Ship Motion Simulator Research Articles

Validation of a distributed simulation of ship replenishment at sea with model tests

A simulation of ship motions during replenishment at sea was validated using dedicated model test data. Motions of the supply ship and receiving ship are influenced by hydrodynamic forces and forces from replenishment gear used to transfer payloads. Simulated entities include rudders and propellers, with associated controllers. The composite simulation was implemented as a distributed simulation using the high-level architecture. An experimental model test program was developed for a tanker and destroyer conducting replenishment in head seas at a speed of 15 knots. The simulation gives generally good agreement with the model tests for heave, roll, and pitch motions, with some noted exceptions. For dynamic positioning of the destroyer relative to the tanker, there is very good agreement for mean values but underprediction of lower frequency sway and yaw motions. The variation of heave and roll motion accuracy is likely due to the hydrodynamic force prediction method using the frequency domain Green function for zero forward speed, thus not accurately modelling the propagation of radiated and diffracted waves between vessels. Prediction of viscous roll forces using semi-empirical methods likely contributed to differences between simulated and model test roll motions. The underprediction of lower frequency sway and yaw motions for the destroyer in waves could be caused by the ship motion predictions not including second-order wave drift forces.

An Improved Classic Washout Algorithm Based on Tilted Coordinated Channel for Ship Motion Simulator

The motion washout aims to bring the actual movement of the ship back to motion simulator, and to provide as real motion as possible in the limited space of the simulator. The difficulty of the classic washout algorithm lies in the choice of filter parameters. If the parameters are too small, the effect of the simulation will not be achieved, and if the parameters are too large, the effect of the simulated continuous acceleration will be reduced, resulting in false intimation. This paper redesigned the tilt coordination channel to match the effects of simulating sustained acceleration and the reduce false intimation.

Design of Classical Washout Algorithm for Six Degree of Freedom Ship Motion Simulator

The motion washout aims to bring the actual movement of the ship back to the six degree of freedom motion simulator, and to provide as real motion as possible in the limited space of the simulator. The emphasis of the classic washout algorithm lies in the choice of parameters. This paper analyzes the time domain response of the filter and combines the platform motion range with the human sensory system threshold to impose performance requirements on the system. To optimize the parameter selection according to the system performance, and get a good result of motion washout.

Time-domain simulator for short-term ship manoeuvring prediction: development and applications

ABSTRACTThis paper presents a short-term time-domain algorithm for ship motion simulation. Plane motion was considered, and thus, a three degrees of freedom model was used. The main inputs of the model are: propellers speed, rudder angles and initial conditions (initial position/orientation and linear/rotational velocity). The outputs are final ship position and orientation after a given simulation time. The data available in the Voyage Data Recorder and the results of sea trials performed before the ship delivery were used to estimate the needed parameters, implementing a simple but reliable linear regression scheme. The proposed model was applied to Costa Concordia manoeuvring simulation in order to assess its reliability in terms of trajectory prediction. Finally, as an example of application, the simulator was implemented in a real-time manoeuvring predictor, which is capable of foreseeing the ship position up to 40 s ahead in time, supporting the Commander in emergency operations.

A Parallel Manipulator for Simulating the Ship Seakeeping Trial

In this work, a ship motion simulator based on a parallel manipulator able to replicate the seakeeping trial is introduced. The mobility of the moving platform is explained through the theory of screws which reveals the existence of three constraint systems reciprocal to the motion-screw system of a central passive kinematic chain. Thereafter, the forward displacement analysis leads to five quadratic equations which are solved by means of homotopy continuation methods. On the other hand, the input–output equations of velocity and acceleration of the parallel manipulator are systematically obtained by resorting to the theory of screws. Finally, the dynamics of the parallel manipulator is approached through a harmonious combination of the theory of screws and the principle of virtual work. A case study is included with the purpose to numerically exemplify the application of the method.

A Mobile Manoeuvring Simulation System for Design, Verification and Validation of Marine Automation Systems

Applications for SIL and HIL testing in design, verification, and validation of marine systems are expected to increase. With this in view the concept for a mobile simulation system is presented, which aims at enhancing factory and on board simulation based testing. A modular network-based system architecture is proposed providing: real-time process simulation, hardware interfaces, test tools, a mobile bridge console, and 3D-visualization. For the purpose of flexible solutions a modular and scalable approach to simulating ship motion in six degrees of freedom is incorporated. Finally preliminary modelling and simulation results from the current design stage are presented.

