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IEEE International Electric Machines and Drives Conference

作者： Michele Roffi Fernando J. T. E. Ferreira Anibal T. De Almeida Institute of Systems and Robotics Department of Electrical and Computer Engineering University of Coimbra

ISBN: (纸本)9781509042821

Worldwide electric motor market is moving towards Premium/IE3, Super-Premium/IE4 and Ultra-Premium/IE5 efficiency classes. Therefore, motor manufacturers are constantly improving the overall design of three-phase asynchronous and synchronous motors and all the details with impact in the losses count, even if, individually, they just lead to efficiency gains of a fraction of a percentage point. In industry, most of the self-ventilated motors are driving unidirectional applications, such as fans, pumps, and compressors, and, therefore, the replacement of the typical bidirectional centrifugal fans of the external cooling system with a unidirectional axial fan may lead to a decrease in the acoustic noise and to a gain in the overall motor efficiency. In this paper, numerical simulations and experimental tests of different designs of axial fans and the respective comparison with the traditional centrifugal fans are presented. The tested axial fan prototypes were printed in plastic using a 3D printer. One of the novel axial fan designs led to a slight gain in the motor efficiency, maintaining the same operating temperature. That axial fan can be further optimized in order to require less power, have a better dynamic airflow, and produce less acoustic noise.

关键词： Acoustic noise Axial fan Centrifugal fan CFD Cooling fan Electric motors Fan-cooled motors Motor energy efficiency Self-ventilated motors Self-cooled motors

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3D Object Tracking using RGB and LIDAR Data

3D Object Tracking using RGB and LIDAR Data

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IEEE International Conference on Intelligent Transportation systems

作者： Alireza Asvadi Pedro Girao Paulo Peixoto Urbano Nunes Institute of Systems and Robotics (ISR) Department of Electrical and Computer Engineering (DEEC) University of Coimbra

ISBN: (纸本)9781509018901

Object tracking is one of the key components of the perception system of autonomous cars and ADASs. With tracking, an ego-vehicle can make a prediction about the location of surrounding objects in the next time epoch and plan for next actions. Object tracking algorithms typically rely on sensory data (from RGB cameras or LIDAR). In fact, the integration of 2D-RGB camera images and 3D-LIDAR data can provide some distinct benefits. This paper proposes a 3D object tracking algorithm using a 3D-LIDAR, an RGB camera and INS (GPS/IMU) sensors data by analyzing sequential 2D-RGB, 3D point-cloud, and the ego-vehicle's localization data and outputs the trajectory of the tracked object, an estimation of its current velocity, and its predicted location in the 3D world coordinate system in the next time-step. Tracking starts with a known initial 3D bounding box for the object. Two parallel mean-shift algorithms are applied for object detection and localization in the 2D image and 3D point-cloud, followed by a robust 2D/3D Kalman filter based fusion and tracking. Reported results, from both quantitative and qualitative experiments using the KITTI database demonstrate the applicability and efficiency of the proposed approach in driving environments.

关键词： red-green-blue colour model Lidar two dimentional images Cameras Current velocity Object detection Three Dimensions tracking objects

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Rewinding strategy aided by FEA as a solution to increase efficiency of industrial motors 22

Rewinding strategy aided by FEA as a solution to increase ef...

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22nd International Conference on electrical Machines, ICEM 2016

作者： Aguiar, V.P.B. Pontes, R.S.T. Neto, T. R. Fernandes Ferreira, F.J.T.E. Motor Driven Systems Laboratory Department of Electrical Engineering Federal University of Ceará Fortaleza CE60440554 Brazil Institute of Systems and Robotics Department of Electrical and Computer Engineering University of Coimbra Coimbra Portugal

ISBN: (纸本)9781509025381

This paper presents a proper model and methodology to improve the efficiency class of a squirrel-cage induction motor during rewinding. The modeling approach is based on the finite element model, i.e. two-dimensional model coupled with the rotor equivalent circuit (first stage) and the stator equivalent circuit (second stage). Results obtained with finite element analysis are compared with those obtained with analytical calculations. It is demonstrated that, during rewinding, if an improved winding configuration is used, efficiency gains can be obtained, allowing to improve the efficiency class of the motor, from IE2 to IE3, respecting the specified limits of NEMA & IEC performance indicators, namely, breakdown torque, locked-rotor torque, and locked-rotor current. In 79% of the simulated cases the efficiency gain allowed the studied motor to reach the IE3 class. © 2016 IEEE.

