Vessel Rolling Research Articles

Rolling table centrifuge modelling of partially saturated granular material to inform on instability during solid bulk cargo transport

The response of partially saturated granular cargoes during maritime transportation has resulted in the capsize and sinking of 27 bulk carriers at sea and the loss over 90 seafarers’ lives in the last decade. The partially saturated granular material response to energy imparted during cargo loading, ship engine vibrations and vessel rolling motions from sea states causes a change in state of the granular cargo, which can lead to vessel instability and ultimately capsize. However, the mechanisms driving the response of partially saturated granular cargos within a bulk carrier hold are not well understood. This paper presents results from an experimental study of rolling table centrifuge model tests on a partially saturated silica sand to contribute to improved understanding of the response of granular cargoes during maritime transport. Observed settlement, pore pressure, moisture content and density changes during and/or following a sequence of large amplitude rolling motions are presented. The results indicate that for the conditions considered, a progressive upwards migration of pore water during rolling led to creation of a free surface of water above the granular sample that was left in a denser, lower moisture content sample compared to its initial state. Sloshing of free water on top of even a competent cargo during rolling motions of the ship can contribute to loss of ship stability and ultimately capsize.

Adaptive Neural Network Control of Zero-Speed Vessel Fin Stabilizer Based on Command Filter

This paper proposes a zero-speed vessel fin stabilizer adaptive neural network control strategy based on a command filter for the problem of large-angle rolling motion caused by adverse sea conditions when a vessel is at low speed down to zero. In order to avoid the adverse effects of the high-frequency part of the marine environment on the vessel rolling control system, a command filter is introduced in the design of the controller and a command filter backstepping control method is designed. An auxiliary dynamic system (ADS) is constructed to correct the feedback error caused by input saturation. Considering that the system has unknown internal parameters and unmodeled dynamics, and is affected by unknown disturbances from the outside, the neural network technology and nonlinear disturbance observer are fused in the proposed design, which not only combines the advantages of the two but also overcomes the limitations of the single technique itself. Through Lyapunov theoretical analysis, the stability of the control system is proved. Finally, the simulation results also verify the effectiveness of the control method.

3D active dynamic actuation model for offshore cranes

AbstractThe handling of offshore payloads is a critical operation that presents numerous challenges, in particular related to the required precision in controlling their oscillations in a safe and accurate manner. The uncontrolled payload oscillations induced by the rolling movement of the vessel have been historically mitigated by the experience of on‐deck operators by means of taglines. The availability of experienced personnel is not always present, and a manual control operation still presents inconsistent performances and a high risk for the safety of men and machines. This study presents a novel approach to an antisway control conceived to mitigate such problems and possibly to automate some of the operations concerning the payload sway control that are currently done manually. In particular, a system consisting of a translating trolley actuated through a proportional–integral–derivative controller is taken into consideration to mitigate the oscillations induced by the vessel's rolling and pitching motion onto a three‐dimensional 8 degrees of freedom with double‐pendulum model representing the hanging payload. The study is completed through an analysis aimed to characterize the bandwidth and frequency response of the controlled closed‐loop system and highlight all the potential areas of interest for which further characterization is needed.

Numerical investigation on the effect of the vessel rolling angle and period on the energy harvest

In order to harvest effectively the mechanical energy produced in the process of vessel rolling, an energy harvest unit installed on the vessel is designed to utilize the mechanical energy. Firstly, the structure of the unit is proposed, and the relevant mathematical model is established. The solution of the mathematical model is given by Newmark- β method. Then, the influence of vessel rolling period and angle on the unit’s power and related parameters of the block is studied by MATLAB simulation. The results show that when the vessel is rolling, the energy harvest unit has a considerable power generation effect, the rolling period and angle of the vessel have a great impact on the power of the unit. Under the condition of the same period, the vessel with a larger rolling angle corresponds to larger peak gravity component, peak angular displacement, peak linear velocity of block and average power of the unit. In addition, under the same sea conditions, numerical simulations carried out on the rolling motion of 70,000, 100,000, and 150,000-ton bulk vessels and related parameters of the unit, indicating that the instantaneous power of the unit is not uniform in actual sea conditions, but it can output power continuously.

