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Data analysis of an oscillating flapping wing is conducted for developing a transfer function model especially for heave force data series from the CFD environment for different geometries of flapping wings. The wing experiences a combination of vertical and angular oscillatory motion, while travelling at constant forward speed. The vertical motion is induced by the random motion of the ship in waves,...
Within the framework of the Italian national project MARIS (Marine Autonomous Robotics for InterventionS), in this paper a control law based on a virtual decomposition approach for underwater vehicles carrying a n-degrees-of-freedom manipulator is presented. The control law, already known in the literature, has been customized for the specific set-up of MARIS. Being based on the Newton-Euler formulation,...
Buoyancy systems are used in submarines and various submersible equipment such as ARGO floats but are rarely incorporated in Remotely Operated Vehicles (ROVs). This paper presents a system for automated lifting and buoyancy control for a remotely operated sea crawler. This system, consisting of hydraulic, electric and control subsystems, allows the operator to navigate the vehicle to any desired depth...
The paper deals with the problem of designing tactile sensors for underwater applications. The tactile sensors are used in many terrestrial applications, but research in underwater tactile perception remains limited because of the scarcity of underwater tactile sensors. In this paper the authors, after a review on underwater sensors available in commerce and in literature, propose a conceptual design...
Underwater gliders are high efficiency underwater vehicles without propeller systems. The glider is capable of sawtooth motion in the vertical plane and spiral motion along a circular helix which is aligned with gravity. Both of the two types of motion are stable and have been observed on most commercially gliders. An underwater glider is able to turn head if the two types of motion are cooperated,...
In this study, analytical study to optimally arrange the multi-piles and the concrete base parts of the steel-concrete hybrid substructure for offshore wind was carried out. In order to minimize wave force and wave-induced bending moment subjected to the substructure system, diffraction and structural analysis were carried out for three types of hybrid substructure to the concrete base height. As...
When modules are installed on the seafloor they often need to interface with existing equipment. The modules will therefore need to be positioned and oriented precise. Today this is done by using guide-wires, or by using a manually controlled ROV. Both these methods are costly and time consuming. This paper propose a system for automating the ROV. We believe that such system will make installations...
Wave forces on coastal-bridge decks are calculated by Euler's equations, and by nonlinear shallow-water wave equations. Euler's equations are solved by use of an open source Computational Fluid Dynamics (CFD) software, namely OpenFOAM. In the numerical wave tank, Euler's equations are solved for both water and air above, and the free-surface is determined by a Volume of Fluid interface tracking method...
The purpose of this work is to describe a possibility of installation of a wave converter in Sicily, in the Mediterranean Sea. In this paper we present the design of buoyant electrical generator, in particular, wave linear permanent magnet generator which can make wave energy converted to electrical energy.
A functional scale prototype has been constructed for a single-piston pump (SPP) that will be used as a building block in the core technology of a novel wave energy converter termed the Ocean Grazer: the multi-pump, multi-piston power take-off (MP2PTO) system. Experimental measurements performed with this scale prototype show that volumetric losses in the pumping system dictate its total efficiency,...
Study of this article was conducted on horizontal axis tidal turbines in a demonstration project of a 500kW ocean energy independent power supply system. Considering the depth of the sea site where the turbines would be deployed, seabed seated supporting structure was adopted in construction of two turbine units. As a typical tidal current energy resource zone in North part of China, the flow velocity...
Wave energy is a promising new player in the renewable energy field. The exploitable power within the world's oceans is significant and many developers try to capture it by developing wave energy converter (WEC) concepts. This research focussed on the conversion of the WEC motions into usable electricity by the power take-off system (PTO). Specifically, a hydraulic PTO system with an accumulator as...
This paper presents an approach of analyzing the sawtooth and spiraling equilibrium motion of underwater gliders which is actuated by a single internal movable and rotatable mass. The equations are derived and then solved through a recursive algorithm. Hydrodynamic coefficients of the underwater glider are calculated by computational fluid dynamics (CFD) software packages. The motions of the underwater...
The effect of the rubber sealing on the bandwidth of an optoelectronic force/torque sensor for underwater robotic applications is investigated in this paper. If compared to commercial F/T sensors, such as the ones for industrial applications, the sensor here described is designed in such a way to present a considerable compliance to deal with uncertainties both in the object shape and in the environments...
During re-entry operations in offshore drilling, the drill pipe needs to be monitored in order for the drillship to maintain or change its position. In oil and gas drillings, conventional remotely operated vehicles (ROVs) are used for such operations. However, in scientific drillings, conventional ROVs cannot be used because target water depths can be as large as 7,000 m. The scientific drilling vessel...
This paper considers the hierarchical control strategy for enhancing the captured and converted powers in heaving wave energy converters. The hierarchical control strategy consists of a higher hierarchical controller (HHC) and a lower hierarchical controller (LHC). The main role of the HHC is to provide the optimum reference for the LHC. The LHC follows the reference despite the existence of perturbations...
This paper presents a decision support system (DSS) to help Command and Control (C2) operators. Hereby, the METOC-driven vessel interdiction system (MVIS) is presented. It is aimed to help the decision-making process in case of interdiction operations so that the success rate increases. In particular, MVIS yields the best location along a predicted path to interdict a vessel in the best meteorological...
This paper presents a novel double-sided linear synchronous generator intended for applications in Wave Energy Conversion. The proposed open slot structure of the proposed generator simplifies the manufacturing process. The external and internal stators are in a relative position to each other that improves magnetic flux utilization and reduces oscillations in reluctance for different translator positions...
In this work a punting gait model, describing a robot running underwater, is studied with respect to unknown variations of the ground and design parameters of the robot. The model, described through a dynamical system, is actuated with an open-loop control and exhibits self-stabilizing running, represented by the limit cycle of the system, on flat terrain. By introducing a simulated uneven terrain...
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