79 research outputs found

    Is the virtual homologation for pedestrian protection viable?

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    One out of five deceased in traffic accidents is a pedestrian. In addition, pedestrians represent the 20 % of the hospitalized injured people. The deadliness rate of a pedestrian crash is significantly greater than for the rest of accidents. Thus, pedestrian crash is one of the more lethal traffic accidents and, consequently, pedestrians are the most vulnerable road users. Vehicle's design can influence immensely in the risk of seriousness of the accident. Regulations are the legal instruments in order to establish if a vehicle achieves the minimum safety requirements. Nevertheless, homologation implies costly and destructive tests. This problem could be solved by simulation techniques. Analyzing the viability of a virtual homologation is the main goal of this article. After studying pedestrian crash biomechanics, virtual tests will be performed using Finite Element software (Ls-Dyna) to assess the influence of the design of vehicle and the effect of a safety system (active bonnet). Comparison between virtual tests results and real tests allows deducing if the virtual homologation for pedestrian protection is viable

    Determining the stress distribution in a bicycle crank under in-service loads

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    New techniques have been introduced in the design process of most of the components of a bicycle. One of the main purposes of this introduction is trying to achieve the best weight/rigidity relation. However, all these advances have to take into account the security of the rider. Unexpected failures of some components such as stem, handlebar, or cranks, can cause serious injuries to cyclists and have to be prevented. Standard EN 14781:2006 establishes the safety and performance requirements that every bicycle and every component must fit from the point of view of fatigue failure. In this work, several bicycles cranks will be experimentally tested under the loading conditions of the reference standard. The stresses on the critical points will be analyzed to determine the influence of any variation in the test conditions. According to obtained data, several changes in the conditions of the standard will be proposed. Also, loading tolerance values for the test will be suggested, because they are not established in the standard

    Material characterization for FEM simulation of sheet metal stamping processes

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    Sheet metal forming is an important technology in manufacturing, especially in the automotive industry. Today, engineering simulation tools based on the finite elements method are employed regularly in the design of stamping dies for sheet metal parts. However, a bad material model choice or the use of nonaccurate enough parameters can lead to imprecise simulation results. This work uses ANSYS LS-DYNA software to analyze several material models and the influence of their parameter values in FEM simulation results. The main tool to solve these problems is an application designed to assist die stamp designers. The program allows a procedure to be defined to obtain the values of the properties of an unknown material, which combines finite element simulations with real experimental results. Results obtained for the simulation of a real automotive part are analyzed and compared with the real experimental results. Parameters involved in each material model have been identified, and their influence in final results has been quantified. This is very useful to fit material properties in other simulations. This paper fulfils an identified need in the manufacturing industry. In fact, the proposed application is currently being used by a manufacturer of automotive components

    New Procedure for the Kinematic and Power Analysis of Cyclists in Indoor Training

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    This article belongs to the Special Issue Sensor Technology for Sports Science.In this research, the performance and movements of amateur and professional cyclists were analyzed. For this, reflective markers have been used on different parts of the body of the participants in conjunction with sports cameras and a mobile power meter. The trajectories of the markers have been obtained with the software Kinovea and subsequently analyzed using error ellipses. It is demonstrated that the error ellipses help determine movement patterns in the knees, back, and hip. The covariance of the error ellipses can be indicative of the alignment and symmetry of the frontal movement of the knees. In addition, it allows verifying the alignment of the spine and the symmetry of the hip. Finally, it is shown that it is necessary to consider the uncertainty of the power devices since it considerably affects the evaluation of the cyclists’ performance. Devices with high uncertainty will demand a greater effort from the cyclist to meet the power required in the endurance test developed. The statistical magnitudes considered help to analyze power and evaluate the cyclists’ performance

    Surface Electromyography Study Using a Low-Cost System: Are There Neck Muscles Differences When the Passenger Is Warned during an Emergency Braking Inside an Autonomous Vehicle?

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    Deaths and serious injuries caused by traffic accidents is a concerning public health problem. However, the problem can be mitigated by the Autonomous Emergency Braking (AEB) system, which can avoid the impact. The market penetration of AEB is exponentially growing, and non-impact situations are expected to become more frequent. Thus, new injury patterns must be analysed, and the neck is particularly sensitive to sudden acceleration changes. Abrupt braking would be enough to be a potential risk for cervical spine injury. There is controversy about whether or not there are differences in cervical behaviour depending on whether passengers are relaxed or contract their muscles before the imminent accident. In the present manuscript, 18 volunteers were subjected to two different levels of awareness during an emergency braking test. Cervical muscles (sternocleidomastoid and trapezius) were analysed by the sEMG signal captured by means of a low-cost system. The differences observed in the muscle response according to gender and age were notable when passengers are warned. Gender differences were more significant in the post-braking phase. When passengers were relaxed, subjects older than 35 registered higher sEMG values. Meanwhile, when passengers contract their muscles, subjects who were younger than or equal to 35 years old experienced an increment in the values of the sEMG signals

    Study of the Emergency Braking Test with an Autonomous Bus and the sEMG Neck Response by Means of a Low-Cost System

