scholarly journals A Novel Three-SPR Parallel Platform for Vessel Wave Compensation

2020 ◽  
Vol 8 (12) ◽  
pp. 1013
Author(s):  
Yong Zhan ◽  
Huichun Tian ◽  
Jianan Xu ◽  
Shaofei Wu ◽  
Junsheng Fu
Keyword(s):  
Compensation Effect ◽  
Kinematic Model ◽  
Inverse Kinematic ◽  
Ship Motion ◽  
Forward Kinematics ◽  
Positioning System ◽  
Sea State ◽  
Dynamic Positioning System ◽  
Upper Deck ◽  
Parallel Platform

A wave compensation platform based on 3-SPR parallel platform is designed for marine ships with a dynamic positioning system. It can compensate for the heave, rolling, and pitching movement of a vessel under level 4 sea state. The forward kinematics of the mechanism is used to draw the central point position workspace and the attitude workspace of the moving deck of the compensation platform. The compensation effects of the 3-RPS parallel compensation platform and the 3-SPR parallel compensation platform are compared, and the feasibility and superiority of the compensation scheme using the 3-SPR parallel compensation platform are proved. To lower the working height of the upper deck of the compensation platform and reduce the extension range of the support legs, the structure of the compensation platform is optimized, and a novel 3-SPR parallel platform is designed. Finally, a simulation model was established. Using the inverse kinematic model as a compensation movement solver which can online calculate the length of branch legs based on the measured heaving, rolling, and pitching values of vessels, the compensation effect of the new structure under a certain sea state is simulated. The result demonstrated the efficiency of the ship motion decoupling movement of the newly designed compensation platform and proved the competence of it.

Modeling and Simulation of Ship Motion for Dynamic Positioning Vessel

2014 ◽  
Vol 919-921 ◽  
pp. 2127-2130
Author(s):  
Pei Wen Yu ◽  
Hui Chen
Keyword(s):  
Modeling And Simulation ◽  
Wind Wave ◽  
Ship Motion ◽  
Dynamic Positioning ◽  
Positioning System ◽  
Dynamic Positioning System ◽  
Oil Supply ◽  
Mmg Model ◽  
Simulation Results

The paper presents a method to build MMG model of ship motion for a oil supply vessel (OSV) with dynamic positioning system. It is assumed that the ship motion exposed to environment disturbances like wind, wave & currents, The simulation results show that the model of the vessel and environment disturbances are suitable, and the method is practicable .

Realistic Adaptive DP Controller for Flotel Operating in Side-by-Side Configuration With FPSO

2019 ◽  
Author(s):  
A. Yenduri ◽  
A. R. Magee ◽  
J. Liu ◽  
W. Xu ◽  
A. Choudhary ◽  
...  
Keyword(s):  
Neural Network ◽  
Shielding Effect ◽  
Dynamic Positioning ◽  
Positioning System ◽  
Sea State ◽  
Large Wave ◽  
Dynamic Positioning System ◽  
The Neural Network ◽  
Ocean Environment ◽  
State Detector

Abstract Side-by-side operation of multiple floaters in the ocean environment is very challenging and the operators always prefer a maximum operable weather window, in order to minimise the cost incurred from the downtime. The safety of the gangway connecting the floaters is very crucial and its dynamic response in the ocean environment raises concerns during operations. Therefore, an efficient dynamic positioning system is essential to maintain the floater and ultimately, the gangway response within the desired limits. In this work, a novel dynamic positioning system for floater operating aside another vessel is presented. The system includes an adaptive controller combined an optimised thruster allocation law and with a sea state detector. The adaptive control is achieved by using the barrier Lyapunov function and a predictor-based method in combination with the neural network scheme. The limitations include the saturation of inputs and the forbidden zones due to thruster-thruster or thruster-hull interaction. An optimised allocation for lower fuel consumption, wear and tear of the thruster equipment and to ensure the resultant command in the respective direction of the azimuth thrusters is designed. The optimisation here is a non-convex problem and a locally convex reformulation of second order is implemented. The presence of unknown shielding effect due to nearby vessel in a side-by-side configuration and input time delay is also considered in the development of this thruster allocation law. In order to overcome these effects, a novel sea state detector is designed. The sea state detector can effectively monitor the variation of drift wave-induced force on the vessel and activate the neural network compensator in the controller when a large wave drift force is identified. Simulation studies are conducted to verify the efficiency of this dynamic position system and a demonstration of flotel in side-by-side configuration with a turret moored FPSO is presented for the non-collinear ocean environment.

