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IEEE International Conference on Acoustics, Speech, and Signal Processing

作者： Pinar Oguz-Ekim Joao Gomes Joao Xavier Paulo Oliveira Institute for Systems and Robotics-Instituto Superior Tecnico Department of Electrical and Computer Engineering Lisboa Portugal

ISBN: (纸本)9781424442959

This paper addresses the problem of locating a single source from noisy range measurements in wireless sensor networks. An approximate solution to the maximum likelihood location estimation problem is proposed, by redefining the problem in the complex plane and relaxing the minimization problem into semidefinite programming form. Existing methods solve the source localization problem either by minimizing the maximum likelihood function iteratively or exploiting other semidefinite programming relaxations. In addition, using squared range measurements, exact and approximate least squares solutions can be calculated. Our relaxation for source localization in the complex plane (SLCP) is motivated by the near-convexity of the objective function and constraints in the complex formulation of the original (non-relaxed) problem. Simulation results indicate that the SLCP algorithm outperforms existing methods in terms of accuracy, particularly in the presence of outliers and when the number of anchors is larger than three.

关键词： Single source localization maximum likelihood estimation nonconvex and nonsmooth minimization semidefinite programming maximum likelihood estimation Position measurement Ranging measurements Complex Plane maximum likelihood relaxation Boat anchors outliers Objective function Wireless sensor networks

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Three phase tooth-concentrated interspersed windings with low space harmonic content

Three phase tooth-concentrated interspersed windings with lo...

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International Conference on electrical Machines, ICEM

作者： Mihail V. Cistelecan Fernando J.T.E. Ferreira Mihail Popescu Institute of Electrical Machines Bucharest Romania Department of Electrical Engineering of the Engineering Institute of Coimbra (ISEC) Institute of Systems and Robotics University of Coimbra Coimbra Portugal

The paper presents a new possibility of obtaining lower space harmonic content for the fractional-slot, tooth-concentrated windings by interspersing the phase windings. By using multiple layer windings it is possible to reduce or even to cancel some space sub-harmonics having as final result lower eddy current losses induced by the armature reaction in the iron structure of the rotor. The general method of multiplying the winding and relatively shifting by one (or more) slots is presented in the paper. The application of the method is developed for the general case of the windings having Z=2p±1 where, instead of double layers winding, the partial three or even four layers winding is obtained. The example of application is given for 15 slots, 14 poles, three phase concentrated windings which is presented and analyzed as primitive windings.

关键词： Windings Coils Harmonic analysis Teeth Wounds Rotors Equations

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Fault detection and isolation of an aircraft using set-valued observers

Fault detection and isolation of an aircraft using set-value...

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18th IFAC Symposium on Automatic Control in Aerospace, ACA 2010

作者： Rosa, Paulo Silvestre, Carlos Shamma, Jeff S. Athans, Michael Institute for Systems and Robotics Instituto Superior Tecnico Av. Rovisco Pais 1 1049-001 Lisboa Portugal Georgia Institute of Technology School of Electrical and Computer Engineering Atlanta GA United States Department of EECS MIT United States

ISBN: (纸本)9783902661968

This paper describes an application of a new fault detection and isolation (FDI) technique based on set-valued observers (SVOs) to a linear parameter varying (LPV) longitudinal aircraft dynamic model. The FDI strategy adopted herein computes and uses the set-valued estimates of the SVOs to eliminate models of the plant that are not compatible with the set of observations provided by the aircraft sensor suite and actuation data. The design of the SVOs takes into account model uncertainty and disturbances, thus avoiding false alarms due to such perturbations. The behavior of the proposed solution is assessed in simulation, by deliberately generating hard and soft sensor/actuator faults. The results show that the faults take, in general, only a few iterations to be detected and isolated, therefore paving the way for the use of the proposed methodology in practical applications.