Dynamical Rolling Analysis of a Vessel in Regular Beam Seas

This paper deals with the dynamical analysis of a vessel that leads to capsize in regular beam seas. The complete investigation of nonlinear behaviors includes sub-harmonic motion, bifurcation, and chaos under variations of control parameters. The vessel rolling motions can exhibit various undesirab...

Hard- and Software Implementation of Emergency Prevention System for Maritime Transport

Hard- and software of a marine Euler-angle orientation control system is described. Vessel rolling and pitching are controlled by ballast tank level adjustment. A method for compensating the deviation of vessel’s plane from horizon plane in emergency situations is offered. Using roll and pitch angles data it calculates the parameters of emergency cargo displacement characteristics.

Modelling the stability of iron ore bulk cargoes during marine transport

The safe maritime transport of bulk commodities, such as iron ore, by large bulk carriers is vitally dependent on the stability of the cargo. During transport there is a propensity that cargo shift may be triggered under the vessel's rolling motion. The study presented in this paper aims to model the critical stress conditions within iron ore bulk cargoes from a bulk solids flow perspective, from which the maximum roll angle of the vessel prior to cargo slip can be predicted. Comparison of the new theoretical approach to the classic slope stability model was conducted with similar results achieved. The influence of the failed material mass after the cargo slip event on the overall cargo stability is then examined using the discrete element method. The new theoretical and numerical approaches provide a means to predict the stability and evaluate the potential safety hazards during maritime transport of iron ore bulk cargoes.

Long-Term Extreme Response and Reliability of a Vessel Rolling in Random Beam Seas

In this paper, the long-term extreme response of a vessel rolling in random beam seas and the associated reliability evaluation are addressed. The long-term response analysis is based on the upcrossing rates of the roll motion under different sea states. Generally, for nonlinear roll motion in random seas, the high-level roll response is sensitive and closely related to the nonlinear effects associated with the restoring and damping terms. Therefore, assessing the corresponding statistics of the random roll motion with low probability levels is difficult and time-consuming. In this work, the Markov theory is introduced in order to tackle this problem. Specifically, for the dead ship condition, the random roll excitation moment is approximated as a filtered white noise process by applying a second-order linear filter and an efficient four-dimensional (4D) path integration (PI) technique is applied in order to calculate the response statistics. Furthermore, the reliability evaluation is based on the well-known Poisson estimate as well as on the upcrossing rate calculated by the 4D PI method. The long-term analysis and reliability evaluation of the nonlinear roll motion in random seas, which consider the variation of the sea states could be a valuable reference for ship stability research.

Application of Navy Color and Effects Model in Warship Virtual Scene Design

With the decreasing cost, VR technology has come back to hit of research again, the combination of it and warship mission virtual scene design has make it a new hot spot. This article gives three navy colors, which are the blue, the white and the grey, analyzes the ordinary special effect technology includes disaster spreading model, float condition model and vessel rolling model, conducts design work with naval color language and special effects model.

Efficient Monte Carlo simulation and Grim effective wave model for predicting the extreme response of a vessel rolling in random head seas

In this paper, a computationally efficient Monte Carlo simulation (MCS) approach is introduced in order to estimate the extreme response statistics of parametric rolling in random longitudinal seas. Basically, parametric roll is caused by sufficiently large oscillations of the roll restoring moment occurring within certain frequencies of wave encounter (approximately twice the natural roll frequency). The concept of the Grim effective wave is applied herein in order to approximate the variation of the restoring moment in random waves. A fourth order linear filter is introduced to model the random effective wave amplitude process, which is assumed to be the driving process for the variation of the restoring term as well as for the stochastic nonlinear system of the roll motion by application of the Grim effective wave approximation. For the stochastic dynamical system, the roll response is a random process and an extrapolation procedure is developed for estimating the extreme values of the response statistics by assuming regular behavior in the tail region of the mean upcrossing rate. The rationality of the linear filter model and the feasibility of an efficient MCS method based on extrapolation techniques for predicting the extreme roll response are illustrated. Furthermore, the phenomenon of parametric roll in random seas as well as the effect of vessel speed on the stochastic roll response are investigated.

Real-time Needle Steering in Response to Rolling Vein Deformation by a 9-DOF Image-Guided Autonomous Venipuncture Robot.