Initial Design and Analysis of a Compressed Natural Gas Transport System

2021 ◽  
Author(s):  
Decao Yin ◽  
Halgeir Ludvigsen ◽  
Halvor Lie ◽  
Ivar Fylling
Keyword(s):  
Natural Gas ◽  
Positioning System ◽  
Preliminary Design ◽  
Sea State ◽  
Compressed Natural Gas ◽  
Environmental Loads ◽  
Dynamic Positioning System ◽  
Flexible Pipes ◽  
Natural Gas Transport ◽  
Positioning Analysis

Abstract Offloading hoses/flexible pipes are used to transfer compressed natural gas (CNG) from an intermediate floating storage and offloading unit (FSO) to CNG vessel (GASVESSEL). The floating hoses are subjected to environmental loads that are mainly waves, current, and vessel motions from both the FSO and the CNG vessel. Preliminary design of loading/unloading system and dynamic positioning system has been performed. Dynamic analysis of the loading/offloading hose and positioning analysis of the FSO and CNG vessel have been carried out numerically in this study. It is verified that the designed loading/unloading system and positioning system of the two vessels (FSO and CNG vessel) are able to operate safely under the sea-state Hs = 6 m within the defined ESD1 zone.

Design of Optimal Controller for Dynamic Positioning System

2011 ◽  
Vol 308-310 ◽  
pp. 2127-2130 ◽  
Author(s):  
Pei Wen Yu ◽  
Hui Chen
Keyword(s):  
Kalman Filter ◽  
White Noise ◽  
Wind Wave ◽  
Ship Motion ◽  
Optimal Controller ◽  
Dynamic Positioning ◽  
Positioning System ◽  
Dynamic Positioning System ◽  
Simulation Results

The paper presents a method to design a LQG controller for dynamic positioning system. It is assumed that these are corrupted with white noise hence a Kalman filter is applied to observe the ship motion exposed to environment disturbances like wind, wave & currents, The simulation results show that the performance of the filter and controller are suitable, and the method is practicable .

Effects of Wave Drift Forces on Maneuvering of Ship

2008 ◽  
Author(s):  
Takeshi Kinoshita ◽  
Weiguang Bao ◽  
Motoki Yoshida ◽  
Yasunori Nihei ◽  
Yongze Xu ◽  
...  
Keyword(s):  
Dynamic Positioning ◽  
Positioning System ◽  
Ocean Engineering ◽  
Sea State ◽  
Dynamic Positioning System ◽  
Wave Drift ◽  
Wave Basin ◽  
Wave Drift Damping ◽  
Wave Drift Forces ◽  
Drift Forces

The dynamic positioning system of floating ocean structures requires hydrodynamic force derivatives to construct an accurate maneuvering model. In a severe sea state, the effects of ambient wave field on the maneuvering properties are not negligible. To investigate wave drift forces affecting on maneuvering of a ship relating to dynamic positioning system, an innovative model test, i.e. the Planer Motion Mechanism (PMM) test in waves is discussed in the present paper. Meanwhile, a theory to evaluate wave drift force including wave drift damping and wave drift added mass is summarized. Some examples of experiments done in Ocean Engineering Wave Basin of Institute of Industrial Science, University of Tokyo are presented and compared with calculated results based on the above theory.

Riser Instrumentation: Deep Water Drilling Campaign Results

1985 ◽  
Vol 107 (4) ◽  
pp. 408-414
Author(s):  
J.-C. Schawann ◽  
C. Sparks
Keyword(s):  
Ship Motion ◽  
Ship Motions ◽  
Positioning System ◽  
Two Dimensional ◽  
Dynamic Positioning System ◽  
Long Period ◽  
Simultaneous Measurements ◽  
Large Ship ◽  
Different Depths ◽  
Water Depths

During the 1982–1983 drilling campaign in the Mediterranean, two wells were drilled by the Discoverer Seven Seas in record water depths of 1714 m and 1252 m. The riser was equipped with instruments to measure tensions, moments and angles at points close to the extremities. Simultaneously ship motions and environmental conditions including current measurements at various depths were recorded by ELF AQUITAINE and I.F.P. A large quantity of data relating to riser behavior was gathered and recorded. The results available for publication include raw data relating to the evolution of current at different depths, long period lateral ship motion acting at the riser top end, induced by the dynamic positioning system. Simultaneous measurements of angles at extremities were recorded to confirm the validity of two-dimensional riser analysis. Measurements of riser parameters made with deliberately large ship excursions from the vertical, enabled the riser practical profile to be compared with the theoretical one. Measurements, made with the riser hung off in storm conditions, confirmed the existence of large dynamic tensions and enabled them to be compared with the theoretical values. Correlation of the fluctuation of cable tension with ship heave has led to practical values of tensioner stiffness.

