Grasping unknown objects in clutter by superquadric representation

© 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.In this paper, a quick and efficient method is presented for grasping unknown objects in clutter. The grasping method relies on real-time superquadric (SQ) representation of partial view objects and incomplete object modelling, well suited for unknown symmetric objects in cluttered scenarios which is followed by optimized antipodal grasping. The incomplete object models are processed through a mirroring algorithm that assumes symmetry to first create an approximate complete model and then fit for SQ representation. The grasping algorithm is designed for maximum force balance and stability, taking advantage of the quick retrieval of dimension and surface curvature information from the SQ parameters. The pose of the SQs with respect to the direction of gravity is calculated and used together with the parameters of the SQs and specification of the gripper, to select the best direction of approach and contact points. The SQ fitting method has been tested on custom datasets containing objects in isolation as well as in clutter. The grasping algorithm is evaluated on a PR2 robot and real time results are presented. Initial results indicate that though the method is based on simplistic shape information, it outperforms other learning based grasping algorithms that also work in clutter in terms of time-efficiency and accuracy.Peer ReviewedPostprint (author's final draft

Singularity-free computation of quaternions from rotation matrices in E4 and E3

A real orthogonal matrix representing a rotation in E4 can be decomposed into the commutative product of a left-isoclinic and a right-isoclinic rotation matrix. The double quaternion representation of rotations in E4 follows directly from this decomposition. In this paper, it is shown how this decomposition can be performed without divisions. This avoids the common numerical issues attributed to the computation of quaternions from rotation matrices. The map from the 4×4 rotation matrices to the set of double unit quaternions is a 2-to-1 covering map. Thus, this map cannot be smoothly inverted. As a consequence, it is erroneously assumed that all inversions should necessarily contain singularities that arise in the form of quotients where the divisor can be arbitrarily small. This misconception is herein clari¿ed. When particularized to three dimensions, it is shown how the resulting formulation outperforms, from the numerical point of view, the celebrated Shepperd’s method.Peer ReviewedPostprint (author's final draft

On Cayley's factorization with an application to the orthonormalization of noisy rotation matrices

The final publication is available at link.springer.comA real orthogonal matrix representing a rotation in four dimensions can be decomposed into the commutative product of a left- and a right-isoclinic rotation matrix. This operation, known as Cayley's factorization, directly provides the double quaternion representation of rotations in four dimensions. This factorization can be performed without divisions, thus avoiding the common numerical issues attributed to the computation of quaternions from rotation matrices. In this paper, it is shown how this result is particularly useful, when particularized to three dimensions, to re-orthonormalize a noisy rotation matrix by converting it to quaternion form and then obtaining back the corresponding proper rotation matrix. This re-orthonormalization method is commonly implemented using the Shepperd-Markley method, but the method derived here is shown to outperform it by returning results closer to those obtained using the Singular Value Decomposition which are known to be optimal in terms of the Frobenius norm.Peer ReviewedPostprint (author's final draft

The international traineeships network at UPF

This work is a preliminary study aimed at assessing the impact of international traineeships at Universitat Pompeu Fabra (UPF) in the framework of the Erasmus+ Programme. The deployment of post-EHEA traineeships has already been studied in previous works, and a comparison is performed between local and international traineeships. The study is based on a survey among students taking part in these international traineeships, by adapting the previous questionnaire and including contextual aspects.Peer ReviewedPostprint (published version

Narrativa y deporte en la Literatura española del siglo XX

Las líneas que conforman este trabajo tienen varias pretensiones. En primer lugar, realizar un acercamiento al panorama general literario del siglo XX en relación a la literatura deportiva. En segundo lugar, profundizar en ejemplos concretos de género narrativo a través de comentarios enfocados al tratamiento del deporte. Por último, realizar una reflexión final acerca de cómo ha funcionado la deportividad en los ejemplos anteriormente presentados, atendiendo a su razón de ser, su trayectoria y su funcionamiento en el mundo cultural del siglo XX. La decisión de centrarme en el género narrativo atiende, primeramente, al hecho de que, dentro del escaso estudio pormenorizado que existe de la literatura deportiva, el género más cultivado ha sido el de la poesía. Por esta razón, me resultó interesante el tratamiento de este género, que, junto al teatro y al ensayo, ha quedado ensombrecido en lo que se refiere a los estudios realizados. Bien es cierto que la creación poética con temática deportiva ha sido cultivada en mayor proporción en la primera parte de siglo si se compara con los otros géneros, pero el transcurso del tiempo, como podrá verse, muestra una inversión en este sentido. La poesía va perdiendo potencia creadora dando paso a la narrativa en el siglo XX, precediendo al total desarrollo que alcanzará en el siglo XXI, fenómeno que, aunque interesante, no se desarrolla en este trabajo. Los ejemplos seleccionados para su estudio en las páginas siguientes intentan abarcar, en la medida de lo posible, un abanico de obras que se extienda a lo largo del todo el siglo XX, comenzando por los años veinte hasta llegar a los últimos años de los noventa. Ciertamente, los estudios teóricos existentes en relación con la literatura deportiva se centran, fundamentalmente, en aportar un listado de títulos y autores de obras de los diferentes géneros., Sin embargo, la tarea de análisis y estudio detenido en cada obra es prácticamente inexistente, siendo la poesía el género más estudiado.Departamento de Literatura Española y Teoría de la Literatura y Literatura ComparadaMáster en Estudios Filológicos Superiores: Investigación y Aplicaciones Profesionale

El Terme norma en els diccionaris de llengua catalana i de llengua castellana

Aquest treball és un estudi sobre el terme norma, en el sentit de norma lingüística, en diccionaris normatius i d'ús de llengua catalana i de llengua castellana. L'objectiu principal és detectar pistes que ens donin informació sobre la concepció de norma que es vehicula en els diccionaris a través de la mateixa definició de norma i de les ocurrències del terme en la resta dels articles lexicogràfics dels diccionaris.This paper is a study of the term norm, in the sense of linguistic norm, in normative and descriptive dictionaries of Catalan and Spanish. The main goal is to obtain clues that give us information about the dictionaries’ concept of norm. This is achieved by studying the definitions proper and the occurrences of the term in the lexicographic articles

El desarrollo musical en la educación primaria. Detección y actuación de futuros músicos

Treball de Final de Grau en Mestre o Mestra d'Educació Primària. Codi: MP1040. Curs acadèmic 2015-2016Este trabajo analiza los diversos autores que han hablado sobre el desarrollo musical de los niños relacionándolo con desarrollo evolutivo de los niños durante la etapa de educación primaria. Esta investigación es precisa para establecer la media en el desarrollo musical y así poder detectar en las aulas de primaria aquellos alumnos que tienen potencial, actitud, capacidad…para la música. El objetivo es enmendar la poca información que poseen los maestros generalistas y en algunos casos los especialistas de música sobre este tema. Después de una revisión teórica, se crea una serie de indicaciones para verificar si existen o no tales condiciones y en el caso que sea positivo se ejecutarán unas pautas para derivarlo al lugar correspondiente con la finalidad de desarrollar dichas facultadesThis work analyses different authors that talk about the children’s musical development related to child’s development during the primary school. This research is necessary to set an average in the musical development and be able to find in the classrooms those children who have the potential, attitude and ability to make music. The aim is to amend the insufficient information that teachers and some music specialists have about the issue. After a theoretical review, a series of indicators are created to check whether such conditions exist or not. If so, some guidelines will be executed in order to send the children to the best place for develop those abilitie