Azimuth method for ship position in celestial navigation

Van-Suong NGUYEN,Nam-Kyun IM,Quang-Dan DAO 국제이네비해양경제학회 2017 International Journal of e-Navigation and Maritime Vol.7 No.1

The methods of celestial navigation to fix the ship position in line with the stars are only applied in the twilight time interval when both the celestial bodies and the horizon apppear simultaneously. This means that these methods cannot be used during the night even if the stars are visible. This paper proposes a novel approach which uses the azimuth of the celestial body in order to establish the great circle equation relating the observed body to the ship position when the celestial bodies appear. In addition, the proposed method does not demand the horizon and sextant equipment as with the previous methods. The key advantage which differentiates this method from previous ones is its ability to determine the ship position during the night when the horizon is invisible. Firstly, the vector calculus is applied to find the mathematical equation for the ship position through analyzing the relationship between the ship position and the great-circle azimuth of the observed body. Secondly, the equation system for the ship position is expanded into a standard system in which the input for the proposed mathematical system are the great-circle azimuth and the coordinates of the observed body. Finally, the numerical technique is also proposed to solve the nonlinear system for the ship position. To verify the validation of this proposed method, a numerical experiment is carried out and the results show that it can be applied well in practice.

The Interpolation Method for the missing AIS Data of Ship

Van-Suong Nguyen,Nam-kyun Im,Sang-min Lee 한국항해항만학회 2015 한국항해항만학회지 Vol.39 No.5

The interpolation of missing AIS data can be used for recovering the lost data of a ship’s state which is then able to produce useful information for VTS stations or other ships. Previous research has introduced some interpolating methods however there are some problems with regard to missing AIS data. This paper proposes one new method which includes linear interpolation, cubic Hermit interpolation and an identification mechanism to overcome some of those limitations, first AIS data regarding ship position, COG, SOG and HDG is divided into separate time series, then the characteristic of the missing data is investigated into through using an identification mechanism, an appropriate interpolation is selected to fit all the time series which matches the characteristics. Numerical experiments are carried out using real AIS data to validate the algorithm of this approach and the results are compared with the previous method, after which the actual missing area is suggested to be interpolated by the proposed method. The interpolation results show this approach can be applied well in practice.

The Interpolation Method for the missing AIS Data of Ship

Nguyen, Van-Suong,Im, Nam-kyun,Lee, Sang-min Korean Institute of Navigation and Port Research 2015 한국항해항만학회지 Vol.39 No.5

The interpolation of missing AIS data can be used for recovering the lost data of a ship's state which is then able to produce useful information for VTS stations or other ships. Previous research has introduced some interpolating methods however there are some problems with regard to missing AIS data. This paper proposes one new method which includes linear interpolation, cubic Hermit interpolation and an identification mechanism to overcome some of those limitations, first AIS data regarding ship position, COG, SOG and HDG is divided into separate time series, then the characteristic of the missing data is investigated into through using an identification mechanism, an appropriate interpolation is selected to fit all the time series which matches the characteristics. Numerical experiments are carried out using real AIS data to validate the algorithm of this approach and the results are compared with the previous method, after which the actual missing area is suggested to be interpolated by the proposed method. The interpolation results show this approach can be applied well in practice.

Development of Computer Program for Solving Astronomical Ship Position Based on Circle of Equal Altitude Equation and SVD-Least Square Algorithm

Van-Suong Nguyen,Namkyun Im 한국항해항만학회 2014 한국항해항만학회지 Vol.38 No.2

This paper presents an improvement for calculating method of astronomical ship position based on circle of equal altitude equation. In addition, to enhance the accuracy of ship position achieved from solving equation system, the authors used singular value decomposition (SVD) in least square method instead of normal decomposition. In maths, the SVD was proved more numerically stable than normal decomposition. Therefore, the solution of equation system will be more efficient and the result would be more accurate than previous methods. By proposal algorithm, a computer program have been developed to help the navigators in calculating directly ship position when the modern equipment has failure. Finally, some of experiments are carried out to verify effectiveness of proposed algorithm, the results show that the accuracy of ship position based on new method is better than the intercept method.