Integrated method of analysis, visualization, and hardware for ship motion simulation

Abstract Traditionally, graphs were the only way to show the results of ship motion analyses. They did not usually impose any feeling about how fast the ship could move or how large the positions of the ship changed. Currently, integrated simulations combining physics-based analyses with IT technologies, such as virtual reality (VR), motion platforms, or other hardware, can offer a potential solution. In ship motion analyses, the dynamic ship response can be obtained by considering the environmental loads, such as ocean waves, and VR technology can be used to visualize the analysis results in the virtual world. We can see the ship motion relative to textures of real objects, including the water and sky, as if in the real world. The results calculated from the ship motion analysis can also be transferred to the motion platform to generate realistic movements. However, it is not easy to integrate three different technologies in one system because they have different purposes and have been developed individually. To solve this problem, an integrated simulation framework based on three different technologies is proposed. The proposed framework can be used to synchronize the simulation time and exchange the data through the middleware using a standardized data structure. Furthermore, we can easily add new components or remove the existing components in the simulation. To verify the efficiency and applicability of the proposed framework, the motion simulation of a drillship is applied. Highlights We propose an integrated simulation framework for analysis, visualization, and hardware. Multibody dynamics is used for the motion analysis. We perform the integrated motion simulation of a drillship. The motion analysis, visualization, and motion platform of a drillship are perfectly synchronized.

Prospect of open-cell solid foams for floating-platform multiphase reactor applications – Maldistribution susceptibility and hydrodynamic behavior

Open-cell solid foams are tested for the first time as prospective structured packings in floating columns to evaluate their potential for offshore multiphase reactor applications. Using a hexapod ship motion simulator and low-intrusive wire-mesh sensors, the effect of floating vessel motions on the hydrodynamic behavior of SiSiC foam packed beds operated with concurrent descending gas-liquid flow was comprehensively investigated. The response of gas-liquid distribution, overall bed pressure drop, and liquid axial dispersion to column tilts as well as translational and rotational motions was acquired and compared to their corresponding stationary (onshore) analog configuration. Maldistribution sensitivity and susceptibility of solid-foam packed beds subject to ship tilts and accelerations were interpreted in terms of fluid uniformity factor. Moreover, a stimulus-response tracer pulse technique and a macro-mixing model were used to estimate the liquid mean residence time and Péclet number. Similar to random packings, fluid maldistribution was found to prevail in solid-foam beds with deviations from uniformity greater for rotational than for translational perturbations. Vessel tilts and oscillations adversely affect open-cell foam bed hydrodynamic performance yielding transient gas-liquid segregated flow regimes, oscillations of pressure drop and uniformity factor, as well as notable deviation from liquid plug flow.

CFD simulations of steady drift and yaw motions in deep and shallow water

In this paper, computational fluid dynamics (CFD) simulation of steady ship motions at different drift angles, yaw rates, rudder angles, and their combinations are carried out for KRISO Very Large Crude Carrier 2 (KVLCC2) tanker ship. The simulations are conducted with the commercial steady state Reynolds averaged Navier-Stokes (RANS) flow solver SHIPFLOW®. The hydrodynamic forces in horizontal plane and the moment around the vertical axis acting on the ship are determined in deep- and shallow water. Resulting forces and moment are compared to experimental data found in literature. Influence of the water depth is shown with the forces and moment, with the velocity and the turbulent kinetic energy behind the ship and with the pressure distribution on the hull.

Hydrodynamics of gas-liquid cocurrent upflow in oscillating packed beds for offshore marine applications

In this study, the hydrodynamic behavior of inclined stationary and oscillating packed beds with gas-liquid cocurrent upflow mode of operation was investigated. Comprehensive hydrodynamic experiments were carried out using embedded low-intrusive Wire-Mesh Sensors (WMSs) and a hexapod ship motion simulator in order to properly understand the effect of column inclination and movements on gas-liquid flow distribution in the bed cross-section, overall pressure drop, liquid saturation, and pulsing flow inception. Furthermore, liquid residence time and Péclet number estimated by a stimulus-response technique and a macro-mixing model were presented and discussed with respect to the prevailing flow regimes. The results revealed that the column deviation from the vertical posture and tilting motions significantly alter the hydrodynamics prevailing in the packed bed operating in a concurrent upflow mode. Development of gas-liquid disengagement zones, oscillations in the pressure drop and uniformity factor time series, departure from liquid plug flow character, and delay in the inception of pulsing flow regime were observed as a result of bed inclination and oscillations.

Coupled simulation of nonlinear ship motions and a free surface tank

This paper investigates the coupled nonlinear dynamics of a vessel with a free surface tank onboard. To this end, a 6-DOF ship motions simulation code is coupled with a CFD solver addressing the behaviour of the fluid in the tank. The nonlinear ship motions code is of the blended (hybrid) type, intended for the simulation of free running vessels in waves. The nonlinear CFD solver is a GPU-based 3D Weakly-Compressible Smoothed-Particle Hydrodynamic (WCSPH) solver. Numerical results are presented for the nonlinear roll motion of a vessel with and without a free surface tank in regular beam waves with different steepnesses. Nonlinear phenomena are identified and discussed.

Application of Ship Motion Simulation in Reliability Assessment of Ship Entrance into the Port

Application of Ship Motion Simulation in Reliability Assessment of Ship Entrance into the Port

3D Simulation of Ship Motions to Support the Planning of Rescue Operations on Damaged Ships

Abstract The paper describes a software system to simulate the ship motions in a crisis situation. The scenario consists of a damaged ship subjected to wave excitation forces generated by a random sea state. The simulation is displayed in an interactive Virtual Environment allowing the visualization of the ship motions. The numerical simulation of the sea surface and ship motions requires intensive computation to maintain the real-time or even the fast-forward simulations, which are the only ones of interest for these situations. Dedicated tools to analyse the ship behaviour in time are also described. The system can be useful to evaluate the responses of the ship to the current sea state, namely the amplitude, variations and tendencies of ship motions, and help the planning and coordination of rescue operations.

