Path Planning Based on Parametric Curves

Parametric curves are extensively used in engineering. The most commonly used parametric curves are, Bézier, B-splines, (NURBSs), and rational Bézier. Each and every one of them has special features, being the main difference between them the complexity of their mathematical definition. While Bézier curves are the simplest ones, B-splines or NURBSs are more complex. In mobile robotics, two main problems have been addressed with parametric curves. The first one is the definition of an initial trajectory for a mobile robot from a start location to a goal. The path has to be a continuous curve, smooth and easy to manipulate, and the properties of the parametric curves meet these requirements. The second one is the modification of the initial trajectory in real time attending to the dynamic properties of the environment. Parametric curves are capable of enhancing the trajectories produced by path planning algorithms adapting them to the kinematic properties of the robot. In order to avoid obstacles, the shape modification of parametric curves is required. In this chapter, an algorithm is proposed for computing an initial Bézier trajectory of a mobile robot and subsequently modifies it in real time in order to avoid obstacles in a dynamic environment

Towards a Vector Field Based Approach to the Proper Generalized Decomposition (PGD)

[EN] A novel algorithm called the Proper Generalized Decomposition (PGD) is widely used by the engineering community to compute the solution of high dimensional problems. However, it is well-known that the bottleneck of its practical implementation focuses on the computation of the so-called best rank-one approximation. Motivated by this fact, we are going to discuss some of the geometrical aspects of the best rank-one approximation procedure. More precisely, our main result is to construct explicitly a vector field over a low-dimensional vector space and to prove that we can identify its stationary points with the critical points of the best rank-one optimization problem. To obtain this result, we endow the set of tensors with fixed rank-one with an explicit geometric structureThis research was funded by the GVA/2019/124 grant from Generalitat Valenciana and by the RTI2018-093521-B-C32 grant from the Ministerio de Ciencia, Innovacion y Universidades. DocumentFalco, A.; Hilario Pérez, L.; Montés Sánchez, N.; Mora Aguilar, MC.; Nadal, E. (2021). Towards a Vector Field Based Approach to the Proper Generalized Decomposition (PGD). Mathematics. 9(1):1-14. https://doi.org/10.3390/math9010034S1149

Detección de Defectos en Carrocerías de Vehículos Basado en Visión Artificial: Diseño e Implantación

