CRIIS - Indexed Articles in Journals

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    A Practical approach of Modeling and Parameters Estimation for OmniDirectional Mobile Robots
    ( 2009) André Conceição ; António Paulo Moreira ; Paulo José Costa
    This paper presents a non-linear modeling approach for omnidirectional mobile robots.
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    Modeling and Control of the MARES Autonomous Underwater Vehicle
    ( 2010) Nuno Cruz ; Bruno Miguel Ferreira ; Aníbal Matos ; Miguel Armando Pinto
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    High-level programming and control for industrial robotics: using a hand-held accelerometer-based input device for gesture and posture recognition
    ( 2010) Pedro Neto ; J. Norberto Pires ; António Paulo Moreira
    Purpose - Most industrial robots are still programmed using the typical teaching process, through the use of the robot teach pendant. This is a tedious and time-consuming task that requires some technical expertise, and hence new approaches to robot programming are required. The purpose of this paper is to present a robotic system that allows users to instruct and program a robot with a high-level of abstraction from the robot language. Design/methodology/approach - The paper presents in detail a robotic system that allows users, especially non-expert programmers, to instruct and program a robot just showing it what it should do, in an intuitive way. This is done using the two most natural human interfaces (gestures and speech), a force control system and several code generation techniques. Special attention will be given to the recognition of gestures, where the data extracted from a motion sensor (three-axis accelerometer) embedded in the Wii remote controller was used to capture human hand behaviours. Gestures dynamic hand positions) as well as manual postures (static hand positions) are recognized using a statistical approach and artificial neural networks. Findings - It is shown that the robotic system presented is suitable to enable users without programming expertise to rapidly create robot programs. The experimental tests showed that the developed system can be customized for different users and robotic platforms. Research limitations/implications - The propose
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    HUMANOID LOW-LEVEL CONTROLLER DEVELOPMENT BASED ON A REALISTIC SIMULATION
    ( 2010) José Lima ; António Paulo Moreira ; José Alexandre Gonçalves ; Pedro Gomes Costa
    This article describes a joint trajectory optimized controller developed in a humanoid robot simulator following the real robot characteristics. As simulation is a powerful tool for speeding up the control software development, the proposed accurate simulator allows to fulfill this goal. The simulator, based on the Open Dynamics Engine and GLScene graphics library, provides instant visual feedback. The proposed simulator, with realistic dynamics, allows to design and test behaviors and control strategies without access to the real hardware in order to carry out research on robot control without damaging the real robot. The low-level joints controller techniques, such as acceleration, speed, and energy consumption minimization, are discussed and experimental results are presented in order to validate the proposed simulator.
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    IntellWheels: A Modular Development Platform for Intelligent Wheelchairs
    ( 2011) Rodrigo Antonio Marques Braga ; António Paulo Moreira ; Marcelo Petry ; Luis Paulo Reis
    Intelligent wheelchairs can become an important solution to assist individuals suffering from disabilities and are thus unable to perform their daily activities using classic powered wheelchairs. This paper describes the concept and design of IntellWheels, a modular platform to facilitate the development of intelligent wheelchairs through a multi-agent system paradigm. In fact, modularity is achieved not just in the software perspective, but also through a generic hardware framework, which was designed to fit, in a straightforward manner, almost any commercial powered wheelchair. Experimental results demonstrate the successful integration of all modules in the platform, providing a safe motion to the intelligent wheelchair. Furthermore, the results achieved with a prototype running in autonomous mode, in a simulated and mixed reality environments, also demonstrate the potential of our approach. Although some future research is still necessary in order to fully accomplish its objectives, preliminary tests have shown that IntellWheels will be able to effectively reduce user's limitations, offering them a much more independent life.