关键词： Linear systems

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Preface

Communications and Control Engineering

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Communications and Control engineering 2011年第9780857292551期 vii-xi页

作者： Sun, Zhendong Ge, Shuzhi Sam College Automation Science & Engineering Center for Control and Optimization South China University of Technology Guangzhou510640 China Robotics Institue and Institute of Intelligent Systems and Information Technology University of Electronic Science and Technology of China Chengdu China Department of Electrical and Computer Engineering The National University of Singapore Singapore Singapore

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Three phase tooth-concentrated multiple-layer fractional windings with low space harmonic content

Three phase tooth-concentrated multiple-layer fractional win...

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IEEE Energy Conversion Congress and Exposition, ECCE

作者： Mihail V. Cistelecan Fernando J. T. E. Ferreira Mihail Popescu Research Institute of Electrical Machines Romania Department of Electrical Engineering of the Engineering Institute of Coimbra (ISEC) Coimbra Portugal Institute of Systems and Robotics University of Coimbra Portugal

The possibility of obtaining lower space harmonic content for the fractional-slot, tooth-concentrated windings by multiplying the number of coils, leading to bigger number of layers in the armature slots is presented. By using multiple layer windings it is possible to reduce or even to cancel some space sub-harmonics having as final result lower eddy current losses induced by the armature reaction in the iron structure of the rotor. The general method of doubling (or trebling) the winding and relatively shifting by one (or more) slots is presented in the paper. Two examples of three phase concentrated windings are presented and analyzed as primitive windings, 12 slots/10poles and 9 slots/8 poles. In the first case the only existing space sub-harmonic is reduced firstly from 35.9% (from fundamental wave) to 9.6% and finally it is canceled by using different number of turns per coils. In the second case the two existing sub-harmonics are reduced and balanced by using the developed method.

关键词： Windings Harmonic analysis Coils Teeth Wounds Rotors Armature

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A face attention technique for a robot able to interpret facial expressions

IFIP Advances in Information and Communication Technology

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IFIP Advances in Information and Communication Technology 2010年 314卷 335-342页

作者： Simplício, Carlos Prado, José Dias, Jorge Institute of Systems and Robotics Department of Electrical Engineering and Computers University of Coimbra Coimbra Portugal School of Technology and Management Institute Polytechnic of Leiria Leiria Portugal

ISBN: (纸本)9783642116278

Automatic facial expressions recognition using vision is an important subject towards human-robot interaction. Here is proposed a human face focus of attention technique and a facial expressions classifier (a Dynamic Bayesian Network) to incorporate in an autonomous mobile agent whose hardware is composed by a robotic platform and a robotic head. The focus of attention technique is based on the symmetry presented by human faces. By using the output of this module the autonomous agent keeps always targeting the human face frontally. In order to accomplish this, the robot platform performs an arc centered at the human;thus the robotic head, when necessary, moves synchronized. In the proposed probabilistic classifier the information is propagated, from the previous instant, in a lower level of the network, to the current instant. Moreover, to recognize facial expressions are used not only positive evidences but also negative. © 2010 Springer Berlin Heidelberg.

关键词： Human robot interaction

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Vision-based quadrotor stabilization using a pan and tilt camera

Vision-based quadrotor stabilization using a pan and tilt ca...

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2010 49th IEEE Conference on Decision and Control

作者： D. Cabecinhas C. Silvestre R. Cunha Department of Electrical Engineering and Computer Science and Institute for Systems and Robotics Instituto Superior Tecnico 1049-001 Lisboa Portugal

ISBN: (纸本)9781424477456

This paper proposes a nonlinear control architecture for the stabilization of a quadrotor vehicle based on image measurements of a set of landmarks obtained from a pan and tilt camera. The vehicle is stabilized vertically using an additional vertical position sensor and lateral-longitudinal stabilization is achieved with a nested saturation control law by feedback of image measurements, body attitude, and angular rate. Additionally, the pan and tilt camera is actively actuated to to keep the landmarks visible in the image sensor for most operating conditions. Simulation results are presented to assess the performance of the proposed control architecture.

关键词： Control Architecture Sensors (image) Cameras TILT landmarks position sensor

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Impact of voltage sags and continuous unbalance on variable-speed drives

Impact of voltage sags and continuous unbalance on variable-...