关键词： Frequency domain analysis

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A contribution of demand response for the reliability of a power system 16

A contribution of demand response for the reliability of a p...

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16th International Conference on Environment and electrical engineering, EEEIC 2016

作者： Gaspar, Claudia Gomes, Alvaro Institute of Systems and Robotics Department of Electrical and Computer Engineering University of Coimbra Coimbra3030-290 Portugal INESC Coimbra Department of Electrical and Computer Engineering University of Coimbra Coimbra3030-290 Portugal

ISBN: (纸本)9781509023196

Reliability is a crucial issue in modern power systems, being, in simple words, the ability to continuously and efficiently supply loads without neglecting the quality of service while keeping the power grid stable. In general, reliability can be improved by using more reliable components (generators) or by adding redundancy, being this extra generation known as reserves. Insufficient reserve margin may originate instability and severe problems in power systems. Adequacy is related with the provision of sufficient generation resources to meet the demand and the reserves requirements. The higher the redundancy level the higher the costs, thus a trade-off between the reliability degree and the investment requirements is needed. In this work is investigated if controllable demand can be actively used as an alternative to generation units for guaranteeing adequate reliability indices in short term operation of power systems. The goal is assessing the feasibility of using demand side resources-controllable demand-instead of generation for improving the reliability indices. An evolution strategy has been implemented to design adequate control actions, to be applied over end-use loads, and their impacts on the reliability indices have been assessed. The obtained results showed that, when adequately designed, demand control actions can effectively contribute for a more reliable operation of the power system, being an alternative to the redundant generation in short term. © 2016 IEEE.

关键词： Redundancy

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Selective strong structural minimum cost resilient co-design for regular descriptor linear systems

arXiv

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arXiv 2017年

作者： Popli, Nipun Pequito, Sérgio Kar, Soummya Pedro Aguiar, A. Ilić, Marija Department of Electrical and Computer Engineering Carnegie Mellon University PittsburghPA15213 United States Department of Electrical and Systems Engineering School of Engineering and Applied Science University of Pennsylvania PhiladelphiaPA19104 United States Institute for System and Robotics Instituto Superior Técnico University of Lisbon Lisbon Portugal Porto Portugal

This paper addresses the problem of minimum cost resilient actuation-sensing-communication co-design for regular descriptor systems while ensuring selective strong structural system's properties. More specifically, the problem consists of determining the minimum cost deployment of actuation and sensing technology, as well as communication between the these, such that decentralized control approaches are viable for an arbitrary realization of regular descriptor systems satisfying a pre-specified selective structure, i.e., some entries can be zero, nonzero, or either zero/nonzero. Towards this goal, we rely on strong structural systems theory and extend it to cope with the selective structure that casts resiliency/robustness properties and uncertainty properties of system's model. Upon such framework, we introduce the notion of selective strong structural fixed modes as a characterization of the feasibility of decentralized control laws. Also, we provide necessary and sufficient conditions for this property to hold, and show how these conditions can be leveraged to determine the minimum cost resilient placement of actuation-sensing-communication technology ensuring feasible solutions. In particular, we study the minimum cost resilient actuation and sensing placement, upon which we construct the solution to our problem. Finally, we illustrate the applicability the main results of this paper on an electric power grid example. Copyright © 2017, The Authors. All rights reserved.