Kinematics Modeling of a Notched Continuum Manipulator

2015 ◽  
Vol 7 (4) ◽  
Author(s):  
Zhijiang Du ◽  
Wenlong Yang ◽  
Wei Dong
Keyword(s):  
Curve Fitting ◽  
Inverse Kinematics ◽  
Degrees Of Freedom ◽  
Kinematic Model ◽  
Inverse Kinematic ◽  
Forward Kinematics ◽  
Kinematics Modeling ◽  
Continuum Manipulators ◽  
Continuum Manipulator ◽  
The Continuum

In this paper, the kinematics modeling of a notched continuum manipulator is presented, which includes the mechanics-based forward kinematics and the curve-fitting-based inverse kinematics. In order to establish the forward kinematics model by using Denavit–Hartenberg (D–H) procedure, the compliant continuum manipulator featuring the hyper-redundant degrees of freedom (DOF) is simplified into finite discrete joints. Based on that hypothesis, the mapping from the discrete joints to the distal position of the continuum manipulator is built up via the mechanics model. On the other hand, to reduce the effect of the hyper-redundancy for the continuum manipulator's inverse kinematic model, the “curve-fitting” approach is utilized to map the end position to the deformation angle of the continuum manipulator. By the proposed strategy, the inverse kinematics of the hyper-redundant continuum manipulator can be solved by using the traditional geometric method. Finally, the proposed methodologies are validated experimentally on a triangular notched continuum manipulator which illustrates the capability and the effectiveness of our proposed kinematics for continuum manipulators and also can be used as a generic method for such notched continuum manipulators.

scholarly journals A New Approach of Soft Joint Based on a Cable-Driven Parallel Mechanism for Robotic Applications

Mathematics ◽  
2021 ◽  
Vol 9 (13) ◽  
pp. 1468
Author(s):  
Luis Nagua ◽  
Carlos Relaño ◽  
Concepción A. Monje ◽  
Carlos Balaguer
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Kinematic Model ◽  
Experimental Tests ◽  
Humanoid Robots ◽  
Inverse Kinematic ◽  
Element Analysis ◽  
New Approach ◽  
Flexible Polymer ◽  
The Mathematical Model

A soft joint has been designed and modeled to perform as a robotic joint with 2 Degrees of Freedom (DOF) (inclination and orientation). The joint actuation is based on a Cable-Driven Parallel Mechanism (CDPM). To study its performance in more detail, a test platform has been developed using components that can be manufactured in a 3D printer using a flexible polymer. The mathematical model of the kinematics of the soft joint is developed, which includes a blocking mechanism and the morphology workspace. The model is validated using Finite Element Analysis (FEA) (CAD software). Experimental tests are performed to validate the inverse kinematic model and to show the potential use of the prototype in robotic platforms such as manipulators and humanoid robots.

scholarly journals Sea State Monitoring by Ship Motion Measurements Onboard a Research Ship in the Antarctic Waters

2021 ◽  
Vol 9 (1) ◽  
pp. 64
Author(s):  
Silvia Pennino ◽  
Antonio Angrisano ◽  
Vincenzo Della Corte ◽  
Giampaolo Ferraioli ◽  
Salvatore Gaglione ◽  
...  
Keyword(s):  
Transfer Functions ◽  
Wave Spectrum ◽  
Weather Forecast ◽  
Ship Motion ◽  
State Monitoring ◽  
Sea State ◽  
Peak Period ◽  
Research Ship ◽  
Antarctic Waters ◽  
The Antarctic

A parametric wave spectrum resembling procedure is applied to detect the sea state parameters, namely the wave peak period and significant wave height, based on the measurement and analysis of the heave and pitch motions of a vessel in a seaway, recorded by a smartphone located onboard the ship. The measurement system makes it possible to determine the heave and pitch acceleration spectra of the reference ship in the encounter frequency domain and, subsequently, the absolute sea spectra once the ship motion transfer functions are provided. The measurements have been carried out onboard the research ship “Laura Bassi”, during the oceanographic campaign in the Antarctic Ocean carried out in January and February 2020. The resembled sea spectra are compared with the weather forecast data, provided by the global-WAM (GWAM) model, in order to validate the sea spectrum resembling procedure.

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