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Publicações

Publicações por Alfredo Martins

2019

Image Cleaning and Enhancement Technique for Underwater Mining

Autores
Rajesh, SD; Almeida, JM; Martins, A;

Publicação
OCEANS 2019 - MARSEILLE

Abstract
The exploration of water bodies from the sea to land filled water spaces has seen a continuous increase with new technologies such as robotics. Underwater images is one of the main sensor resources used but suffer from added problems due to the environment. Multiple methods and techniques have provided a way to correct the color, clear the poor quality and enhance the features. In this paper, we present the work of an Image Cleaning and Enhancement Technique which is based on performing color correction on images incorporated with Dark Channel Prior(DCP) and then taking the converted images and modifying them into the Long, Medium and Short(LMS) color space, as this space is the region in which the human eye perceives colour. This work is being developed at INESC TEC robotics and autonomous systems laboratory. Our objective is to improve the quality of images for and taken by robots with the particular emphasis on underwater flooded mines. The paper describes the architecture and the developed solution. A comparative analysis with state of the art methods and of our proposed solution is presented. Results from missions taken by the robot in operational mine scenarios are presented and discussed and allowing for the solution characterization and validation.

2021

Graph-SLAM Approach for Indoor UAV Localization in Warehouse Logistics Applications

Autores
Moura, A; Antunes, J; Dias, A; Martins, A; Almeida, J;

Publicação
2021 IEEE INTERNATIONAL CONFERENCE ON AUTONOMOUS ROBOT SYSTEMS AND COMPETITIONS (ICARSC)

Abstract
Unmanned Aerial Vehicles (UAVs) are a key ingredient in the industry and in warehouse logistics digital transformation process, providing the ability to perform automatic cyclic counting and real-time inventory, localize hard-to-find items and reach narrow storage areas. The use of UAVs poses new challenges, such as indoor autonomous localization and navigation, collision avoidance and automated UAV fleet management. This paper addresses the development of a vision-based Graph-SLAM approach for UAV indoor localization without predefined warehouse markers positions. A framework is proposed and developed to support different commercial UAV platforms, allowing the estimation in real-time of the UAV position and attitude. Indoor experimental tests were carried out in order to evaluate the performance of the developed method, comparing the results obtained with an approach based on the pre-mapped markers position indoor localization method.

2022

3DupIC: An Underwater Scan Matching Method for Three-Dimensional Sonar Registration

Autores
Ferreira, A; Almeida, J; Martins, A; Matos, A; Silva, E;

Publicação
SENSORS

Abstract
This work presents a six degrees of freedom probabilistic scan matching method for registration of 3D underwater sonar scans. Unlike previous works, where local submaps are built to overcome measurement sparsity, our solution develops scan matching directly from the raw sonar data. Our method, based on the probabilistic Iterative Correspondence (pIC), takes measurement uncertainty into consideration while developing the registration procedure. A new probabilistic sensor model was developed to compute the uncertainty of each scan measurement individually. Initial displacement guesses are obtained from a probabilistic dead reckoning approach, also detailed in this document. Experiments, based on real data, demonstrate superior robustness and accuracy of our method with respect to the popular ICP algorithm. An improved trajectory is obtained by integration of scan matching updates in the localization data fusion algorithm, resulting in a substantial reduction of the original dead reckoning drift.

2022

An holistic monitoring system for measurement of the atmospheric electric field over the ocean - the SAIL campaign

Autores
Barbosa, S; Dias, N; Almeida, C; Amaral, G; Ferreira, A; Lima, L; Silva, I; Martins, A; Almeida, J; Camilo, M; Silva, E;

Publicação
OCEANS 2022

Abstract
The atmospheric electric field is a key characteristic of the Earth system. Despite its relevance, oceanic measurements of the atmospheric electric field are scarce, as typically oceanic measurements tend to be focused on ocean properties rather than on the atmosphere above. This motivated the set-up of an innovative campaign on board the sail ship NRP Sagres focused on the measurement of the atmospheric electric field in the marine boundary layer. This paper describes the monitoring system that was developed to measure the atmospheric electric field during the planned circumnavigation expedition of the sail ship NRP Sagres.

2021

COLLECTION AND LIFE SUPPORT IN A HYPERBARIC SYSTEM FOR DEEP-SEA ORGANISMS

Autores
Viegas, D; Figueiredo, A; Coimbra, J; Dos Santos, A; Almeida, J; Dias, N; Lima, L; Silva, H; Ferreira, H; Almeida, C; Amaro, T; Arenas, F; Castro, F; Santos, M; Martins, A; Silva, E;

Publicação
OCEANS 2021: SAN DIEGO - PORTO

Abstract
This paper presents the development of a hyperbaric system able to collect, transport and maintain deep-sea species in controlled condition from the sea floor up to the surface (HiperSea System). The system is composed by two chambers coupled with a transference set-up. The first chamber is able to reach a maximum of 1km depth collecting both benthic and pelagic deep-sea species. The second chamber is a life support compartment to maintain the specimens alive at the surface, in hyperbaric conditions.

2022

A SMACC based mission control system for autonomous underwater vehicles

Autores
Carvalho, D; Martins, A; Almeida, JM; Silva, E;

Publicação
2022 OCEANS HAMPTON ROADS

Abstract
Scientific and environmental focused deep sea exploration is being expanded and as such a new class of Autonomous Underwater Vehicle (AUV) capable of accessing deep underwater sea bed environment for long periods of time is being deployed. This type of vehicle and the mission environment poses challenges to the mission development as these operations contain many systems that must work together to ensure that the mission requirements are met and that the vehicle is operated safely. As such, a solution based on the SMACC library for Robotic Operating System (ROS) was proposed and tested using a simulator. The results shown were based on the simulation of three missions representative of different scenarios for a deep sea exploration AUV and they were evaluated on the completion of the mission plan.

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