle à topologie variable des convertisseurs statiques (modèle discret idéal des semi-conducteurs), principalement en vue de leur propre simulation et notamment celle des entraînements électromécaniques

Thermocapillary convective flows generated by laser points or patterns: Comparison for the noncontact micromanipulation of particles at the interface

This letter compares the controlled manipulation of micrometer size particles using thermocapillary convective flows generated by laser points or patterns. Such flows are generated when a surface tension stress is generated at the fluid/gas interface due to a thermal gradient. Laser heating allows to generate fast, localized flows that are used to displace a particle towards a desired position. However, these flows are repulsive and so the system is unstable. Although using the simple laser spot with a closed-loop control enables to control the particle displacement, the control of the particle movement direction is somehow difficult and the particle position stabilization remains challenging. In this letter, it is proposed to use laser patterns to overcome these limitations. Experimental tests are performed using a 500-μm-diameter steel spherical particle that is displaced towards a target position. The preliminary experimental results show that it is possible to overcome the above mentioned limitations while still obtaining maximal particle velocities ranging from 4 to 9 mm/s during the displacement phase. © 2016 IEEE

Impedance-based real-time position sensor for lab-on-a-chip devices

International audienceThis paper presents the theoretical and experimental development of an integrated position sensor for lab-on-a-chip devices. The interest for single cell analysis is growing. However, this requires monitoring and controlling cell displacements in real time during their journey in the chip. Due to the high number of cells that must be monitored at the same time, classical vision-based sensors are not suitable. This paper aims to present an alternative based on impedance measurement. The position of the cells is obtained from the variation of impedance measured between two electrodes. This technique presents several advantages: the sensor is integrated into the chip, the measurement electrodes are compatible with the fabrication process of actuation electrodes for dielectrophoresis, the sampling time of the sensor is high and the position of the cells can be obtained in real time. This article highlights the concept of position-sensitive impedance sensing. The design of the chip, and in particular of the electrodes, is discussed to improve the sensitivity and repeatability of the measurement. The issue of real-time detection in a noisy environment is solved by using an extended Kalman filter. As a first proof of concept, this article presents experimental validation on a 1D case to determine the longitudinal position of 8.7 μm diameter beads in a channel