A New Methodology for the Evaluation of the Maneuvering Characteristics of Surface Ship Models

2008 ◽  
Author(s):  
Joel T. Park ◽  
David D. Hayden ◽  
Joseph H. Kim ◽  
Mark P. Melendez
Keyword(s):  
Calibration Data ◽  
Number Range ◽  
Ship Model ◽  
Surface Ship ◽  
Straight Line ◽  
Free Running ◽  
Quantitative Results ◽  
Turn Radius ◽  
Approach Velocity ◽  
Velocity Calibration

An Arc Second Indoor Global Positioning System (IGPS) has been applied in the evaluation of the maneuvering characteristics of surface ships. The system consists of a series of laser transmitters located around the Maneuvering and Seakeeping (MASK) Basin at the David Taylor Model Basin (DTMB) in West Bethesda, Maryland. Receivers for the location of the model within the MASK are installed on a free-running surface ship model. Since the system provides position of the model within the basin as a function of time, velocity is also computed from finite differences of position and time. The system has been effective in providing velocity calibration data versus propeller shaft speed in straight-line runs. The characteristics of circle maneuvers have also been determined from the system such as the steady turn radius as a function of approach velocity and rudder angle, velocity in a turn, and the drift angle. Quantitative results are provided for a surface ship model in circle maneuvers and velocity calibration from straight-line runs. The typical Froude number range for a test is typically 0.1 < Fr < 0.4 with an uncertainty of ±0.0048 at the 95% confidence level.

scholarly journals Modified Vector Field Path-Following Control System for an Underactuated Autonomous Surface Ship Modelin the Presence of Static Obstacles

2021 ◽  
Vol 9 (6) ◽  
pp. 652
Author(s):  
Haitong Xu ◽  
Miguel A. Hinostroza ◽  
C. Guedes Guedes Soares
Keyword(s):  
Control System ◽  
Vector Field ◽  
Path Following ◽  
Field Method ◽  
Integrated System ◽  
Ship Model ◽  
Surface Ship ◽  
Path Following Control ◽  
Exponentially Stable ◽  
Vector Field Method

A modified path-following control system using the vector field method for an underactuated autonomous surface ship model is proposed in the presence of static obstacles. With this integrated system, autonomous ships are capable of following the predefined path, while avoiding the obstacles automatically. It is different from the methods in most published papers, which usually study path-following and obstacle collision avoidance, separately. This paper considers the coupled path following and collision avoidance task as a whole. Meanwhile, the paper also shows the heading control design method in the presence of static obstacles. To obtain a strong stability property, a nonlinear autopilot is designed based on the manoeuvring tests of the free-running ship model. The equilibrium point of the controller is globally exponentially stable. For the guidance system, a novel vector field method was proposed, and the proof shows the coupled guidance and control system is uniform semi-global exponentially stable (USGES). To prevent the obstacles near the predefined path, the proposed guidance law is augmented by integrating the repelling field of obstacles so that it can control the ship travel toward the predefined path through the obstacles safely. The repelling field function is given considering the obstacle shape and collision risk using the velocity obstacle (VO) algorithm. The simulations and ship model test were performed to validate the integrated system of autonomous ships.

Analysis of Straight-Line Motion of Towed Ships

1991 ◽  
Vol 35 (04) ◽  
pp. 304-313
Author(s):  
Fotis Andrea Papoulias
Keyword(s):  
Dynamic Response ◽  
Periodic Solutions ◽  
Bifurcation Theory ◽  
Loss Of Stability ◽  
Nonlinear Analyses ◽  
Surface Ship ◽  
Numerical Integrations ◽  
Straight Line ◽  
Linear And Nonlinear ◽  
Dynamic Loss

The problem of dynamic loss of stability in steady towing of a surface ship is considered. The two coordinates of the towing point and the towline length are the main bifurcation parameters. Bifurcation theory techniques are used in order to compute equilibrium and periodic solutions. The results are confirmed by numerical integrations. It is shown that both linear and nonlinear analyses are required to thoroughly understand, predict, and evaluate the system dynamic response.

