CRAS - Indexed Articles in Journals

Permanent URI for this collection


Recent Submissions

Now showing 1 - 5 of 54
  • Item
    Design, Modeling, and Simulation of a Wing Sail Land Yacht
    ( 2021) Vítor Tinoco ; Benedita Malheiro ; Manuel Santos Silva ; 5855 ; 5655 ; 8387
    Autonomous land yachts can play a major role in the context of environmental monitoring, namely, in open, flat, windy regions, such as iced planes or sandy shorelines. This work addresses the design, modeling, and simulation of a land yacht probe equipped with a rigid free-rotating wing sail and tail flap. The wing was designed with a symmetrical airfoil and dimensions to provide the necessary thrust to displace the vehicle. Specifically, it proposes a novel design and simulation method for free rotating wing sail autonomous land yachts. The simulation relies on the Gazebo simulator together with the Robotic Operating System (ROS) middleware. It uses a modified Gazebo aerodynamics plugin to generate the lift and drag forces and the yawing moment, two newly created plugins, one to act as a wind sensor and the other to set the wing flap angular position, and the 3D model of the land yacht created with Fusion 360. The wing sail aligns automatically to the wind direction and can be set to any given angle of attack, stabilizing after a few seconds. Finally, the obtained polar diagram characterizes the expected sailing performance of the land yacht. The described method can be adopted to evaluate different wing sail configurations, as well as control techniques, for autonomous land yachts.
  • Item
    Three-Dimensional Mapping in Underwater Environment
    ( 2019) Alexandra Nunes ; Aníbal Matos ; 5158 ; 6869
    Autonomous underwater vehicles are applied in diverse fields, namely in tasks that are risky for human beings to perform, as optical inspection for the purpose of structures quality control. Optical sensors are more appealing cost and they supply a larger quantity of data. Lasers can be used to reconstruct structures in three dimensions, along with cameras, which create a faithful representation of the environment. However, in this context a visual approach was used and the paper presents a method that can put together the three-dimensional information that has been harvested over time, combining also RGB information for surface reconstruction. The map construction follows the motion estimated by a odometry method previously selected from the literature. Experiments conducted using real scenario show that the proposed solution is able to provide a reliable map for objects and even the seafloor.
  • Item
    A mosaicking technique for object identification in underwater environments
    ( 2019) Alexandra Nunes ; Ana Gaspar ; Andry Maykol Pinto ; Aníbal Matos ; 5446 ; 6869 ; 6868 ; 5158
    Purpose: This paper aims to present a mosaicking method for underwater robotic applications, whose result can be provided to other perceptual systems for scene understanding such as real-time object recognition. Design/methodology/approach: This method is called robust and large-scale mosaicking (ROLAMOS) and presents an efficient frame-to-frame motion estimation with outlier removal and consistency checking that maps large visual areas in high resolution. The visual mosaic of the sea-floor is created on-the-fly by a robust registration procedure that composes monocular observations and manages the computational resources. Moreover, the registration process of ROLAMOS aligns the observation to the existing mosaic. Findings: A comprehensive set of experiments compares the performance of ROLAMOS to other similar approaches, using both data sets (publicly available) and live data obtained by a ROV operating in real scenes. The results demonstrate that ROLAMOS is adequate for mapping of sea-floor scenarios as it provides accurate information from the seabed, which is of extreme importance for autonomous robots surveying the environment that does not rely on specialized computers. Originality/value: The ROLAMOS is suitable for robotic applications that require an online, robust and effective technique to reconstruct the underwater environment from only visual information. © 2018, Emerald Publishing Limited.
  • Item
    Learning Engineering with EPS@ISEP: Developing Projects for Smart Sustainable Cities
    ( 2019) Ferreira,P ; Guedes,P ; Benedita Malheiro ; Manuel Santos Silva ; 5655 ; 5855
    This paper presents an overview on how the European Project Semester capstone programme offered by the Instituto Superior de Engenharia do Porto (EPS@ISEP) fosters learning by challenging engineering, business and product development undergraduates to address sustainability issues afflicting cities and communities nowadays. This will be done by analysing the reports and the learning journey of three multicultural and multidisciplinary EPS@ISEP teams during the design, development and test of a smart billboard, a self-oriented solar mirror and a level monitoring system for waste oil bins. These three projects were conducted within EPS@ISEP, a project-based learning framework dedicated to the development of key engineering skills, namely multidisciplinary teamwork, inter-cultural communication, ethical and sustainability-oriented problem-solving. The involved students contributed, not only, to make cities more inclusive, safe, resilient and sustainable, one of UNESCO’s sustainable development goals, but learnt and practiced together sustainability-driven design, while searching for an innovative solution for a smart city problem. This conclusion is supported by the analysis of the content the three project reports.
  • Item
    Rigid wing sailboats: A state of the art survey
    ( 2019) Friebe,A ; Ferreira,P ; Guedes,P ; Benedita Malheiro ; Manuel Santos Silva ; Waller,M ; 5655 ; 5855