Analysis of Different Feature Selection Criteria Based on a Covariance Convergence Perspective for a SLAM Algorithm

This paper introduces several non-arbitrary feature selection techniques for a Simultaneous Localization and Mapping (SLAM) algorithm. The feature selection criteria are based on the determination of the most significant features from a SLAM convergence perspective. The SLAM algorithm implemented in this work is a sequential EKF (Extended Kalman filter) SLAM. The feature selection criteria are applied on the correction stage of the SLAM algorithm, restricting it to correct the SLAM algorithm with the most significant features. This restriction also causes a decrement in the processing time of the SLAM. Several experiments with a mobile robot are shown in this work. The experiments concern the map reconstruction and a comparison between the different proposed techniques performance. The experiments were carried out at an outdoor environment composed by trees, although the results shown herein are not restricted to a special type of features

Flexible system of multiple RGB-D sensors for measuring and classifying fruits in agri-food Industry

The productivity of the agri-food sector experiences continuous and growing challenges that make the use of innovative technologies to maintain and even improve their competitiveness a priority. In this context, this paper presents the foundations and validation of a flexible and portable system capable of obtaining 3D measurements and classifying objects based on color and depth images taken from multiple Kinect v1 sensors. The developed system is applied to the selection and classification of fruits, a common activity in the agri-food industry. Being able to obtain complete and accurate information of the environment, as it integrates the depth information obtained from multiple sensors, this system is capable of self-location and self-calibration of the sensors to then start detecting, classifying and measuring fruits in real time. Unlike other systems that use specific set-up or need a previous calibration, it does not require a predetermined positioning of the sensors, so that it can be adapted to different scenarios. The characterization process considers: classification of fruits, estimation of its volume and the number of assets per each kind of fruit. A requirement for the system is that each sensor must partially share its field of view with at least another sensor. The sensors localize themselves by estimating the rotation and translation matrices that allow to transform the coordinate system of one sensor to the other. To achieve this, Iterative Closest Point (ICP) algorithm is used and subsequently validated with a 6 degree of freedom KUKA robotic arm. Also, a method is implemented to estimate the movement of objects based on the Kalman Filter. A relevant contribution of this work is the detailed analysis and propagation of the errors that affect both the proposed methods and hardware. To determine the performance of the proposed system the passage of different types of fruits on a conveyor belt is emulated by a mobile robot carrying a surface where the fruits were placed. Both the perimeter and volume are measured and classified according to the type of fruit. The system was able to distinguish and classify the 95% of fruits and to estimate their volume with a 85% of accuracy in worst cases (fruits whose shape is not symmetrical) and 94% of accuracy in best cases (fruits whose shape is more symmetrical), showing that the proposed approach can become a useful tool in the agri-food industry.This project has been supported by the National Commission for Science and Technology Research of Chile (Conicyt) under FONDECYT grant 1140575 and the Advanced Center of Electrical and Electronic Engineering - AC3E (CONICYT/FB0008)

PROPUESTA ALTERNATIVA PARA LA ENSEÑANZA DE LA GEOMETRÍA ANALÍTICA UTILIZACIÓN DE RECURSOS DE LA WEB

Las Nuevas Tecnologías de la Comunicación y la Información han revolucionado la forma de vida, de comunicación y por supuesto los entornos de enseñanza y de aprendizaje. En la comunidad universitaria ha quedado tradicionalmente institucionalizada la educación presencial como la modalidad más efectiva en la cual el profesor y los estudiantes están físicamente presentes en un mismo espacio-tiempo. La comunicación oral, característica en la enseñanza convencional, está acompañada normalmente por gestos y códigos de la comunicación no verbal. Sin embargo por razones, didácticas, epistemológicas y también económicas, de espacio, de tiempo, surge la necesidad de implementar otras alternativas educativas, que superen la coincidencia estricta del profesor y del alumno en un mismo lugar y en el mismo tiempo. En el ámbito universitario es posible combinar estratégicamente encuentros presenciales entre docentes y alumnos con el estudio no presencial, para lograr el mejor aprovechamiento del recurso docente. En este contexto se desarrolla el Proyecto de investigación Las Nuevas Tecnologías de la Información y la Comunicación: su aplicación en áreas de la formación básica de Carreras de Ingeniería, en el marco del cual nos propusimos incorporar un modelo de aprendizaje a través de la Webquest para la enseñanza de la Geometría Analítica

Machinery for potato harvesting: a state-of-the-art review

Potatoes are the fourth most important crop for human consumption. In the 18 century, potatoes saved the European population from starvation, and since then, it has become one of the primary crops cultivated in countries such as Spain, France, Germany, Ukraine and the United Kingdom. Potato production worldwide reached 368.8 million tonnes in 2019, 371.1 million tonnes in 2020, and 376.1 million tonnes in 2021, with production expected to grow alongside the worldwide population. However, the agricultural sector is currently suffering from urbanization. With the next generation of farmers relocating to cities, there is a diminishing and ageing agricultural workforce. Consequently, farms urgently need innovation, particularly from a technology perspective. As a result, this work is focused on reviewing the worldwide developments in potato harvesting, with an emphasis on mechatronics, the use of intelligent systems and the opportunities that arise from applications utilising the Internet of Things (IoT). Our work covers worldwide scientific publications in the last five years, sustained by public data made available from different governments. We end our review by providing a discussion on the future trends derived from our analysis