KAJIAN SEAKEEPING KAPAL FERRY RO-RO 750 GT BERBASIS PENGUJIAN HIDRODINAMIKA

ROTOR ◽  
2018 ◽  
Vol 11 (2) ◽  
pp. 8
Author(s):  
Mujahid Syaiful Ahmad
Keyword(s):  
Test Procedure ◽  
Test Methods ◽  
Ocean Basin ◽  
Test Results ◽  
M Wave ◽  
Ship Model ◽  
Measurement Results ◽  
Free Running ◽  
Ship Behavior ◽  
Large Investment

The Ferry Ro-Ro is a ship that functions to crossing inter island and to transport vehicles, passengers and goods. Building a ship requires a very large investment value so that the design of the ship is a very important consideration by conduct the intens study to determine the performance of a ship, one of them is the performance of the ship motion, endurance, and reliability while sailing which can be seen by conducting a hydrodynamic test in the form of a seakeeping test on the Ferry Ro-Ro Ship Model. This study conduct the seakeeping testing due to Ferry Ro-Ro 750 GT Ship Model which aims to predict the pattern of ship behavior by using the seakeeping test methods at Manoeuvering and Ocean Basin at Laboratorium Hidrodinamika Indonesia at Balai Teknologi Hirdoinamika - BPPT with th parameter Wave Height Hs = 2.50 m, Wave Period Tp = 9.00 s by heading 180 deg and 135 deg, and model scale is 1 : 21.19. The seakeeping test procedure for the Ferry Ro-Ro 750 GT Ship Model is based on ITTC No 7.5-02-07-02 standards. Testing of the ship model is conducted by using the method of free running where ship moving at a speed of 12 knots (actual scale). Analysis of measurement results is displayed in the form of Response Amplitude Operator (RAO) and statical analysis. The hydrodynamic test results in the form of a seakeeping test of Ferry Ro-Ro 750 GT Ship Model shows the value of Root Mean Square (RMS) of each direction of the ship relative to the direction of arrival of the wave (heading) 180 deg with roll value = 0.825 deg and pitch value = 2.231 deg. And heading 135 deg with roll value = 2.410 deg and pitch value = 1.797 deg, where NORDFORSK 1987 criteria standard for RMS roll value is 6 deg, and RMS pitch value is 1.5 deg. Keywords: Seakeeping, Ferry Ro-Ro, Hydrodynamics

6 Degree of Freedom Motion Analysis of Surface Ship Models

2011 ◽  
Author(s):  
Joel T. Park ◽  
Andrew L. Silver ◽  
Richard C. Bishop
Keyword(s):  
Motion Analysis ◽  
Optical System ◽  
Surface Effect ◽  
Degree Of Freedom ◽  
National Metrology Institute ◽  
Ship Model ◽  
Surface Ship ◽  
Surface Effect Ship ◽  
Optical Motion ◽  
Analysis System

A 6 degree of freedom (DOF) optical motion analysis system has been adapted for the measurement of surface ship model motion. The motions measured by the optical system are surge, sway, heave, roll, pitch, and yaw. Apparently, the calibration of the system is not traceable to a National Metrology Institute (NMI). Measurement results are compared to on-board instruments for the measurement of roll, pitch, and heave, which were calibrated prior to the test. Test results are presented for a Large Medium Speed Roll-on Roll-off (LMSR) ship model with a Transformable Craft (T-Craft) Surface Effect Ship (SES) in tandem connected by a ramp. The LMSR model was attached to a carriage in a rectangular wave-making basin. The results presented in this paper were conducted at a simulated Sea-State 4 and model speed of 0.372 m/s. The results were in reasonable agreement in pitch and roll where the instrument calibration uncertainties were between ±0.19° and ±0.67°, while the manufacturer’s specification is ±1.0°. Heave was measured near the stern by the optical system. The uncertainty in the correction to the center of gravity is estimated to be ±17 mm for the LMSR in comparison to the direct measurement of heave by a string pot at the cg, where the calibration uncertainty was ±1.3 mm.

Comparisons of DES and LES Turbulent Model for Simulation of Surface Ship Airwake

2016 ◽  
Author(s):  
Congmin Li ◽  
Weijian Jiang ◽  
Jie Cheng ◽  
Zongxin Yu ◽  
Zhiguo Zhang
Keyword(s):  
Experimental Measurement ◽  
Measurement Data ◽  
Separated Flow ◽  
Flow Region ◽  
Turbulent Model ◽  
Ship Model ◽  
Surface Ship ◽  
Simulation Results ◽  
Turbulent Models ◽  
Computational Resources

