Lifting Operation Simulation of a Dynamic-Position Crane Vessel

2013 ◽  
Author(s):  
Shangmao Ai ◽  
Liping Sun ◽  
Chuanyun Cheng
Keyword(s):  
Time Domain ◽  
Pid Control ◽  
Weak Coupling ◽  
Time Sequence ◽  
Irregular Waves ◽  
Dynamic Positioning ◽  
Wave Direction ◽  
Sea State ◽  
Control Equation ◽  
Made In

A time domain method, weakly coupling the block and crane vessel in time sequence, has been developed for lifting operation of the dynamic-position crane vessel. Restoring thrust is distributed by the dynamic positioning PID control system and directly acted on the crane vessel’s control equation as external force; the weak coupling simulation between the block and crane vessel is realized through the sling elastic deformation. Lifting operation simulation of a dynamic-position crane vessel in irregular waves shows that the posture of crane vessel relative to the wave direction in the lifting operation should be adjusted as soon as possible, and had better be made in ahead sea state to improve the security of the suspension stage.

Time-Domain Dynamic Analysis for Dynamic Positioning System of Deepwater Semi-Submersible

2012 ◽  
Vol 204-208 ◽  
pp. 4518-4522 ◽  
Author(s):  
Li Ping Sun ◽  
Shu Long Cai ◽  
Jing Chen
Keyword(s):  
Dynamic Analysis ◽  
Deep Water ◽  
Time Domain ◽  
Pid Control ◽  
Oil And Gas ◽  
Dynamic Positioning ◽  
Positioning System ◽  
Dynamic Positioning System ◽  
The Time Domain ◽  
Thrust Allocation

Semi-submersible plays an important role in ocean oil and gas exploitation. This paper carried out some researches for the dynamic positioning system (DPS) of a deep water semi- submersible. Mathematic modal was made, and a special program was created with M-language for the time-domain dynamic analysis of the dynamic positioning system of the deep water semi-submersible, on basis of the mathematic modal. PID control strategy, kalman filtering theory and optimal thrust allocation method were used in the analysis. Simulation result indicated the DPS of this platform is safe and efficient.

scholarly journals Semi-submersible Offshore Coupled Motion in Irregular Waves

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Baoji Zhang ◽  
Ying Wang
Keyword(s):  
Return Period ◽  
Simple Algorithm ◽  
Wave Force ◽  
Hydrodynamic Performance ◽  
Irregular Waves ◽  
Offshore Platforms ◽  
Wave Direction ◽  
Motion Response ◽  
Irregular Wave ◽  
Control Equation

In order to predict the hydrodynamic performance of semi-submersible offshore platform accurately, based on CFD theory, continuous equation and N-S equation as the control equation, RNG type k-ε model as turbulence model, using the finite difference method to discretize the control equation，using the Semi-Implicit Method for Pressure Linked Equation (SIMPLE) algorithm to solve the control equation，using the VOF method to capture the free surface. The numerical wave tank of irregular wave is established, and the wave force and motion response of the semi-submersible platform under irregular wave are studied. Based on the Jonswap spectrum density function, for a certain area of two irregular waves (South China sea, a-ten-year return period, a-hundred-year return period) sea condition, five wave direction Angle (0 °, 30 °, 45 °, 60 °, 90 °), a total of 10 kinds of conditions of the motion response of semi-submersible platform are simulated, through analysis and comparison of simulation results, the influence law of wave angle, wave period and wave height on platform motion is obtained. Compared with the experimental values, the results of heave and pitch are close to the experimental data under the sea condition of 2, 0 degree wave angles. The research results in this paper can provide reference for the design and motion response prediction of practical semi-submersible offshore platforms.

Frequency, Stochastic and Time Domain Models for an Articulated Wave Power Device

2008 ◽  
Author(s):  
Jose´ J. Caˆndido ◽  
Paulo A. P. Justino
Keyword(s):  
Stochastic Model ◽  
Time Domain ◽  
Domain Model ◽  
Irregular Waves ◽  
Power Device ◽  
Wave Power ◽  
Regular Waves ◽  
Sea State ◽  
Frequency Model ◽  
Non Linear

A frequency domain model to describe the behaviour of an articulated system in regular waves is developed. A stochastic model is found for the articulated wave power device. Probability density functions for relevant parameters that characterize the wave power system behaviour are found for different sea state conditions. Average values for useful power and capture length are also obtained for these sea state conditions. A time domain model is also developed for the articulated wave power device. Results for a linear power take-off configuration and regular waves are obtained and compared to the results obtained from the frequency model. A non-linear power take-off configuration is found. Results in regular wave conditions are obtained for this configuration, set in terms of different characteristic parameters. Results for this non-linear configuration for the power take-off and irregular waves are also computed and presented. Finally, these results are compared to the results obtained from the stochastic model.

