CRIIS - Other Publications

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    3-D Position Estimation from Inertial Sensing: Minimizing the Error from the Process of Double Integration of Accelerations
    ( 2013) Neto,P ; Norberto Pires,JN ; António Paulo Moreira
    This paper introduces a new approach to 3-D position estimation from acceleration data, i.e., a 3-D motion tracking system having a small size and low-cost magnetic and inertial measurement unit (MIMU) composed by both a digital compass and a gyroscope as interaction technology. A major challenge is to minimize the error caused by the process of double integration of accelerations due to motion (these ones have to be separated from the accelerations due to gravity). Owing to drift error, position estimation cannot be performed with adequate accuracy for periods longer than few seconds. For this reason, we propose a method to detect motion stops and only integrate accelerations in moments of effective hand motion during the demonstration process. The proposed system is validated and evaluated with experiments reporting a common daily life pick-and-place task.
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    Anechoic Chamber Interference Tests on a Bluetooth Low Energy Front-End Towards a Subcutaneous Glucose Sensor
    ( 2012) Sérgio Santos Silva ; António Paulo Moreira ; Salviano Soares ; António Valente
    Background: The metabolic disorder which entails the absent or reduced control of blood glucose in the body by means of insulin dependence (Type 1) or intolerance (Type 2) affected more than 382 million people in 2013. Although only 13% of patients die from diabetes, there are a significant number of costly, dangerous health complications that appear if the correct control is not taken. Glucose subcutaneous Bluetooth Low-Energy sensor can help patients to constantly monitor their glucose levels and issue alarms to a cellular phone. Several tests regarding interference, robustness and coexistence were made to ensure Quality of Service in order to achieve medical diagnostic status. Materials and Methods: All measurements were performed in a full anechoic chamber with walls, ceiling and floor covered with high loss microwave absorbers. A PC USB Dongle acts as receiver for the Java developed application, where several data sets for each location were recorded.
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    DEVELOPMENT OF A QUADRUPED ROBOT MODEL IN SIMMECHANICS (TM)
    ( 2013) Manuel Santos Silva ; Barbosa,RS ; Castro,TS
    The presented work allowed the creation of a quadruped robot model (with flexible body, its legs and its hip and knee joints) in the virtual simulation program Simmechanics (TM). The final objective is to use this simulation model to optimize quadruped robot locomotion. The model developed accepts different gaits by direct introduction of the angular positions of the knee and hip joints. Feet-ground interaction was also modelled using a theoretic model described in the literature.
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    Development of a quadruped robot model in simmechanicsTM
    ( 2013) Manuel Santos Silva ; Barbosa,RS ; Castro,TS
    The presented work allowed the creation of a quadruped robot model (with flexible body, its legs and its hip and knee joints) in the virtual simulation program SimmechanicsTM. The final objective is to use this simulation model to optimize quadruped robot locomotion. The model developed accepts different gaits by direct introduction of the angular positions of the knee and hip joints. Feet-ground interaction was also modelled using a theoretic model described in the literature.
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    Diffusion of innovation simulation using an evolutionary Algorithm
    ( 2013) Sampaio,L ; Varajao,J ; Eduardo Pires ; Paulo Moura Oliveira
    The diffusion of innovation theory aims to explain how new ideas and practices are disseminated among social system members. A significant number of the existing models is based on the use of parameters which determine the process of innovation adoption, and rely on simple mathematical functions centered in the observation and description of diffusion patterns. These models enable a more explicit diffusion process study, but their use involves the estimation of diffusion coefficients, usually obtained from historical data or chronological series. This raises some application problems in contexts where there is no data or the data is insufficient. This paper proposes the use of evolutionary computation as an alternative approach for the simulation of innovation diffusion within organizations. To overcome some of the problems inherent to existing models an evolutionary algorithm is proposed based on a probabilistic approach. The results of the simulations that were done to validate the algorithm revealed to be very promissing in this context. Simulation experiment results are presented that reveals a very promising approach of the proposed model. © 2013 Springer-Verlag Berlin Heidelberg.
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    Editorial of the topical collection "state of the art on autonomous robot systems and competitions"
    ( 2021) Lau,N ; Manuel Santos Silva ; Luís Paulo Reis ; Cascalho,JM ; 5655 ; 5741
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    Entropy Diversity in Multi-Objective Particle Swarm Optimization
    ( 2013) Eduardo Pires ; Tenreiro Machado,JAT ; Paulo Moura Oliveira
    Multi-objective particle swarm optimization (MOPSO) is a search algorithm based on social behavior. Most of the existing multi-objective particle swarm optimization schemes are based on Pareto optimality and aim to obtain a representative non-dominated Pareto front for a given problem. Several approaches have been proposed to study the convergence and performance of the algorithm, particularly by accessing the final results. In the present paper, a different approach is proposed, by using Shannon entropy to analyze the MOPSO dynamics along the algorithm execution. The results indicate that Shannon entropy can be used as an indicator of diversity and convergence for MOPSO problems.
