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Nonlinear adaptive dept. tracking and attitude control of an underwater towed vehicle

IFAC Proceedings Volumes 2009年第18期42卷 211-216页

作者： Francisco Curado Teixeira Antonio Pedro Aguiar Antonio Pascoal Centre for Environmental and Marine Studies University of Aveiro Portugal Institute for Systems and Robotics and Dept. Electrical Engineering Instituto Superior Técnico

This paper addresses the problem of simultaneous dept. tracking and precise attitude control of an underwater towed vehicle integrated in a two-stage towing arrangement. A nonlinear Lyapunov-based output feedback controller is designed to operate in the presence of plant parameter uncertainty and proven to regulate pitch, yaw, and dept. tracking errors to zero. When subjected to bounded external disturbances, the tracking errors converge to a neighborhood of the origin that can be made arbitrarily small. In the implementation proposed, a nonlinear observer is used to estimate the linear velocities used by the controller. The results obtained with computer simulations including sea wave driven disturbances and sensor noise, show that the controlled system exhibits good performance about different operating conditions and holds considerable potential for oceanographic missions that require simultaneous dept. and attitude control.

关键词： Nonlinear control adaptive control Lyapunov methods trajectory tracking underwater towed vehicle

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Aspect ratio dependent etch modulation for CMOS-MEMS applications

Aspect ratio dependent etch modulation for CMOS-MEMS applica...

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TRANSDUCERS 2009 - 15th International Conference on Solid-State Sensors, Actuators and Microsystems

作者： Gilgunn, P.J. Alfaro, J.F. Fedder, G.K. Electrical and Computer Engineering Dept. Carnegie Mellon University Pittsburgh PA United States Institute for Complex Engineered Systems Carnegie Mellon University Pittsburgh PA United States Robotics Institute Carnegie Mellon University Pittsburgh PA United States Silicon Microstructures Inc. Milpitas CA United States

ISBN: (纸本)9781424441938

A unified, semi-empirical model of etch dept. for a Bosch-type, inductively coupled plasma (ICP), silicon deep reactive ion etch (DRIE) process is reported. Aspect ratio dependent etch modulation (ARDEM) is modeled using Coburn and Winters' approach with Dushman's approximation of the vacuum conductance correction factor. The use of microdonut test structures to extract model parameters is described. The model is accurate to within 9% for an open-field dept. of 150 μm on microdonut test structures. An application of ARDEM in the processing of CMOS-MEMS devices is presented. ©2009 IEEE.

关键词： Modulation

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Continuous-time consensus with discrete-time communication

Continuous-time consensus with discrete-time communication

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European Control Conference (ECC)

作者： João Almeida Carlos Silvestre António M. Pascoal Panos J. Antsaklis Institute for Systems and Robotics Instituto Superior Técnico Lisboa Portugal Dept. of Electrical Engineering Univ. of Notre Dame IN USA

This paper describes a solution to a consensus problem whereby a group of agents evolve in continuous-time and exchange information at discrete instants of times. In the setup adopted each agent is viewed as a node in a graph, its evolution is represented by a scalar node variable, and all agents seek to agree on a common value. The agents are allowed to exchange information among each other but only at specified update times. The topology of the communication network can change over time and the information received by one agent from a subset of the other agents may be outdated. The solution proposed relies on the introduction of an extra variable for each agent that is updated instantaneously at update times. In between updates, both the node and the extra variables evolve in a continuous fashion. The proof that consensus is achieved is done by reducing the system under study to a discrete-time equivalent one and resorting to results on consensus for discrete-time systems.

关键词： Delays Delay effects Topology Convergence Equations Europe Vectors

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Temporally and spatially deconflicted path planning for multiple autonomous marine vehicles

Temporally and spatially deconflicted path planning for mult...

