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Learning and generalising object extraction skill for contact-rich disassembly tasks: an introductory study
Full text linkRemanufacturing automation must be designed to be flexible and robust enough to overcome the uncertainties, conditions of the products, and complexities in the planning and operation of the processes. Machine learning methods, in particular reinforcement learning, are presented as techniques to learn, improve, and generalise the automation of many robotic manipulation tasks (most of them related to grasping, picking, or assembly). However, not much has been exploited in remanufacturing, in particular in disassembly tasks. This work presents the state of the art of contact-rich disassembly using reinforcement learning algorithms and a study about the generalisation of object extraction skills when applied to contact-rich disassembly tasks. The generalisation capabilities of two state-of-the-art reinforcement learning agents (trained in simulation) are tested and evaluated in simulation, and real world while perform a disassembly task. Results show that at least one of the agents can generalise the contact-rich extraction skill. Besides, this work identifies key concepts and gaps for the reinforcement learning algorithms’ research and application on disassembly tasks
Development of a Thermal Analysis Tool for Linear Machines
Full text linkThe thermal design is one of the most important stages in the design process of electrical machines. Thanks to software packages, like Motor-CAD, rotating machine designers can predict the thermal operation of the machines with high precision. However, a Motor-CAD equivalent for linear machines does not exist. Thus, linear machine designers must develop specific thermal analysis tools when designing the machines. In this article, a generic thermal analysis tool for different kinds of linear machines is presented. The model has been designed in MATLAB Simulink. Hence, it should be easy to implement for most engineers. The article describes the configuration of the different elements of the tool. The calibration parameters and procedure, and typical values of the calibration variables, are also given in the document. Finally, in order to demonstrate the generic nature of the tool, the model is experimentally validated via DC thermal tests to a linear induction machine and a linear switched-flux permanent magnet machine. The results show that, despite being simple and easy to implement, the model can predict the thermal operation of different machines with high precision
Mondragon Unibertsitateko HUHEZIko ikasle hasiberrien hizkuntza-hautuak eta arrazoiak
Full text linkIkerketa honetan aztertu ditugu unibertsitatean hasi berri diren ikasleen hizkuntzahautuak
eta horien arrazoiak. Horretarako, Mondragon Unibertsitateko HUHEZIko
lehenengo mailako Hezkuntzako Graduetako ikasleak hiru hizkuntza-profil ezberdinetan
sailkatu ditugu eta profil horietako ikasleekin eztabaida-taldeak egin ditugu
hizkuntzen inguruan dituzten pertzepzio eta usteak jasotzeko. Emaitzek erakusten
dute aztertutako hiru hizkuntza-tipologietako ikasleek euskararen gaitasunarekiko
autopertzepzio positiboa dutela, nahiz eta hizkuntza-hautuetan ezberdintasunak
dauden hiruretan. Euskal elebidunak dira euskaraz gaztelaniaz baino erosoago
sentitzen diren bakarrak eta bizi diren gune soziolinguistikoak eta gertuko sarearen
nolakotasunak baldintzatzen dute neurri handian egiten duten hizkuntza-hautua.
Euskal elebidunentzat hizkuntzak balio identitarioa duen bezala, gainerako ikasleentzat
balio instrumentala du eta kasu gehienetan eskolako hizkuntzatzat daukate.This study analysed the language choices of first-year student-teachers in the Faculty
of Humanities and Education at Mondragon University and the reasons behind them. To this
end, students-teachers were classified into three language profiles and focus groups were
held with each profiles to reflect on their perceptions and beliefs about languages. The results
showed that the student-teachers of the three language profiles examined have, a positive selfperception
of their competence in Basque, although there are differences in language choices
among them. Basque dominant are the only ones who feel more comfortable in Basque than
in Spanish, and both the sociolinguistic areas in which they live and their social networks
largely conditioned their language choices. For Basque dominant bilinguals the language has
an identity value, but for the rest of the student-teachers, it has merely an instrumental value,
and in most cases, they relate it only to school
Monitorización longitudinal de la compliancia pulmonar basada en la TIE en pacientes infectados por COVID-19
Full text linkEl COVID-19 es una infección vírica que causa complicaciones en el sistema respiratorio. Los síntomas más comunes sugieren que las tecnologías de imagen médica pueden ofrecer información relevante sobre el diagnóstico, tratamiento, y posterior recuperación de este tipo de infecciones. Entre estas técnicas de imagen se encuentra la Tomografía de Impedancia Eléctrica (TIE), la cual se trata de una técnica no invasiva, libre de radiación ionizante y de uso continuo seguro que genera imágenes utilizando secuencias de inyecciones de corriente eléctrica y mediciones de voltaje alrededor del cuerpo. Por todo ello, la TIE podría considerarse como una herramienta adecuada para el estudio y monitorización del comportamiento regional de los pulmones infectados. Además, esta técnica podría también ser una herramienta válida para una clasificación preliminar entre los fenotipos del COVID-19. Este estudio se basa en la monitorización longitudinal de dos pacientes infectados por el nuevo coronavirus: los resultados indican que uno de los pacientes podría pertenecer al fenotipo H, mientras que el segundo podría clasificarse como tipo L. Se ha concluido que la TIE es una herramienta muy útil a la hora de recopilar información sobre el COVID-19, así como de sus diferentes fenotipos
A Coloured Petri Net- and D* Lite-Based Traffic Controller for Automated Guided Vehicles
Full text linkMobile robots, such as Automated Guided Vehicles (AGVs), are increasingly employed in automated manufacturing systems or automated warehouses. They are used for many kinds of applications, such as goods and material handling. These robots may also share industrial areas and routes with humans. Other industrial equipment (i.e., forklifts) could also obstruct the outlined routes. With this in mind, in this article, a coloured Petri net-based traffic controller is proposed for collision-free AGV navigation, in which other elements moving throughout the industrial area, such as humans, are also taken into account for the trajectory planning and obstacle avoidance. For the optimal path and collision-free trajectory planning and traffic control, the D* Lite algorithm was used. Moreover, a case study and an experimental validation of the suggested solution in an industrial shop floor are presented