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    Erratum: Corrigendum to ‘Design of Posicast PID control systems using a gravitational search algorithm’  (Neurocomputing (2015) 167 (18–23)(S0925231215005597)(10.1016/j.neucom.2014.12.101))
    ( 2016) Paulo Moura Oliveira ; Eduardo Pires ; Novais,P
    The author's wishes to make the following correction: all the IAE values presented in the paper are multiplied by a factor of 100. The authors would like to apologise for any inconvenience caused. © 2015 Elsevier B.V.
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    The European Project Semester at ISEP Learning to Learn Engineering
    ( 2013) Benedita Malheiro ; Manuel Santos Silva ; Ribeiro,MC ; Guedes,P ; Ferreira,P
    The European Project Semester at ISEP (EPS@ISEP) is a one semester project-based learning programme addressed to engineering students from diverse scientific backgrounds and nationalities. The students, organized in multicultural teams, are challenged to solve real world multidisciplinary problems, accounting for 30 ECTU. The EPS package, although focused on project development (20 ECTU), includes a series of complementary seminars aimed at fostering soft, project-related and engineering transversal skills (10 ECTU). This paper presents the study plan, resources, operation and results of the EPS@ISEP that was created in 2011 to apply the best engineering education practices and promote the internationalization of ISEP. The results show that the EPS@ISEP students acquire during one semester the scientific, technical and soft competences necessary to propose, design and implement a solution for a multidisciplinary problem.
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    Evaluation of sensors and algorithms for person detection for personal robots
    ( 2013) Tonelo,C ; António Paulo Moreira ; Germano Veiga
    The main objective of this project was to evaluate the sensing system for person detection in the scope of its integration in a mobile robotic platform for Ambient Assisted Living. Two sensors were considered, a camera and a depth sensor. For the camera (2D), 3 different algorithms were implemented: face detection, tracking and recognition. For the depth sensor the whole body detection was tested using skeleton tracking. The results showed that the face detection and recognition algorithms had a very small range, and the face tracking demonstrated to reach a higher distance. However, the latter exhibited poor results when confronted with illumination variations. The skeleton tracking algorithm provided good results, being capable of tracking relatively close to the sensor and up to 3 meters distance. Thus, the 2D face recognition can be used for short distances to identify the person, while the 3D skeleton tracking can be appropriated for distant tracking of the person. This work showed that the integration of these sensing systems, in a robotic platform, can make a robust robot capable of human interaction in home environments. © 2013 IEEE.
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    Fast 3D Map Matching Localisation Algorithm
    ( 2013) Pinto,M ; António Paulo Moreira ; Aníbal Matos ; Héber Miguel Sobreira ; Filipe Neves Santos
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    FEUPCAR 2.0: Overview of a Low-cost Robot for Autonomous Driving Competitions
    ( 2013) Vidal,AA ; Luís Paulo Reis ; António Paulo Moreira
    Robotic autonomous driving is a very complex task that tries to replicate the human behavior when performing such task. This paper presents a high-level overview of an architecture applicable for small-scale vehicles in autonomous driving competitions. A special emphasis is given on the sensory and navigation sub-systems since they are the most prominent intelligent decision layers. The former is almost entirely based on computer vision, processing the raw image content from two ordinary and inexpensive "web-cams", conveying further relevant information to the later, on a real-time basis. The proposed architecture was implemented with minimal interventions to an Ackermann-like vehicle which was originally designed for recreational purposes, serving as a "proof of concept" of the developed system. Results show that a low-cost, scalable and modular system can be easily integrated on regular small-scale vehicles obtaining exciting results at a minimal cost.
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    Humanoid Gait Optimization Resorting to an Improved Simulation Model
    ( 2013) José Lima ; José Alexandre Gonçalves ; Paulo José Costa ; António Paulo Moreira
    The simulation of a robot with a high number of joints can easily become unstable. Numerical errors on the first joint of the chain are propagated to the other joints. This is a very common problem in humanoid robots. A way to plan the gait for these robots is using simulation and optimization techniques. This paper addresses a new approach to optimizing gait parameter sets using an adaptive simulated annealing optimization algorithm, combined with a new joint model that reduces its instability. The new model and the optimization are implemented in SimTwo (a developed physical robot simulator that is capable of simulating user defined robots in a three-dimensional space, since it includes a physical model based on rigid body dynamics) and results are shown that validate the approach.
