1,720,989 research outputs found
A shockproof hull made of foam: A useful project for operations on uneven ice
No full textThe aim of this paper is to describe an innovative composite structure called SoftHull developed for marine and amphibious vehicles capable of deforming without breaking under external actions. It is composed by a hull made of elastic and lightweight foam, supported by a rigid frame and protected by a flexible "skin" so that it can absorb shocks and withstand to most of the unpredictable lacerations that can occur during operations. The peculiar structure of SoftHull is constituted by a bulky volume of closed cells foam tracing the shape of the hull, which warrants the buoyancy in every condition. This part is protected by an external rigid skin made by a thin layer of a resistant but deformable material. The framework sustains the superstructures and absorbs the small loads transmitted by the elastic hull. The two parts are connected in such a way that the soft-hull results resiliently linked to the upper rigid part
Multipurpose air cushion platform
No full textThe aim of this paper is to describe the hovercraft "MACP", Multipurpose Air Cushion Platform arising from the 7thFP project named "Hoverspill". This project deals with the innovative design of a hovercraft for rapid Oil Spill in emergency situations. The developed vehicle is an Air-cushion platform characterized by compact size, wide cargo space and modularity which provide several utilizations, both for research & development and for working purposes (e.g. oil Spill emergency, bathymetric surveys, search and rescue). In this study we describe the main issues that led to the definitions of the vehicle. We summarize the main tools of the project and the systems installed on-board. More, we introduce the SoftHullTM, an innovative composite structure to solve the wear and fragility problem is described. Reports are given on the modular propulsion system and on the different techniques to improve the turning of hovercrafts. Finally we outline testing results which suggest future applications of our results for the research on hovercrafts and boats
Investigation into the steering ability problems of compact hovercrafts
No full textThe present paper investigates the requirements and the turning ability problems of the hovercrafts characterized by compact dimensions (with small width, powerful engine and big propellers). These vehicles require a very accurate control system, to combine the command of turning or trim with the possibility of reversing the thrust. In this article we briefly describe compact hovercrafts and focus on the various systems projected to improve their turning ability. We give an account of the steps which led to achieve our technical solutions and show the various systems of passive control surfaces adopted: to verify the different assessed implementations, several on-field tests have been performed on two vehicles, the Hover4 and the Multipurpose Air Cushion Platform (MACP). Finally we illustrate the ultimate chosen version of the system, in particular we outline the positive effects of the adoption of an unusual axis of rotation used to solve the problems created by the vertical rudders, whose centre is higher than the barycentre of the vehicle
Adaptive steering control for an azimuth thrusters-based autonomous vessel
No full textThe proposed paper presents the design and development of the combined guidance and control strategies for the autonomous navigation of unmanned vessels characterised by azimuth-based thrust architecture. Autonomous marine vehicles (AMVs) are consolidated technological tools commonly employed for different tasks such as exploration, sampling and intervention. With the final aim of autonomous shipping, the AMVs capabilities have to be migrated and adapted towards the reliable and safe control of commercial-like unmanned vessels. These last are spreading thanks to a number of technological research projects. The employment of unconventional hull shapes combined with propulsive layout based on azimuth thrusters requires robust guidance techniques to provide precise and reliable motion control during navigation. The paper introduces a dual-loop guidance and control scheme able to provide advanced navigation capabilities. An inner control loop, devoted to the actuation of the azimuth thrusters, allows the tracking of reference course angle (namely the autopilot). Such a control loop is characterised by a modified PD regulation scheme, where a novel adaptive derivative component is inserted in order to improve the convergence curve towards the required course reference. The outer guidance loop, based on Lyapunov and virtual-target approach, allows the vessel to track generic desired paths, thus enhancing the autonomous navigation capabilities. The paper will provide a deep design and analysis approach for the developed techniques, as well as simulation results of the combined guidance and control scheme, proving the reliability of the proposed approach in different operative conditions
Remote data collection near marine glacier fronts unmanned vehicles for autonomous sensing, sampling in the north pole
No full texte-URoPe: a reconfgurable AUV/ROV for man-robot underwater cooperation
No full textThis work describes the new Unmanned Marine Vehicle e-URoPe developed by CNR-ISSIA. This Remotely Operated Vehicle is realized using the most innovative technical capabilities in order to achieve a fexible structure, adequate to withstand external impacts. The peculiar characteristics of the vehicle, on which is based the design concept, are: easiness of construction, facility of re-confguration and fexibility. Furthermore the vehicle could be completely modifed without big eforts in terms of money and time. The vehicle can be equipped with diferent types of sensors in order to make it fexible and adaptable to various applications such as sampling of water or objects, underwater manipulation, cooperation with underwater operators or with other underwater vehicles, mapping of underwater ground and detection of vegetation lying on the seabed
SWAMP, an Autonomous Surface Vehicle expressly designed for extremely shallow waters
