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Publications

Publications by CRAS

2003

Improving the numerical efficiency of the B and D estimates produced by the combined deterministic-stochastic subspace identification algorithms

Authors
dos Santos, PL; de Carvalho, JLM;

Publication
42ND IEEE CONFERENCE ON DECISION AND CONTROL, VOLS 1-6, PROCEEDINGS

Abstract
In this paper we find some linear dependencies on the matrices used for B and D estimation by the Van Overschee and De Moore non-biased versions of the Combined Deterministic-Stochastic Subspace Identification algorithms (CDSSI). These dependencies allow us to formulate algorithms that significantly improve the numerical efficiency on estimating these parameters without loss of accuracy. Experiences performed on practical data sets showed that the robust versions of these algorithms are twice as fast as the robust version proposed by Van Overschee and De Moore.

2003

Resistivity imaging applied to improved electrical grounding of wind energy stations

Authors
M. Moura, R; Rodrigues, B; Dias, A; Normando Ramos, A; Gonçalves, E; Antas Botelho, J;

Publication
9th EAGE/EEGS Meeting

Abstract

2002

Dynamic optimization in the coordination and control of autonomous underwater vehicles

Authors
de Sousa, JB; Matos, A; Pereira, FL;

Publication
PROCEEDINGS OF THE 41ST IEEE CONFERENCE ON DECISION AND CONTROL, VOLS 1-4

Abstract
The coordination and control problems arising in team composition and tasking of autonomous underwater vehicles are discussed in the framework of dynamic optimization. Team composition and tasking are specified in terms of sets and relations among the elements of these sets. Results from dynamic optimization and non-smooth analysis are used to show that these coordination and control problems can be phrased in terms of concepts such as invariance, solvability, monotonicity, and switchings among value functions.

2002

Hamilton-Jacobi conditions for an impulsive control problem

Authors
Pereira, FL; Matos, AC; Silva, GN;

Publication
NONLINEAR CONTROL SYSTEMS 2001, VOLS 1-3

Abstract
A vector-valued impulsive control problem is considered whose dynamics, defined by a differential inclusion, are such that the vector fields associated with the singular term do not satisfy the so called Frobenius condition. A concept of proper solution based on a reparametrization procedure is adopted which enables the derivation of optimality conditions of the Hamilton-Jacobi type. These conditions are obtained by taking a limit of those for an appropriate sequence of auxiliary "standard" optimal control problems approximating the original one. Copyright (C) 2001 IFAC.

2002

A dynamically configurable architecture for the control of autonomous underwater vehicles

Authors
Borges Sousa, J; Lobo Pereira, F; Pereira da Silva, E;

Publication
Proceedings of OCEANS'94

Abstract

2002

On the design and implementation of a mobile robotic system

Authors
Borges Sousa, J; Lobo Pereira, F; Pereira da Silva, E; Martins, A; Matos, A; Almeida, J; Cruz, N; Tunes, R; Cunha, S;

Publication
Proceedings of Tenth International Symposium on Intelligent Control

Abstract

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