Zigzag Maneuver Research Articles

Design and Implementation of an Asynchronous Finite State Controller for Wheeled Mobile Robots

Wheeled mobile robots (WMRs) can navigate in uncontrolled environments with the assistance of electronic or physical devices. Several works have been conducted on the control and management of the path-tracking of a vehicle in different road scenarios. This paper aims to create an asynchronous finite state control law for a WMR. The control law is based on a proportional–integral–derivative controller, and the performance of the proposed model is evaluated in virtual and real environments in two different scenarios. In the first one, the WMR must perform a zig-zag maneuver between obstacles, while the second one involves a double left lane change. In the proposed scenarios, the WMR drives along a path until an obstacle is detected at less than 50 cm, causing the WMR to check whether the first lane is free to go and move on. These scenarios and the related required engineering approaches seem particularly suitable for system engineering in a student’s laboratory for the design and implementation of automated guidance system modeling.

Research on the influence of trimaran side hull layout on its manoeuvrability

In this paper, the numerical simulation method is used to calculate the hydrodynamics of the trimaran under different longitudinal and lateral side hull positions to predict the maneuvering motion, and then analyze the influence of the side hull layout on its Manoeuvrability. Firstly, based on the finite volume method (FVM),numerical simulation of the Captive Model Tests such as towing tests, circular motion tests, static heel tests, and roll decay motion tests are carried out by solving the 3-D unsteady Reynolds-Averaged Navier-Stokes (URANS) equations to determine the hydrodynamic coefficients for a mathematical model of the ship maneuvering motion, and to explore the hydrodynamic performance changes of trimaran under different working conditions and side hull layouts. Next, the turning maneuvering motion and Zig-zag maneuvering motion of the trimaran were predicted by combining with the 4-degree-of-freedom MMG model. Finally, the influence of different side hull layouts on the trimaran's maneuvering performance and the hull's heeling attitude under maneuvering motion was explored by comparing the maneuvering motion parameters.

Nonparametric modeling of ship maneuvering motion in waves based on Gaussian process regression

A robust and easy-to-operate method based on Gaussian process regression (GPR) is proposed for nonparametric modeling of ship maneuvering in waves. The wave parameters that are difficult to measure are not needed when identifying the dynamic model. In order to extract the wave effect from the ship motion data, the black-box model is modified relative to that used for calm water case. Taking the KCS container ship and the S-175 container ship as study objects, the nonparametric models based on GPR are identified by utilizing the experimental data of turning circle maneuver of KCS model and zigzag maneuvers of S-175 model in regular waves. Using the identified nonparametric models, turning circle maneuver of KCS model and zigzag maneuvers of S-175 model in regular waves are predicted, and the prediction results are compared with the model test data to verify the proposed method of nonparametric modeling and to evaluate the performances of the identified nonparametric models. It shows that the trajectory of turning circle maneuver and the heading angle of zigzag maneuvers are well predicted, indicating that the nonparametric model based on GPR with the modified black-box model can predict the maneuvering motion in regular waves accurately.

Numerical simulation of ship maneuvring by a hybrid method with propulsive factors in waves taken into account

In this paper, based on the open-source code OpenFOAM, a hybrid method coupling the FNPT-based QALE-FEM and the viscous flow method is used to simulate the turn and zigzag maneuvers of the single-screw ship in waves. The external domain adopts the fully nonlinear potential flow theory to simulate the wave tank. The internal domain simulates the interaction between waves and ships by the viscous flow method. The 6DOF motion equations are combined with the propulsive factors in waves to simulate the ship maneuvering during the simulation. The KVLCC2 model is used for numerical simulation. The numerical method is validated by the comparison with the self-propelled maneuvering test. Then, the turning and zigzag maneuvers of the ship in different initial wave headings and wave parameters are simulated, and the influences of wave heading and wave parameters on ship maneuvering are discussed.

