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Publications

Publications by CRAS

2017

Signed Distance Function Based Surface Reconstruction of a Submerged Inland Mine Using Continuous-time SLAM

Authors
Bleier, M; Dias, A; Ferreira, A; Pidgeon, J; Almeida, J; Silva, E; Schilling, K; Nuechter, A;

Publication
IFAC PAPERSONLINE

Abstract
The planning of mining operations in water filled open-pit mines requires detailed bathymetry to create a mine plan and assess the involved risks. This paper presents post processing techniques for creating an improved 3D model from a survey carried out using an autonomous surface vehicle with a multibeam sonar and a GPS/INS navigation system. Inconsistencies of the created point cloud as a result of calibration errors or GPS signal loss are corrected using a continuous-time simultaneous localization and mapping (SLAM) solution. Signed distance function (SDF) based mapping is employed to fuse the measurements from multiple runs into a consistent representation and reduce sensor noise. From the signed distance function model we reconstruct a 3D surface mesh. We use this terrain model to establish a virtual reality scene for immersive data visualization of the mining operations for testing and planing during development. Results of the proposed approach are demonstrated on a dataset captured in an abandoned submerged inland mine.

2017

UAV Cooperative Perception for Target Detection and Tracking in Maritime Environment

Authors
Amaral, G; Silva, H; Lopes, F; Ribeiro, JP; Freitas, S; Almeida, C; Martins, A; Almeida, J; Silva, E;

Publication
OCEANS 2017 - ABERDEEN

Abstract
This paper addresses the topic of target detection and tracking using a team of UAVs for maritime border surveillance. We present a novel method on how to integrate the perception into the control loop using two distinct teams of UAVs that are cooperatively tracking the same target. We demonstrate and evaluate the effectiveness of our approach in a simulation environment.

2017

Collision Avoidance for Safe Structure Inspection with Multirotor UAV

Authors
Azevedo, F; Oliveira, A; Dias, A; Almeida, J; Moreira, M; Santos, T; Ferreira, A; Martins, A; Silva, E;

Publication
2017 EUROPEAN CONFERENCE ON MOBILE ROBOTS (ECMR)

Abstract
The multirotor UAVs are being integrated into a wide range of application scenarios due to maneuverability in 3D, versatility and reasonable payload of sensors. One of the application scenarios is the inspection of structures where the human intervention is difficult or unsafe and the UAV can provide an improvement of the collected data. At the same time introduce challenges due to low altitude missions and also the fact of being manually operated without line of sight. In order to overcome these issues, this paper presents a LiDAR-based realtime collision avoidance algorithm, denoted by Escape Elliptical Search Point with the ability to be integrated into autonomous and manned modes of operation. The algorithm was validated in a simulation environment developed in Gazebo and also in a mixed environment composed by a real robot in an outdoor scenario and simulated obstacle and LiDAR.

2017

Fish Farming Autonomous Calibration System

Authors
Lopes, F; Silva, H; Almeida, JM; Pinho, C; Silva, E;

Publication
OCEANS 2017 - ABERDEEN

Abstract
The fish farming industry is becoming widespread all over the world. By 2039 most of the fish we eat will come from the fish farming industry. In this work, we propose an autonomous robotic solution for indoor fish farming biomass estimation. Our proposed system moves silently on top of the tank borders using differential wheels and a structured light vision system (SLS). The SLS system is composed by a camera and two line lasers (projectors) equipped with a line beam that allows to obtain the fish depth profile present in the tank to perform biomass estimation. Results in laboratory and in real aquaculture environment with live fish are presented.

2017

Simulation Environment for Underground Flooded Mines Robotic Exploration

Authors
Sytnyk, D; Pereira, R; Pedrosa, D; Rodrigues, J; Martins, A; Dias, A; Almeida, J; Silva, E;

Publication
OCEANS 2017 - ABERDEEN

Abstract
Underwater experiments with unmanned vehicles are complex, costly, time-consuming and in some circumstances potentially dangerous, involving the risk of losing or damaging the robots. The nature of the underwater environment, makes it very difficult, for researchers, to observe the evolution of the running system. Simulators are useful tools for the development of unmanned vehicle software, algorithm benchmarking and system preliminary validation. In this work, the problem of simulating a complex underwater scenario for marine robotics and a comparative analysis of simulators for marine robotics are presented. Relevant sensors for underwater robots under development, such as multibeam and imaging 2D sonar were implemented in two simulators and tested in a realistic experimental scenario like a flooded mine.

2017

UAV Cooperative Perception based on DDS communications network

Authors
Ribeiro, JP; Fontes, H; Lopes, M; Silva, H; Campos, R; Almeida, JM; Silva, E;

Publication
OCEANS 2017 - ANCHORAGE

Abstract
This paper focus on the use of unmanned aerial vehicle teams for performing cooperative perception using Data Distribution Service (DDS) Network. We develop a DDS framework to manage the incoming and out bounding network traffic of multiple types of data that is exchanged inside the UAV network. Experimental results both in laboratory and in actual flight are presented to help characterize the proposed system solution.

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