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International Conference on electrical Machines, ICEM

作者： Fernando J. T. E. Ferreira Anibal T. de Almeida Ge Baoming Institute of Systems and Robotics Polo II University of Coimbra Coimbra Portugal Department of Electrical Engineering Engineering Institute of Coimbra Coimbra Portugal School of Electrical Engineering Beijing Jiaotong University Beijing China

The use of variable-speed drives (VSDs) is increasing fast. The operation and the output voltage quality of such devices can be significantly affected by power supply voltage sags and continuous unbalance, ultimately influencing the performance of the controlled motor. This paper presents an analysis of the impact of such power supply anomalies on VSDs with 3-phase diode rectifier and PWM voltage-source inverter, which are the most used in the low/medium power range. In VSD applications requiring ride-through capability to voltage sags, the investment in extra DC-bus capacitance can be cost-effective, particularly when the motor driven system stop leads to significant injuries, including loss of production. The extra DC-bus capacitance also improves the output voltage in VSDs fed from unbalanced power supplies.

关键词： Capacitance Inverters Voltage fluctuations Harmonic analysis Power quality Rectifiers

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On asymptotic consensus value in directed random networks

On asymptotic consensus value in directed random networks

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IEEE Conference on Decision and Control

作者： Victor M. Preciado Alireza Tahbaz-Salehi Ali Jadbabaie Department of Electrical and Systems Engineering University of Pennsylvania Philadelphia PA USA Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA USA General Robotics Automation Sensing and Perception (GRASP) Laboratory Department of Electrical and Systems Engineering University of Pennsylvania Philadelphia PA USA

ISBN: (纸本)9781424477456

We study the asymptotic properties of distributed consensus algorithms over switching directed random networks. More specifically, we focus on consensus algorithms over independent and identically distributed, directed random graphs, where each agent can communicate with any other agent with some exogenously specified probability. While different aspects of consensus algorithms over random switching networks have been widely studied, a complete characterization of the distribution of the asymptotic value for general asymmetric random consensus algorithms remains an open problem. In this paper, we derive closed-form expressions for the mean and an upper bound for the variance of the asymptotic consensus value, when the underlying network evolves according to an i.i.d. directed random graph process.

关键词： Eigenvalues and eigenfunctions Switches Markov processes Silicon Upper bound Closed-form solution Convergence

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Multiple marine vehicle deconicted path planning with currents and communication constraints

Multiple marine vehicle deconicted path planning with curren...

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作者： Häusler, Andreas J. Ghabcheloo, Reza Pascoal, António M. Aguiar, A. Pedro Institute for Systems and Robotics Dept. of Electrical Engineering Instituto Superior Técnico Av. Rovisco Pais No. 1 1049-001 Lisboa Portugal Department of Intelligent Hydraulics and Automation Tampere Univ. of Technology P.O. Box 589 33101 Tampere Finland

ISBN: (纸本)9783902661876

Recent research in multiple autonomous marine vehicle (AMV) applications shows that versatile path planning algorithms are of crucial importance to cooperative control scenarios. These algorithms need to be lightweight in terms of running time and capable of incorporating different factors inuencing a given mission, like AMV dynamic constraints and environmental conditions. In addition, the path planner needs to take into account requirements imposed by multiple vehicle scenarios (of which collision avoidance is an important issue), and inter-vehicle communication constraints. Mission-related measures have to be incorporated additionally, such as minimization of energy usage over all participating AMVs, and simultaneous arrival of the AMVs at their designated target destinations, to name but a few. These aspects pose considerable challenges both from a theoretical and practical implementation standpoint. This paper presents a versatile path planning algorithm for deconicted multiple AMV missions at sea, incorporating single vehicle dynamical constraints as well as an inter-vehicle communication constraint. Additionally, it takes into account unknown constant ocean currents, and gives an overview on time-coordinated path following, a a closed-loop methodology to execute the planned mission, reducing the need for replanning in the presence of disturbances. The paper finishes with an outlook on important future directions to advance the algorithm.

关键词： Motion planning

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