No full textWetlands, the geographic areas where water meets the earth, are ecosystems essential for life and an increasing number of conventions, directives and research projects recognise the necessity of protecting them. Nevertheless the number, quality and spacial resolution of surveys is modest due to the absence of expressly addressed tools. In this paper the design, construction and testing of the first prototype of an innovative class of Autonomous Surface Vehicles (ASVs) for the extremely shallow water and remote areas of wetlands is presented. SWAMP (Shallow Water Autonomous Multipurpose Platform) is a full y electric, modular, portable, lightweight, and highly-controllable ASV. It is a catamaran, equipped with four thrusters azimuth Pump-Jet thrusters that are flush with the hull and specifically designed for this vehicle. SWAMP is also characterised by small draft soft-foam, unsinkable hull structure with high modularity and a flexible hardware/software architecture. Each hull can be considered as a single vehicle, being equipped with a full navigation, guidance and control package, as well as propulsion, power and communication systems. The extreme modularity is also guaranteed thanks to the adoption of on-board Wi-Fi communication architecture: the two mono-hull vehicles are connected via Wi-Fi as well as all the modules aboard each of them
Wetlands monitoring: hints for innovative autonomous surface vehicles design
No full textWetlands are geographic areas where water meets the earth. They cover between 5% and 8% percent of the Earth’s surface including coastal areas, swamps rivers and lakes. They are essential ecosystems for human life. Various international conventions, directives and projects work on their protection that can help fighting the disasters resulting also from climate change. However, the acquisition and monitoring of environmental parameters in these areas is often difficult and ineffective. Classical vehicles (boats or wheeled vehicles) are not adequate in these areas and sometimes they are inaccessible or dangerous to human beings (critical or extreme environments). The development and the exploitation of innovative unmanned technologies can make surveys faster, more efficient and precise. Autonomous Surface Vehicles (ASVs) can work over extended periods of time and less staffing is required thanks to the high level of autonomy. In this paper, several technological solutions are explored and a modular and portable ASV with an innovative propulsion system suitable for working in shallow water is described
Design of an obstacle detection system for marine autonomous vehicles
No full textThe need for the transfer of robotic technology from the research laboratories to civilian applications is now a major issue for the robotic community. In the field of marine robotics is particularly important to endow the robot with a safe and highly reliable Navigation Guidance and Control (NGC) system which enables the Unmanned Surface Vehicle (USV) to safely navigate even in presence of human activities such as commercial and recreational traffic, swimmers, rowers, etc. A key aspect to achieve a safe autonomous navigation is the ability of the robot to recognize well in advance the presence of an unexpected, potentially moving, obstacle. This function represents the base brick for the development of a collision avoidance systems smart enough to reactively detect unexpected obstacles and perform the necessary avoidance maneuvers to safely prevent collisions. The present paper describes the design of an a innovative obstacle detection sensor, combining both passive and active optical devices and based on a new concept of optronic system. It is specifically conceived for collision avoidance tasks in marine environments, designed to be easily mounted on small-medium sized USVs. Its innovation consists in the interaction between the different integrated sensors, that are in fact totally decoupled. The paper presents the functional architecture of the object detection sensor together with the preliminary mechanical design. Moreover some experimental data collected by the sensor are reported, and some simulations, highlighting the ability of the system to detect and correctly avoid both still obstacles and mobile traversing obstacles, are shown
Monitoring of sea-ice-atmosphere interface in the proximity of arctic tidewater glaciers: The contribution of marine robotics
No full textThe Svalbard archipelago, with its partially closed waters influenced by both oceanic conditions and large tidal glaciers, represents a prime target for understanding the effects of ongoing climate change on glaciers, oceans, and ecosystems. An understanding of the role played by tidewater glaciers in marine primary production is still affected by a lack of data from close proximity to glacier fronts, to which, for safety reasons, manned surface vessels cannot get too close. In this context, autonomous marine vehicles can play a key role in collecting high quality data in dangerous interface areas. In particular, the contribution given by light, portable, and modular marine robots is discussed in this paper. The state-of-the-art of technology and of operating procedures is established on the basis of the experience gained in campaigns carried out by Italian National Research Council (CNR) robotic researchers in Ny-Alesund, Svalbard Islands, in 2015, 2017, and 2018 respectively. The aim was to demonstrate the capability of an Unmanned Semi-Submersible Vehicle (USSV): (i) To collect water samples in contact with the front of a tidewater glacier; (ii) to work in cooperation with Unmanned Aerial Vehicles (UAV) for sea surface and air column characterisation in the proximity of the fronts of the glaciers; and (iii) to perform, when equipped with suitable tools and instruments, repetitive sampling of water surface as well as profiling the parameters of the water and air column close to the fronts of the tidewater glaciers. The article also reports the issues encountered in navigating in the middle of bergy bits and growlers as well as the problems faced in using some sensors at high latitudes
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