Wireless HROV Control with Compressed Visual Feedback Using Acoustic and RF Links

Underwater cooperative robotics offers the possibility to perform challenging intervention applications, such as recovering archeological objects as within the context of the MERBOTS research project, or grasping, transporting and assembly of big objects, using more than one mobile manipulator, as faced by the TWINBOT project. In order to enhance safety during the intervention, it is reasonable to avoid the umbilical, also giving more mobility to the robots, and enabling a broader set of cooperative movements. Several solutions, based on acoustic, radiofrequency (RF) or Visual Light Communication (VLC) have been proposed for underwater communications in the literature. This paper presents the architecture of an underwater wireless communication framework for the control of multiple semi-autonomous robots in cooperative interventions. The proposed framework is composed of several modules as the virtual reality interface using UWSim, the Underwater Multi-robot Cooperative Intervention Remote Control Protocol (UMCI-RCP) and a Generic Link Layer (GLL). UMCI-RCP allows the control of an underwater robot over limited communication links. UMCI-RCP integrates a progressive compression algorithm that provides visual feedback at a constant rate and ensures image reception even in channels with loses. The Time Division Multiple Access (TDMA) medium access strategy minimizes the jitter of transmitted packets. The GLL has been designed in order to provide support for multimodal transmission (i.e. acoustic, RF and VLC) and also to interface with the UWSim-NET simulator so that facilitates the experimentation either with a real or with a simulated modem. The possibility of exchange real and simulated devices in the proposed framework are demonstrated by means of a teleoperation experiment with a BlueROV equipped with the S100 RF modems. Hardware-In-the-Loop (HIL) capabilities are demonstrated repeating the experiment with the real modems and modeling the BlueROV, and also modeling both the modems and the BlueROV

Sparse Givens resolution of large system of linear equations: applications to image reconstruction

In medicine, computed tomographic images are reconstructed from a large number of measurements of X-ray transmission through the patient (projection data). The mathematical model used to describe a computed tomography device is a large system of linear equations of the form AX=B. In this paper we propose the QR decomposition as a direct method to solve the linear system. QR decomposition can be a large computational procedure. However, once it has been calculated for a specific system, matrices Q and R are stored and used for any acquired projection on that system. Implementation of the QR decomposition in order to take more advantage of the sparsity of the system matrix is discussed.This work is partially supported by Generalitat Valenciana GVPRE/2008/303 and the Spanish M.E.C. grant MTM2009-08587.Rodríguez Álvarez, MJ.; Sánchez, F.; Soriano Asensi, A.; Iborra Carreres, A. (2010). Sparse Givens resolution of large system of linear equations: applications to image reconstruction. Mathematical and Computer Modelling. 52(7-8):1258-1264. https://doi.org/10.1016/j.mcm.2010.03.01612581264527-

Underwater Wireless Communications for Cooperative Robotics with UWSim-NET

The increasing number of autonomous underwater vehicles (AUVs) cooperating in underwater operations has motivated the use of wireless communications. Their modeling can minimize the impact of their limited performance in real-time robotic interventions. However, robotic frameworks hardly ever consider the communications, and network simulators are not suitable for HIL experiments. In this work, the UWSim-NET is presented, an open source tool to simulate the impact of communications in underwater robotics. It gathers the benefits of NS3 in modeling communication networks with those of the underwater robot simulator (UWSim) and the robot operating system (ROS) in modeling robotic systems. This article also shows the results of three experiments that demonstrate the capabilities of UWSim-NET in modeling radio frequency (RF) and acoustic links in underwater scenarios. It also permits evaluating several MAC protocols such as additive links online Hawaii area (ALOHA), slotted floor acquisition multiple access (S-FAMA) and user defined protocols. A third experiment demonstrated the excellent capabilities of UWSim-NET in conducting hardware in the loop (HIL) experiments

QR-Factorization Algorithm for Computed Tomography (CT): Comparison With FDK and Conjugate Gradient (CG) Algorithms

[EN] Even though QR-factorization of the system matrix for tomographic devices has been already used for medical imaging, to date, no satisfactory solution has been found for solving large linear systems, such as those used in computed tomography (CT) (in the order of 106 equations). In CT, the Feldkamp, Davis, and Kress back projection algorithm (FDK) and iterative methods like conjugate gradient (CG) are the standard methods used for image reconstruction. As the image reconstruction problem can be modeled by a large linear system of equations, QR-factorization of the system matrix could be used to solve this system. Current advances in computer science enable the use of direct methods for solving such a large linear system. The QR-factorization is a numerically stable direct method for solving linear systems of equations, which is beginning to emerge as an alternative to traditional methods, bringing together the best from traditional methods. QR-factorization was chosen because the core of the algorithm, from the computational cost point of view, is precalculated and stored only once for a given CT system, and from then on, each image reconstruction only involves a backward substitution process and the product of a vector by a matrix. Image quality assessment was performed comparing contrast to noise ratio and noise power spectrum; performances regarding sharpness were evaluated by the reconstruction of small structures using data measured from a small animal 3-D CT. Comparisons of QR-factorization with FDK and CG methods show that QR-factorization is able to reconstruct more detailed images for a fixed voxel size.This work was supported by the Spanish Government under Grant TEC2016-79884-C2 and Grant RTC-2016-5186-1.Rodríguez-Álvarez, M.; Sánchez, F.; Soriano Asensi, A.; Moliner Martínez, L.; Sánchez Góez, S.; Benlloch Baviera, JM. (2018). QR-Factorization Algorithm for Computed Tomography (CT): Comparison With FDK and Conjugate Gradient (CG) Algorithms. IEEE Transactions on Radiation and Plasma Medical Sciences. 2(5):459-469. https://doi.org/10.1109/TRPMS.2018.2843803S4594692