Training in higher education in the Covid-19 context: A case study of operation management training in a Business Innovation and Project Management Master
Full text linkThe main objective of this paper is to describe the programme implemented through the use of information and communication technologies (ICT) for the development and acquisition of quality engineering (QE)-related competences in the context of the Covid-19 pandemic. In the 100% face-to-face context, different products, such as catapults and paper helicopters, are used to apply the theoretical concepts of Six Sigma in a real environment, which would be impossible in an online or blended learning context. To overcome the difficulties due to the Covid-19 pandemic, a new programme has been defined that includes continuous ICT use, with a simulator of an injection process to generate the necessary data to develop practice. The programme and the simulator used have successfully replaced the practices and products previously used in a 100% face-to-face environment, allowing students to acquire QE-related competences in a practical way in a non-face-to-face environment
Contact pressure and sliding velocity ranges in sheet metal forming simulations
Full text linkIn the last few years many efforts have been carried out in order to better understand what the real contact between material and tools is. Based on the better understanding new friction models have been developed which have allowed process designers to improve numerical results in terms of component viability and geometrical accuracy. The new models define the coefficient of friction depending on different process parameters such as the contact pressure, the sliding velocity, the material strain, and the tool temperature. Many examples of the improvements achieved, both at laboratory scale and at industrial scale, can be found in the recent literature. However, in each of the examples found in the literature, different ranges of the variables affecting the coefficient of friction are covered depending on the component analysed and the material used to produce such component. The present work statistically analyses the contact pressure and sliding velocity ranges achieved during numerical simulation (FEM) of sheet metal forming processes. Nineteen different industrial components representing a high variety of shapes have been studied to cover a wide range of casuistic. The contact pressure and sliding velocity corresponding to typical areas of the tooling have been analysed though numerical simulation in each case. This study identifies the ranges of contact-pressure and sliding velocities occurring in sheet metal forming aimed to set the characterization range for future friction studies
A new equivalent circuit model parametrization methodology based on current pulse tests for different battery technologies
Full text linkWith growing global commitment to renewable energy generation, the role of energy storage systems has become a central issue in traction power applications, such as electric vehicles, trains, and elevators. To achieve the optimal integration of batteries in such applications, without unnecessary oversizing, improvements in the process of battery selection are needed. Specifically, it is necessary to develop models able to predict battery performance for each particular application. In this paper, a methodology for the parametrization of a battery equivalent circuit model (ECM) based on capacity and pulse tests is presented. The model can be extrapolated to different battery technologies, and was validated by comparing simulations and experimental tests with lead-acid and lithium-ion batteries
Analytical Model to Calculate Radial Forces in Permanent-Magnet Synchronous Machines
Full text linkThere are three principal sources of noise and vibration in electrical machines: electromagnetic sources, mechanical sources, and aerodynamic sources. Nowadays, one of the major advantages of permanent-magnet synchronous machines is their torque density. This density is achieved through a high magnetic flux density in the air gap, which is achieved through hard magnets. Unfortunately, in these machines, electromagnetic forces have been identified as the main source of vibration and noise, and high magnetic flux densities make these vibrations and noises more significant. With the aim of better understanding the relationship between electromagnetic forces and design variables, this article, which is the continuation of previous work, firstly describes a study of the sources of magnetic forces in permanent-magnet synchronous machines. Subsequently, an analytical model for the computation of the radial forces originating from electromagnetic sources in permanent-magnet synchronous machines is stated. This model analyzes the forces on both the rotor surface and the base of the stator tooth. The analytical results were corroborated through simulations using the finite element method (FEM) and also by experimental tests performed over two prototypes. The results achieved by the analytical model show good agreement with both FEM results and experimental measurements
In-depth Life Cycle Cost Analysis of a Hydrogen Electric Multiple Unit
Full text linkThis paper analyses the life cycle costs of railway projects involving hydrogen electric multiple units. The analysis focuses on the interrelation between the selected lithium-ion battery technology, the designed energy management strategy, and the fuel cell and battery sizes. In particular, 3 lithium-ion battery technologies and 4 strategies are proposed, leading to a sensitivity analysis composed of 12 cases. For each case, an approach for the optimal sizing of the fuel cell and battery is proposed. A scenario based on a real railway line is introduced and the obtained results are compared with the performance of a traditional diesel-electric multiple unit. The results show that a reduction of the hydrogen price is required so as the hydrogen-based option becomes competitive compared to the diesel-based one. The best result of the sensitivity analysis is obtained with an off-line optimization-based strategy and LTO batteries