关键词： Describing functions

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Dynamics over signed networks

arXiv

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arXiv 2017年

作者： Shi, Guodong Altafini, Claudio Baras, John S. Australian Center for Field Robotics School of Aerospace Mechanical and Mechatronic Engineering University of Sydney NSW Australia Division of Automatic Control Department of Electrical Engineering Linköping University LinköpingSE-58183 Sweden Institute for Systems Research Department of Electrical and Computer Engineering University of Maryland College ParkMD20742 United States

A signed network is a network with each link associated with a positive or negative sign. Models for nodes interacting over such signed networks, where two different types of interactions take place along the positive and negative links, respectively, arise from various biological, social, political, and economic systems. As modifications to the conventional DeGroot dynamics for positive links, two basic types of negative interactions along negative links, namely the opposing rule and the repelling rule, have been proposed and studied in the literature. This paper reviews a few fundamental convergence results for such dynamics over deterministic or random signed networks under a unified algebraic-graphical method. We show that a systematic tool of studying node state evolution over signed networks can be obtained utilizing generalized Perron-Frobenius theory, graph theory, and elementary algebraic recursions. Copyright © 2017, The Authors. All rights reserved.

关键词： Algebra

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Influence of slot geometry on air gap magnetic flux density of rotating machines 16

Influence of slot geometry on air gap magnetic flux density ...

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16th International Conference on Environment and electrical engineering, EEEIC 2016

作者： De Lima, Rodrigo Alves Coimbra, A. C. Paulo Almeida, Tony Gomes, Viviane Margarida Pereira, Thiago Martins Alves, Aylton Jose Calixto, Wesley Pacheco Program in Electronic Systems and Automation PGEA Department of Electrical Engineering ENE University of Brasilia UnB Brazil Institute of Systems and Robotics ISR University of Coimbra UC Portugal Experimental and Technological Research and Study Group NExT Federal Institute of Goias IFG Brazil

ISBN: (纸本)9781509023196

The objective of this work is to investigate the influence of slotted air gap constructive parameters on magnetic flux density of rotating machines. For this purpose, different approaches were used to solve the air gap field diagram using finite element method and the magnetic field distribution uniformity was evaluated by Carter's factor calculation. Sensitivity analysis of slot constructive parameters was performed and results show that slot geometry modifies the magnetic flux on air gap and shifts the air gap magnetic equipotential midline of double slotted machines. © 2016 IEEE.

关键词： Finite element method

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LiDAR-Based control of autonomous rotorcraft for the inspection of pier-like structures: Proofs

arXiv

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arXiv 2017年

作者： Guerreiro, Bruno J. Silvestre, Carlos Cunha, Rita Cabecinhas, David Institute for Systems and Robotics LARSyS Instituto Superior Técnico Universidade de Lisboa Av. Rovisco Pais 1 Lisboa1049 Department of Electrical and Computer Engineering Faculty of Science and Technology University of Macau Taipa Macau IST

This is a complementary document to the paper presented in [1], where more detailed proofs are provided for some results. The main paper addresses the problem of trajectory tracking control of autonomous rotorcraft in operation scenarios where only relative position measurements obtained from LiDAR sensors are possible. The proposed approach defines an alternative kinematic model, directly based on LiDAR measurements, and uses a trajectory-dependent error space to express the dynamic model of the vehicle. An LPV representation with piecewise affine dependence on the parameters is adopted to describe the error dynamics over a set of predefined operating regions, and a continuous-time H2 control problem is solved using LMIs and implemented within the scope of gain-scheduling control theory. In this document, Section A presents the stability analysis of the attitude inner-loop presented in [1, Section II.B], whereas Section B presents a more detailed version of the stability and performance guarantees for the LPV system, extending the results presented in [1, Section IV.A]. Copyright © 2017, The Authors. All rights reserved.

关键词： Continuous time systems

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Webcam-Based Tachometer for In-Field Induction Motor Load Estimation

Webcam-Based Tachometer for In-Field Induction Motor Load Es...

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International Conference on electrical Machines

作者： Fernando J. T. E. Ferreira Fernando J. P. Lopes Institute of Systems and Robotics (ISR-UC) Department of Electrical and Computer Engineering University of Coimbra Dep. of Electrical Engineering Polytechnic Institute of Coimbra (IPC/ISEC)

