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Publicações

Publicações por CRAS

2008

Autonomous sailboats: an emerging technology for ocean sampling and surveillance

Autores
Cruz, NA; Alves, JC;

Publicação
OCEANS 2008, VOLS 1-4

Abstract
Autonomous sailboats are robotic vessels that use wind energy for propulsion and control the sails and rudders without human intervention. The use of autonomous sailboats for ocean sampling has been tentatively proposed before, but there have been minor efforts towards the development and deployment of actual prototypes, due to a number of technical limitations and significant risks of operation. Currently, most of the limitations have been surpassed, with the availability of extremely low power electronics, flexible computational systems, reliable communication devices and high performance renewable power sources. At the same time, some of the major risks have been mitigated, allowing this emerging technology to become an effective tool for a wide range of applications in real scenarios. We illustrate some of these scenarios and we describe the status of the current efforts being made to develop operational prototypes.

2008

A project driven digital design course using FPGAs

Autores
Araujo, AJ; Alves, JC;

Publicação
19th EAEEIE (European Association for Education in Electrical and Information Engineering) Annual Conference - Formal Proceedings

Abstract
This paper presents a project based teaching experience in an advanced digital systems design course with emphasis on design methodologies and laboratory assignments. Projects are the core of the practised teaching methodology and are structured in a pedagogical format according to the course programme. The use of the FPGA technology as the most suitable implementation technology for digital design teaching purposes is discussed. The course structure, oriented to the development of real working digital systems, challenges the students and increases their motivation. This way, the learning process is improved and the classes are more productive. A laboratory development infrastructure based on a FPGA device, used to implement a real-time video processing system, is presented. Examples of laboratory projects implemented with this infrastructure in a recent course edition are also presented. © 2008 IEEE.

2008

A reconfigurable computing system for an autonomous sailboat

Autores
Alves, JC; Ramos, TM; Cruz, NA;

Publicação
OGAI Journal (Oesterreichische Gesellschaft fuer Artificial Intelligence)

Abstract
This paper presents the computing infrastructure used in an autonomous unmanned small-scale sailboat. The system is based on a FPGA and includes custom designed interfaces for the various sensors and actuators used in the sailboat. The central processing unit is a 32-bit 50 MHz RISC microprocessor implemented as a soft IP core in the FPGA. The computing system runs uClinux, a simplified version of the popular Linux operating system. The usage of a reconfigurable platform enables a quick reconfiguration of the logic circuit implemented in the FPGA, facilitating the development stage and allowing a dynamic switch among different implementations, according to the navigation requirements and environmental conditions.

2008

A custom processor for a TDMA solver in a CFD application

Autores
Oliveira, F; Santos, CS; Castro, FA; Alves, JC;

Publicação
RECONFIGURABLE COMPUTING: ARCHITECTURES, TOOLS AND APPLICATIONS

Abstract
This paper presents a custom processor designed to execute a time consuming function in a CFD application. The selected function implements the method TDMA (Tri-Diagonal Matrix Algorithm) for solving a tri-diagonal system of equations. The custom processor was implemented in a commercial PCI prototyping board based on Virtex4LX FPGAs and uses a dedicated memory cache system, address generators and a deep pipelined floating-point datapath. Running at 100MHz and assuming the input data already in the cache memories, the system reaches a throughput greater than 1.4GFLOPS.

2008

Shallow Water Height Mapping With Interferometric Synthetic Aperture Sonar

Autores
Silva, SR; Cunha, S; Matos, A; Cruz, N;

Publicação
OCEANS 2008, VOLS 1-4

Abstract
Height mapping of shallow water areas is an important task for many commercial and scientific applications like river navigability, infrastructure maintenance or natural resource monitoring. The use of an autonomous boat presents several advantages that case the use of synthetic aperture images to create three-dimensional topographic maps through interferometric techniques. Sample data obtained during test trials illustrate how synthetic aperture can be used to generate imagery and bathymetry data.

2008

The MARES AUV, a Modular Autonomous Robot for Environment Sampling

Autores
Cruz, NA; Matos, AC;

Publicação
OCEANS 2008, VOLS 1-4

Abstract
In this paper, we discuss the design aspects and the development of the MARES AUV, a 1.5m long vehicle, weighting 32kg, designed and built at the University of Porto, Portugal. This vehicle is highly maneuverable, with the ability to move in the vertical plane, controlling pitch and vertical velocity; forward velocity can also be determined, anywhere between 0 and 2 m/s. MARES can easily integrate any new payload within reason, finding applications in a wide range or areas, such as pollution monitoring, scientific data collection, sonar mapping, underwater video or mine countermeasures.

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