[ES] Este artículo describe el diseño e implementación de un novedoso sistema de inspección basado en visión artificial para detectar defectos en carrocerías de vehículos automóviles. El sistema ha sido implantado en la factoría Ford de Almussafes (Valencia) como consecuencia de varios proyectos de I+D entre Ford España, S.A. y el Instituto de Diseño y Fabricación de la Universidad Politécnica de Valencia que han derivado en dos patentes internacionales. El sistema se basa en la detección de defectos mediante un barrido de iluminación, estando el sistema de visión fijo, al igual que el objeto a inspeccionar. Tras la adquisición de las imágenes, los defectos se detectan como consecuencia de las transiciones generadas por el barrido de iluminación al verse deformado el patrón de reflexión. La alta sensibilidad del sistema permite detectar defectos milimétricos de 0.2 mm de diámetro, gracias al efecto de amplificación causado por el propio barrido de iluminación. La principal innovación introducida por este proyecto industrial reside en el hecho del que el sistema es capaz de detectar casi el 100% de los defectos detectados mediante inspección humana. Esto ha supuesto mejoras significativas en la reducción del número de vehículos rechazados, además de una reducción del consumo energético, pintura utilizada, del menor impacto medioambiental y por supuesto una reducción en los costes de producción. El sistema también ha supuesto una mejora de las condiciones laborales de los trabajadores al reducirse los problemas como la fatiga ocular. En la actualidad el sistema está siendo rediseñado para su implantación y explotación en otras factorías Ford a nivel mundial con varios modelos de vehículos.Esta investigación, financiada por Ford-España, ha contado con las siguientes subvenciones públicas: Programa Nacional de Fomento de la Investigación Técnica (PROFIT), Sector Automoción, Ref. FIT-110200-2001-30 y FIT-110200-2003-33, (2001 y 2003) y PROGRAMA NOEMI-GESTA. La solución industiral quedó Finalista con Mención de Honor en los 7º Premios a las "Mejores Innovaciones Tecnológicas en Automoción Salón Inter. del Automóvil" (Barcelona, 2009).Tornero Montserrat, J.; Armesto, L.; Mora Aguilar, MC.; Montés Sánchez, N.; Herraez Martínez, A.; Asensio, JM. (2012). Detección de Defectos en Carrocerías de Vehículos Basado en Visión Artificial: Diseño e Implantación. Revista Iberoamericana de Automática e Informática Industrial (RIAI). 9(1):93-104. https://doi.org/10.1016/j.riai.2011.11.010S9310491Alders, K., M. Lehe and G. Wan (2000). Method for the automatic recognition of surface defects in body shells and device for carrying out said method. Patent PCT/EP98/04291 Audi AG.Aluze, Denis, Fred Merienne, Christophe Dumont and Patrick Gorria (2002). Vision system for defect imaging, detection, and characterization on a specular surface of a 3d object. Image and Vision Computing 20(8), 569-580.Azorín López, Jorge (2007). Modelado de sistemas para visión de objetos especulares: inspección visual automática en producción industrial. PhD thesis. Universidad de Alicante. Departamento de Tecnología Informática y Computación.Balzer, Jonathan, Sebastian Höfer and Jürgen Beyerer (2011). Multiview specular stereo reconstruction of large mirror surfaces. In: CVPR. pp. 2537-2544.Clarke, D.A. (1990). Panel surface flaw inspection. Patent US4920385 Diffracto Ltd.IDF (2009). Video ford. http://idf.webs.upv.es/descargas/quality control based on artificial vision.mpg y http://idf.webs.upv.es/descargas/ford spanish.mpg.Imanishi, M., K. Yoshida, T. Asaeda, Y. Suzuki S. Chida and M. Watanabe (1998). Surface defect inspection apparatus. Patent US5726705 Nissan Motor, CO.Kammel, S. and F. Puente Leon (2003). Head-mounted display for interactive inspection of painted free-form surfaces. In: Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series (C. E. Rash & C. E. Reese, Ed.). Vol. 5079 of Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series. pp. 254-264.Kammel, S. and F. Puente Leon (2005a). Deflectometric measurement of specular surfaces. In: Instrumentation and Measurement Technology Conference. pp. 531-536.Kammel, S. and F. P. Leon (2005b). Deflectometric measurement of specular surfaces. In: Instrumentation and Measurement Technology Conference, 2005. IMTC 2005. Proceedings of the IEEE. Vol. 1. pp. 531-536.Kammel, Soeren (2002). Automated optimization of measurement setups for the inspection of specular surfaces. Vol. 4567. SPIE. pp. 199-206.Kuhlmann, L. (1995). On automatic visual inspection of reflective surfaces. PhD thesis. University of Denmark.Leon, F. Puente and S. Kammel (2003). Image fusion techniques for robust inspection of specular surfaces. In: Multisensor, Multisource Information Fusion: Architectures, Algorithms, and Applications. Vol. 5099. pp. 77-86.Leon, F. Puente and S. Kammel (2006). Inspection of specular and painted surfaces with centralized fusion techniques. Measurement 39(6), 536-546.Li, J., J.M. Parker and Z. Hou (2005). An intelligent system for real time automatic defect inspection on specular coated surfaces. In: Proc. SPIE Visual Communications and Image Processing.Li, Jinhua (2006). A, Intelligent System for Defect Inspection of Specular Painted Ceramic Tiles. PhD thesis. University of Kentucky.Lu, Feng and Evangelos Milios (1994). Robot pose estimation in unknown environments by matching 2d range scans. Journal of Intelligent and Robotic Systems 18, 249-275.Martinez, Silvia Satorres, Juan Gomez Ortega, Javier Gamez Garcia and Alejandro Sanchez Garcia (2010). A machine vision for automated headlamp lens inspection. In: Vision Sensors and Edge Detection. pp. 63-80. InTech.Perard, Denis and Juergen Beyerer (1997). Three-dimensional measurement of specular free-form surfaces with a structured-lighting reflection technique. Vol. 3204. SPIE. pp. 74-80.Pernkopf, Franz and Paul O’Leary (2003). Image acquisition techniques for automatic visual inspection of metallic surfaces. NDT&E International 36, 609-617.Prior, Miguel A., Jose Simon, Alvaro Herraez, Jose M. Asensio, Josep Tornero, Ana V. Ruescas and Leopoldo Armesto (2010). Inspection system and method of defect detection on specular surfaces. PCT/IB2010/052193 Ford España, S.A.Seulin, R, F. Merienne and P. Gorria (2001). Dynamic lighting system for specular surface inspection. In: Proc. Of SPIE. pp. 199-206.Seulin, R., F. Merienne and P. Gorria (n.d.). Machine vision system for specular surface inspection: Use of simulation process as a tool for design and optimization.Seulin, R., N. Bonnot, F. Merienne and P. Gorria (2002a). Simulation process for the design and optimization of a machine vision system for specular surface inspection. In: Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series (K. G. Harding & J. W. Miller, Ed.). Vol. 4567 of Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series. pp. 129-140.Seulin, Ralph, Frederic Merienne and Patrick Gorria (2002b). Simulation of specular surface imaging based on computer graphics: application on a vision inspection system. EURASIP J. Appl. Signal Process. 2002, 649-658