大型鉱石船が荷役中に遭遇した気象・海象条件と船体運動の相関に関する調査研究

In the authors’ previous study, a field observation on ship motions, waves, wind and mooring loads was conducted for a 45,500DWT bulk carrier at a harbor which faces to the Pacific Ocean. The terminal for the bulk carrier was located at an exposed area to the ocean, and thus it was concluded that the large ship motions moored along the terminal were induced by swell and long-period wave. Recently a mooring accident occurred at the terminal for a 50kDWT class ore carrier. In this study, the authors have conducted a survey upon the ship mooring and weather condition based on the captain’s report, weather chart and wave data, and also tried to reproduce the ship’s behavior during cargo handling operation through a numerical simulation of ship motions and mooring loads.

Research on Real-Time Simulation System of Ship Motion Based on Simulink

This paper puts forward a development method of ship motion simulation system that can conduct UDP communication in real time. This system is based on Simulink in order to meet the need of modular and fast ship motion simulation systems. First, the mathematics models of ship motion are set up based on the modular ideology, which includes thruster model and models of wind, wave and current. Then, real time simulation module using S-fun function is developed, and built into executable program. This could realize real time communication between ship motion simulation system and visual simulation system and induce real time communication between ship motion system and ship simulation control system. In this way, it can save time and cost when developing the simulation system. This method has been used successfully in the development of real time simulation system of some engineering ship.

Design and Simulation Research of Leveling Tanks System

This paper introduced a leveling tanks system of the ship based on Visual C++. The simulation system is consisted of a leveling tank, a leveling system controller and a ship motion simulator three parts. This paper focuses on the system leveling effect, when the roll is generated by steering as well as loading and wave interference under conditions of direct of the ship. In the research of the ship rolling, which is generated by steering, tanks model combining of traditional four degrees of freedom, getting a new four degrees of freedom "Ship-Tank" movement mathematical model. We calculate the motion state of the ship, and output multiple parameter information of ship motion based on the mathematical model, and then level the roll motion generated by ship steering using control strategies. Simulation results show that, in the conditions of both direct and steering, the system is able to achieve the desired effect of leveling, and thereby it provides reliable basics for designing and researching of leveling tanks.

Modeling and Simulation of Ship Motion for Dynamic Positioning Vessel

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 .

Mal de debarquement, motion sickness and the effect of an artificial horizon

Exposure to unfamiliar motion patterns commonly results in motion sickness and a false perception of motion, termed mal de debarquement, on the return to stable conditions. To investigate whether motion sickness severity is correlated with the duration and severity of mal de debarquement; to study the possible preventive effect of projecting earth-referenced scenes (an artificial horizon) during exposure to motion on the development of mal de debarquement. Thirty subjects were exposed to the recorded motion profile of a boat in a 3-degrees-of-freedom ship motion simulator. During the simulated voyage, the study participants were repeatedly put through a performance test battery and completed a motion sickness susceptibility questionnaire, while self-referenced and earth-referenced scenes were projected inside the simulator cabin. Six hours post disembarkation, subjects completed a questionnaire on mal de debarquement duration and severity. Mal de debarquement, mostly of mild severity, was reported following 59% of the exposures to the provocative motion profile, and in 79% of cases lasted less than 6 hours. The incidence of mal de debarquement, its duration, and the severity of symptoms did not differ between the various artificial horizon projection modes. Significant correlations were found between motion sickness severity and the duration and severity of the mal de debarquement that followed. The significant correlations found between motion sickness severity and mal de debarquement duration and severity imply that both syndromes might stem from a failure to adapt to new motion conditions. There is a disparity between the previously reported reduction in motion sickness symptoms by an artificial horizon, and its failure to influence the duration and symptoms of mal de debarquement. This might be explained by the different response in the two syndromes, physical versus cognitive.

東北地方太平洋沖地震津波来襲時の桟橋係留大型石炭船の挙動再現について

The 2011 Tohoku earthquake and tsunami at 14:46 JST on March 11, 2011 affected large areas of the eastern and northern part of Japan, and many sea disasters against vessels moored along terminal inside harbor basins occurred. The authors conducted surveys upon sea disasters of a Very Large Crude Carriers (VLCC) at S-Port and an Aframax tanker at O-Port. There was also a severe disaster of large coal carrier at H-Port, which encountered a tsunami of tsunami wave height beyond 10 meters and damaged mooring equipment such as fenders and mooring lines, and unloader of coal, entirely. In this paper, the authors have also tried to reproduce the ship's behavior and analyze the mooring loads during the tsunami through a numerical simulation of tsunami and ship motion.

A 6-DOF Deep-ocean Mining Ship Motion Simulator

A 6-DOF Deep-ocean Mining Ship Motion Simulator