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作者： Häusler, Andreas J. Ghabcheloo, Reza Pascoal, António M. Aguiar, A. Pedro Kaminer, Isaac I. Dobrokhodov, Vladimir N. 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 Department of Mechanical and Astronautical Engineering Naval Postgraduate School Monterey CA 93943 United States

ISBN: (纸本)9783902661517

There is currently a surge of interest in the development of advanced systems for cooperative control of multiple autonomous marine vehicles. Central to the implementation of these systems is the availability of efficient algorithms for multiple vehicle path planning that can take explicitly into account the capabilities of each vehicle and existing environmental conditions. Multiple vehicle path planning methods build necessarily on key concepts and algorithms for single vehicle path following. However, they go one step further in that they must explicitly address intervehicle collision avoidance, together with a number of criteria that may include simultaneous times of arrival at the assigned target points and energy minimization, to name but a few. As such, they pose considerable challenges both from a theoretical and practical implementation standpoint. This paper is a short overview of multiple vehicle path planning techniques. The exposition is focused on specific algorithms developed in the scope of research work in which the authors have participated. Namely, algorithms that ensure that at no time will two vehicles get closer in space than a desired safety distance, that is, achieve trajectory deconfliction. The algorithms make ample use of direct optimization methods that lead to efficient and fast techniques for path generation using a polynomial-based approach. The paper affords the reader a fast paced presentation of key algorithms that had their genesis in the aircraft field, discusses the results of simulations, and suggests problems that warrant further consideration. © 2009 IFAC.

关键词： Motion planning

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An efficient algorithm for extrinsic calibration between a 3D laser range finder and a stereo camera for surveillance

An efficient algorithm for extrinsic calibration between a 3...

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International Conference on Advanced robotics (ICAR)

作者： H. Aliakbarpour P. Nunez J. Prado K. Khoshhal J. Dias Dept. Electrical and Computer Engineering University of Coimbra Portugal Portugal ISIS Group Universidad de Málaga Spain Dept. Tecnología de los Computadores y las Comunicaciones Universidad de Extremadura Spain Institute of Systems and Robotics Department Electrical and Computer Engineering University of Coimbra Portugal

The combined use of 3D laser range finders (LRF) and cameras is increasingly common in the navigation application for autonomous mobile robots. The integration of laser range information and images requires the estimation of the Euclidean 3-dimensional transformation between the coordinate systems of the LRF and the cameras. This paper describes a new and efficient method to perform the extrinsic calibration between a 3D LRF and a stereo camera with the aid of inertial data. The main novelty of the proposed approach compared to other state of the art calibration procedures is the use of an inertial measurement unit (IMU), which decreases the number of points needed to a robust calibration. Furthermore, a freely moving bright spot is the only calibration object. A set of virtual 3D points is made by waving the bright spot through the working volume in three different planes. Its projections onto the images are found with sub-pixel precision and verified by a robust RANSAC analysis. These same points are extracted according to the laser scan data and are corresponded to the virtual 3D points in the stereo pair. Experimental results presented in this paper demonstrate the accuracy of our approach. Furthermore, the applicability of the proposed technique is high, only requiring of an inertial sensor coupled to the sensor platform. This approach has been also extended for a camera network.

关键词： Calibration Cameras Surveillance Robot vision systems Robustness Navigation Mobile robots Measurement units Image analysis Data mining

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Novelty detection and 3D shape retrieval based on Gaussian Mixture Models for autonomous surveillance robotics

Novelty detection and 3D shape retrieval based on Gaussian M...