Acciones que realiza la Universidad Nacional del Chaco Austral en el marco de los Voluntariados Universitario

Periódicamente el Ministerio de Educación de la Nación convoca a Facultades, Cátedras y estudiantes de Universidades e Institutos Universitarios Nacionales para la presentación de proyectos de trabajo voluntario que promuevan la vinculación de estas instituciones con la comunidad en que se insertan, a través de propuestas orientadas a mejorar la calidad de vida de su población. Dichas convocatorias, de carácter público y abierto, proponen incentivar el compromiso de los estudiantes de nivel superior universitario con el medio social, propiciando su participación en la construcción de alternativas de desarrollo local. En este marco, docentes del Departamento de Matemática de la Universidad Nacional del Chaco Austral (UNCAus), han presentado y fueron seleccionados Proyectos de Voluntariado Universitario que tienen por objetivo iniciar y abordar acciones específicas de articulación e integración entre el Nivel Medio /Polimodal y la UNCAus. En este trabajo se presentan las actividades realizadas, los resultados obtenidos, las conclusiones y recomendaciones que orientan a la formulación y ejecución de nuevas propuestas para sostener y reforzar el vínculo Universidad – Sociedad

UN EJEMPLO DE INTEGRACIÓN REGIONAL Movilidad e Intercambio

Las Universidades Nacionales del NOA, desde las Unidades Académicas que ofrecen carreras de Ingeniería, elaboraron propuestas con el objeto de promover la constitución de ámbitos de reflexión y planificación sobre articulación y flexibilización de planes de estudios, en vista a la integración del sistema de Educación Superior; logrando: diseñar un Ciclo Común Articulado (CCA) para la familia de Carreras de Ingeniería, ejecutar acciones para su efectiva puesta en marcha y, dar a conocer a otras Universidades Nacionales promoviendo su incorporación en ellas. De este modo, se buscó favorecer la movilidad de estudiantes entre las Universidades participantes y estimular el desarrollo de innovaciones académicas y de gestión, potenciando las fortalezas que poseen. El diseño, adecuado a veintidós carreras, ha sido organizado a partir de áreas curriculares con contenidos y bibliografía básica comunes y rangos de cargas horarias. Este proceso innovador e inédito para la región, ha necesitado del desarrollo de normativas específicas para garantizar que los estudios realizados por los alumnos en otra Universidad del consorcio, tenga un reconocimiento académico en la Universidad receptora, ha permitido impulsar modelos y ha favorecido la participación en los ciclos generales de conocimientos básicos con actividades que serían mejoradas con el uso de las NTIyCs.

A comprehensive performance evaluation of different mobile manipulators used as displaceable 3D printers of building elements for the construction industry

The construction industry is currently technologically challenged to incorporate new developments for enhancing the process, such as the use of 3D printing for complex building structures,which is the aim of this brief. To do so, we show a systematic study regarding the usability and performance of mobile manipulators as displaceable 3D printing machinery in construction sites,with emphasis on the three main different existing mobile platforms: the car-like, the unicycleand the omnidirectional (mecanum wheeled), with an UR5 manipulator on them. To evaluate its performance, we propose the printing of the following building elements: helical, square, circular and mesh, with different sizes. As metrics, we consider the total control effort observed in the robots and the total tracking error associated with the energy consumed in the activity to get a more sustainable process. In addition, to further test our work, we constrained the robot workspace thus resemblingreal life construction sites. In general, the statistical results show that the omnidirectional platform presents the best results –lowest tracking error and lowest control effort– for circular, helicoidal and mesh building elements; and car-like platform shows the best results for square-like building element. Then,an innovative performance analysis is achieved for the printing of building elements, with a contribution to the reduction of energy consumptio

Collision-free navigation of N-trailer vehicles with motion constraints

In this work, a collision-free navigation strategy for N-trailer vehicles is proposed. This approach is based on a scalable cascaded control scheme to perform several tasks simultaneously: trajectory tracking control, off-track error reduction, external obstacles avoidance, and inter-vehicle collision avoidance. To validate the proposed strategy, a Generalized N-trailer (GNT) structure with a car-like tractor and 10 trailers is tested in simulation to track an U-shape trajectory in presence of unknown obstacles, similar to the trajectories that agricultural vehicles must perform in real applications. The well-known information about external infrastructure is also considered to reduce unsafe trailers off-track errors in turning scenarios. Moreover, the motion constraints imposed by the car-like tractor physical limitations and the interconnections between trailers are also considered by restricting the control input in order to avoid collision between trailers. The simulation results obtained showed a safe navigation which performed feasible maneuvers without collisions between the vehicles' chain and any trailer or external obstacle