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Based on a recently proposed leg-based stairclimbing wheelchair, this work presents the control architecture for this mechanism. The objective of this work is to propose a step by step control methodology, which can define the positions of the wheels to climb up/down stairs. This will simplify the control of the seventeen actuators involved in climbing up and down tasks. The strategy proposed in this work makes the system robust to sensor uncertainties and small errors in the mechanical parameters, making the structure safer. This control architecture facilitates the practical implementation of the kinematic control. In addition, this strategy is also useful to optimize the configuration of the mechanism.

Due to their robustness, compactness, simplicity, and the possibility of nonlinear torque curves, spiral springs are being increasingly contemplated for industrial application. Recent manufacturing technologies and materials allow for the creation of spiral springs of various shapes and geometries able to provide the required torque curves. Modeling the behavior of this kind of springs is highly complex due to the strong nonlinearities arisen from large deflections and the possibility of coiling of strip length around the spring barrel or arbor. For this reason, up to our knowledge, existing models only provide design features such as deflection and torque curve for the simplest strip geometries, and fewer models supply, only if no strip coiling occurs, reactions at the strip-barrel and strip-arbor clampings. In addition, to our knowledge, just semi-empirical models for strip-barrel, -arbor and -strip contact forces or friction torques were available. In this work, we introduce a novel general, an analytical quasistatic model for the calculation of all the above spring characteristics for any length-dependent strip material and initial geometry and strip cross-sectional shape and for any barrel and arbor radii. The strip deflection curvatures are calculated minimizing the sum of elastic and gravitational potential energies under geometrical constraints associated with eventual strip coiling. Once the curvatures are calculated, the spring internal, contact, and reaction forces can be straightforwardly calculated by solving the elastica differential equations. Friction is taken into account by evaluating the contact conditions at the strip coiled sections.

The development of a robotics project, in which students and teachers from different areas of knowledge participate, is an opportunity to develop transversal skills in university studies. When this project is motivated by participation in an international robotics contest, such as EUROBOT, the motivation of students is greater. This article presents the organization of the teaching innovation project in which the activity is framed, as well as the successful results after two years of implementation.

JT-60SA is the superconducting tokamak that will be operated at the Naka Fusion Institute of QST (the National Institutes for Quantum and Radiological Science and Technology) in Japan. The project is being developed under the framework of the Broader Approach Agreement between the EU and Japan (started in 2007) for an early realization of the fusion energy, aimed at conducting supportive and complementary work for the ITER experimental program towards DEMO. The assembly of the tokamak components as well as the related equipment was completed last year and the device is currently undergoing the integrated commissioning phase.Within the European contribution, Spain was one of the stakeholders that committed it, as a Voluntary Contributor, to design and manufacture one of the main components of the device: the cryostat. The cryostat is a large stainless steel vacuum vessel, 14 m diameter, 16 m high, which encloses the tokamak and provides the vacuum boundary (10−3 Pa) necessary to limit the heat loads on the magnets operated at cryogenic temperatures. The component is made up of the Cryostat Base (CB), the Cryostat Vessel Body Cylindrical Section (CVBCS), both designed and fabricated in Spain (through the National Fusion Laboratory at Ciemat), as well as the cryostat top lid (CTL) designed and procured by Japan (through QST).Within the manufacturing phases of the CB and CVBCS an extensive test program was carried out at Ciemat that focussed on the characterization of the welding processes selected for the manufacturing before their final approval. The aim of this paper is to present the results of the mechanical and microstructural tests performed on the welded joints.