Active learning in digital communications with low-cost software defined radio

Las comunicaciones digitales se enseñan tradicionalmente en sesiones de laboratorio desde un punto de vista teórico, utilizando plataformas de simulación. Sin embargo, el sistema de Acreditación Académica incluye la dimensión de "lo que se espera que los estudiantes sean capaces de hacer", lo que plantea la necesidad de disminuir la brecha entre las sesiones de laboratorio simuladas y un enfoque más práctico y realista. En este trabajo, proponemos una metodología para mejorar el aprendizaje de los aspectos prácticos relacionados con los cursos de Comunicaciones Digitales, así como para aumentar la motivación de los estudiantes, mediante el uso de dispositivos de radio definida por software de bajo coste. Esta metodología se ha aplicado en el Grado en Ingeniería Telemática de la Escuela Técnica Superior de Ingeniería de la Universidad de Valencia, España. Con el objetivo de mejorar el compromiso de los estudiantes de máster y de grado, se ha implementado una metodología de aprendizaje basado en proyectos. En el trabajo se describe la metodología, se describen varias actividades de laboratorio basadas en el estándar 802.11 y se dan recomendaciones para la implementación de esta metodología.UV-SFPIE PID-1353656Digital Communications have been traditionally taught in laboratory sessions from a theoretical point of view, using simulation platforms. However, current Academic Accreditation includes the dimension of “what students are expected to be able to do”, which poses the need of decreasing the gap between standard simulated laboratory sessions and more practical and realistic approaches. In this paper, we propose a methodology to enhance the learning of practical aspects related to Digital Communications courses, as well as increasing the student’s engagement, via the use of low-cost software defined radio devices. This methodology has been applied in the Degree in Telematics Engineering at the School of Engineering from the University of Valencia, Spain. With the aim of improving the engagement of both master and undergraduate students, a project based learning methodology has been implemented. In the paper, the methodology is described, several laboratory activities based on the 802.11 standard are presented, and recommendations for practice are given

Innovación en docencia de sistemas de comunicación en el Grado de Ingeniería Telemática de la UVEG

En la docencia de sistemas de comunicación hay una componente teórica elevada. La percepción de los estudiantes al estudiar estas asignaturas es negativa. Este trabajo explica la motivación y la estrategia seguida para reorientar esta percepción a partir de la introducción de elementos de Software De fined Radio y USRPs en diferentes asignaturas del Grado y del Máster de Ingeniería Telecomunicación de la Universitat de València.UV-SFPIE RMD15-314373In teaching Communication Systems, we find a high theoretical component. The perception about the related subjects cause a negative perception in the students. This work explains the motivation and the strategy followed to re-orientate this perception by introducing Software Defi ned Radio elements (like USRPs) in different subjects in the Degree and the Master in Telecommunication Engineering at the University of Valencia

VentQsys: Low-cost open IoT system for CO2 monitoring in classrooms

In educational context, a source of nuisance for students is carbon dioxide (CO2) concentration due to closed rooms and lack of ventilation or circulatory air. Also, in the pandemic context, ventilation in indoor environments has been proven as a good tool to control the COVID-19 infections. In this work, it is presented a low cost IoT-based open-hardware and open-software monitoring system to control ventilation, by measuring carbon dioxide (CO2), temperature and relative humidity. This system provides also support for automatic updating, auto-self calibration and adds some Cloud and Edge offloading of computational features for mapping functionalities. From the tests carried out, it is observed a good performance in terms of functionality, battery durability, compared to other measuring devices, more expensive than our proposal

Aplicación de la teoría de respuesta al ítem para el análisis del uso de Matlab Grader en el Grado en Ingeniería Telemática