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2009 IEEE/RSJ International Conference on Intelligent Robots and systems

作者： P. Núñez P. Drews R. Rocha M. Campos J. Dias ISIS Group Universidad de Málaga Spain Dept. Tecnologia de los Computadores y las Comunicaciones Universidad de Extremadura Spain Institute of Systems and Robotics Department Electrical and Computer Engineering University of Coimbra Portugal Dept. Computer Science Federal University of Minas Gerais Brazil Dept. Electrical and Computer Engineering University of Coimbra Portugal

This paper describes an efficient method for retrieving the 3-dimensional shape associated to novelties in the environment of an autonomous robot, which is equipped with a laser range finder. First, changes are detected over the point clouds using a combination of the Gaussian mixture model (GMM) and the earth mover's distance (EMD) algorithms. Next, the shape retrieval is achieved using two different algorithms. First, new samplings are generated from each Gaussian function, followed by a random sampling consensus (RANSAC) algorithm to retrieve geometric primitives. Furthermore, a new algorithm is developed to directly retrieve the shape according to the mathematical space of Gaussian mixture. In this paper, the set of geometric primitives has been limited to the set C = {sphere, cylinder, plane} . The two shape retrieval methods are compared in terms of computational cost and accuracy. Experimental results in various real and simulated scenarios demonstrate the feasibility of the approach.

关键词： Shape Surveillance Intelligent robots Mobile robots Simultaneous localization and mapping Clouds Sampling methods Navigation Robotic assembly Change detection algorithms

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Cooperative Autonomous Marine Vehicle motion control in the scope of the EU GREX Project: Theory and Practice

Cooperative Autonomous Marine Vehicle motion control in the ...

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OCEANS - Europe

作者： A. Aguiary J. Almeiday M. Bayaty B. Cardeiray R. Cunhay A. Hauslery P. Mauryay A. Oliveiray A. Pascoaly A. Pereira M. Rufinoy L. Sebastiaoy C. Silvestrey F. Vanniy Dept. Electrical Engineering and Institute for Systems and Robotics (ISR) Instituto Superior Tecnico (IST) Lisbon Portugal Department Computer Science University슠of슠Southern California USA Dept. Computer Science Univ. Southern California (USC) USA

This paper describes the core of the research work done by the ISR/IST team on cooperative autonomous marine vehicle (AMV) motion control in the scope of the EU Project GREX - coordination and control of cooperating heterogeneous unmanned systems in uncertain environments. The first part of the paper affords the reader a concise introduction to the general problem of cooperative motion control of fleets of AMVs by highlighting illustrative mission scenarios developed collectively by the GREX partners and summarizing the main challenges that they pose to system engineers. This is followed by the description of a general architecture for cooperative autonomous marine vehicle control in the presence of time-varying communication topologies and communication losses that is rooted in a solid control-theoretic framework. The results of simulations with the NetMar SyS - networked marine systems simulator - of ISR/IST are presented and show the efficacy of the algorithms developed for cooperative motion control. The last part of the paper focuses on practical issues and describes the results of tests at sea in the Azores, in the Summer of 2008. The paper concludes with a critical review of the work done and a discussion of theoretical and practical implementation issues that warrant further research and development effort.

关键词： Marine vehicles Motion control Communication system control Control systems Automotive engineering systems engineering and theory Network topology Solids Testing Research and development

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A General Framework for Multiple Vehicle Time-Coordinated Path Following Control

A General Framework for Multiple Vehicle Time-Coordinated Pa...

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2009 American Control Conference (ACC 2009)

作者： Reza Ghabcheloo Isaac Kaminer A. Pedro Aguiar Antonio Pascoal Department of Inteligent Hydraulics and Automation Tampere Univ of Technology P.O.Box 589 33101 Tampere Finland Department of Mechanical and Astronautical Engineering Naval Postgraduate School Monterey CA 93943 USA Dept. Electrical Engineering and Computers and the Institute for Systems and Robotics Instituto Superior Tecnico Av. Rovisco Pais 1 1049-001 Lisboa Portugal

