Towards a real-time vision-based navigation system for a small-class UUV

This paper deals with the problem of navigation for an unmanned underwater vehicle (UUV) through image mosaicking. It represents a first step towards a real-time vision-based navigation system for a small-class low-cost UUV. We propose a navigation system composed by: (i) an image mosaicking module which provides velocity estimates; and (ii) an extended Kalman filter based on the hydrodynamic equation of motion, previously identified for this particular UUV. The obtained system is able to estimate the position and velocity of the robot. Moreover, it is able to deal with visual occlusions that usually appear when the sea bottom does not have enough visual features to solve the correspondence problem in a certain area of the trajectory

Augmented state Kalman filtering for AUV navigation

Addresses the problem of estimating the motion of an autonomous underwater vehicle (AUV), while it constructs a visual map ("mosaic" image) of the ocean floor. The vehicle is equipped with a down-looking camera which is used to compute its motion with respect to the seafloor. As the mosaic increases in size, a systematic bias is introduced in the alignment of the images which form the mosaic. Therefore, this accumulative error produces a drift in the estimation of the position of the vehicle. When the arbitrary trajectory of the AUV crosses over itself, it is possible to reduce this propagation of image alignment errors within the mosaic. A Kalman filter with augmented state is proposed to optimally estimate both the visual map and the vehicle position

Planar homography: accuracy analysis and applications

Projective homography sits at the heart of many problems in image registration. In addition to many methods for estimating the homography parameters (R.I. Hartley and A. Zisserman, 2000), analytical expressions to assess the accuracy of the transformation parameters have been proposed (A. Criminisi et al., 1999). We show that these expressions provide less accurate bounds than those based on the earlier results of Weng et al. (1989). The discrepancy becomes more critical in applications involving the integration of frame-to-frame homographies and their uncertainties, as in the reconstruction of terrain mosaics and the camera trajectory from flyover imagery. We demonstrate these issues through selected examples

WMR navigation using local potential field corridors and narrow local occupancy grid perception

Path planning and control strategies applied to autonomous mobile robots should fulfil safety rules as well as achieve final goals. Trajectory planning applications should be fast and flexible to allow real time implementations as well as environment interactions. The methodology presented uses the on robot information as the meaningful data necessary to plan a narrow passage by using a corridor based on attraction potential fields that approaches the mobile robot to the final desired configuration. It employs local and dense occupancy grid perception to avoid collisions. The key goals of this research project are computational simplicity as well as the possibility of integrating this method with other methods reported by the research community. Another important aspect of this work consist in testing the proposed method by using a mobile robot with a perception system composed of a monocular camera and odometers placed on the two wheels of the differential driven motion system. Hence, visual data are used as a local horizon of perception in which trajectories without collisions are computed by satisfying final goal approaches and safety criteria

Knowledge integration within an applied mobile robot summer course

This paper presents the use of a mobile robot platform as an innovative educational tool in order to promote and integrate different curriculum knowledge. Hence, it is presented the acquired experience within a summer course named ldquoapplied mobile roboticsrdquo. The main aim of the course is to integrate different subjects as electronics, programming, architecture, perception systems, communications, control and trajectory planning by using the educational open mobile robot platform PRIM. The summer course is addressed to a wide range of student profiles. However, it is of special interests to the students of electrical and computer engineering around their final academic year. The summer course consists of the theoretical and laboratory sessions, related to the following topics: design & programming of electronic devices, modelling and control systems, trajectory planning and control, and computer vision systems. Therefore, the clues for achieving a renewed path of progress in robotics are the integration of several knowledgeable fields, such as computing, communications, and control sciences, in order to perform a higher level reasoning and use decision tools with strong theoretical base

Local WMR navigation with monocular data

This article presents recent WMR (wheeled mobile robot) navigation experiences using local perception knowledge provided by monocular and odometer systems. A local narrow perception horizon is used to plan safety trajectories towards the objective. Therefore, monocular data are proposed as a way to obtain real time local information by building two dimensional occupancy grids through a time integration of the frames. The path planning is accomplished by using attraction potential fields, while the trajectory tracking is performed by using model predictive control techniques. The results are faced to indoor situations by using the lab available platform consisting in a differential driven mobile robot

Local model predictive control experiences with differential driven wheeled mobile robots

This work extends a previously developed research concerning about the use of local model predictive control in differential driven mobile robots. Hence, experimental results are presented as a way to improve the methodology by considering aspects as trajectory accuracy and time performance. In this sense, the cost function and the prediction horizon are important aspects to be considered. The aim of the present work is to test the control method by measuring trajectory tracking accuracy and time performance. Moreover, strategies for the integration with perception system and path planning are briefly introduced. In this sense, monocular image data can be used to plan safety trajectories by using goal attraction potential fields

Plane-to-plane positioning from image-based visual servoing and structured light

In this paper we face the problem of positioning a camera attached to the end-effector of a robotic manipulator so that it gets parallel to a planar object. Such problem has been treated for a long time in visual servoing. Our approach is based on linking to the camera several laser pointers so that its configuration is aimed to produce a suitable set of visual features. The aim of using structured light is not only for easing the image processing and to allow low-textured objects to be treated, but also for producing a control scheme with nice properties like decoupling, stability, well conditioning and good camera trajectory

