Victor Lobo | Universidade Nova de Lisboa (original) (raw)

Papers by Victor Lobo

Scientific Data, Dec 6, 2023

The pose (3D position and orientation) of an Unmanned Aerial Vehicle (UAV) during the landing pro... more The pose (3D position and orientation) of an Unmanned Aerial Vehicle (UAV) during the landing process aboard a ship can be estimated using a 3D model-based vision system approach. The developed vision system is based on a standard Red, Green and Blue (RGB) camera using one workstation for processing data located on the ship's deck. A ground-based vision system allows the use of small size and weight UAV, due to the low computer requirements onboard. The proposed architecture is based on a Particle Filter (PF) scheme and has three stages: importance sampling, importance weighting and resampling. In the importance sampling, we detect bounding box candidates and apply an appearance-based pose sampler to retrieve the most likely poses. After this, we fuse information from the current frame with information from the previous time step using an Unscented Kalman Filter (UKF) for the translational motion filtering and an Unscented Bingham Filter (UBiF) for the rotational motion filtering. In the importance weighting stage, we use a color based likelihood metric to deal with the expected real sky background filled with clouds. In the resampling stage, we eliminate particles with low importance weights and replicate high weight ones. Results show that performance is compatible with the automatic landing system requirements.

Lecture Notes in Mechanical Engineering, 2020

Portugal é um dos países com maior consumo de medicamentos per capita. O consumo de medicamentos ... more Portugal é um dos países com maior consumo de medicamentos per capita. O consumo de medicamentos implica, não só, riscos para o doente, como também um forte encargo para o Serviço Nacional de Saúde. A polimedicação, apontada por muitos autores como o consumo simultâneo de pelo menos cinco fármacos, pode ter consequências de extrema gravidade para o doente e é responsável por muitos internamentos. A consciência desta situação levou Portugal à criação de um projecto pioneiro, MAISCINCO, de divulgação e aconselhamento farmacoterapêutico da população. Neste trabalho utilizaram‐se os dados do 4o Inquérito Nacional de Saúde (2005/06), instrumento que avalia a saúde da população portuguesa, realizado em Portugal Continental e nas Regiões Autónomas dos Açores e da Madeira. Introdução

Developments in Maritime Technology and Engineering, 2021

OCEANS 2015 - Genova, 2015

The SEAGULL project aims at the development of intelligent systems to support maritime situation ... more The SEAGULL project aims at the development of intelligent systems to support maritime situation awareness based on unmanned aerial vehicles. It proposes to create an intelligent maritime surveillance system by equipping unmanned aerial vehicles (UAVs) with different types of optical sensors. Optical sensors such as cameras (visible, infrared, multi and hyper spectral) can contribute significantly to the generation of situational awareness of maritime events such as (i) detection and georeferencing of oil spills or hazardous and noxious substances; (ii) tracking systems (e.g. vessels, shipwrecked, lifeboat, debris, etc.); (iii) recognizing behavioral patterns (e.g. vessels rendezvous, high-speed vessels, atypical patterns of navigation, etc.); and (iv) monitoring parameters and indicators of good environmental status. On-board transponders will be used for collision detection and avoidance mechanism (sense and avoid). This paper describes the core of the research and development work done during the first 2 years of the project with particular emphasis on the following topics: system architecture, automatic detection of sea vessels by vision sensors and custom designed computer vision algorithms; and a sense and avoid system developed in the theoretical framework of zero-sum differential games.

ABSTRACT In this paper we present a set of field tests for detection of human in the water with a... more ABSTRACT In this paper we present a set of field tests for detection of human in the water with an unmanned surface vehicle using infrared and color cameras. These experiments aimed to contribute in the development of victim target tracking and obstacle avoidance for unmanned surface vehicles operating in marine search and rescue missions. This research is integrated in the work conducted in the European FP7 research project Icarus aiming to develop robotic tools for large scale rescue operations. The tests consisted in the use of the ROAZ unmanned surface vehicle equipped with a precision GPS system for localization and both visible spectrum and IR cameras to detect the target. In the experimental setup, the test human target was deployed in the water wearing a life vest and a diver suit (thus having lower temperature signature in the body except hands and head) and was equipped with a GPS logger. Multiple target approaches were performed in order to test the system with different sun incidence relative angles. The experimental setup, detection method and preliminary results from the field trials performed in the summer of 2013 in Sesimbra, Portugal and in La Spezia, Italy are also presented in this work.

Advances in Intelligent Systems and Computing, 2014

Every system is subject, along its life cycle, to several degradation processes that progressivel... more Every system is subject, along its life cycle, to several degradation processes that progressively degrade its state and increase its probability of failure (reliability reduction). This is true for the generality of systems—mechanical, electrical, software, human or organizational. If nothing is made—if there is no maintenance—every system will eventually fail. In order to start the condition control and improve its reliability, fixed sensors should be chosen in order to collect data of vibration, oil and water pressure, and temperature and particle size- among others. The actual equipment condition must be known, estimated or predicted from the collected data [1]. Unless the state or condition of system is directly observed, that condition is a latent variable in the sense of statistical theory—a variable not directly observed but with observable effects in the manifest variables, as the just mentioned observed variables associated to sensors. To provide support for the decision maker—at last for critical selected systems—it has been shown that some control statistical techniques are effective to ascertain trends and predict needs of future interventions out of observed data. When data is not appropriate, the combination of statistical techniques with simulations and can be considered. With this work we intend to show that control charts can be decisive as instruments of control of equipment monitoring and functioning [4], although there are some problems when applied to the conditioned maintenance; some of those problems can be overcome using a EWMAQ modified chart, adjusting its parameters [3].