Turn and zigzag manoeuvres of Delft catamaran 372 using CFD-based system simulation method

Special demands in marine applications such as large capacities in transportation and fast deployment in military operations have brought multihull concepts forward. Open deck areas, high stability characteristics, and a wide range of operating speeds are some of the strong sides of these vessels. The fact that few studies have been done on manoeuvring performance predictions of these types of ships has been the main source of motivation in conducting this study. A fast multihull form, Delft Catamaran 372 (DC372), has been selected for computational fluid dynamics (CFD)-based system simulation application. CFD method has been subjected to a verification and validation (V&V) process using the latest solution verification techniques and available comparison data in the literature. The computerized planar motion mechanism (CPMM) approach has been applied to determine all the necessary hydrodynamic derivatives stated in Abkowitz's manoeuvring model. A new approach to analysis of manoeuvring performance of multihull vessels, discrete study of hull components (DSHC), has been introduced for the interpretation of manoeuvring coefficients. The dynamic manoeuvre system simulator (DynaMaSS) in which a waterjet and conventional steering/propulsion units (SPUs) are implemented, has been presented for the 20-degree turning circle (TC20) and 20/20 zigzag (ZZ20) manoeuvre simulations of DC372. The manoeuvring coefficients of DC372 have been determined at a satisfactory level by the CFD method. Successful results and solution strategies have been presented for DC372.

Assessment of CFD-Based Ship Maneuvering Predictions Using Different Propeller Modeling Methods

Propeller modeling in virtual captive model tests is crucial to the prediction accuracy of ship maneuvering motion. In the present study, the Computational Fluid Dynamics (CFD) method with two propeller modeling methods, Sliding Mesh (SM) and Multiple Reference Frames (MRF), was used to simulate the captive model tests for a KVLCC2 tanker model. The virtual captive model tests, including for resistance, self-propulsion, rudder force, oblique towing, circular motion, oblique towing and steady turning tests with rudder angle, were conducted by solving the Reynolds-averaged Navier–Stokes (RANS) equations. The computed hydrodynamic forces, hydrodynamic derivatives, and hull-propeller-rudder interaction coefficients were validated against the available captive model test data and the CFD results obtained by a Body Force (BF) method in the literature. Then the standard turning circle and zig-zag maneuvers were simulated by using the MMG (Maneuvering Modeling Group) model with the computed hydrodynamic derivatives and hull-propeller-rudder interaction coefficients, and the results were validated against available free-running model test data. The most satisfactory agreement in terms of the ship hydrodynamic forces and maneuvering parameters and the most accurate rudder normal force were obtained by the SM method rather than by the MRF or the BF methods, while the lateral forces and yaw moments obtained by the SM and the MRF methods were all in good agreement with the model test data.

Z-Drive Escort Tug manoeuvrability model and simulation, Part II: A full-scale validation

A deep insight into the manoeuvring characterisation of a wider class of Azimuthal Stern Drive Escort tugs (ASD) is undertaken with the scope of defining a real-time parametric manoeuvring simulation code for the free-sailing and towing operations. In the part I of the work a physics-based 4-DOF prediction parametric tool for the dynamic behaviour of the ASD tug has been developed, and a validation with model-scale Escort-towing tests has been presented. In the present paper a second validation methodology, based on full-scale measurements, is discussed. This verification envisages simulator’s capability of describing the free-sailing performance of a different but compatible hull, having dimensions, propulsion, skeg characteristics significantly different with respect to the “parent design” used to develop the tool. The experimental campaign involves the measurements purposely performed during sea trials onto two sister-ship ASD new-buildings (RM3213). Turning circle, zig-zag manoeuvres, and Dieudonne’ spiral tests are deeply analysed and the results used for validation purpose. The simulation results showed a satisfactory agreement with the full scale manoeuvres, positively demonstrating the ability of the parametric mathematical formulations to forecast customised tug manoeuvrability for tug design purposes.

자유항주모형시험과 회귀분석을 통한 선체 동역학 모델의 개발

The present study suggests a procedure of establishing a ship dynamics modeling by regression of free-running model test results. The hydrodynamic force and moment of the whole model ship is derived from the low-pass filtered acceleration in the turning circle and zigzag maneuver tests. Force and moment of the propeller and rudder are separated from that of the whole ship to acquire the hull force and moment terms, based on the principles of the component model. The low-pass filter frequency is verified in prior to dynamics modeling, to find the threshold frequency of 2.5 Hz. The dynamics modeling of the hull is compared with the component modeling by captive model tests. Because of strong correlation between sway velocity, yaw angular velocity, and heel angle, each maneuvering coefficient is not able to be validated, but the whole modeling shows good agreement with the captive model tests.