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    This article belongs to the Special Issue Development of Innovative Sensor Platforms for Field AnalysisNowadays, due to the advances and the increasing implementation of the autonomous braking systems in vehicles, the non-collision accident is expected to become more common than a crash when a sudden stop happens. The most common injury in this kind of accident is whiplash or cervical injury since the neck has high sensitivity to sharp deceleration. To date, biomechanical research has usually been developed inside laboratories and does not entirely represent real conditions (e.g., restraint systems or surroundings of the experiment). With the aim of knowing the possible neck effects and consequences of an automatic emergency braking inside an autonomous bus, a surface electromyography (sEMG) system built by low-cost elements and developed by us, in tandem with other devices, such as accelerometers or cameras, were used. Moreover, thanks to the collaboration of 18 participants, it was possible to study the non-collision effects in two different scenarios (braking test in which the passenger is seated and looking ahead while talking with somebody in front of him (BT1) and, a second braking test where the passenger used a smartphone (BT2) and nobody is seated in front of him talking to him). The aim was to assess the sEMG neck response in the most common situations when somebody uses some kind of transport in order to conclude which environments are riskier regarding a possible cervical injury

    Four chamber right ventricular longitudinal strain versus right free wall longitudinal strain. Prognostic value in patients with left heart disease

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    Background: There is no consensus on which right ventricle (RV) strain parameter should be used in the clinical practice: four chamber RV longitudinal strain (4CH RV-LS) or free wall longitudinal strain (FWLS). The aim of this study was to analyze which RV strain parameter better predicts prognosis in patients with left heart disease. Methods: One hundred and three outpatients with several degrees of functional tricuspid regurgitation severity secondary to left heart disease were prospectively included. 4CH RV-LS and FWLS were assessed using speckle tracking. Left ventricular (LV) systolic function was determined using LV ejection fraction and RV systolic function using tricuspid annular plane systolic excursion (TAPSE). Patients were followed up for 23.1 ± 12.4 months for an endpoint of cardiac hospitalization due to heart failure. Results: The cutoff value related to RV dysfunction (TAPSE < 17 mm) was lower, in absolute value, for 4CH RV-LS (4CH RV-LS = –17.3%; FWLS = –19.5%). There were 33 adverse events during the follow-up. Patients with 4CH RV-LS > –17.3% (log rank [LR] = 22.033; p < 0.001); FWLS > –19.5% (LR = 12.2; p < 0.001), TAPSE < 17 mm (LR = 17.4; p < 0.001) and LV systolic dysfunction (LR = 13.3; p < 0.001) had lower event-free survival (Kaplan Meier). In Cox multivariate analysis, 4CH RV-LS > –17.3% (hazard ratio [HR] = 3.593; p < 0.002), TAPSE < 17 (HR = 2.093; p < 0.055) and LV systolic dysfunction (HR = 2.087; p < 0,054) had prognostic value, whereas FWLS did not reach significance. Conclusions: Although both 4CH RV-LS and FWLS have prognostic value, 4CH RV-LS is a better predictor of episodes of heart failure in patients with left heart disease, providing additional information to that obtained by TAPSE.

    Project ARES: Driverless transportation system. Challenges and approaches in an unstructured road

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    This article belongs to the Special Issue Intelligent Control of Mobile Robotics.The expansion of electric vehicles in urban areas has paved the way toward the era of autonomous vehicles, improving the performance in smart cities and upgrading related driving problems. This field of research opens immediate applications in the tourism areas, airports or business centres by greatly improving transport efficiency and reducing repetitive human tasks. This project shows the problems derived from autonomous driving such as vehicle localization, low coverage of 4G/5G and GPS, detection of the road and navigable zones including intersections, detection of static and dynamic obstacles, longitudinal and lateral control and cybersecurity aspects. The approaches proposed in this article are sufficient to solve the operational design of the problems related to autonomous vehicle application in the special locations such as rough environment, high slopes and unstructured terrain without traffic rules.Research is supported by the Spanish Government through the CICYT projects (PID2019-104793RB-C31 and RTI2018-096036-B-C21), the Comunidad de Madrid through SEGVAUTO-4.0-CM (P2018/EMT-4362) and through EAI of the Ministry of Science and Innovation of the Government of Spain project RTI2018-095143-B-C2

    IMECE2011-63392 CHARACTERIZATION OF THE NOISE EMISSIONS OF A PASSENGER VEHICLE

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    ABSTRACT One of the main sources of noise pollution in cities is vehicle traffic. In this paper a characterization of the noise emission of a passenger vehicle has been carried out. With this aim a representative driving route for noise emission has been defined in order to study the influence of the driver typology and vehicle type. Therefore, this investigation has been developed in three phases: Firstly, usual driving in an urban area like Madrid has been characterized with a specific driving route. In addition, several vehicle models with great presence in the existing fleet of cars have been selected. Several drivers have covered the driving route at different times of the day and previous parameters have been measured in each test in order to determine average values of behavior. Secondly, the type of vehicles and drivers influence in noise emissions has been deeply analyzed. To achieve this aim a sample of vehicles has been instrumented to obtain physical measurements of the variables that can influence the noise emission level. Positions, velocities, accelerations (longitudinal and lateral) and time have been analyzed using a GPS sensor. Parameters such as, engine speed, engine load, throttle position and engine temperature have been studied through the vehicle CAN BUS and a set of microphones has measured the emitted noise in several points of the vehicle. In order to study the ecological and safety impact in urban and interurban roads by means of the measurement of noise emissions the analysis of the driver behaviour is of paramount importance. To conclude, the previous data has been analyzed and noise equivalent levels have been identified with different test configurations

    Uso de museos y exposiciones de Madrid para el estudio del cambio social. Una propuesta de mejora en las prácticas docentes de los estudios de comunicación

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    Este proyecto de innovación docente se propone alinear las necesidades docentes de la enseñanza del Cambio Social, la necesaria formación en contenidos audiovisuales y la disposición de los museos y exposiciones de abrirse a público joven y convertirse en espacios formativos y de reflexión sobre el cambio social. Es clara la necesidad de las profesiones comunicativas de encontrar nichos de empleo
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