2018
Authors
Santos, PV; Alves, JC; Ferreira, JC;
Publication
U.Porto Journal of Engineering
Abstract
2018
Authors
Pinto, VH; Cruz, NA; Almeida, RM; Goncalves, CF;
Publication
OCEANS 2018 MTS/IEEE CHARLESTON
Abstract
Underwater sensing and mapping operations using autonomous vehicles are becoming widely used. This article describes an automated system to launch and recover an AUV. It can operate in any host platform and can transport any torpedo-shaped vehicle with 0.2 meters of diameter, length up to 3 meters and weight up to 1000 N. The system ensures a restrained transportation of the vehicle and guarantees that it performs a smooth entrance in the water. It was instrumented for continuous status remote monitoring, using linear and angular motion sensors, as well as enables to remotely take control over the operation. Experimental results carried out within the XPRIZE competition demonstration scope are presented.
2018
Authors
Pinto, AF; Cruz, NA; Pinto, VH; Ferreira, BM;
Publication
2018 OCEANS - MTS/IEEE KOBE TECHNO-OCEANS (OTO)
Abstract
This paper presents an overview of a generalized 6 degrees of freedom model for surface vessels and explains how it can be extended for twin hull surface vehicles. The extended model takes into account the hull characteristics (dimensions and location), which are important to improve the accuracy of simulations and the performance of controllers. The method involves the calculation of the submerged volume of each hull, location of each hull's center of buoyancy and restoring forces/ torques due to buoyancy contributions. To evaluate the proposed model, some simulations were performed, using an example of allocation of propulsion system and realistic hydrodynamic coefficients (added mass and damping) and inertial tensors.
2018
Authors
Sousa, JP; Ferreira, BM; Cruz, NA;
Publication
2018 IEEE/OES AUTONOMOUS UNDERWATER VEHICLE WORKSHOP (AUV)
Abstract
Unmanned Underwater Vehicles (UUVs), such as Autonomous Underwater Vehicles (AUVs) and Remotely Operated Vehicles (ROVs) are versatile tools, suitable for many activities in different fields, and have seen an increase in usage, making them an area of interest in the study of robotics. The performance of any underwater vehicle in any given task is deeply affected by the precision of its localization system. The main challenge in underwater localization is the significant attenuation of any Radio Frequency (RF) signal underwater, which prevents the use of many common location methods such as the Global Positioning System (GPS). Many methods have been studied for the localization of UUVs, including the use of acoustic beacons. One of these methods is the use of a single moving beacon to obtain acoustic ranges, as opposed to a stationary single beacon, which restricts the UUV's trajectory or multiple beacons, involving more hardware, complicating missions' logistics and increasing costs. In this paper, a guidance algorithm based on the Fisher Information Matrix is proposed for an Autonomous Surface Vehicle to serve as a beacon vehicle and aid in the navigation of a UUV. The approach performances are assessed by means of simulations of the complete system under realistic conditions.
2018
Authors
Cruz, NA; Alves, JC; Ferreira, BM; Matos, AC;
Publication
Challenges and Innovations in Ocean In Situ Sensors: Measuring Inner Ocean Processes and Health in the Digital Age
Abstract
Robotic vehicles are already deployed around the globe as a preferred tool for ocean sampling, from surface coastal waters down to the deepest remote locations. They are mainly used to perform routine measurement tasks, with obvious benefits in terms of space and time density, as well as accuracy in the localization of measurements. As the underlying technology matures, new features are being introduced and validated in operational scenarios, enabling new paradigms in ocean observation. This chapter describes the latest developments in marine robotics, presented in different stages of maturity, and sheds light on upcoming features available to the scientific community.
2018
Authors
Gaspar, AR; Nunes, A; Pinto, AM; Matos, A;
Publication
ROBOTICS AND AUTONOMOUS SYSTEMS
Abstract
Public datasets are becoming extremely important for the scientific and industrial community to accelerate the development of new approaches and to guarantee identical testing conditions for comparing methods proposed by different researchers. This research presents the Urban@CRAS dataset that captures several scenarios of one iconic region at Porto Portugal These scenario presents a multiplicity of conditions and urban situations including, vehicle-to-vehicle and vehicle-to-human interactions, cross-sides, turn-around, roundabouts and different traffic conditions. Data from these scenarios are timestamped, calibrated and acquired at 10 to 200 Hz by through a set of heterogeneous sensors installed in a roof of a car. These sensors include a 3D LIDAR, high-resolution color cameras, a high-precision IMU and a GPS navigation system. In addition, positioning information obtained from a real-time kinematic satellite navigation system (with 0.05m of error) is also included as ground-truth. Moreover, a benchmarking process for some typical methods for visual odometry and SLAM is also included in this research, where qualitative and quantitative performance indicators are used to discuss the advantages and particularities of each implementation. Thus, this research fosters new advances on the perception and navigation approaches of autonomous robots (and driving).
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