Black-box modeling of ship maneuvering motion based on multi-output nu-support vector regression with random excitation signal

This paper proposes a novel method for offline black-box modeling of ship maneuvering by utilizing the training data from random maneuvers under medium rudder angle with random amplitude and duration. The identification algorithm adopted is a multi-output ν(‘nu’)-Support Vector Regression, MO-ν-SVR, that has higher computational efficiency and better operability than a conventional ν-SVR. The ONRT vessel is taken as the study object, and numerical simulations are conducted to provide the training, validation and testing datasets. The superiority of the proposed random maneuver over the standard zig-zag maneuver is demonstrated by a contrastive study where the excitation signals from the random maneuver and the 20°/20° zig-zag maneuver are used for training the model separately. To examine the robustness of the proposed modeling method and the identified model, three levels of white noise are added into the raw simulation data for training the model. To explore the effectiveness and generalization ability of the identified model on different motion patterns of ship maneuvering, course-keeping, course-changing, and turning motions are examined separately. The results demonstrate that the model trained by the excitation signals of the random maneuver has better generalization ability and robustness, verifying the feasibility and practicality of the proposed modeling method.

Numerical simulation of turn and zigzag Maneuvres of trimaran in calm water and waves by a hybrid method

As one of the widely used high-performance ships, the hydrodynamic characteristics of the trimaran ships have been widely investigated in recent years. But, the study on the maneuverability and the skill of the maneuvering simulation are still limited. In this paper, a hybrid method coupling the FNPT-based (fully nonlinear potential flow theory) QALE-FEM (quasi arbitrary Lagrangian-Eulerian finite element method) with the viscous flow method is applied to simulate the turn and zigzag maneuvers of the trimaran in both calm water and waves. The environment of calm water and incident waves is simulated by the numerical tank of QALE-FEM. The maneuvering of the trimaran is carried out in the scope of the numerical tank by the viscous flow method. The grid convergence test is carried out first, and the computed results are compared with the experimental results. Then, the turn and zigzag maneuvers of a trimaran model in both calm water and waves are simulated to study the trimaran's maneuvering characteristics.

Hybrid Control Architecture of an Unmanned Surface Vehicle Used for Water Quality Monitoring

The study of water quality in reservoirs, lakes, and coasts is an activity that mainly uses human-crewed marine vehicles to obtain site parameters such as temperature, conductivity, salinity, pH, and others. This task is facilitated by unmanned vehicles, which improve data quality in hazardous areas and minimize human exposure. This work presents a novel methodology based on systems engineering concepts and hybrid control architecture for a catamaran-class unmanned surface vehicle (USV) named EDSON-J, for remote water quality monitoring activities with payload instrumentation. Critical aspects of the project development are considered, such as requirements, risk management, design flexibility, logical decomposition, functional classification, verification, integration and validation, and technological plan. The applied methodology proposes the main components for the vehicle, a main computer running robotic operating system (ROS) with deliberative control architecture for high-level tasks and a secondary computer running finite state machine (FSM) with hierarchical control architecture for low-level tasks, executing control and navigation algorithms. The results are given through missions of water quality monitoring, attaching a multiparameter payload sonde. Manual and automatic mode controls are suitable for circular and zig-zag maneuvers and show better performance for the proposed platform, guaranteeing the specifications and requirements of the vehicle design and validating the proposed hybrid control architecture.

Identification of Ship Hydrodynamic Derivatives Based on LS-SVM with Wavelet Threshold Denoising

Nowadays, system-based simulation is one of the main methods for ship manoeuvring prediction. Great efforts are usually devoted to the determination of hydrodynamic derivatives as required for the mathematical models used for such methods. System identification methods can be applied to determine hydrodynamic derivatives. The purpose of this work is to present a parameter identification study based on least-squares support-vector machines (LS-SVMs) to obtain hydrodynamic derivatives for an Abkowitz-type model. An approach for constructing training data is used to reduce parameter drift. In addition, wavelet threshold denoising is applied to filter out the noise from the sample data during data pre-processing. Most of the resulting derivatives are very close to the original ones—especially for linear derivatives. Although the errors of high-order derivatives seem large, the final predicted results of the turning circle and zigzag manoeuvres agree pretty well with the reference ones. This indicates that the used methods are effective in obtaining manoeuvring hydrodynamic derivatives.

