Indirect Methods for Robot Skill Learning

Robot learning algorithms are appealing alternatives for acquiring rational robotic behaviors from data collected during the execution of tasks. Furthermore, most robot learning techniques are stated as isolated stages and focused on directly obtaining rational policies as a result of optimizing only performance measures of single tasks. However, formulating robotic skill acquisition processes in such a way have some disadvantages. For example, if the same skill has to be learned by different robots, independent learning processes should be carried out for acquiring exclusive policies for each robot. Similarly, if a robot has to learn diverse skills, the robot should acquire the policy for each task in separate learning processes, in a sequential order and commonly starting from scratch. In the same way, formulating the learning process in terms of only the performance measure, makes robots to unintentionally avoid situations that should not be repeated, but without any mechanism that captures the necessity of not repeating those wrong behaviors. In contrast, humans and other animals exploit their experience not only for improving the performance of the task they are currently executing, but for constructing indirectly multiple models to help them with that particular task and to generalize to new problems. Accordingly, the models and algorithms proposed in this thesis seek to be more data efficient and extract more information from the interaction data that is collected either from expert\u2019s demonstrations or the robot\u2019s own experience. The first approach encodes robotic skills with shared latent variable models, obtaining latent representations that can be transferred from one robot to others, therefore avoiding to learn the same task from scratch. The second approach learns complex rational policies by representing them as hierarchical models that can perform multiple concurrent tasks, and whose components are learned in the same learning process, instead of separate processes. Finally, the third approach uses the interaction data for learning two alternative and antagonistic policies that capture what to and not to do, and which influence the learning process in addition to the performance measure defined for the task

Rehabilitation process using electromyography and biofeedback

Treballs Finals de Grau d'Enginyeria Biomèdica. Facultat de Medicina i Ciències de la Salut. Universitat de Barcelona. Curs: 2020-2021. Director: José Luis Parreño Catalan. Tutor: Manel Puig Vidal.A good rehabilitation routine is essential for the best possible recovery after an injury or to increase the quality of life of those who suffer from neuromusculoskeletal diseases. It is of particular relevance to maintain the motivation throughout all the process, for which videogames may play an essential role. Biofeedback is a process that provides real time information from psychophysiological recordings about the levels at which physiological systems are functioning. In this project the biofeedback system has been implemented by means of a low-cost EMG system created using Arduino. The EMG system has been developed using an Olimexino-328 microcontroller and an EMG-Shield, both from Olimex. The program was developed using Arduino IDE. To assess the quality of the signal of the prototype, it was compared to a professional EMG device, the DataLog from Biometrics Ltd. The comparison showed promising results although it could be improved by means of post-processing algorithms. An audio-visual Biofeedback system targeting maximum strength and explosiveness of the muscles was created using Python. Flappy Bird game commands were changed to control them with the EMG low-cost prototype. The flap logic of the game is guided by a threshold fixed automatically by the software at the 60% of the maximum signal obtained by the EMG system. The system was tested to optimize its performance and fix possible flaws. Although it is simple and further investigation may be needed, having in mind the fewer resources used, the system performance is encouraging, and a clinical trial should be performed to assess its real behaviour, usefulness, and efficiency for rehabilitation purposes

Neutron capture on ^{205}Tl: depicting the abundance pattern of lead isotopes in s-process nucleosynthesis

Proposal: Neutron capture on 205Tl: depicting the abundance pattern of lead isotopes in s-process nucleosynthesisWe propose to use the TOF technique to measure the neutron capture cross section of 205Tl(n,gamma) over the full energy range of stellar interest. An accurate measurement of this cross section is needed for a complete and consistent understanding of the s-process nucleosynthesis of the heaviest nuclei which are produced in low-mass and low metallicity AGB-stars. The only previous TOF measurement has yield only a partial information, insufficient for a reliable analysis of the complex branching pattern around 205Pb and 205Tl. Furthermore, there is also a discrepancy of 40% between the two previous activation measurements made at kT=24 keV. The cross section of 205Tl(n,gamma) is particularly relevant because it affects the equilibrium that is established in some stellar conditions between the 205Tl -> 205Pb bound-state Beta-decay and the 205Pb -> 205Tl E.C. decay. This effect induces a complex interplay which influences the final s-process abundance of both nuclei. We propose to measure accurately and with high resolution the 205Tl(n,gamma) cross section by using a set of four C6D6 detectors in combination with the pulsed neutron-source of CERN n_TOF.Preprin

Sindicalismo y negociación colectiva en la España democrática (1975-2005): el caso de Renfe

El objetivo de este trabajo es el de analizar un periodo de la historia de España desde la óptica de la acción sindical en una de las principales empresas del país. El trabajo se inicia con una introducción en la que se contextualizan los principales acontecimientos políticos y económicos, para proseguir con un estudio del desarrollo del sindicalismo en la etapa democrática. Se analiza la complejidad del movimiento sindical en los primeros momentos de la Transición, con especial atención a los resultados de las elecciones sindicales y la firma de los diferentes convenios colectivos. Los años 80 significaron la consolidación de los sindicatos de clase, y ahí se estudian la diferentes estrategias seguidas por las distintas organizaciones en su acción sindical. En los 90, con la aparición de los sindicatos profesionales se asiste a una notable transformación del sindicalismo ferroviario. El trabajo se introduce en los primeros años del siglo XXI para valorar las transformaciones derivadas del proceso de liberalización del sector ferroviario. Se concluye con una serie de reflexiones sobre los ciclos habidos en el sindicalismo ferroviario en la etapa democrática, incidiendo en lo relativo a los escenarios de la acción sindical, la representatividad y la negociación .Spanish Political Transition; Spanish Railroads; Labor-Management Relations; Trade Unions; Collective Bargaining; Long Run

Environmental and Human Controls of Ecosystem Functional Diversity in Temperate South America

The regional controls of biodiversity patterns have been traditionally evaluated using structural and compositional components at the species level, but evaluation of the functional component at the ecosystem level is still scarce. During the last decades, the role of ecosystem functioning in management and conservation has increased. Our aim was to use satellite-derived Ecosystem Functional Types (EFTs, patches of the land-surface with similar carbon gain dynamics) to characterize the regional patterns of ecosystem functional diversity and to evaluate the environmental and human controls that determine EFT richness across natural and human-modified systems in temperate South America. The EFT identification was based on three descriptors of carbon gain dynamics derived from seasonal curves of the MODIS Enhanced Vegetation Index (EVI): annual mean (surrogate of primary production), seasonal coefficient of variation (indicator of seasonality) and date of maximum EVI (descriptor of phenology). As observed for species richness in the southern hemisphere, water availability, not energy, emerged as the main climatic driver of EFT richness in natural areas of temperate South America. In anthropogenic areas, the role of both water and energy decreased and increasing human intervention increased richness at low levels of human influence, but decreased richness at high levels of human influence