The ITER equatorial visible and infrared Wide Angle Viewing System (WAVS) provides surface temperature measurements of plasma facing components by infrared (IR) thermography being one of its main roles to protect them from damage. It also images the plasma emission in the visible range. The diagnostic, which comprises 15 lines of sight distributed in four equatorial ports (3, 9, 12 and 17), will contribute to Machine protection, Basic control and Physics analysis in ITER. The design of the diagnostic in the equatorial port 12 (EP12) - comprising three lines of sight - is currently being developed within a Framework Partnership Agreement through a Specific Grant granted by F4E to the Consortium formed by CEA, Ciemat and Bertin Technologies. EP12 has to be operative for the ITER first plasma. The overview of the WAVS opto-mechanical design for the ex-vessel components in EP12 will be presented in the paper. The ex-vessel optics are composed of mirrors and refractive elements which relay the exit image of the port plug at the vacuum window up to the cameras placed inside a shielded cabinet in the Port Cell. The image relay through the Interspace, Bioshield and Port Cell has to cover a length of almost 10 m in order to reach the detectors. The refractive elements are arranged in sub-assemblies (optical modules) mechanically mounted in barrels and next assembled on a support structure. The assembly of these modules on site will be also presented in the paper. Furthermore, the Optical Hinge which is the first component of the ex-vessel optical chain (formed by two folding mirrors) aims to compensate the differential motion between the vacuum vessel and the building, in normal operation and baking. The mechanical assembly and the operation of this component will be also described in the paper.

This article explores the influence of the appearance of micropitting in different types of additives added to a polyalphaolefinic low-viscosity base oil, namely a polyalphaolefin PAO6. Additives commonly used in mechanical transmissions by gears were used, i.e., extreme pressure, anti-wear and friction modifier. For the study, we have conducted a series of tests on a disc machine under various operating conditions. The temperature and surface roughness of the test specimens have been changed in order to study different lubricant specific film thicknesses, as the last is one of the most influential parameters on the appearance of micropitting. Tests have shown the important influence of the additives, and their concentration, in the development of micropitting and their associated effects, depending on the operating conditions of the contact. Along with the study of the effect of additives, the influence of specific film thickness on the friction coefficient, surface appearance, conditions of lubrication, and wear was also studied.

[EN] This paper describes different simulation tools developed in the Universidad de Alcalá in order to teach photovoltaic energy engineering. A web application is compared to other tools, such as spreadsheets and applications in Matlab environment, developed by the authors. In all the cases, the tools are focused on learning project engineering., [ES] En este trabajo, se describen diferentes herramientas de simulación empleadas en asignaturas de la Universidad de Alcalá para la enseñanza de la energía solar fotovoltaica. Se compara el uso de una aplicación web con otras herramientas como hojas de cálculo y aplicaciones en entorno Matlab. Todas las herramientas descritas han sido desarrolladas por los autores, haciendo especial énfasis en su enfoque didáctico, sin por ello perder todo el rigor y la funcionalidad necesarios en este tipo de simuladores.

Two ways of determining Bridgman's parameters are presented to estimate the equivalent Bridgman stress–strain (BSS) curve after the onset of necking in cylindrical specimens. The accurate experimental determination of the minimum necking radius, r N , and the radius of curvature of the necking, R N , are considered to be the main problems in applying Bridgman's model to obtain the equivalent BSS curve and describe the plastic behaviour of materials. Using the combined technique of 2D digital image correlation and fringe projection, the 3D positions and displacements of the surface elements are determined for each load stage of a tensile test on steel, aluminium (Al) and copper (Cu) bars. The axial displacements are well fitted with an empirical function that allows accurate estimation of the beginning of necking and its location on the specimen. From the 3D positions, both Bridgman's parameters are estimated by adjusting a torus to the necking zone. The 3D measurements around the necking position have to be well defined to obtain the parameters in a feasible way, because the real necking profile does not fit well with the half-circle proposed by Bridgman. Nonetheless, the estimated r N parameters are noisy, affecting the BSS curve. Therefore, an alternative and simpler way for estimating r N and R N is also proposed, only requiring the measurement of total axial displacements along the loading axis of each surface element. In this way, the BSS curve obtained is smooth, although it somewhat underestimates the same curve obtained using experimentally measured 3D data.

In recent years, the study and design of wearable antennas have been empowered given the success of Wireless Body Area Networks (WBAN) for healthcare and medical purposes. This work analyses a flexible textile antenna whose performance can be optimised by the careful selection of the substrate thickness of the textile material, and by varying the antenna&rsquo, s geometrical shape. After considering these parameters, several arrangements of antennas were simulated using the Computer Simulation Technology software (CST). The results of the simulations were compared to the experimental prototypes manufactured on a flexible felt material for a range of thicknesses and curvatures of the antenna substrate. Such antenna designs can be utilised in off-body communications and ISM applications.