Venipuncture is the most common invasive medical procedure performed in the United States and the number one cause of hospital injury. Failure rates are particularly high in pediatric and elderly patients, whose veins tend to deform, move, or roll as the needle is introduced. To improve venipuncture accuracy in challenging patient populations, we have developed a portable device that autonomously servos a needle into a suitable vein under image guidance. The device operates in real time, combining near-infrared and ultrasound imaging, computer vision software, and a 9 degrees-of-freedom robot that servos the needle. In this paper, we present the kinematic and mechanical design of the latest generation robot. We then investigate in silico and in vitro the mechanics of vessel rolling and deformation in response to needle insertions performed by the robot. Finally, we demonstrate how the robot can make real-time adjustments under ultrasound image guidance to compensate for subtle vessel motions during venipuncture.

Stochastic Dynamic Analysis and Reliability of a Vessel Rolling in Random Beam Seas

This article presents a four-dimensional (4D) path integration (PI) approach to study the stochastic roll response and reliability of a vessel in random beam seas. Specifically, a 4D Markov dynamic system is established by combing the single-degree-of freedom model used to represent the ship rolling behavior in random beam seas with a second-order linear filter used to approximate the stationary roll excitation moment. On the basis of the Markov property of the coupled 4D dynamic system, the response statistics of roll motion can be obtained by solving the Fokker-Planck equation of the dynamic system via the 4D PI method. The theoretical principle and numerical implementation of the current state of the art 4D PI method are presented. Moreover, the numerical robustness and accuracy of the 4D PI method are evaluated by comparing with the results obtained by the application of Monte Carlo simulation (MCS). The influence of the restoring terms and the damping terms on the stochastic roll response are investigated. Furthermore, based on the well-known Poisson assumption and the response statistics yielded by the 4D PI technique, evaluation of the reliability associated with high-level response is performed. The performance of the Poisson estimate for different levels of external excitations is evaluated by the versatile MCS technique.

Stochastic Dynamic Analysis and Reliability of a Vessel Rolling in Random Beam Seas

Stochastic Dynamic Analysis and Reliability of a Vessel Rolling in Random Beam Seas

Inland vessel rolling due to severe beam wind: A step towards a realistic model

All the present ship stability regulations include, in some way, the analysis of a ship heeling when exposed to a severe beam wind. Although the scenarios for such stability analysis are (mostly) clear and sound, the methods of the calculation are already outdated. The authors, therefore, aim to contribute to the development of new rules, based on a more advanced probabilistic approach (see [Hofman M, Bačkalov I. Weather criterion for seagoing and inland vessels — Some new proposals. In: Proceedings of international conference on marine research and transportation. 2005. p. 53–62; Hofman M, Maksić I, Bačkalov I. Some disturbing aspects of inland vessel stability rules. Journal of Ship Technology, New Delhi 2006; 2(2): 1–14]). In their previous research, for the sake of simplicity, a single nonlinear differential equation of ship rolling was applied as the basis of the analysis. In the present investigation, a more realistic model of coupled nonlinear roll and sway equations is introduced, and the behavior of inland container vessels due to severe beam gusting wind analyzed. The analysis reveals significant discrepancies of the results obtained by the different models, and shows that previous simplified approach overestimated the risk of flooding. It proves, however, the main conclusions of the earlier investigation concerning the deficiency of the present inland container vessel stability rules.

袋体を用いた船舶による液体輸送に関する基礎的研究

We propose a mean of efficient fluid transportation using large fluid bag in cargo hold and research the bag tention spcific with rolling by an experiment. Moreover we observe the effect of sloshing control way using fluid bag. The initial tention for the fluid bag is strong under dry condition and the variable tention for fluid bag is weak under dry condition more than under water condition. On the other side, the initial tention is offset by the bouyancy under water condition and the variable tention grow strong owing to the fluid bag motion due to the vessel oscillation. The variable tention grow strong near the fluid natural period. However, it is not so big problem, because the original vessel rolling natural period and fluid natural period is out of resonance. The impact force of the fluid sloshing does not occur under dry condition as the free water surfacs is restricted by the bag. Moreover the impact force becomes smaller than usual fluid transpotation.

Recent research on wind loading

The paper reviews some of the research carried out over the past ten years into the effect of wind on vessel rolling and capsize. Two main techniques are discussed: the so-called discrete gust, where a vessel at its extreme windward roll angle is acted upon by a sudden increase in windspeed, and the stochastic approach, where the steady-state response to a random sequence of wind pulses is calculated. Some model experiments in a wind-wave tank are also described and compared.