Due to the combination of the forward speed and the prevailing wind for surface ship traveling in the ocean, the airflow passing over the ship’s superstructure causes the formation of a disturbed flow region and the large speed gradients of the mean wind over the flight deck, known as the ship airwake. This airwake would cause significant influence on the performance of the helicopter rotor during its taking off or landing, increase the operation workload of the pilot and even cause safe-landing issues, especially when the wind sweeps over the deck. This paper presents a numerical simulation of flow across the ship superstructure using DES and LES turbulent model. The ship model used for simulation is the standard SF2 surface ship model with experimental measurement data which could be used for the CFD code validation. The simulation results are compared with the experimental measurement data, and the comparison with experimental results shows good match for both DES and LES turbulent models. Simulation results show that a series of vortex had been generated after the flow separation with asymmetric characteristics. From upstream to downstream, the vortex intensity decreases, but suddenly increases after encountering the chimney. The comparison between DES and LES turbulent models shows the similar flow field and vortex structure around the ship superstructure with same grid sets. Both DES and LES are superior to RANS in solving ship airwake. The comparisons of DES and LES turbulent models show that DES can reflect the separated flow with limited computational resource and LES simulation could get higher resolution of the fluid flow structure with enough computational resources.

scholarly journals Variable Structure Controller for Surface Ship Steering

2017 ◽  
Vol 2 (2) ◽  
Author(s):  
Ringo Rimbe ◽  
Raidandi Danwe ◽  
Babagana M Mustapha
Keyword(s):  
Sliding Mode ◽  
Linear Time ◽  
Variable Structure ◽  
Time Varying ◽  
Variable Structure Systems ◽  
Ship Model ◽  
Linear Time Invariant ◽  
Surface Ship ◽  
Ship Steering ◽  
Time Varying Environment

A Lyapunov approach to constructing switching surfaces for variable structure systems is investigated in this paper. The method guarantees sliding mode for any initial condition of the state vector and asymptotic stability is always achieved during sliding motion. An application for  the design of  a variable structure ship steering controller is carried out and  simulation results are presented. The designed controller exhibits robustness as applied to a linear time-invariant ship model and a time varying non-linear  ship model operating in  an uncertain and  time-varying environment.

Validation of Numerical Motion Simulations by Direct Comparison With Time Series From Ship Model Tests in Deterministic Wave Sequences

2005 ◽  
Author(s):  
Gu¨nther F. Clauss ◽  
Janou Hennig ◽  
Heike Cramer ◽  
Kay-Enno Brink
Keyword(s):  
Time Series ◽  
Wave Train ◽  
Test Procedure ◽  
Weather Conditions ◽  
Ship Design ◽  
Ship Motions ◽  
Validation Data ◽  
Ship Model ◽  
Validity Range ◽  
Free Running

Ship safety under normal and severe weather conditions is determined by ship design, approval, and operation. Numerical simulation of ship motions has proven to be a valuable tool for ship design evaluation — not only for accident investigations and studies addressing fundamental stability related phenomena, but also during the design process. A sufficient number of simulations provide a data basis for polar plots to judge the ship’s situation in a sea state — defined by significant wave height and characteristic period — with respect to load case, encounter angle and ship speed. Application of data provided by numerical tools has to take into account the validity range of the model and has to be validated sufficiently by model test data. For providing useful validation data, the exact correlation of wave excitation and ship motion in model testing is indispensable. In the framework of the German research project SINSEE, this is achieved by a fully automated test procedure with a free running ship model in combination with deterministic generation of tailored realistic wave sequences and their transformation to the moving reference frame of the cruising ship. The resultant wave train can be directly correlated with time series of motions — registered by an optical system — and forces. In this paper, these methods are applied to investigate pre-simulated seakeeping scenarios in the model basin and compare the results directly to the simulation results.

scholarly journals Real-Time Parameter Estimation of a Nonlinear Vessel Steering Model Using a Support Vector Machine

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Haitong Xu ◽  
M. A. Hinostroza ◽  
Vahid Hassani ◽  
C. Guedes Soares
Keyword(s):  
Support Vector Machine ◽  
Real Time ◽  
Time Parameter ◽  
Least Square ◽  
Training Data ◽  
Support Vector ◽  
Dynamic Parameters ◽  
Ship Model ◽  
Free Running ◽  
Marine Vessels

The least-square support vector machine (LS-SVM) is used to estimate the dynamic parameters of a nonlinear marine vessel steering model in real-time. First, maneuvering tests are carried out based on a scaled free-running ship model. The parameters are estimated using standard LS-SVM and compared with the theoretical solutions. Then, an online version, a sequential least-square support vector machine, is derived and used to estimate the parameters of vessel steering in real-time. The results are compared with the values estimated by standard LS-SVM with batched training data. By comparison, a sequential least-square support vector machine can dynamically estimate the parameters successfully, and it can be used for designing a dynamic model-based controller of marine vessels.

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