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    Identifying different visual patterns in web users behaviour
    ( 2013) Goncalves,M ; Tânia Vilela Rocha ; Luís Gonzaga Magalhães ; Emanuel Peres Correia ; Maximino Bessa ; Chalmers,A
    On the internet one can find all kinds of information and perform a multitude of tasks such as searching for information about any subject, purchase goods and services, or enquiring about a particular company. When navigating the web, our focus (where we look) can be captured involuntary through a visual stimulus, or may be directed in a controlled manner depending on the task that we are performing. The layouts of web sites range from simple to highly complex. When creating new layouts, knowing what information is most important when a user is performing a task and which areas are supposed to attract his/her attention are important issues in order to make a web site easier to interpret and consequently their usability. In this paper we present an eye tracking study of users' visual behaviour when surfing on websites and investigate if it is possible to determine likely visual patterns. We show that the visual patterns are different depending on the task that is being performed and not on the web site where it is being carried out. © 2011 ACM.
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    Increasing Illumination Invariance of SURF Feature Detector through Color Constancy
    ( 2013) Petry,MR ; António Paulo Moreira ; Luís Paulo Reis
    Most of the original image feature detectors are not able to cope with large photometric variations, and their extensions that should improve detection eventually increase the computational cost and introduce more noise to the system. Here we extend the original SURF algorithm increasing its invariance to illumination changes. Our approach uses the local space average color descriptor as working space to detect invariant features. A theoretical analysis demonstrates the impact of distinct photometric variations on the response of blob-like features detected with the SURF algorithm. Experimental results demonstrate the effectiveness of the approach in several illumination conditions including the presence of two or more distinct light sources, variations in color, in offset and scale.
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    An Industrial Robotics Course Based on a Graphical Simulation Package
    ( 2013) Manuel Santos Silva
    In recent years there has been an increasing introduction of industrial robots in the manufacturing industry, with several studies that predict the increased dissemination of robots in industrial and service sectors. On the other hand, there is often the lack of people able to plan the introduction of these equipments in manufacturing environments and to operate it after its inception. This leads to the need to train undergraduates in the operation and programming of industrial robots. Due to the Portuguese economic situation, there is a lack of funding for the higher schools, leading to the need of finding innovative ways to teach these subjects. Bearing in mind these ideas, in this paper is described a course on industrial robotics, which is based in the achievement of the practical training using commercial off-theshelf robot simulation software for off-line programming.
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    Intelligent state changing applied to multi-robot systems
    ( 2013) Nascimento,TP ; António Paulo Moreira ; Scolari Conceicao,AGS ; Bonarini,A
    The target searching problem is a situation where a formation of multi-robot systems is set to search for a target and converge towards it when it is found. This problem lies in the fact that the target is initially absent and the formation must search for it in the environment. During the target search, false targets may appear dragging the formation towards it. Therefore, in order to avoid the formation following a false target, this paper presents a new methodology using the Takagi-Sugeno type fuzzy automaton (TS-TFA) in the area of formation control to solve the target searching problem. The TS fuzzy system is used to change the formation through the modifications in the states of the automaton. This change does not only switch the rules and therefore the state of each robot, but also the controllers and cost functions. This approach amplifies the versatility of the formation of mobile robots in the target searching problem. In this paper, the TS-TFA is presented and its implications in the formation are explained. Simulations and results with real robot are presented where it can be noticed that the formation is broken to maximize the perception range based on each robot's observation of a possible target. Finally this work is concluded in the last section.
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    IntellWheels: Intelligent wheelchair with user-centered design
    ( 2013) Petry,MR ; António Paulo Moreira ; Brígida Mónica Faria ; Luís Paulo Reis
    Intelligent wheelchairs can become an important solution to assist physically impaired individuals who find it difficult or impossible to drive regular powered wheelchairs. However, when designing the hardware architecture several projects compromise the user comfort and the wheelchair normal usability in order to solve robotic problems. In this paper we describe the main concepts regarding the design of the IntellWheels intelligent wheelchair. Our approach has a user-centered perspective, in which the needs and limitations of physically impaired users are given extensive attention at each stage of the design process. Finally, our design was evaluated through a public opinion assessment. A statistical analysis suggested that the design was effective to mitigate the visual and ergonomic impacts caused by the addition of sensorial and processing capabilities on the wheelchair. © 2013 IEEE.
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    Introduction to the Special Issue “Robotica 2016”
    ( 2019) José Lima ; Cunha,B ; Manuel Santos Silva ; Leitao,P ; 5156 ; 5655