The design of autonomous robots, able to closely cooperate with human users in shared tasks, provides many new challenges for robotics research. Compared to industrial applications, robots working in human environments will need to have human-like abilities in their cognitive and motor behaviors. Here we present a model for generating trajectories of a high degree of freedom robotics arm-hand system that reflects optimality principles of human motor control. The process of finding a human-like trajectory among all possible solutions is formalized as a large-scale nonlinear optimization problem. We compare numerically three existing solvers, IPOPT, KNITRO and SNOPT, in terms of their real-time performance in different reach-to-grasp problems that are part of a human-robot interaction task. The results show that the SQP methods obtain better results than the IP methods. SNOPT finds optimal solutions for all tested problems in competitive computational times, thus being the one that best serves our purpose.

The growth of wind farms has motivated the development of computational and experimental approaches which supplement needs related to teaching and research in the field of engineering. Even though there have already been recognized advances made in the field of computational modeling, the development of viable means through experiment to clarify the operation of wind farm complexes has become relevant to this area. In light of these facts, this study focuses on a comparative evaluation of two strategies which emulate wind turbines: one based on d.c. motors, the other on three-phase induction motors. In both cases, the apparatus is modeled on time-domain representation techniques and motor driving structures are proposed, allowing for the reproduction of features typically found in wind turbines. Lastly, experiments are realized and the results discussed for the confirmation of potentialities, along with the efficiency of the strategies used.

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Este artigo tem como finalidade fornecer uma contribuição aos estudos de transformadores sob condições não-senoidais empregando, para tanto, ferramenta computacional embasada em elementos finitos. Os estudos foram realizados em um transformador de distribuição a seco de 1 MVA, utilizando o software ANSYS Maxwell® 3D, objetivando-se, assim, a influência dos harmônicos e sua propagação. Os resultados das simulações em condições senoidais foram validados, dando condições para prosseguir com as análises sob distorção harmônicas de tensão. Os resultados encontrados, nesta última análise, tanto para a propagação das distorções quanto para a elevação das perdas, mostraram-se condizentes com a literatura científica correlata ao tema.