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Publications

Publications by Paulo José Costa

2004

RoboCup-2003 - New scientific and technical advances

Authors
Pagello, E; Menegatti, E; Bredenfel, A; Costa, P; Christaller, T; Jacoff, A; Polani, D; Riedmiller, M; Saffiotti, A; Sklar, E; Tomoichi, T;

Publication
AI MAGAZINE

Abstract
This article reports on the RoboCup-2003 event. RoboCup is no longer just the Soccer World Cup for autonomous robots but has evolved to become a coordinated initiative encompassing four different robotics events: (1) Soccer, (2) Rescue, (3) junior (focused on education), and (4) a Scientific Symposium. RoboCup-2003 took place from 2 to 11 July 2003 in Padua (Italy); it was colocated with other scientific events in the field of AT and robotics. In this article, in addition to reporting on the results of the games, we highlight the robotics and AT technologies exploited by the teams in the different leagues and describe the most meaningful scientific contributions.

2008

A nonlinear model predictive control strategy for trajectory tracking of a four-wheeled omnidirectional mobile robot

Authors
Conceicao, AS; Moreira, AP; Costa, PJ;

Publication
OPTIMAL CONTROL APPLICATIONS & METHODS

Abstract
This paper presents a nonlinear model-based predictive controller (NMPC) for trajectory tracking of a four-wheeled omnidirectional mobile robot. Methods of numerical optimization to perform real-time nonlinear minimization of the cost function are used. The cost function penalizes the robot's position error, the robot's orientation angle error, and the control effort. Experimental results of the trajectories following and the performances of the methods of optimization are presented. Copyright (C) 2007 John Wiley & Sons, Ltd.

2009

Design of a Mobile Robot for RoboCup Middle Size League

Authors
Conceicao, AS; Moreira, AP; Costa, PJ;

Publication
2009 6TH LATIN AMERICAN ROBOTICS SYMPOSIUM

Abstract
This article presents a design of a four-wheeled omnidirectional mobile robot for RoboCup Middle Size League. The mobile robot was built for the 5dpo-2000 Robotic Soccer team from the Department of Electrical and Computer Engineering at the University of Porto, Portugal. The robot's architecture and communication structure are presented. A nonlinear modeling and a motion analysis based on the dynamics, kinematics, and DC motors are analyzed. This model could find the nonlinear saturation elements, such as limits of current of the motors, amplitude of the applied voltage in the motors, and frictions related to equation of motion. Simulation results are provided to demonstrate the performance of the proposed project.

2009

A nonlinear mobile robot modeling applied to a model predictive controller

Authors
Conceicao, AS; Moreira, AP; Costa, P;

Publication
Proceedings of the ACM Symposium on Applied Computing

Abstract
This paper presents a nonlinear modeling approach of an omnidirectional mobile robot to predict the robot behavior in a model-based predictive controller (MPC). Parameters related to dynamic equations of the robot and restriction of the robot's motors are considered in the modeling. Simulation results and real results of navigation are provided to demonstrate the performance of the proposed modeling approach. Copyright 2009 ACM.

2005

Architecture control and model identification of a Omni-Directional Mobile Robot

Authors
Conceicao, AS; Moreira, AP; Costa, PJ;

Publication
2005 PORTUGUESE CONFERENCE ON ARTIFICIAL INTELLIGENCE, PROCEEDINGS

Abstract
This paper presents a architecture control and model identification of a onmi-Directional Mobile Robot It is divided into the three stages. Stage one proposes a procedure for dynamic model identification and control of the "motor + reduction + encoder" process of the Robot's Motors. Second, proposes the identification of a dynamic model for the whole mobile robot considering it as a multi-variable system. Third, presents a algorithm for perfect trajectory tracking of Omni-Directional Mobile Robots, based on restriction on motor's velocities. This algorithm combines the restriction on motor's velocities and the kinematic model of mobile robot to generate ideal drive velocities for the mobile robot to follow the trajectories correctly with the best possible performance.

2008

ANALYSIS OF THE BEHAVIOR OF MOORED TANKERS

Authors
Pinto, FT; Gomes, FV; Santos, PR; Soares, CG; Fonseca, N; Santos, JA; Moreira, AP; Costa, P; Dias, EB;

Publication
PROCEEDINGS OF THE 27TH INTERNATIONAL CONFERENCE ON OFFSHORE MECHANICS AND ARCHTIC ENGINEERING - 2008, VOL 4

Abstract
Moored ship behavior inside harbors and, therefore, the operational and security conditions at a port terminal does not have a straightforward relationship with local environmental conditions. Due to the diversity and complexity of the phenomena involved it is important to use a methodology that combines physical model tests with numerical simulations, taking advantage of potential synergies. Results of prototype measurements are also a key element to making the validation and calibration of both physical and numerical models possible. This paper focuses on studying the behavior of moored tankers using combined methodology. Aspects related with the inclusion in the numerical models of shallow water effects, non-linear characteristics of mooring lines and fenders, the influence of harbor boundaries and viscous damping are analyzed and discussed. The role of physical modeling as a tool to address/quantify some of the conditions and to provide data for the calibration of numerical models is presented, as well as the methodology defined for the study of the operational conditions at an existing berth. This methodology includes the development of a computer vision system to measure ship motion at the port terminal (prototype). Actual operational conditions at the berth are also described in the paper.

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