Robust Parameter Estimation of an Empirical Manoeuvring Model Using Free-Running Model Tests

The work presents the identification and validation of the hydrodynamic coefficients for the surge, sway, and yaw motion. This is performed in two ways: using simulated data and free-running test data. The identification and validation with the simulation data are carried out using a 25° turning test and a 20°−20° zigzag manoeuvring test. For the free-running test data, two zigzag manoeuvres are used: 30°−30° zigzag for identification and 20°−20° zigzag for validation. A nonlinear manoeuvring model is proposed based on the standard Euler equations, and the hydrodynamic coefficients are computed using empirical equations. To obtain robust results, the truncated singular value decomposition is employed to diminish the multicollinearity and the parameter uncertainties due to noise. The validation is carried out by comparing the result of the measured values with the predictions obtained using the manoeuvring models. Finally, a sensitivity analysis for the simulation data is performed to understand the influence of the parameters in the manoeuvres.

Investigating the effect of rudder profile on 6DOF ship course-changing performance

Zigzag is one of the most crucial standard ship maneuvering tests performed to evaluate the yaw-checking ability. However, conducting experiments and studying the flow in free-running maneuver tests such as the zigzag test is associated with many complexities and restrictions. An alternative method is a simulation in a computational fluid dynamics environment. This study uses 6DOF direct 10/10 and 20/20 zigzag maneuver simulation to investigate conventional marine rudder profiles such as NACA 0025, IFS, HSVA, Wedgetail, and flapped on the course changing ability of a containership is investigated.The results show that the HSVA and NACA 0025 profiles have almost the same performance, but the IFS profile performed better than the two. Furthermore, rudder performance significantly improves with changes such as adding wedge or flap. Finally, comparing results with experimental data shows that numerical computations are suitable and accurate for predicting ship maneuverability.

DEVELOPMENT OF A 1:30 SCALE SAILING MODEL OF OCEANBIRD

With the current developments of wind powered and wind assisted vessels comes the need for realistic ship model testing. Traditional test methods of free sailing models are somewhat limited by the difficulties to mimic the effects of the wind propulsion systems or at least for recreating them at the correct scale. Simulations are possible but time consuming and they cannot grasp all aspects that free sailing models comprise. At the KTH Maritime Robotics Laboratory, a 1:30 scale model of Oceanbird was developed and equipped with numerous sensors to enable accurate and realistic measurements while sailing in unrestrained waters. The paper presents the model’s equipment and experimental results showing the abilities of the sailing demonstrator to gather high quality data for manoeuvring and aerodynamic studies. In particular, the definition of a zigzag manoeuvre for sailing ships is explained and results of tests are evaluated regarding manoeuvrability and aerodynamics.

Parameters’ Identification of Vessel Based on Ant Colony Optimization Algorithm

In this paper, the ant colony optimization (ACO) method is used to identify the parameters of a 3-DOF nonlinear vessel model. Identifying the parameters is abstracted as a nonlinear optimization problem to solve through the ant colony optimization algorithm. The identification procedure is divided into two parts. The first part of the identification procedure is to identify the parameters related to surge motion. The second part of the identification procedure is to identify the rest parameters of the vessel’s kinetics model. In the surge model identification procedure, the transient motor speed is used to generate the training data, and in the sway and yaw motion identification procedure, the zigzag maneuvering with different motor speeds is used to generate the training data. All the parameters are identified by the ACO method and the least-square (LS) method based on the training data and then validated on the validation data. The prediction performance of parameters identified by different methods is compared in the simulation to demonstrate the effectiveness of the ACO algorithm.