The evolution of the ventilatory ratio is a prognostic factor in mechanically ventilated COVID-19 ARDS patients

Background: Mortality due to COVID-19 is high, especially in patients requiring mechanical ventilation. The purpose of the study is to investigate associations between mortality and variables measured during the first three days of mechanical ventilation in patients with COVID-19 intubated at ICU admission. Methods: Multicenter, observational, cohort study includes consecutive patients with COVID-19 admitted to 44 Spanish ICUs between February 25 and July 31, 2020, who required intubation at ICU admission and mechanical ventilation for more than three days. We collected demographic and clinical data prior to admission; information about clinical evolution at days 1 and 3 of mechanical ventilation; and outcomes. Results: Of the 2,095 patients with COVID-19 admitted to the ICU, 1,118 (53.3%) were intubated at day 1 and remained under mechanical ventilation at day three. From days 1 to 3, PaO2/FiO2 increased from 115.6 [80.0-171.2] to 180.0 [135.4-227.9] mmHg and the ventilatory ratio from 1.73 [1.33-2.25] to 1.96 [1.61-2.40]. In-hospital mortality was 38.7%. A higher increase between ICU admission and day 3 in the ventilatory ratio (OR 1.04 [CI 1.01-1.07], p = 0.030) and creatinine levels (OR 1.05 [CI 1.01-1.09], p = 0.005) and a lower increase in platelet counts (OR 0.96 [CI 0.93-1.00], p = 0.037) were independently associated with a higher risk of death. No association between mortality and the PaO2/FiO2 variation was observed (OR 0.99 [CI 0.95 to 1.02], p = 0.47). Conclusions: Higher ventilatory ratio and its increase at day 3 is associated with mortality in patients with COVID-19 receiving mechanical ventilation at ICU admission. No association was found in the PaO2/FiO2 variation

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field

Estimación de posturas de agarre en base a ACP y RN

Comunicación presentada en el XXI Congreso Nacional de Ingeniería Mecánica, celebrado en Elche en Noviembre de 2016.La investigación en manos antropomorfas robóticas y protésicas experimenta un auge en la actualidad. Unos diseños intentan lograr un agarre estable y diestro mientras que otros pretenden alcanzar un elevado grado de antropomorfismo y de apariencia cosmética. Sin embargo, las prótesis de mano existentes suelen ser muy simples desde un punto de vista biomecánico. Esto se debe a la complejidad de establecer una interacción adecuada entre el amputado y una prótesis de múltiples grados de libertad, que requeriría numerosas señales de control independientes y un controlador inteligente. Una innovación en el ámbito del control de manos artificiales podría derivarse de la observación e imitación del comportamiento biomecánico natural, en base a un espacio de dimensionalidad reducida. El presente trabajo plantea la utilización del análisis de componentes principales (ACP), para reducir la dimensionalidad del problema de control, en combinación con las redes neuronales (RN), para predecir la posturas de la mano en dos tipos de agarre sobre objetos cilíndricos: un agarre de potencia (cilíndrico) y un agarre de precisión (pinza con 5 dedos). El objetivo es determinar el mínimo número de entradas de control necesarias para que una mano protésica avanzada pueda realizar actividades de la vida diaria en base a patrones posturales identificados y evaluar su posibilidad de control real. Para ello, se realizaron experimentos de agarre con 16 sujetos diestros y 4 cilindros de diversos diámetros durante los que se registró la posición de 32 marcadores. A partir de estos datos se calcularon los ángulos de articulación de la mano para cada postura de agarre (PA). Posteriormente, se realizó un ACP sobre los datos de PA, obteniendo 7 componentes principales (posturas propias de agarre, PPA) que determinaron las sinergias posturales producidas durante el agarre. El resultado se simuló mediante OpenSim. Los datos obtenidos se utilizaron para entrenar y validar una RN para estimar PA a partir de las PPA, con una arquitectura previamente validada compuesta por dos capas. Finalmente, se calculó la raíz cuadrada del error cuadrático medio global y por articulación de la predicción realizada por la RN con respecto a la postura experimental, obteniendo resultados alentadores.El presente trabajo está financiado por la Generalitat Valenciana a través del proyecto GV/2015/101

Weaning from mechanical ventilation in intensive care units across 50 countries (WEAN SAFE): a multicentre, prospective, observational cohort study

