Optimal identification of potential-radiation hydrodynamics for moored floating structures—a new general approach in state space

Jordan, M.A.; Beltrán-Aguedo, Reinel

doi:10.1016/j.oceaneng.2004.01.007

Cited by 19 publications

(17 citation statements)

References 17 publications

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“…where S m and L m are the mooring cable stiffness and the cable horizontal length, respectively [17,18]; • The restoring force, f rs (t) , which represents the force applied by the auxiliary spring units installed between the translator of the PMLG and the system's point of interaction at the seabed. f rs (t) is modelled as a spring force, such as, f rs (t) = S rs z(t), where S rs represents the spring stiffness coefficient; • The losses force, f l (t), which includes the losses due to friction, viscosity, and non-ideal PTO mechanisms.…”

Section: Heaving Wec Dynamicsmentioning

confidence: 99%

An Intelligent Fuzzy Logic Controller for Maximum Power Capture of Point Absorbers

et al. 2014

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This article presents an intelligent fuzzy logic controller (FLC) for controlling single-body heaving wave energy converter (WEC) or what is widely known as "Point Absorber". The controller aims at maximizing the energy captured from the sea waves. The power take-off (PTO) limitations are addressed implicitly in the fuzzy inference system (FIS) framework. In order to enhance the WEC power capturing bandwidth and make it less susceptible to wave environment irregularities and the system parametric uncertainties, the controller is built to have a self-configurable capability. This also eliminates the need to repeatedly run in-situ tuning procedure of the fuzzy controller or switch between several controllers based on the operating conditions. The fuzzy membership functions (MFs) are optimally tuned using particle swarm optimization (PSO) algorithm. To alleviate the computational burden associated with performing on-line optimization, the fuzzy controller is tuned at a rate significantly lower than the system sampling time. The suggested PSO-FLC has shown promising results compared with the fixed structure fuzzy logic controller (FS-FLC) and other passive control strategies. Several computer simulations were carried out to evaluate the controller effectiveness by applying different sea-states and analyzing the resultant WEC dynamics.

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Section: Heaving Wec Dynamicsmentioning

confidence: 99%

An Intelligent Fuzzy Logic Controller for Maximum Power Capture of Point Absorbers

et al. 2014

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“…Relations (14) and (15) were obtained by interpolating various curves γ (ω; D, d) for a set of values of D and d and normalizing with respect to γ (ω; 2, 15). Using Fig.…”

Section: Equations Of Motion: Modelmentioning

confidence: 99%

Numerical stability analysis and control of umbilical–ROV systems in one-degree-of-freedom taut–slack condition

Jordan

Bustamante

2006

Nonlinear Dyn

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In this paper, the stability of an umbilical-ROV system under nonlinear oscillations in heave motion is analyzed using numerical methods for the uncontrolled and controlled cases comparatively. Mainly the appearance of the so-called taut-slack phenomenon on the umbilical cable produced by interactions of monochromatic waves and an operated ROV is specially focused. Nonlinear elements were considered as nonlinear drag damping, bilinear restoring force and saturation of the actuators. Free-of-taut/slack stability regions are investigated in a space of physical bifurcation parameters involving a set of both operation and design parameters. They indicate a wide diversity in qualitative behaviors, both in the periodicity and possible routes to chaos from the stability regions to outside. For detection of periodicity of the nonlinear oscillations inside and outside the stability regions, a method based on Cauchy series is developed. The first part of the results is dedicated to the stability of the uncontrolled dynamics. These results suggest the design of a control system that is able to counteract hefty hauls of the cable during the sinking/lifting operation under perturbation. A combination of a force and cinematic controller based on nonlinear model-reference control is proposed. Through a comparative study of the stability regions for uncontrolled and controlled dynamics, it is shown that the control system can extend considerably these regions without appearance of the taut-slack phenomenon despite the presence of wave perturbations. The limits between the taut and taut-slack zones are defined by the wave steepness and the available energy of the actuators.

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“…This radiation is captured according to the linear Theory of Airy as potential-radiation loads influencing the inertia and kinematics of the dynamics. They are associated with radiated waves in an ideal fluid and can be stated in the time domain by means of state-space-model approaches (Jiang, 1991;Schelin et al, 1993;Jordán and Beltrán-Aguedo, 2003) or a convolution approach (Cummins, 1962;Olgivie, 1964). This is…”

Section: Generalized Potential-radiation Forcementioning

confidence: 99%

“…An approach to identify coefficients of mooring lines in dynamic operation with measures of the forces and position at their upper extremes is presented in Jordán and Beltrán-Aguedo (2004a). The estimation of potential-radiation models is analyzed in Jordán and Beltrán-Aguedo (2004b). In the present work, we complete the identification of the whole system.…”

Section: Introductionmentioning

confidence: 99%

On-line identification and convergence analysis of excitation-force and drag-force models for moored floating structures

Jordan

2006

Ocean Engineering

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Optimal identification of potential-radiation hydrodynamics for moored floating structures—a new general approach in state space

Cited by 19 publications

References 17 publications

An Intelligent Fuzzy Logic Controller for Maximum Power Capture of Point Absorbers

An Intelligent Fuzzy Logic Controller for Maximum Power Capture of Point Absorbers

Numerical stability analysis and control of umbilical–ROV systems in one-degree-of-freedom taut–slack condition

On-line identification and convergence analysis of excitation-force and drag-force models for moored floating structures

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