There are many standards worldwide dealing with safety issues in robots and adequate protections for their industrial use. Two main safeguard actions are considered to avoid mechanical risks, namely physical or non-physical protections and design guidelines for robots and their components. Nevertheless, there is a lack of specific standards for service robots. Safety in these robots needs a new point of view. It requires a strategy to be changed from pre-contact to post-contact safety, since it is not possible to avoid human–robot interaction. On the other hand, in automotive industry crash test results are used for assessing car safety by means of safety indices. In this paper, quantitative head injury indices for automobiles are analysed and a new safety index for robots NIR is derived. The similitude between NIR and indices used in automotive industry lets the new index to take advantage of previous results and knowledge available in automotive field. Results with NIR are compared with those given by e...

The aim of this investigation was to setup the procedure to measure the efficiency of market control activities in the European framework. This was carried out by means of analysing the data collected in the last five campaigns of control of industrial products (Cordero and Munoz Sanz, 2009), performed yearly by the Safety Machinery Lab (Spain). The reliability of the control process or a certain product regarding safety is thus characterised by means of a mathematical model. The goal of each campaign is to verify whether a particular product falls within the scope of the Machinery Directive (Directive 2006/42/EC; Real Decreto 1644/2008) (on forwards MD).2Directive 2006/42/EC, that came into force on 29 June 2006. Spain transposed Machinery Directive 2006/42/EC (onwards MD) to national regulation as Real Decreto 1644/2008. 2 This implies to verify compliance with essential health and safety requirements related to the design and construction of machinery and, to test machine according to related Harmonised Standards. A methodology of experimental design was applied. Sample context (representative population, experimental design, selection criteria) and final sample were defined from data collected during 2002-2006 campaigns. In a first phase, data were analysed to evaluate their quality, to arrange them in a proper way and to make a trend analysis. Repeated behaviours in the same population (analysis of signpost) were also checked and relations among different product types were setup. Once the preliminary conclusions were got from this qualitative study, a second phase, quantitative, based on the mathematical post-processing of testing results was developed. It lays down the base that supports the mathematical model. This second phase, which represents the behaviour of the activities of market control, is the matter of discussion of present paper.

This article aims to highlight the current status of compliance to Machinery Directive 98/37/EC (transposed to Spanish regulation as RD 56/1995, of 20th January) (a new directive numbered as 2006/42/EC [Directive 2006/42/EC of the European Parliament and of the Council of 17 may 2006 on machinery, and amending Directive 95/16/EC (recast). OJ L157/24-86, 9.6.2006.], that recasts and replaced 98/37/ED directive and its amendments, came into force on 29 June 2006; it will not be applied until 29th December 2009. European Member States have a lead-time of two years to adopt and publish the national laws and regulations transposing the provisions of the new Directive into national law. Latest 10th October, Spain transposed Machinery Directive 2006/42/EC to national regulation as Real Decreto 1644/2008 [Real Decreto 1644/2008, de 10 de octubre, por el que se establecen las normas para la comercializacion y puesta en servicio de las maquinas. BOE 246/2008, de 11 octubre 2008. Paginas 40995–41030]) of a particular family of machinery (hand-held, medium and small-size, deeply introduced in the market, of low-medium cost), that any user, professional or non-professional, can acquire as first-hand in any of the sales points (whether or not experts in these kind of products). At the same time, it emphasises the most significant shortcomings and non-conformities found, after analyzing the results of five consecutive Campaigns of Control of Industrial Products performed by one of the labs (placed in Spain) involved in the market surveillance European Program.

Current brief aims to introduce the concept of safety in European industrial sectors, particularly in mechanics and machinery industry. It also highlights the importance to ensure an even level of machinery safety along the European Union, setting up the appropriate frame and procedures to keep it under control. An overview over market surveillance activities for machinery (regulations, main actors and their roles) first at Community level, and secondly an approach to one of the Member States is also introduced.