Control framework for dexterous manipulation using dynamic visual servoing and tactile sensors’ feedback

Tactile sensors play an important role in robotics manipulation to perform dexterous and complex tasks. This paper presents a novel control framework to perform dexterous manipulation with multi-fingered robotic hands using feedback data from tactile and visual sensors. This control framework permits the definition of new visual controllers which allow the path tracking of the object motion taking into account both the dynamics model of the robot hand and the grasping force of the fingertips under a hybrid control scheme. In addition, the proposed general method employs optimal control to obtain the desired behaviour in the joint space of the fingers based on an indicated cost function which determines how the control effort is distributed over the joints of the robotic hand. Finally, authors show experimental verifications on a real robotic manipulation system for some of the controllers derived from the control framework.

Assessment of corrective measures for alleviating slope instabilities in carbonatic Flysch formations: Alicante (SE of Spain) case study

As is well known, in order to select remediation measures to correct or prevent slope instabilities, it is essential to identify and characterize the instability mechanisms. This task is especially complex for heterogeneous rock masses such as Flysch formations. This paper addresses the assessment of corrective measures used in carbonate Flysch formations by classifying and grouping field data reported in an available database in order to associate this data with various instability mechanisms and stratigraphic column types as well as with the corrective measures taken to stabilise them. For this purpose, 194 slopes have been geomechanically characterized, mainly by considering the observed instability mechanisms. The corrective measures that were applied have been evaluated for their suitability and performance, and, if applicable, the causes of their malfunction have been also studied. As a result, some guidelines based on the observed behaviour and the suitability of the correction measure as a function of instability type are proposed for similar slopes.

Feedback mitjançant screencast. Percepció dels/de les alumnes i repercussió en el seu aprenentatge

L’avaluació i els comentaris que la complementen i/o suporten són un element de correcció i redirecció de l’aprenentatge dels estudiants. Els imputs que reben els ajuden a assimilar allò que ja han aprés i a comprendre com millorar tot allò que encara no han adquirit de forma adequada. La correcció manual tradicional sobre paper no admet grans arguments ni explicacions i acaba per resumir-se en l’assenyalament de les errades i, en algunes ocasions, dels encerts. L’espai físic i temporal són, sovint, els elements que posen barreres a explicacions més específiques i desenrotllades. L’ús del screencast (gravació audiovisual de la pantalla de l’ordinador i del so al seu voltant) permet enregistrar en pantalla la imatge del treball rebut pel professor, el moviment del ratolí sobre el text/les imatges i la veu del professor fent els comentaris necessaris sense limitacions d’espai ni temps. He aplicat d’aquesta pràctica docent per primera vegada el curs present. Amb el present estudi em propose conèixer quina percepció tenen els/les alumnes d’aquesta incorporació tecnològica a l’avaluació, com repercuteixen els comentaris en àudio al seu aprenentatge i si tenen cap suggeriment que ajude a acceptar, rebutjar i/o millorar el feedback i la valoració mitjançant screencast.

Organic distributed feedback laser to monitor solvent extraction upon thermal annealing in solution-processed polymer films

Solution-processed polymer films are used in multiple technological applications. The presence of residual solvent in the film, as a consequence of the preparation method, affects the material properties, so films are typically subjected to post-deposition thermal annealing treatments aiming at its elimination. Monitoring the amount of solvent eliminated as a function of the annealing parameters is important to design a proper treatment to ensure complete solvent elimination, crucial to obtain reproducible and stable material properties and therefore, device performance. Here we demonstrate, for the first time to our knowledge, the use of an organic distributed feedback (DFB) laser to monitor with high precision the amount of solvent extracted from a spin-coated polymer film as a function of the thermal annealing time. The polymer film of interest, polystyrene in the present work, is doped with a small amount of a laser dye as to constitute the active layer of the laser device and deposited over a reusable DFB resonator. It is shown that solvent elimination translates into shifts in the DFB laser wavelength, as a consequence of changes in film thickness and refractive index. The proposed method is expected to be applicable to other types of annealing treatments, polymer-solvent combinations or film deposition methods, thus constituting a valuable tool to accurately control the quality and reproducibility of solution-processed polymer thin films.