Background Current management practices and outcomes in weaning from invasive mechanical ventilation are poorly understood. We aimed to describe the epidemiology, management, timings, risk for failure, and outcomes of weaning in patients requiring at least 2 days of invasive mechanical ventilation. Methods WEAN SAFE was an international, multicentre, prospective, observational cohort study done in 481 intensive care units in 50 countries. Eligible participants were older than 16 years, admitted to a participating intensive care unit, and receiving mechanical ventilation for 2 calendar days or longer. We defined weaning initiation as the first attempt to separate a patient from the ventilator, successful weaning as no reintubation or death within 7 days of extubation, and weaning eligibility criteria based on positive end-expiratory pressure, fractional concentration of oxygen in inspired air, and vasopressors. The primary outcome was the proportion of patients successfully weaned at 90 days. Key secondary outcomes included weaning duration, timing of weaning events, factors associated with weaning delay and weaning failure, and hospital outcomes. This study is registered with ClinicalTrials.gov, NCT03255109. Findings Between Oct 4, 2017, and June 25, 2018, 10 232 patients were screened for eligibility, of whom 5869 were enrolled. 4523 (77·1%) patients underwent at least one separation attempt and 3817 (65·0%) patients were successfully weaned from ventilation at day 90. 237 (4·0%) patients were transferred before any separation attempt, 153 (2·6%) were transferred after at least one separation attempt and not successfully weaned, and 1662 (28·3%) died while invasively ventilated. The median time from fulfilling weaning eligibility criteria to first separation attempt was 1 day (IQR 0–4), and 1013 (22·4%) patients had a delay in initiating first separation of 5 or more days. Of the 4523 (77·1%) patients with separation attempts, 2927 (64·7%) had a short wean (≤1 day), 457 (10·1%) had intermediate weaning (2–6 days), 433 (9·6%) required prolonged weaning (≥7 days), and 706 (15·6%) had weaning failure. Higher sedation scores were independently associated with delayed initiation of weaning. Delayed initiation of weaning and higher sedation scores were independently associated with weaning failure. 1742 (31·8%) of 5479 patients died in the intensive care unit and 2095 (38·3%) of 5465 patients died in hospital. Interpretation In critically ill patients receiving at least 2 days of invasive mechanical ventilation, only 65% were weaned at 90 days. A better understanding of factors that delay the weaning process, such as delays in weaning initiation or excessive sedation levels, might improve weaning success rates

Weaning from mechanical ventilation in intensive care units across 50 countries (WEAN SAFE): a multicentre, prospective, observational cohort study

Background: Current management practices and outcomes in weaning from invasive mechanical ventilation are poorly understood. We aimed to describe the epidemiology, management, timings, risk for failure, and outcomes of weaning in patients requiring at least 2 days of invasive mechanical ventilation. Methods: WEAN SAFE was an international, multicentre, prospective, observational cohort study done in 481 intensive care units in 50 countries. Eligible participants were older than 16 years, admitted to a participating intensive care unit, and receiving mechanical ventilation for 2 calendar days or longer. We defined weaning initiation as the first attempt to separate a patient from the ventilator, successful weaning as no reintubation or death within 7 days of extubation, and weaning eligibility criteria based on positive end-expiratory pressure, fractional concentration of oxygen in inspired air, and vasopressors. The primary outcome was the proportion of patients successfully weaned at 90 days. Key secondary outcomes included weaning duration, timing of weaning events, factors associated with weaning delay and weaning failure, and hospital outcomes. This study is registered with ClinicalTrials.gov, NCT03255109. Findings: Between Oct 4, 2017, and June 25, 2018, 10 232 patients were screened for eligibility, of whom 5869 were enrolled. 4523 (77·1%) patients underwent at least one separation attempt and 3817 (65·0%) patients were successfully weaned from ventilation at day 90. 237 (4·0%) patients were transferred before any separation attempt, 153 (2·6%) were transferred after at least one separation attempt and not successfully weaned, and 1662 (28·3%) died while invasively ventilated. The median time from fulfilling weaning eligibility criteria to first separation attempt was 1 day (IQR 0-4), and 1013 (22·4%) patients had a delay in initiating first separation of 5 or more days. Of the 4523 (77·1%) patients with separation attempts, 2927 (64·7%) had a short wean (≤1 day), 457 (10·1%) had intermediate weaning (2-6 days), 433 (9·6%) required prolonged weaning (≥7 days), and 706 (15·6%) had weaning failure. Higher sedation scores were independently associated with delayed initiation of weaning. Delayed initiation of weaning and higher sedation scores were independently associated with weaning failure. 1742 (31·8%) of 5479 patients died in the intensive care unit and 2095 (38·3%) of 5465 patients died in hospital. Interpretation: In critically ill patients receiving at least 2 days of invasive mechanical ventilation, only 65% were weaned at 90 days. A better understanding of factors that delay the weaning process, such as delays in weaning initiation or excessive sedation levels, might improve weaning success rates. Funding: European Society of Intensive Care Medicine, European Respiratory Society