An Efficient Approach for Modeling and Control of a Quadrotor

2016 ◽  
Vol 4 (2) ◽  
pp. 1-16
Author(s):  
Ahmed S. Khusheef
Keyword(s):  
Pid Control ◽  
Control Method ◽  
Mechanical Design ◽  
Loop Control ◽  
Modeling And Control ◽  
Loop Control System ◽  
And Control ◽  
Close Loop Control ◽  
Close Loop Control System ◽  
Made In

 A quadrotor is a four-rotor aircraft capable of vertical take-off and landing, hovering, forward flight, and having great maneuverability. Its platform can be made in a small size make it convenient for indoor applications as well as for outdoor uses. In model there are four input forces that are essentially the thrust provided by each propeller attached to each motor with a fixed angle. The quadrotor is basically considered an unstable system because of the aerodynamic effects; consequently, a close-loop control system is required to achieve stability and autonomy. Such system must enable the quadrotor to reach the desired attitude as fast as possible without any steady state error. In this paper, an optimal controller is designed based on a Proportional Integral Derivative (PID) control method to obtain stability in flying the quadrotor. The dynamic model of this vehicle will be also explained by using Euler-Newton method. The mechanical design was performed along with the design of the controlling algorithm. Matlab Simulink was used to test and analyze the performance of the proposed control strategy. The experimental results on the quadrotor demonstrated the effectiveness of the methodology used.

scholarly journals A Comparison of Time-Domain Implementation Methods for Fractional-Order Battery Impedance Models

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4415
Author(s):  
Brian Ospina Agudelo ◽  
Walter Zamboni ◽  
Eric Monmasson
Keyword(s):  
Fractional Order ◽  
Time Domain ◽  
Li Ion Batteries ◽  
Simulation Framework ◽  
Frequency Range ◽  
Interesting Approach ◽  
Li Ion ◽  
Impedance Parameters ◽  
Impedance Models ◽  
Made In

This paper is a comparative study of the multiple RC, Oustaloup and Grünwald–Letnikov approaches for time domain implementations of fractional-order battery models. The comparisons are made in terms of accuracy, computational burden and suitability for the identification of impedance parameters from time-domain measurements. The study was performed in a simulation framework and focused on a set of ZARC elements, representing the middle frequency range of Li-ion batteries’ impedance. It was found that the multiple RC approach offers the best accuracy–complexity compromise, making it the most interesting approach for real-time battery simulation applications. As for applications requiring the identification of impedance parameters, the Oustaloup approach offers the best compromise between the goodness of the obtained frequency response and the accuracy–complexity requirements.

Alternative Methodologies for Subsea Flexible Strength Analysis

2018 ◽  
Author(s):  
Anskey A. Miranda ◽  
Fred P. Turner ◽  
Nigel Barltrop
Keyword(s):  
Real World ◽  
Wave Train ◽  
Irregular Waves ◽  
Wave Crest ◽  
Strength Analysis ◽  
New Wave ◽  
Regular Wave ◽  
Wave Analysis ◽  
Sea State ◽  
Irregular Wave

This paper presents a study of the analysis methodologies used to predict the most likely response of flexibles in a subsea environment, with the aim of determining an efficient and reliable prediction methodology. The most accurate method involves simulating multiple wave realisations of a real world sea state, i.e. irregular waves, and post-processing the results to determine the most probable maximum (MPM). Due to the computationally intensive nature of this approach, however, regular wave analysis is typically used to determine flexible response. This approach considers the maximum wave within a design storm at a desired period; the choice of periods may leave room for uncertainty in the conservatism of the approach. With proper screening, regular wave analysis can be a valid yet overly conservative approach resulting in over design and additional cost. However, if screened incorrectly, there is a possibility that the choice of periods could give results that are under conservative. In addition to regular wave analysis, the paper presents two alternative methodologies to determine the most likely response, with the focus on reducing the computational resources required. The first alternative is an ‘Irregular Wave Screen’ approach in which the wave train is screened at areas of interest for waves within a user defined threshold of the maximum wave height, in addition to other user defined parameters. Only waves within these parameters are simulated to determine responses. The second alternative is the ‘New Wave’ approach, which models the most probable wave elevation around the maximum wave crest. The calculated new wave is then placed at the desired location to determine responses. The responses of the Regular, Irregular Wave Screen and New Wave methodologies are compared with the Irregular MPM approach to determine their feasibility to predict the response of flexibles in a real world irregular sea state with lower computational requirements.

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