Earth mainly consists of water, and monitoring and controlling pollution is essential. To ensure ... more Earth mainly consists of water, and monitoring and controlling pollution is essential. To ensure the surveillance and control of illegal or accidental spills of dangerous and harmful substances into the sea at the European level, the CleanSeaNet satellite monitoring system (service) was developed and implemented by the European Maritime Safety Agency (EMSA). This system's main objective is to alert coastal states of possible spills in their Exclusive Economic Zone, thus allowing the necessary legal and combat actions (cleaning) to be taken in the affected area. A drift model for the spill behavior over time was proposed to be able to act on the right location, considering the existing weather conditions. In addition to verifying the areas most affected by spills and how they behave over time, considering the weather conditions, we must propose a national network of unmanned vehicles (air and surface) that allows us to reduce costs and optimize monitoring and control tasks. It is shown that we could quickly decrease the response time and operational costs with the developed approach.

Marine Technology Society Journal, 2021

Unmanned air systems are becoming ever more important in modern societies but raise a number of u... more Unmanned air systems are becoming ever more important in modern societies but raise a number of unresolved problems. There are legal issues with the operation of these vehicles in nonsegregated airspace, and a pressing requirement to solve these issues is the development and testing of reliable and safe mechanisms to avoid collision in flight. In this article, we describe a sense and avoid subsystem developed for a maritime patrol unmanned air system. The article starts with a description of the unmanned air system, that was developed specifically for maritime patrol operations, and proceeds with a discussion of possible ways to guarantee that the unmanned air system does not collide with other flying objects. In the system developed, the position of the unmanned air system is obtained by the global positioning system and that of other flying objects is reported via a data link with a ground control station. This assumes that the detection of those flying objects is done by a radar in the ground or by self-reporting via a traffic monitoring system (such as automatic identification system). The algorithm developed is based on game theory. The approach is to handle both the procedures, threat detection phase and collision avoidance maneuver, in a unified fashion, where the optimal command for each possible relative attitude of the obstacle is computed off-line, therefore requiring low processing power for real-time operation. This work was done under the research project named SEAGULL that aims to improve maritime situational awareness using fleets of unmanned air system, where collision avoidance becomes a major concern.

The development of intelligent systems to support maritime situation awareness is the main goal o... more The development of intelligent systems to support maritime situation awareness is the main goal of the SEAGULL project. By equipping unmanned aerial vehicles (UAVs) with different types of optical sensors we target an intelligent maritime surveillance system. In this paper we present experiments performed with an hyperspectral camera to detect oil spills. We have developed a detection algorithm that automatically informs the base station of an oil spill in case a spectral signature recognized as oil is found on open sea. This contributes significantly to the generation of situational awareness of maritime events such as detection and georeferencing of oil spills or hazardous and noxious substances. After a brief overview of the SEAGULL platform and architecture, we focus on presenting the algorithms for automatic detection of oil spills with a hyperspectral camera on board an UAV.

InTech eBooks, Aug 23, 2017

The development of maritime unmanned tools for search and rescue operations is not a trivial task... more The development of maritime unmanned tools for search and rescue operations is not a trivial task. A great part of maritime unmanned systems developed did not target such application, being more focused on environmental monitoring, surveillance or defence. In opposition to these applications, search and rescue operations need to take into account relevant issues such as the presence of people or other vessels on the water. Building upon user requirements and overall integrated components for assisted rescue and unmanned search operations (ICARUS) system architecture, this chapter addresses the development of unmanned maritime systems. It starts with an overview of the approach where a twotier solution was adopted to address safety issues and then proceeds to detail each of the developed technologies.

Artificial Intelligence and Law

Decisions of regulatory government bodies and courts affect many aspects of citizens’ lives. Thes... more Decisions of regulatory government bodies and courts affect many aspects of citizens’ lives. These organizations and courts are expected to provide timely and coherent decisions, although they struggle to keep up with the increasing demand. The ability of machine learning (ML) models to predict such decisions based on past cases under similar circumstances was assessed in some recent works. The dominant conclusion is that the prediction goal is achievable with high accuracy. Nevertheless, most of those works do not consider important aspects for ML models that can impact performance and affect real-world usefulness, such as consistency, out-of-sample applicability, generality, and explainability preservation. To our knowledge, none considered all those aspects, and no previous study addressed the joint use of metadata and text-extracted variables to predict administrative decisions. We propose a predictive model that addresses the abovementioned concerns based on a two-stage cascade...

Scientific Data, Dec 6, 2023

Lecture Notes in Mechanical Engineering, 2020

Developments in Maritime Technology and Engineering, 2021

OCEANS 2015 - Genova, 2015

Advances in Intelligent Systems and Computing, 2014

Marine Technology Society Journal, 2021

InTech eBooks, Aug 23, 2017

Artificial Intelligence and Law

A Ground Based Vision System for UAV Pose Estimation, Sep 30, 2014

1. Introduction (Motivation and Objectives) 2. 3D Model-Based Pose Estimation System 3. Simulat... more 1. Introduction (Motivation and Objectives)
2. 3D Model-Based Pose Estimation System
3. Simulation and Experimental Results
4. Conclusions

A Ground-Based Vision System for UAV Autonomous Landing, May 29, 2014

• System for Autonomous landing;