ISBN: (纸本)9781424445233

This paper describes a general framework for the study of multiple vehicle, time-coordinated path following (TC-PF) control problems. An example is the situation where a group of vehicles is tasked to maneuver and arrive at pre-assigned final positions at the same time in a collision-free manner, while reducing some optimality criterion. The time of arrival is not fixed a priori, and the vehicles must negotiate their speeds along the spatial paths that they follow in order to arrive simultaneously and avoid collision. The general framework adopted leads to integrated solutions to TC-PF problems that unfold in three steps: 1) Generation of Deconflicted Trajectories for a group of vehicles, 2) Path Following for each vehicle along its assigned path, and 3) Coordination of the relative motion of the vehicles along their paths, so as to guarantee deconfliction and meet desired temporal constraints such as equal times of arrival. The last step is accomplished by varying the speed of each vehicle about the nominal speed profile computed in step 1, based on the exchange of information with its neighbors. The paper formulates the problem mathematically, offers a general framework for its solution, and illustrates the efficacy of the proposed methodology in simulation with dynamic models of Autonomous Underwater Vehicles (AUVs).

关键词： Marine vehicles Remotely operated vehicles robotics and automation Computational modeling Vehicle dynamics Mathematical model Underwater vehicles Scattering Oceans Sea surface

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Temporally and Spatially Deconflicted Path Planning for Multiple Autonomous Marine Vehicles

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IFAC Proceedings Volumes 2009年第18期42卷 376-381页

作者： Andreas J. Häusler Reza Ghabcheloo António M. Pascoal A. Pedro Aguiar Isaac I. Kaminer Vladimir N. Dobrokhodov 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 Department of Mechanical and Astronautical Engineering Naval Postgraduate School Monterey CA 93943 USA

There is currently a surge of interest in the development of advanced systems for cooperative control of multiple autonomous marine vehicles. Central to the implementation of these systems is the availability of efficient algorithms for multiple vehicle path planning that can take explicitly into account the capabilities of each vehicle and existing environmental conditions. Multiple vehicle path planning methods build necessarily on key concepts and algorithms for single vehicle path following. However, they go one step further in that they must explicitly address inter-vehicle collision avoidance, together with a number of criteria that may include simultaneous times of arrival at the assigned target points and energy minimization, to name but a few. As such, they pose considerable challenges both from a theoretical and practical implementation standpoint. This paper is a short overview of multiple vehicle path planning techniques. The exposition is focused on specific algorithms developed in the scope of research work in which the authors have participated. Namely, algorithms that ensure that at no time will two vehicles get closer in space than a desired safety distance, that is, achieve trajectory deconfliction. The algorithms make ample use of direct optimization methods that lead to efficient and fast techniques for path generation using a polynomial-based approach. The paper affords the reader a fast paced presentation of key algorithms that had their genesis in the aircraft field, discusses the results of simulations, and suggests problems that warrant further consideration.

关键词： Multiple Vehicle Missions Path Planning Spatial Deconfliction Temporal Deconfliction Autonomous Marine Vehicles

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Pseudo phase plane, delay and fractional dynamics

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Journal Europeen des Systemes Automatises 2008年第6-8期42卷 1037-1051页

作者： Lima, Miguel Francisco Martins Machado, José Antonio Tenreiro Crisóstomo, Manuel Marques Dept. of Electrical Engineering Superior School of Technology Polytechnic Institute of Viseu 3504-510 Viseu Portugal Dept. of Electrical Engineering Institute of Engineering Polytechnic Institute of Porto 4200-072 Porto Portugal Institute of Systems and Robotics Dept. of Electrical and Computer Engineering University of Coimbra Polo II 3030-290 Coimbra Portugal

This paper analyses the relationship between the signal delay and the fractional dynamics. It is shown that some experimental signals spectra are approximated by trendlines. Based on the slope of these trendlines the fractional or integer order behavior is determined. For the pseudo phase plane reconstruction of each signal, the time delays are calculated through the fractal dimension, as an alternative to the mutual information that is often used. The slopes of the trendlines spectra reveal a relationship with the fractal dimension of the pseudo phase plane and the corresponding time lag. © 2008 Lavoisier, Paris.

关键词： Fractal dimension

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