ISBN: (纸本)9781509025398

Rotational speed measurement is a key issue in most industries, either for process control, characterization or fault diagnosis. In electric motor driven systems it can be used, for example, to estimate the motor load or pulley-belt transmission slip. Encoders and resolvers are typically used for continuous speed monitoring, requiring mechanical coupling with the rotating shaft/part. If the speed is to be measured at a given instant or during a few moments, noninvasive contactless optical tachometers can be used, using optical reflection or stroboscopic principles. In most cases, stroboscopic tachometers require no reflective elements/strips in the rotating part. However, if the user wants to continuously measure the speed of a given rotating part during the audit/characterization period, with real-time data logging and without sticking reflective strips or introducing shaft-coupled encoders/resolvers, there is no low-cost commercial solution to perform such task. For example, if the user's aim is to continuously estimate the load variation of an induction motor over a day or week, on the basis of the slip/speed value, it is not possible with conventional commercial low-cost contactless equipment, unless the user uses expensive online-operation equipment estimating the speed by means of input voltage/current. Moreover, in some rotating systems/parts not directly driven by an electric motor, the online equipment cannot be used and it is not practical, and in some cases even impossible, to couple an encoder/resolver or stick some reflective strips. In this paper, an innovative nonintrusive low-cost webcam-based tachometer is proposed, developed and experimentally tested. It can be used to easily estimate and record the speed over time in, for example, electrical motors, pulleys, shafts and wind turbines.

关键词： In-field speed measurement Motor speed Noninvasive speed measurement Rotational speed Tachometer Video camera Webcam Motor load estimation

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Common spatial pattern with feature scaling (FSc-CSP) for motor imagery classification 17th

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17th International Conference on Asia Simulation, AsiaSim 2017

作者： Prathama, Yohanes de Britto Hertyasta Shapiai, Mohd Ibrahim Aris, Siti Armiza Mohd Ibrahim, Zuwairie Jaafar, Jafreezal Fauzi, Hilman Department of Electronic Systems Engineering Malaysia-Japan International Institute of Technology Universiti Teknologi Malaysia Jalan Sultan Yahya Petra Kuala LumpurWP Kuala Lumpur54100 Malaysia Centre for Artificial Intelligence and Robotics Universiti Teknologi Malaysia Jalan Sultan Yahya Petra Kuala LumpurWP Kuala Lumpur54100 Malaysia Razak School of Engineering and Advanced Technology Universiti Teknologi Malaysia Jalan Sultan Yahya Petra Kuala LumpurWP Kuala Lumpur54100 Malaysia Faculty of Electrical and Electronic Engineering Universiti Malaysia Pahang PekanPahang26600 Malaysia Department of Computer and Information Sciences Faculty of Science and Information Technology Universiti Teknologi Petronas Seri Iskandar Malaysia Faculty of Electrical Engineering Telkom University Bandung Indonesia

ISBN: (纸本)9789811064623

Brain-computer Interface (BCI) is a way to translate human thoughts into computer commands. One of the most popular BCI type is Electroencephalography (EEG)-based BCI, where motor imagery is considered one of the most effective ways. Previously, to extract useful information, various filters are introduced, such as spatial, temporal, and spectral filtering. A spatial filtering algorithm called Common Spatial Pattern (CSP) was developed and known to have excellent performance, especially in motor imagery for BCI application. In general, there are several approaches in improving CSP such as regularization approach, analytic approach, and frequency band selection. In general, the existing techniques for band selection is either to select or reject the band by ignoring the importance of the band. For example, Binary Particle Search Optimization Common Spatial Pattern (BPSO-CSP) was proposed to choose multiple possible best bands to be used in processing the data. In this paper, we propose an algorithm called Feature Scaling Common Spatial Pattern (FSc-CSP) to overcome the problem of feature selection. Instead of selecting features, the proposed algorithm employs a feature scaling system to scale the importance of each band by using Genetic Algorithm (GA) altogether with Extreme Learning Machine (ELM) as classifier, with 1 signifying the most important bands, declining until 0 for the unused bands, as opposed to the 1 and 0 selection system used in BPSO-CSP. Conducted experiments show that by employing feature scaling, better results can be achieved especially compared to vanilla CSP and feature selection with 100 hidden nodes in three from five BCI Competition III datasets IVa, namely aa, aw and ay, with around 5–8% better results compared to vanilla CSP and feature selection. © Springer Nature Singapore Pte Ltd. 2017.

关键词： Brain computer interface

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