ISEL - Eng. Mecan. - Comunicações
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- 2D PCA-Based localization for mobile robots in unstructured environmentsPublication . Carreira, Fernando; Christo, C.; Valerio, D.; Ramalho, M.; Cardeira, C.; Calado, João Manuel Ferreira; Oliveira, P.In this paper a new PCA-based positioning sensor and localization system for mobile robots to operate in unstructured environments (e. g. industry, services, domestic ...) is proposed and experimentally validated. The inexpensive positioning system resorts to principal component analysis (PCA) of images acquired by a video camera installed onboard, looking upwards to the ceiling. This solution has the advantage of avoiding the need of selecting and extracting features. The principal components of the acquired images are compared with previously registered images, stored in a reduced onboard image database, and the position measured is fused with odometry data. The optimal estimates of position and slippage are provided by Kalman filters, with global stable error dynamics. The experimental validation reported in this work focuses on the results of a set of experiments carried out in a real environment, where the robot travels along a lawn-mower trajectory. A small position error estimate with bounded co-variance was always observed, for arbitrarily long experiments, and slippage was estimated accurately in real time.
- An adaptive IoT management infrastructure for eco transport networksPublication . Calado, João Manuel Ferreira; F. G. Osório, A. Luís; Prata, RicardoThe complexity associated with fast growing of B2B and the lack of a (complete) suite of open standards makes difficulty to maintain the underlying collaborative processes. Aligned to this challenge, this paper aims to be a contribution to an open architecture of logistics and transport processes management system. A model of an open integrated system is being defined as an open computational responsibility from the embedded systems (on-board) as well as a reference implementation (prototype) of a host system to validate the proposed open interfaces. Embedded subsystem can, natively, be prepared to cooperate with other on-board units and with IT-systems in an infrastructure commonly referred to as a center information system or back-office. In interaction with a central system the proposal is to adopt an open framework for cooperation where the embedded unit or the unit placed somewhere (land/sea) interacts in response to a set of implemented capabilities.
- An approach based on fuzzy logic, to improve quality management on research and development centersPublication . Santos, Ricardo; Abreu, António; Calado, João Manuel FerreiraNowadays, with globalization and with the development of emergent economies the Research and Development (R&D) Centres in Europe to survive need to achieve high levels of excellence. In this way, the use of a quality management tools, such as European Foundation for Quality Management (EFQM), can help the managers of such organizations to identify de best practices to enhance the efficiency and effectiveness. Hence, this paper presents a new approach to support managers of R&D centres in the decision-making process in achieving the aims mentioned above, which is based on the EFQM model integrated with Fuzzy Logic. The proposed approach was applied to a Portuguese R&D Centre to assess its overall performance. In order to evaluate the robustness of the proposed approach, the results achieved were compared with the results obtained through a traditional methodology based on RADAR’s Logic.
- An approach to provide efficient choices to a household consumerPublication . Santos, Ricardo; Matias, J. C. O.; Abreu, AntónioIn this work, it will be presented an approach, applied to an energy efficiency problema in buildings, which allows the decision-agent (consumer) to perform a set of efficient choices, suitable to its needs, reducing therefore, the building overall energy consumption during the equipment lifecycle period (usage phase). The approach will use Evolutionary Algorithms (EA), combined with Multicriteria analysis. The quality of EA solutions will be evaluated through the comparison, with the ones, obtained from Simplex method. The EA robustness to the change of its parameters, will also be evaluated, as well as the influence of the objective function on its behavior. The approach can provide the consumer with several and different efficient solutions, with less time than Simplex. I tis also possible to improve the obtained solutions, by choosing adequately the EA`s control parameters, as well the problema formulation.
- An electro-pneumatic prototype to support the teaching of industry 4.0 conceptsPublication . Francisco, Miguel B. R. M.; Mendes, Mário J. G. C.; Calado, João Manuel FerreiraThe appearance of industry 4.0 and the internet of things allowed to shorten the gap between the consumer and the product industry, with the introduction of new digital processes. With this in mind, a project of an electro-pneumatic laboratory prototype tosupporttheteachingoftheindustry4.0conceptswas proposed.Fortheconstructionofthelaboratorysystem was developed a typical industrial electro-pneumatic process (at scale), for which some support components were constructed using 3D modelling. For the automation part of the this system, the control platform of the programmable logic controller, type of programming language and creation of the code were developed. For the supervision system and remote digital control, the human machine interface is based in web pages using a common web browser, with the possibility of decentralized access in every tablet and smartphone. This prototype was simulated and tested, and it will help in the teaching of the 4.0 industry concepts.
