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Publications

Publications by CRAS

2007

Coordinated operation of autonomous underwater and surface vehicles

Authors
Matos, A; Cruz, N;

Publication
2007 OCEANS, VOLS 1-5

Abstract
This work addresses the coordinated operation of an autonomous underwater vehicle and an autonomous surface vessel and its main goal is the development of an infrastructure that allows the surface vessel to dynamically position itself above the underwater vehicle while the later one is collecting data and navigating in long baseline mode using a set of beacons installed in the operation area. Besides a formal statement of the coordination problem, we present results both from real experiments and from simulations that illustrate the proposed solution.

2007

An autonomous boat based Synthetic Aperture Sonar

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

Publication
2007 OCEANS, VOLS 1-5

Abstract
This paper describes a Synthetic Aperture Sonar (SAS) system being developed at the University of Porto to be used in a small autonomous boat for the survey of shallow water environments, such as rivers, deltas, estuaries and dams. Its purpose is to obtain high resolution echo reflectivity maps through synthetic aperture techniques, taking advantage of the high precision navigation system of the boat. In the future the production of bottom tomography maps is also considered through the use of interferometric imaging techniques.

2007

LSAVISION a framework for real time vision mobile robotics

Authors
Silva, H; Almeida, JM; Lima, L; Martins, A; Silva, EP; Patacho, A;

Publication
COMPUTATIONAL MODELLING OF OBJECTS REPRESENTED IN IMAGES: FUNDAMENTALS, METHODS AND APPLICATIONS

Abstract
This paper propose a real-time vision architecture for mobile robotics, and describes a current implementation that is characterised by: low computational cost, low latency, low power, high modularity, configuration, adaptability and scalability. A pipeline structure further reduces latency and allows a paralleled hardware implementation. A dedicated hardware vision sensor was developed in order to take advantage of the proposed architecture. A new method using run length encoding (RLE) colour transition allows real-time edge determination at low computational cost. The real-time characteristics and hardware partial implementation, coupled with low energy consumption address typical autonomous systems applications.

2007

Autonomous surface vehicle docking manoeuvre with visual information

Authors
Martins, A; Almeida, JM; Ferreira, H; Silva, H; Dias, N; Dias, A; Almeida, C; Silva, EP;

Publication
PROCEEDINGS OF THE 2007 IEEE INTERNATIONAL CONFERENCE ON ROBOTICS AND AUTOMATION, VOLS 1-10

Abstract
This work presents a hybrid coordinated manoeuvre for docking an autonomous surface vehicle with an autonomous underwater vehicle. The control manoeuvre uses visual information to estimate the AUV relative position and attitude in relation to the ASV and steers the ASV in order to dock with the AUV. The AUV is assumed to be at surface with only a small fraction of its volume visible. The system implemented in the Autonomous Surface vehicle ROAZ, developed by LSA-ISEP to perform missions in river environment, test autonomous AUV docking capabilities and multiple AUV/ASV coordinated missions is presented. Information from a low cost embedded robotics vision system (LSAVision), along with inertial navigation sensors is fused in an extended kalman filter and used to determine AUV relative position and orientation to the surface vehicle The real time vision processing system is described and results are presented in operational scenario.

2007

Forest fire detection with a small fixed wing autonomous aerial vehicle

Authors
Martins, A; Almeida, J; Almeida, C; Figueiredo, A; Santos, F; Bento, D; Silva, H; Silva, E;

Publication
IFAC Proceedings Volumes (IFAC-PapersOnline)

Abstract
In this work a forest fire detection solution using small autonomous aerial vehicles is proposed. The FALCOS unmanned aerial vehicle developed for remote-monitoring purposes is described. This is a small size UAV with onboard vision processing and autonomous flight capabilities. A set of custom developed navigation sensors was developed for the vehicle. Fire detection is performed through the use of low cost digital cameras and near-infrared sensors. Test results for navigation and ignition detection in real scenario are presented.

2007

SWORDFISH: an autonomous surface vehicle for network centric operations

Authors
Ferreira, H; Martins, R; Marques, E; Pinto, J; Martins, A; Almeida, J; Sousa, J; Silva, EP;

Publication
OCEANS 2007 - EUROPE, VOLS 1-3

Abstract
The design and development of the Swordfish Autonomous Surface Vehicle (ASV) system is discussed. Swordfish is an ocean capable 4.5m long catamaran designed for network centric operations (with ocean and air going vehicles and human operators). In the basic configuration, Swordfish is both a survey vehicle and a communications node with gateways for broadband, Wi-Fi and GSM transports and underwater acoustic modems. In another configuration, Swordfish mounts a docking station for the autonomous underwater vehicle Isurus from Porto University. Swordfish has an advanced control architecture for multi-vehicle operations with mixed initiative interactions (human operators are allowed to interact with the control loops).

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