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    Experiment@Portugal
    ( 2011) Maria Teresa Restivo ; José Carlos Alves ; Alberto Cardoso
    The main goal of the Project Experiment@Portugal is to produce a complete survey of Portuguese developments in remote and virtual labs. This knowledge will provide the conditions for joining forces in order to organize a well structured national website integrating a database of available remote and virtual experiments, categorized for sharing purposes, and looking for delivering valuable contents for high schools and for higher education. It is expected that the final result will bring up a solid team able to offer in this domain a Portuguese partner at international level
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    Intuitive Robot Programming Based on CAD: dealing with unstructured environments - Part II
    ( 2011) N. Mendes ; Pedro Neto ; António Paulo Moreira ; J.N. Pires ; R. Araújo
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    INTUITIVE ROBOT PROGRAMMING BASED ON CAD DEALING WITH UNSTRUCTURED ENVIRONMENTS (1ª parte)
    ( 2011) J. norberto Pires ; Nuno Mendes ; Ricardo Araújo ; António Paulo Moreira ; Pedro Neto
    The global market demands for cheaper, diversified and better quality products are forcing manufacturing companies to change their production facilities. Increasingly, traditional manufacturing is being replaced by flexible manufacturing systems where industrial robots are seen as a fundamental element. Nevertheless, robot programming is still a time consuming task that requires technical expertise. The pu rpose of this paper is to present a human-robot interface that allows non-expert users to teach a robot in a manner similar to that used by humans to teach each other. Another important issue addressed here has to do with how robots deal with uncertainty and the role of sensory feedback as a way to make robots more autonomous and thus face uncertainty.
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    A low-cost laser scanning solution for flexible robotic cells: spray coating
    ( 2012) Marcos André Ferreira ; Pedro Neto ; António Paulo Moreira
    In this paper, an adaptive and low-cost robotic coating platform for small production series is presented. This new platform presents a flexible architecture that enables fast/automatic system adaptive behaviour without human intervention. The concept is based on contactless technology, using artificial vision and laser scanning to identify and characterize different workpieces travelling on a conveyor. Using laser triangulation, the workpieces are virtually reconstructed through a simplified cloud of threedimensional (3D) points. From those reconstructed models, several algorithms are implemented to extract information about workpieces profile (pattern recognition), size, boundary and pose. Such information is then used to on-line adjust the 'base' robot programmes. These robot programmes are offline generated froma 3D computer-aided designmodel of each different workpiece profile. Finally, the robotic manipulator executes the coating process after its 'base' programmes have been adjusted. This is a low-cost and fully autonomous system that allows adapting the robot's behaviour to different manufacturing situations. It means that the robot is ready to work over any piece at any time, and thus, small production series can be reduced to as much as a one-object series. No skilled workers and large setup times are needed to operate it. Experimental results showed that this solution proved to be efficient and can be applied not only for spray coating purpo
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    Localization of Mobile Robots Using an Extended Kalman Filter in a LEGO NXT
    ( 2012) António Paulo Moreira ; Miguel Armando Pinto ; Aníbal Matos
    The inspiration for this paper comes from a successful experiment conducted with students in the 'Mobile Robots' course in the fifth year of the integrated Master's program in the Department of Electrical and Computer Engineering, Faculty of Engineering, University of Porto (FEUP), Porto, Portugal. One of the topics in this Mobile Robots course is 'Localization of Mobile Robots using the Extended Kalman Filter in a LEGO NXT,' which gives the students the opportunity to study the concepts of localization. This experiment comes within the framework of teaching localization concepts in mobile robotics and focuses primarily on explaining the Kalman filter concept. It involves a specific tool developed by the authors and based on LEGO NXT technology. The work presented here could be a helpful guide for teaching concepts related to localization in mobile robotics to ensure adequate understanding of the concept and of the use of the extended Kalman filter (EKF). The LegoFeup robot described here was built using a LEGO Mindstorms NXT and tested both in simulation and in real scenarios. Based on the results obtained, the authors concluded that the developed tool is effective in motivating students. The implementation of the tool, the structure of the Mobile Robots course, and the criteria for student assessment are described in this paper.
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    NOVEL 3D MATCHING SELF-LOCALISATION ALGORITHM
    ( 2012) Aníbal Matos ; Miguel Armando Pinto ; António Paulo Moreira ; Héber Miguel Sobreira
    A new and fast methodology is discussed as a solution to pinpointing the location of a robot called RobVigil, in a robust way, without environment preparation, even in dynamic scenarios. This solution does not require a high computational power. Firstly, the EKF-SLAM is used to find the location of the vehicle, allowing to map the surrounding area in the 3D space. Afterwards, the constructed map is used in a 3D matching algorithm during the normal operation of the vehicle to pinpoint its location. The 3D matching algorithm uses data from a tilting Laser Range Finder. Experimental results on the performance and accuracy of the proposed method are presented in this paper.