- An exploratory approach to capture interpersonal synergies between defenders in footballPublication . Milho, J.; Passos, P.Collective behaviors in football may result from players forming inter¬personal synergies that contribute to performance goals. Due to the huge number of variables that continuously constrain players’ behavior during a game, the way that these synergies are formed remain unclear. In team sports such as football, a common effective defensive tactical strategy is one in that defending players “fill” the space between themselves, disturbing the attackers intentions to get closer to the goal and score. To assemble such situations, we hypothesized that the defenders create a functional synergy, which occurs when components of a system behave as a whole contributing to the development of a specific task (Kelso, 2009). Supported on a previous research in Rugby Union (Passos et al., 2017), we postulate that synergies are—mechanisms that substantiate interpersonal coordination in team sports of Football. It is relevant to state that a general feature of coordination is the mutual dependency among system components (e.g., defenders), which led them to behave (e.g., play) as a whole (Kugler and Turvey, 1987; Kelso, 2009). The creation of a synergy is grounded on a comple¬mentarity between variability and stability, which means that some defending player’s (as components of a system) must vary the manner they interact to stabilize specific performance variables (Black et al., 2007; Passos et al., 2017). On this exploratory study, our aim was to quantify interpersonal synergies in team sport of football, in particular, to quantify dyadic interpersonal synergies between the four field defenders that formed the defensive squad of a football team. We hypothesized that neighboring defending players adjust their relative positions to stabilize an interpersonal distance and as such create interpersonal synergies.
- An optimization approach to generate accurate and efficient lookup tables for engineering applicationsPublication . Magalhães, H.; Marques, F.; Liu, B.; Pombo, João; Flores, P.; Ambrósio, Jorge; Bruni, S.In a wide number of engineering applications, the interpolation of a lookup table (LUT) can substitute expensive calculations. The generation of a LUT consists of pre-calculating a set of quantities from a collection of points that covers the study domain where the interpolation is possible. Nevertheless, the selection of points where the exact calculation is performed is of utmost im-portance for the LUT size and accuracy. Thus, the goal of this paper is to provide a dedicated optimization tool for the generation of accurate and efficient LUT. Here, the domain of the LUT is structured by the so-called layers, in which, the thicknesses of each layer define the distance between pre-calculated points. The optimization problem consists of maximizing the layer thicknesses, that is, min-imizing the LUT size, such that the interpolation errors within the layer domain are kept under specified tolerances. Thus, a sequential design approach is applied to design each layer of the LUT until the layers cover the study domain. To achieve reliable LUT generations, a new optimization algorithm has been imple-mented to reach optimal layers with minimum iterations. The strategy proposed here is applied to generate a LUT to substitute a selected analytical function. The optimization procedures demonstrate not only the performance of the optimiza-tion algorithm, but also its convenience in the generation of multidimensional LUT.
- An optimization approach to generate accurate and efficient lookup tables for engineering applicationsPublication . Magalhães, H.; Marques, F.; Liu, B.; Pombo, João; Flores, P.; Ambrósio, J.; Bruni, S.In a wide number of engineering applications, the interpolation of a lookup table (LUT) can substitute expensive calculations. The generation of a LUT consists of pre-calculating a set of quantities from a collection of points that covers the study domain where the interpolation is possible. Nevertheless, the selection of points where the exact calculation is performed is of utmost importance for the LUT size and accuracy. Thus, the goal of this paper is to provide a dedicated optimization tool for the generation of accurate and eficiente LUT. Here, the domain of the LUT is structured by the so-called layers, in which, the thicknesses of each layer define the distance between pre-calculated points. The optimization problem consists of maximizing the layer thicknesses, that is, minimizing the LUT size, such that the interpolation errors within the layer domain are kept under specified tolerances. Thus, a sequential design approach is applied to design each layer of the LUT until the layers cover the study domain. To achieve reliable LUT generations, a new optimization algorithm has been implemented to reach optimal layers with minimum iterations. The strategy proposed here is applied to generate a LUT to substitute a selected analytical function. The optimization procedures demonstrate not only the performance of the optimization algorithm, but also its convenience in the generation of multidimensional LUT.
- An optimization strategy for customized radiotherapy head immobilization masksPublication . Craveiro, D.S.; Loja, Amélia; Vieira, Lina Oliveira; Vinyas, M.An effective head immobilization is an important requirement in radiotherapy treatment sessions, although it may also be thought in the future as a precious aid in brain medical imaging. Thus, the present work is focused on the stiffness optimization of a customized head immobilization mask, modelled upon the head reconstruction surface based on computerized tomography images. This paper proposes a strategy supported by a metaheuristic optimization technique and a metamodeling approach for the whole mask, illustrated at its most unfavorable region occurring in the gnathion region.
- An overview of critical chain applied to project managementPublication . Correia, Francisco; Abreu, AntónioThe characterization and assessment of the Critical Chain (CC) approach and the adaptation of the Theory of Constraints (TOC) to Project Management is an important element to help promoting the development of this field. Starting with a brief discussion about the CPM method and PERT method, this paper introduces some discussion about the advantages and disadvantages of the CC concerning to traditional approaches.