[ES] El uso de herramientas que permiten un mayor grado de autoaprendizaje y realimentación en procesos evaluativos está creciendo considerablemente en los últimos años. Matlab Grader es una de estas herramientas de autoaprendizaje que permiten un mayorgrado de realimentación y corrección para los estudiantes. En este trabajo se analizala validación de una encuesta madiante la teoría de respuesta al ítem para estudiar la percepción de los estudiantes acerca de la aplicación de Matlab Grader en diferentes asignaturas del Grado en Ingeniería Telemática de la Universitat de València.[EN] The use of tools that allow a greater degree of self-learning and feedback in assessment processes is growing considerably in recent years. Matlab Grader is one such self-learning tool that allows a greater degree of feedback and correction for students. This paper analyses the validation of a survey using item response theory to study the students’ perception of the application of Matlab Grader in different subjects of the Telematics Engineering Degree at the University of Valencia.Vicerectorat de Formació Permanent, Transformació Docent i Ocupació de la Universitat de València UV-SFPIE_PID-2074555; AEI, ref. RYC-2017-22101Segura-García, J.; Botella-Mascarell, C.; Roger, S.; Soriano-Asensi, A.; Sanz-Sabater, M. (2023). Aplicación de la teoría de respuesta al ítem para el análisis del uso de Matlab Grader en el Grado en Ingeniería Telemática. Editorial Universitat Politècnica de València. 417-427. https://doi.org/10.4995/INRED2023.2023.1661641742

Metodologías activas de auto-evaluación basadas en la herramienta Matlab Grader en el Grado en Ingeniería Telemática

[EN] This paper presents an innovation action focused on developing and evaluating active self-assessment methodologies in subjects of the Degree in Telematics Engineering at the Universitat de Val`encia. The tool Matlab Grader has been recently incorporated to the moodle platform of the Universitat de Val`encia. This allows to integrate it efficiently in the teaching-learning process. The results obtained confirm that the incorporation of this tool is beneficial both for teachers, by contributing to the sustainability of correction in large groups, and for students, by providing them with automatic correction and feedback, which increases their motivation.[ES] En este trabajo se presenta una acción de innovación que se centra en desarrollar y evaluar metodologías activas de auto-evaluación en asignaturas del Grado en Ingeniería Telemática de la Universitat de València. Para ello, se utiliza la herramienta Matlab Grader, que se ha incorporado recientemente a la plataforma moodle de la Universitat de València, lo que permite integrarla de forma eficiente en el proceso de enseñanza-aprendizaje. Los resultados obtenidos confirman que la incorporación de esta herramienta es beneficiosa tanto para el profesorado, al contribuir a la sostenibilidad de la corrección frente a grupos numerosos, como para el alumnado, al proporcionarle corrección y realimentación automática, lo que incrementa su motivación.Botella-Mascarell, C.; Soriano-Asensi, A.; Sanz-Sabater, M.; Roger, S.; Segura-Garcia, J. (2022). Metodologías activas de auto-evaluación basadas en la herramienta Matlab Grader en el Grado en Ingeniería Telemática. Editorial Universitat Politècnica de València. 868-881. https://doi.org/10.4995/INRED2022.2022.1583486888

Aprendizaje basado en proyectos en los laboratorios de comunicaciones digitales

Las Comunicaciones Digitales y el Procesado de Señal para Comunicaciones se enseñan tradicionalmente desde un punto de vista teórico. La complejidad y el coste de los sistemas de radiofrecuencia complica mucho la realización de experiencias prácticas en los laboratorios de Comunicaciones. Sin embargo, la Acreditación Académica actual incluye la dimensión de "lo que se espera que los estudiantes sean capaces de hacer". Es por tanto necesario reducir la brecha entre las sesiones de laboratorio basadas en simulaciones y nuevos enfoques más aplicados y realistas. En este trabajo, se presenta la metodología que hemos seguido para introducir los aspectos prácticos relacionados con las Comunicaciones Digitales y el Procesado de Señal a través de dispositivos de radio definida por software de bajo coste. La estrategia propuesta pone a los estudiantes en el centro de su proceso de aprendizaje, lo que ha contribuido a mejorar su implicación en el desarrollo del laboratorio tanto en los estudiantes de máster y grado. A modo de ejemplo se presentan las actividades de laboratorio en base al estándar IEEE 802.11, a partir de la experiencia llevada a cabo se proporcionan recomendaciones para la realización de éstas actividades prácticas.BIA2016-76957-C3-1-RUV-SFPIE-RMD18-841566Digital Communications and Signal Processing for Communications have been traditionally taught from a theoretical point of view. The complexity and cost of radio-frequency systems hampers the realization of practical experiences in the laboratories of Communications. However, current Academic Accreditation includes the dimension of “what students are expected to be able to do”. The decrease of the gap between standard simulated laboratory sessions and more practical and realistic approaches is therefore required. In this paper, we introduce an active learning methodology we have followed in order to introduce practical aspects related to Digital Communications and Signal Processing for Communications courses via low-cost software defined radio devices. The proposed strategy gives the students a key role in their learning process, which has contributed to improve the engagement of both master and under-graduate students. As an example, the laboratory activities the students did based on the IEEE 802.11 standard are presented, and recommendations for practice are given