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    Human versus Virtual Robotics Soccer: A Technical Analysis
    ( 2012) Luís Paulo Reis ; Pedro Abreu ; João Mendes Moreira ; Israel Costa ; Júlio Garganta ; Daniel Castelão
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    Beat tracking for multiple applications: A multi-agent system architecture with state recovery
    ( 2012) Luís Paulo Reis ; João Lobato Oliveira ; Fabien Gouyon ; Matthew Davies
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    Distributed Energy Resources Impact on Distribution System Reliability under Load Transfer Restrictions
    ( 2012) João Peças Lopes ; Armando Sousa ; Mauro Rosa ; Luiz C. Nascimento ; Diego Issicaba
    Wind and solar power are well known intermittent power sources with high availability uncertainties. Hence, whenever they are integrated to distribution systems, these power sources can increase significantly the complexity of system operation. This paper presents an impact analysis of distributed energy resources integration on distribution systems, focusing mainly on reliability aspects. Therefore, an interesting algorithm to correctly determine the amount of capacity that may be transferred to other feeders is presented and discussed, taken into consideration the presence of distributed generation. The methodology is tested in a typical Brazilian distribution system, assuming the integration of a diesel-based combined heat and power unit, wind turbines, and solar panels. The results provide general insights regarding the benefits of applying distributed generation to alleviate load transfer restrictions.
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    Optimization Approach for the Development of Humanoid Robots' Behaviors
    ( 2012) Luís Paulo Reis ; Luís Cruz ; Armando Sousa ; Nuno Lau
    Humanoid robots usually have a large number of degrees of freedom which turns humanoid control into a very complex problem. Humanoids are used in several RoboCup soccer leagues. In this work, the SimSpark simulator of the Simulation 3D will be used. This paper presents an automatic approach for developing humanoid behaviors based on the development of a generic optimization system. The paper describes the adopted architecture, main design choices and the results achieved with the optimization of a side kick and a forward kick. For both skills, the optimization approach allowed the creation of faster and more powerful and stable behaviors.
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    Overcoming Motor-Rate Limitations in Online Synchronized Robot Dancing
    ( 2012) Luís Paulo Reis ; Armando Sousa ; Catarina Brito Santiago ; Fabien Gouyon ; João Lobato Oliveira
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    Indoor Localization System based on Artificial Landmarks and Monocular Vision
    ( 2012) António Paulo Moreira ; Andry Maykol Pinto ; Paulo José Costa
    This paper presents a visual localization approach that is suitable for domestic and industrial environments as it enables accurate, reliable and robust pose estimation. The mobile robot is equipped with a single camera which update sits pose whenever a landmark is available on the field of view. The innovation presented by this research focuses on the artificial landmark system which has the ability to detect the presence of the robot, since both entities communicate with each other using an infrared signal protocol modulated in frequency. Besides this communication capability, each landmark has several high intensity light-emitting diodes (LEDs) that shine only for some instances according to the communication, which makes it possible for the camera shutter and the blinking of the LEDs to synchronize.
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    High-level robot programming based on CAD: dealing with unpredictable environments
    ( 2012) J. norberto Pires ; Pedro Neto ; Nuno Mendes ; Ricardo Araújo ; António Paulo Moreira
    The global market demands for cheaper, diversified and better quality products are forcing manufacturing companies to change their production facilities. Increasingly, traditional manufacturing is being replaced by flexible manufacturing systems where industrial robots are seen as a fundamental element. Nevertheless, robot programming is still a time consuming task that requires technical expertise. The pu rpose of this paper is to present a human-robot interface that allows non-expert users to teach a robot in a manner similar to that used by humans to teach each other. Another important issue addressed here has to do with how robots deal with uncertainty and the role of sensory feedback as a way to make robots more autonomous and thus face uncertainty.