Effects of water depth and speed on ship motion control from medium deep to very shallow water

To extend the knowledge on ship manoeuvring and predict ship's behaviour accurately from medium deep to very shallow water, this paper comprehensively investigates water depth and speed effects on ship's manoeuvrability, steering model and motion control through experimental studies. Free running model tests at four water depths and six speeds were conducted using a scaled ship model in the towing tank at Flanders Hydraulics Research (FHR). The influence of under keel clearance and speed on the acceleration tests and zigzag manoeuvres were firstly analysed. Secondly, the shallow water effect on ship steering model was discussed via theoretical analysis and experimental validation. Then, the investigation of the effects of speed and under keel clearance on the ship motion controller's parameters and performance was executed, and a novel adaptive controller was proposed. To improve controller's performance in shallow water, a scheme was proposed to optimize its parameters. The results indicate that both speed and water depth have considerable influence on ship's manoeuvrability and controllability. Especially, water depth restrictions change the hydrodynamic forces, reduce the propulsion efficiency and manoeuvreability, the ship becomes more difficult to manoeuvre and control in shallow water. These impacts on ship manoeuvring, modelling and motion control cannot be neglected.

Identification modeling and prediction of ship maneuvering motion based on LSTM deep neural network

This paper proposes a novel system identification scheme to obtain a MIMO model of ship maneuvering motion, which can leverage the temporal correlation from the constructed training data to learn the underlying feasible model robust to extraneous noise. The scheme is based on long–short-term-memory (LSTM) deep neural network, which is more easily trained than traditional feedforward neural network with more complicated network structure. First, multiple datasets of simulated standard maneuvers (10°/10° and 20°/20° zigzag, 35° turning circle) of a KVLCC2 model are artificially polluted with white noise of various levels and used simultaneously to train the deep neural network model. Meanwhile, the data of 15°/15° zigzag maneuver are used to facilitate the training process to alleviate overfitting problem. Second, different datasets of modified zigzag tests are used to validate the generalization performance and robustness to noise of the trained neural network model. The training and validation results demonstrate that a mapping between the dynamics of ship motion and the computation in LSTM deep neural network is correctly identified. This mapping indicates that the complex nonlinear features of ship maneuvering motion can be learned from the measured temporal data, using standard training techniques for deep neural networks. An equivalent LSTM deep neural network model with better generalization performance and robustness is established, and its accuracy in predicting ship maneuvering motion is validated.

EXPERIMENTAL AND NUMERICAL INVESTIGATION ON MANEUVERING PERFORMANCE OF SMALL WATERPLANE AREA TWIN HULL

Free running model tests and a system-based method are employed to evaluate maneuvering performance for a Small Waterplane Area Twin Hull (SWATH) ship in this paper. A 3 degrees of freedom Maneuvering Modeling Group (MMG) model is implemented to numerically simulate the maneuvering motions in calm water. Virtual captive model tests are performed by using a Reynolds-averaged Navier-Stokes (RANS) method to acquire hydrodynamic derivatives, after a convergence study to check the numerical accuracy. The turning and zigzag maneuvers are simulated by solving the maneuvering motion model and the predicted results agree well with the experimental data. Moreover, free running model tests are carried out for three lateral separations and the influence of the lateral separations on maneuvering performance is investigated. The research results of this paper will be helpful for the maneuvering prediction of the small waterplane area twin hull ship.

Numerical simulations and analysis of the zig-zag maneuvers of an oil tanker based on a body-force propeller

The course change quality is a crucial measure of ships’ maneuverability and is closely related to the ship navigation safety. Research on zig-zag motion of ships is essential to voyage safety. STARCCM+ based on the ship 6-DOF motion and overset grid technology are used to numerically simulate the zig-zag maneuver of an oil tanker. To simulate the zig-zag motion, a body-force propeller model is adopted instead of the real propeller. The rotation speed of virtual propeller is controlled to achieve the steady self-propulsion state of the ship model and then the rudder turns from 10° to -10° according to the orientation of the ship model. By solving viscous flow field, the motion state and detailed flow field information of the ship model are presented. To verify the accuracy of numerical prediction results, ship model test is launched. Through comparison of results, the numerical simulation can provide reference for preliminary assessment for the course change quality of ships.