Dipartimento di Ingegneria Meccanica, Energetica e Gestionale - Tesi di Dottorato

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Questa collezione raccoglie le Tesi di Dottorato afferenti al Dipartimento di Ingegneria Meccanica, Energetica e Gestionale dell'Università della Calabria.

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Innovative manipulation techniques for underwater robotics
(2019-03-04) Rizzo, Domenico; Furgiuele, Franco; Bruno, Fabio
This thesis is concerned with innovative manipulation techniques for underwater robotics and ocean engineering. In particular, it focuses on challenging problems of three different areas of the underwater manipulation, regarding the position feedback of the robotic arm, the visual feedback, and the manipulation of fragile objects. First, the position feedback has been addressed studying the kinematic performance of a hydraulic manipulator, in term of its accuracy and repeatability, used for underwater artifact cleaning activity. The manipulator has been re-designed during the CoMAS (Insitu conservation planning of Underwater Archaeological Artefacts) project. The results of the study have been of fundamental importance in the development of the control strategies for the control of the ROV and its manipulator. In fact, on the basis of the maximum error positions found and the kinematic performance of the arm it has been defined a “safety range” that allows avoiding collisions among the end-effector’s tool and the artifacts. Second, the visual feedback has been addressed presenting an augmented reality visualization of scene depth for aiding ROV (Remotely Operated Vehicle) pilots in underwater manipulation. The architecture and the software of the system have been developed during the CoMAS project, while in this thesis has been provided the calibration of the whole system. In particular, combining the kinematics of the robotic arm and the standard photogrammetric model of the stereo camera, it has been possible to generate a depth map that shows to the pilots the distances of the surface of the scene objects from the end-effector's pose. Experimental trials have been carried out in the laboratory and in the water tank in order to evaluate and improve the performance of the system, approaching the target softly. Despite the development of these feedbacks, currently, existing robotic manipulators are often too powerful and awkward to handle delicate or complex objects without damaging them. To figure this out, soft end effectors have been studied during my research internship at the faculty of Ocean Engineering of the University of Rhode Island (USA). The research activity has been carried out at the Robotics Laboratory for Complex Underwater Environments (R-CUE). In particular, it focuses on continues the development, prototyping, and testing of compliant jamming grippers based on Soft Robotics technologies. Specifically, the subject is divided into two main projects, studying both a universal jamming gripper and a hybrid toroidal soft gripper. The main purpose the universal jamming gripper has been to complete the integration with the existing arm, design and perform experiments with the gripper in the water tank, and propose refinements to the design of the mechanical and hydraulic system. While, the hybrid toroidal soft gripper has been designed, prototyped, and integrated with the existing arm and hydraulic system, to the end of carrying out a qualitative performance of the gripper in the water tank. The first extended trials of the hybrid toroidal soft gripper have been carried out at the Department of Mechanics, Energy, and Management (DIMEG) at the University of Calabria
Innovative methodologies for multi-view 3D reconstruction of cultural heritage
(2012-11-15) Gallo, Alessandro; Rizzuti, Sergio; Bruno, Fabio
This dissertation focuses on the use of multi-view 3D reconstruction techniques in the field of cultural heritage. To name just a few applications, a digital 3D acquisition can be used for documentation purposes in the event of destruction or damage of an artefact, or for the creation of museums and virtual tourism, education, structural studies, restoration, etc... All these applications require high precision and accuracy to reproduce the details, but there are other important characteristics such as low cost, ease of use, the level of knowledge needed to operate the systems, which have also to be taken into account. At the present time, the interest is growing around the use of images for the digital documentation of cultural heritage, because it is possible to obtain a 3D model by the means of common photographic equipment. In this work, we have investigated multi-view 3D reconstruction techniques in two specific fields that have not been treated in literature: the 3D reconstruction of small objects (from few mm to few cm) and the survey of submerged archaeological finds. As for the 3D reconstruction of small objects, a new methodology based on multi-view and image fusion techniques has been developed. The used approach solves the problems related to the use of macro lenses in photogrammetry, such as the very small depth of field and the loss of quality due to diffraction. Since image matching algorithms cannot work on blurred areas, each image of the sequence is obtained by merging pictures acquired at different focus planes. The methodology has been applied on different case studies, and the results have shown that it is possible to reconstruct small complex objects with a resolution of 20 microns and an accuracy of 10 microns. For which concerns the underwater imaging, a preliminary comparative study between active and passive techniques in turbid water has been conducted. The experimental setup consists in a 3D scanner designed for underwater survey, composed by two cameras and a projector. An analysis on the influence of the colour channel has been conducted, showing how it is possible to obtain a cleaner reconstruction by using the green channel only. The results have shown a denser point cloud when using the passive technique, characterized by missing areas since the technique is more sensible to turbidity. By contrast, the reconstruction conducted with the active technique have shown more stable results as the turbidity increases, but a greater noise. A multi-view passive technique has been experimented for the survey of a submerged structure located at a depth of 5 meters, on a seabed characterized by poor visibility conditions and the presence of marine flora and fauna. We performed an analysis of the performances of a multi-view technique commonly used in air in the first instance, highlighting the limits of the current techniques in underwater environment. In such conditions, in fact, it has not been possible to obtain a complete reconstruction of the scene. The second stage of the process was the testing of image enhancement algorithms in order to improve matching performances in poor visibility conditions. In particular, a variational analysis of the factors that influence the quality of the 3D reconstruction, such as the image resolution and the colour channel, has been performed. For this purpose, the data related to the parameters of interest, such as the number of features extracted or the number of oriented cameras, have been evaluated. The statistical analysis has allowed to find the best combination of factors for a complete and accurate 3D reconstruction of the submerged scenario.
Integrazione di tecniche ottiche e acustiche di imaging 3D in ambiente subacqueo
(2015-12-16) Lagudi, Antonio; Pagnotta, Leonardo; Rizzuti, Sergio; Bruno, Fabio
Optical surveying techniques for 3D reconstruction of submerged archaelogical artefacts
(2014-10-29) De Filippo, Francesco; Pagnotta, Leonardo; Bruno, Fabio
This thesis is concerned with optical surveying techniques for 3D reconstruction in underwater environment. In particular, it focuses on 3D modelling of archaeological areas, lying both in shallow and deep water. Virtual representations of archaeological sites are required by researchers in order to enhance study and preservation methodologies and also to ease promotion and dissemination. The presented work mainly follows two research lines. First, it tackles the main problems arisen for standard 3D reconstruction algorithms and procedures when applied on submarine datasets. Multi-View mapping algorithm has been investigated and enhanced in order to achieve high accuracy reconstruction of two submerged villae, despite the challenging context of Baia Archaeological Park. Then, the textured and high detailed models can be employed for different purposes; in particular, some examples of virtual exploration, simulation for device design and for intervention planning and monitoring are shown. The second research line deals with the implementation of a Simultaneous Localization and Mapping (SLAM) algorithm for Unmanned Underwater Vehicles (UUVs). Some datasets acquired by an UUV equipped with typical navigation sensors and with a stereo-camera have been processed through the implemented Extended Kalman Filter (EKF), in order to perform sensor fusion and enhance both vehicle tracking and 3D scene reconstruction. Additionally, Augmented State Kalman Filter (ASKF) has been implemented in order to exploit optical data for loop closure detection in order to reduce drift error, typical of dead-reckoning navigation.
Studio delle tecnologie di localizzazione acustica subacquea e sviluppo di tecniche per la riduzione dell'errore di posizione
(Università della Calabria, 2023-02-08) Aiello, Rosario; Conte, Enrico; Bruno, Fabio