Mixing and Demixing Into MEMS

In questa tesi si descrive tre espeimenti condotti in laboratorio nel campo della miscelazione di fluidi in canali con dimenzioni inferiori al millimetro, e alla segregazione di in due fasi di una miscela omogenea attraverso il raffreddamento del liquido

Book Review: Feminism & Freedom. by Michael Levin.

Book review: Feminism & Freedom. By Michael Levin. New Brunswick, N.J.: Transaction Books. 1987. Pp. xi, 336. Reviewed by: Brigitte Berger

Control of a hybrid robotic system for computer-assisted interventions in dynamic environments

International audiencePurpose Minimally invasive surgery is becoming the standard treatment of care for a variety of procedures. Surgeons need to display a high level of proficiency to overcome the challenges imposed by the minimal access. Especially when operating on a dynamic organ, it becomes very difficult to align instruments reliably and precisely. In this paper, a hybrid ro-botic system and a dedicated robotic control approach are proposed to assist the surgeon performing complex surgical gestures in a dynamic environment. Methods The proposed hybrid robotic system consists of a rigid robot arm on top of which a continuum robot is mounted in series. The continuum robot is locally actuated with McKibben muscles. A control scheme is adopted based on quadratic programming framework. It is shown that this framework allows enforcing a set of constraints on the pose of the tip, as well as of the instrument shaft, which is commanded to slide in and out through the entry point. Results Through simulation and experiments it is shown how the robot tool-tip is able to follow sinus-oidal trajectories of 0.37 Hz and 2 Hz, corresponding to motion due to breathing and heartbeat respectively, while maintaining the instrument shaft pivoting nicely about the entry point. The positioning and tracking accuracy of such system is shown to lie below 3mm in position and 5 • in angle. Herbert De Praetere is with UZ Leuven, Cardiac surgery, Conclusion The results suggest a good potential for applying the proposed technology to assist the surgeon during complex robot-assisted interventions. It is also illustrated that even when using flexible hence relatively safe end-effectors, it is possible to reach acceptable tracking behaviour at relatively high frequencies

Multi-level-assistance robotic platform for navigation in the urinary system: design and preliminary tests

This work was supported by the ATLAS project. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 813782. This work was also partially supported by French State Funds managed by the “Agence Nationale de la Recherche (ANR)” through the “Investissements d’Avenir” (Investments for the Future) Program under Grant ANR-10-IAHU-02 (IHU-Strasbourg).Peer ReviewedPostprint (published version

Bilateral Energy Transfer for high fidelity haptic telemanipulation

Among the methods to grant the stability of a telemanipulation system, the bilateral time domain passivity framework has the appealing characteristic to consider both, force and velocity signals exchanged between master and slave systems, and the power introduced or dissipated by the elements that compose the telemanipulation system. In previous works, [2, 3], it has been shown how the bilateral passivity controller (BiPC) can preserve stability when the communication channel that conveys data between master and slave is affected by delay. In this work the authors intend to further explore the possibilities offered by the Bilateral Energy Transfer concept as design guideline, and to refine the control schemes already discussed in [3]. The underlying idea of the Bilateral Energy Transfer is to achieve a transport of energy between the two sides of the real system as faithful to an “ideal” (not delayed) system as allowed by the energy leaks. As energy leak is meant the behavior introduced by the not ideality of some components, such as the communication channel. At the same time, in order to obtain easy-to-use system, the control system must preserve, in some extend, the force, velocity, and position correspondences between master and slave. In order to achieve this goal, a modified version of passivity controller is presented. Its main characteristic is that its correction action aimed at dissipating energy, regarded as generated by energy leaks, is limited and deferred in time. Moreover, a drift compensator is introduced whose role is to solve a drift in position introduced by the operation of the same BiPC; in order to maintain the whole system passive, the action of this controller is bounded to the amount of energy that has been dissipated in excess by the BiPC

Constraint-based specification of hybrid position-impedance-force tasks

© 2014 IEEE. This work aims to extend the application field of the constraint-based control framework called iTaSC (instantaneous task specification using constraints) toward tasks where physical interaction between the robot and the environment, or a human, is contemplated. iTaSC, in its original formulation, allows for a systematic derivation of control schemes from task descriptions; tasks are defined as constraints enforced on outputs (e.g. distances, angles), and the iTaSC control takes care to fulfil such constraints by computing desired velocities to be commanded to the robot(s) joints. This approach, being based on a velocity resolution scheme, principally addresses tasks where positioning is the main issue. However, tasks that involve contacts with the environment or with the user, either desired or accidental, can be considered as well, taking advantage of impedance control, when position is controlled, or with force control. This paper describes the implementation of force tasks, and, by the combination of conflicting force and position tasks, impedance control, within the iTaSC formalism. This result is achieved by taking advantage of an approximate physical modelling of the robotic system and the environment. The proposed control scheme is tested by means of experiments where constraints on forces and/or positions described in cylindrical coordinates are imposed on a Kuka LWR arm.status: publishe