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Publications

Publications by CRAS

1999

FAFNER-Accelerating Nesting Problems with FPGAs

Authors
Alves, JC; Ferreira, JC; Albuquerque, C; Oliveira, JF; Ferreira, JS; Matos, JS;

Publication
7th IEEE Symposium on Field-Programmable Custom Computing Machines (FCCM '99), 21-23 April 1999, Napa, CA, USA

Abstract
The nesting problem consists of defining the cutting plan of a piece of raw material in smaller irregular shapes, and has applications in the apparel and footwear industries. Due to its NP-hard nature, the optimal solution can only be guaranteed by exhaustively trying all possible solutions and choosing the best one. Because this is impractical in real-life industrial problems, automatic approaches are based on optimization meta-heuristics that search for sub-optimal but good enough solutions. These optimization techniques rely on the construction and evaluation of several solutions, thus requiring heavy geometric manipulation of the irregular polygons that constitute the problem data. Efficient processing of this geometric information is thus necessary to make effective fully automatic approaches to nesting problems in industrial environments. This paper describes Fafner, an FPGA-based custom computing machine that is used to accelerate the geometric operations, that are in the core of heuristic solutions to the nesting problem. The system is used as an auxiliary processor attached to a low cost personal computer, and combines a custom programmable processor with an array of custom circuits for the processing of irregular polygons.

1999

Estuarine environment studies with Isurus, a REMUS class AUV

Authors
Cruz, N; Matos, A; Martins, A; Silva, J; Santos, D; Boutov, D; Ferreira, D; Pereira, FL;

Publication
OCEANS '99 MTS/IEEE : RIDING THE CREST INTO THE 21ST CENTURY, VOLS 1-3

Abstract
In this paper, we address the current developments of the "PISCIS" project. We focus on the experimental results from recent operational missions with an AUV in a estuarine environment. Besides describing mission planning and logistic details, we also present tools for oceanographic data processing and visualization. This will be demonstrated with some examples of collected data.

1999

Development and implementation of a low-cost LBL navigation system for an AUV

Authors
Matos, A; Cruz, N; Martins, A; Pereira, FL;

Publication
OCEANS '99 MTS/IEEE : RIDING THE CREST INTO THE 21ST CENTURY, VOLS 1-3

Abstract
A reliable navigation system is a key factor for the success of an operational mission with an AUV in a real scenario. In this paper, we address the main issues involved in the implementation of a long baseline (LBL) navigation system for a REMUS AUV. This system replaces both the original hardware and software of the vehicle with a simpler, faster, less expensive and more precise system, based on a Kalman filter. We also discuss the influence of transponder location in the overall performance of the LBL navigation, and present results obtained with this new system in operational missions.

1999

IES an open system for underwater inspection

Authors
Martins, A; Matos, A; Cruz, N; Pereira, FL;

Publication
OCEANS '99 MTS/IEEE : RIDING THE CREST INTO THE 21ST CENTURY, VOLS 1-3

Abstract
This paper describes the specification and design of a prototype of a low cost open system for the inspection of underwater structures based on a remotely operated underwater vehicle under the project IES, a 3 year long effort funded by the Portuguese R&D program Praxis XXI. Unlike commercial approaches, a modular open system characterised by the incorporation of an on-board computer allowing for advanced control capabilities is envisaged. The control console is based on a standard PC and the tether is used only for power delivery and to establish a simple communication channel. In this project, we use advanced hybrid control techniques for sophisticated semi-autonomous operation management and control. The control architecture reuses part of the one designed for the underwater vehicle Isurus operated by the Laboratory of Underwater Systems and Technologies of Porto University. The implementation is designed in order to allow for multiple sensor configurations specified as add-ins. This leads to a dynamic, scalable and flexible system that can be easily configured according to the user specifications.

1999

On the Design of a Control Architecture for an Autonomous Mobile Robot

Authors
Pereira da Silva, E; Pereira, FL; Sousa, JB;

Publication
Advances in Intelligent Autonomous Systems

Abstract

1999

A reconfigurable mission control system for underwater vehicles

Authors
Silva, JE; Martins, A; Pereira, FL;

Publication
OCEANS '99 MTS/IEEE : RIDING THE CREST INTO THE 21ST CENTURY, VOLS 1-3

Abstract
This paper describes the mission control software used in the LSTS/FEUP underwater vehicles. This software follows the guidelines of the generalized vehicle architecture [1], adapts the original idea to encompass the current application requirements and constitutes a first implementation. The work is focused on the design and implementation of an application that can be easily adapted to different vehicle configurations or even to different vehicles. One of the desired goals was to enhance software reusability and to establish a development environment that allows developers with a minimal knowledge of coding details to upgrade the application. To assist this purpose, a CASE tool, which provides modern software development techniques, was used. A simulation environment was also developed whose purpose is to test the applications and to detect possible malfunctions before they occur during mission execution.

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