Visual SLAM for 3D large-scale seabed acquisition employing underwater vehicles

This paper presents a novel technique to align partial 3D reconstructions of the seabed acquired by a stereo camera mounted on an autonomous underwater vehicle. Vehicle localization and seabed mapping is performed simultaneously by means of an Extended Kalman Filter. Passive landmarks are detected on the images and characterized considering 2D and 3D features. Landmarks are re-observed while the robot is navigating and data association becomes easier but robust. Once the survey is completed, vehicle trajectory is smoothed by a Rauch-Tung-Striebel filter obtaining an even better alignment of the 3D views and yet a large-scale acquisition of the seabed

Enhanced Model Selection for motion segmentation

In this paper a novel rank estimation technique for trajectories motion segmentation within the Local Subspace Affinity (LSA) framework is presented. This technique, called Enhanced Model Selection (EMS), is based on the relationship between the estimated rank of the trajectory matrix and the affinity matrix built by LSA. The results on synthetic and real data show that without any a priori knowledge, EMS automatically provides an accurate and robust rank estimation, improving the accuracy of the final motion segmentation

Innovación educativa en la enseñanza de literatura en la facultad de filología de la UCM en el marco del EEES.

Las siguientes líneas muestran la relevancia de la adquisición de competencia en el manejo de información en el marco del Espacio Europeo de Educación Superior y resumen la trayectoria innovadora e investigadora del grupo Literaturas Españolas y Europeas del Texto al Hipertexto (L.E.E.T.Hi.), cuya orientación que tiene como ejes fundamentales los patrones didácticos de la Convergencia Europea y el empleo de los soportes hipertextuales como espacios, no sólo de representación y documentación, sino de generación de nuevas formas de aprendizaje. La investigación de LEETHI se centra en la docencia de las literaturas a través de estos espacios, que generan nuevas formas de lectura y de adquisición de conocimientos de manera asociativa y que, a través de los textos literarios, propician encuentros entre disciplinas y culturas diversas.

Mejoramiento continúo de los avances tecnológicos de la sociedad portuaria regional de Cartagena

El Grupo Puerto de Cartagena, es considerado una de las zonas de actividad logística más importantes del país. Considerando, la Terminal de Contenedores de Cartagena – Contecar S.A. - Como un puerto multipropósito, y la Sociedad Portuaria Regional de Cartagena como un puerto de contenedores y cruceros, el objetivo principal de este trabajo es identificar la evolución tecnológica que ha tenido el puerto para posicionarse como el mejor puerto del Caribe hoy en día. A lo largo de este documento, se mostraran los avances pertinentes que ha logrado el Grupo Puerto de Cartagena, de mano con la competitividad y productividad que representa para el país, donde año tras año el puerto ocupa un lugar importante en el ranking de puertos a nivel mundial. Así como también sus inicios y como llego ha convertirse en la empresa que es hoy en día. Así mismo también se abordarán temas de logística portuaria y los proyectos que tiene el grupo Puerto de Cartagena en los próximos 5 años, en materia de inversión en tecnología.

La reintegración social y económica de los grupos armados ilegales en Colombia: reflexiones a partir de la trayectoria de nueve excombatientes

Esta investigación toma como marco general la Política de Reintegración Social y económica de personas y grupos alzados en armas en Colombia, en donde tras el estudio de las trayectorias en el conflicto de un grupo de 9 excombatientes, se aborda la relación existente entre los beneficios otorgados por dicha política y aquello que facilitó y motivó el ingreso, la permanencia y desmovilización de los grupos armados. Se presenta una caracterización e interpretación conceptual de las denominadas trayectorias en el conflicto, son establecidas relaciones y diferencias entre las organizaciones ilegales FARC y las AUC, se revisan las percepciones que frente a los beneficios del programa de reintegración tienen excombatientes y profesionales de la entidad que lidera dicho proceso y a partir de ello, es argumentada la incidencia que sobre el éxito de esta política tienen las características individuales y particulares, tanto de los excombatientes como de las organizaciones armadas ilegales.

Is maternal deprivation the root of all evil?

In this paper we seriously entertain the question, “Is maternal deprivation the root of all evil?” Our consideration of this question is broken down into three parts. In the fi rst part, we discuss the nature of evil, focusing in particular on the legal concept of depravity. In the second part, we discuss the nurture of evil, focusing in particular on the common developmental trajectory seen in those who are depraved. In the third part, we discuss the roots of evil, focusing in particular on the animal and human research regarding maternal deprivation. Our conclusion is that maternal deprivation may actually be the root of all evil, but only because depraved individuals have been deprived of normative maternal care, which is the cradle of our humanity.

La comprensión temprana de la adquisición del conocimiento: viejas propuestas, nuevos horizontes

Este artículo revisa hallazgos y modelos teóricos en torno a un aspecto del desarrollo de la teoría de la mente, a saber: la comprensión temprana de cómo se adquiere el conocimiento. La revisión realizada indica que mientras la investigación inicial sugiere que esta comprensión emerge a los cuatro años de edad, hallazgos recientes indican que se encuentra ya presente al final del primer año de vida. A partir de esto, la teoría emergente sobre el aprendizaje cultural propuesta por Tomasello y colaboradores propone la integración de ambos hallazgos en una misma trayectoria de desarrollo. A pesar de sus contribuciones, esta novedosa propuesta podría enriquecerse de dos distintas formas: 1) esclareciendo las diferencias específicas en cuanto a la capacidad del infante y la del niño preescolar para comprender los estados mentales como representaciones internas, y 2) especificando los mecanismos que subyacen la trayectoria de desarrollo de la comprensión del comportamiento como el producto de la actividad mental.