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Publications

Publications by Alfredo Martins

2012

Vision-Based Assisted Teleoperation for Inspection Tasks with a Small ROV

Authors
Costa, MJ; Goncalves, P; Martins, A; Silva, E;

Publication
2012 OCEANS

Abstract
It is well-known that ROVs require human intervention to guarantee the success of their assignment, as well as the equipment safety. However, as its teleoperation is quite complex to perform, there is a need for assisted teleoperation. This study aims to take on this challenge by developing vision-based assisted teleoperation maneuvers, since a standard camera is present in any ROV. The proposed approach is a visual servoing solution, that allows the user to select between several standard image processing methods and is applied to a 3-DOF ROV. The most interesting characteristic of the presented system is the exclusive use of the camera data to improve the teleoperation of an underactuated ROV. It is demonstrated through the comparison and evaluation of standard implementations of different vision methods and the execution of simple maneuvers to acquire experimental results, that the teleoperation of a small ROV can be drastically improved without the need to install additional sensors.

2009

Manoeuvre Based Mission Control System for Autonomous Surface Vehicle

Authors
Dias, N; Almeida, C; Ferreira, H; Almeida, J; Martins, A; Dias, A; Silva, E;

Publication
OCEANS 2009 - EUROPE, VOLS 1 AND 2

Abstract
In this work the mission control and supervision system developed for the ROAZ Autonomous Surface Vehicle is presented. Complexity in mission requirements coupled with flexibility lead to the design of a modular hierarchical mission control system based on hybrid systems control. Monitoring and supervision control for a vehicle such as ROAZ mission is not an easy task using tools with low complexity and yet powerful enough. A set of tools were developed to perform both on board mission control and remote planning and supervision. "ROAZ- Mission Control" was developed to be used in support to bathymetric and security missions performed in river and at seas.

2009

Radar Based Collision detection developments on USV ROAZ II

Authors
Almeida, C; Franco, T; Ferreira, H; Martins, A; Santos, R; Almeida, JM; Carvalho, J; Silva, E;

Publication
OCEANS 2009 - EUROPE, VOLS 1 AND 2

Abstract
This work presents the integration of obstacle detection and analysis capabilities in a coherent and advanced C&C framework allowing mixed-mode control in unmanned surface systems. The collision avoidance work has been successfully integrated in an operational autonomous surface vehicle and demonstrated in real operational conditions. We present the collision avoidance system, the ROAZ autonomous surface vehicle and the results obtained at sea tests. Limitations of current COTS radar systems are also discussed and further research directions are proposed towards the development and integration of advanced collision avoidance systems taking in account the different requirements in unmanned surface vehicles

2009

Autonomous Bathymetry for Risk Assessment with ROAZ Robotic Surface Vehicle

Authors
Ferreira, H; Almeida, C; Martins, A; Almeida, J; Dias, N; Dias, A; Silva, E;

Publication
OCEANS 2009 - EUROPE, VOLS 1 AND 2

Abstract
The use of unmanned marine robotic vehicles in bathymetric surveys is discussed. This paper presents recent results in autonomous bathymetric missions with the ROAZ autonomous surface vehicle. In particular, robotic surface vehicles such as ROAZ provide an efficient tool in risk assessment for shallow water environments and water land interface zones as the near surf zone in marine coast. ROAZ is an ocean capable catamaran for distinct oceanographic missions, and with the goal to fill the gap were other hydrographic surveys vehicles/systems are not compiled to operate, like very shallow water rivers and marine coastline surf zones. Therefore, the use of robotic systems for risk assessment is validated through several missions performed either in river scenario (in a very shallow water conditions) and in marine coastlines.

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).

2008

A real time vision system for autonomous systems: Characterization during a middle size match

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

Publication
ROBOCUP 2007: ROBOT SOCCER WORLD CUP XI

Abstract
This paper propose a real-time vision framework for mobile robotics and describes the current implementation. The 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. The real-time characteristics and hardware partial implementation, coupled with low energy consumption address typical autonomous systems applications. A characterization of the implemented system in the Robocup scenario, during competition matches, is presented.

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