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Publications

Publications by António Paulo Moreira

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.

2009

Practical Approach of Modeling and Parameters Estimation for Omnidirectional Mobile Robots

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

Publication
IEEE-ASME TRANSACTIONS ON MECHATRONICS

Abstract
This paper presents a nonlinear modeling approach for omnidirectional mobile robots. Three experimental methods of estimation of the parameters related to dynamic equations of the robot's model ire developed. The estimation methods are based on least-squares methods to obtain the viscous friction coefficients, the coulomb friction coefficients, and the moment of inertia of the robot. Simulation results and real results of navigation are provided to demonstrate the performance of the proposed modeling approach.

2009

Robust and Real-time Teaching of Industrial Robots for Mass Customisation Manufacturing Using Stereoscopic Vision

Authors
Malheiros, P; Costa, P; Moreira, AP; Ferreira, M;

Publication
IECON: 2009 35TH ANNUAL CONFERENCE OF IEEE INDUSTRIAL ELECTRONICS, VOLS 1-6

Abstract
In this paper a method to control and teach industrial robots in real-time by human demonstration is presented. It aims to decrease down-times for reconfigurations and programming costs, particularly in a mass customisation manufacturing scenario. This system uses high-intensity visual markers that make it sufficiently robust for industrial environments not requiring special lighting. An automated camera calibration method was implemented which enables any non-skilled user a quick and easy configuration of the system. The teaching of the robot is achieved by recording the detected points and replaying them to the manipulator, therefore this is a "teaching-by-showing" method. The final program that the robot is uploaded with is a smooth trajectory calculated using all the recorded points, which are analised and grouped into different motion segments according to position and speed.

2011

Shop Floor Scheduling in a Mobile Robotic Environment

Authors
Pinto, AM; Rocha, LF; Moreira, AP; Costa, PG;

Publication
PROGRESS IN ARTIFICIAL INTELLIGENCE

Abstract
Nowadays,it is far more common to see mobile robotics working in the industrial sphere due to the mandatory need to achieve a new level of productivity and increase profits by reducing production costs. Management scheduling and task scheduling are crucial for companies that incessantly seek to improve their processes, increase their efficiency, reduce their production time and capitalize on their infrastructure by increasing and improving production. However, when faced with the constant decrease in production cycles, management algorithms can no longer solely focus on the mere management of the resources available, they must attempt to optimize every interaction between them, to achieve maximinn efficiency for each production resource. In this paper we focus on the presentation of the new competition called Robot Factory, its environment and its main objectives, paying special attention to the scheduling algorithm developed for this specific case study. The findings from the simulation approach have allowed us to conclude that mobile robotic path planning and the scheduling of the associated tasks represent a complex problem that has a strong impact on the efficiency of the entire production process.

2006

Trajectory tracking for Omni-Directional mobile robots based on restrictions of the motor's velocities

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

Publication
IFAC Proceedings Volumes (IFAC-PapersOnline)

Abstract
In this paper, we propose an algorithm that combine the restriction on motor's velocities and the kinematic model of Omni-Directional mobile robots to improve the trajectory's following. The algorithm verifies the reference velocities of the robot and redefine them if necessary, in order to prevent possible saturation on motor's velocities. Simulation results of the algorithm applied to an omnidirectional mobile robot are presented. Copyright © 2006 IFAC.

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