ANN 을 이용한 multi-port 선박 자동 접이안 기초 연구

Van-Suong Nguyen,Nam-Kyun Im,Yu-Chang Seong 해양환경안전학회 2015 해양환경안전학회 학술발표대회 논문집 Vol.2015 No.11

Development of Computer Program for Solving Astronomical Ship Position Based on Circle of Equal Altitude Equation and SVD-Least Square Algorithm

Van-Suong Nguyen,Namkyun Im 한국항해항만학회 2014 한국항해항만학회지 Vol.38 No.2

This paper presents an improvement for calculating method of astronomical ship position based on circle of equal altitude equation. In addition, to enhance the accuracy of ship position achieved from solving equation system, the authors used singular value decomposition (SVD) in least square method instead of normal decomposition. In maths, the SVD was proved more numerically stable than normal decomposition. Therefore, the solution of equation system will be more efficient and the result would be more accurate than previous methods. By proposal algorithm, a computer program have been developed to help the navigators in calculating directly ship position when the modern equipment has failure. Finally, some of experiments are carried out to verify effectiveness of proposed algorithm, the results show that the accuracy of ship position based on new method is better than the intercept method.

Development of Automatic Ship Berthing System Using Artificial Neural Network and Distance Measurement System

Nguyen, Van-Suong,Do, Van-Cuong,Im, Nam-Kyun Korean Institute of Intelligent Systems 2018 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.18 No.1

In the studies on an berthing control of ship, an artificial neural network (ANN) model is commonly employed as the main controller to control the rudder and the propeller. The existing ANN controllers that use the parameters consisting of the ship position and the ship heading as inputs cannot be applied to control automatically the ship into berth in different ports. To deal with this problem, the parameters, such as relative bearing and distance from ship to berth calculated by radar can be used as inputs for the controller. However, the calculation of these factors is not accurate because some errors arise on using radar for berthing process. This leads to the lack of confidence in ship berthing system using the parameters determined by radar. In this research, the neural network based-automatic berthing system is developed for ship by using the parameters which are measured by distance measurement system. By this proposed system, the ship is brought automatically into berth in different ports without retraining the neural network. In addition, this system guarantees that the parameters used for inputs of the neural network is measured exactly and continually. To validate the proposed algorithm, numerical simulations are carried out to two imaginary ports and a real port, and result showed the good performance of the proposed system for automatic ship berthing.

A Theoretical Approach of Astronomical Ship Positioning Using a Single Celestial Body and Secant Technique

Van Suong Nguyen 한국지능시스템학회 2020 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.20 No.1

In this article, a new approach to solve an astronomical ship position is proposed based on a single celestial body and secant technique. The mathematical equations relating the ship position to a celestial body are described using an altitude and an azimuth of celestial body. These equations are established using knowledge of spherical trigonometry. Numerical analysis is then employed based on secant method to solve the mathematical equations for the ship position. This technique uses the altitude and the azimuth simultaneously while existing methods need to observe the altitude either of two celestial bodies or of a single body at two different times. Therefore, it is worth to apply this proposed technique when there is only a single celestial body identified. To validate the feasibility of the proposed technique, two numerical examples were performed.

Development of Automatic Ship Berthing System Using Artificial Neural Network and Distance Measurement System

Van-Suong Nguyen,Van-Cuong Do,Nam-Kyun Im 한국지능시스템학회 2018 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.18 No.1

In the studies on an berthing control of ship, an artificial neural network (ANN) model is commonly employed as the main controller to control the rudder and the propeller. The existing ANN controllers that use the parameters consisting of the ship position and the ship heading as inputs cannot be applied to control automatically the ship into berth in different ports. To deal with this problem, the parameters, such as relative bearing and distance from ship to berth calculated by radar can be used as inputs for the controller. However, the calculation of these factors is not accurate because some errors arise on using radar for berthing process. This leads to the lack of confidence in ship berthing system using the parameters determined by radar. In this research, the neural network based-automatic berthing system is developed for ship by using the parameters which are measured by distance measurement system. By this proposed system, the ship is brought automatically into berth in different ports without retraining the neural network. In addition, this system guarantees that the parameters used for inputs of the neural network is measured exactly and continually. To validate the proposed algorithm, numerical simulations are carried out to two imaginary ports and a real port, and result showed the good performance of the proposed system for automatic ship berthing.

Automatic Ship Berthing Based on Fuzzy Logic

Van-Suong Nguyen,Namkyun Im 한국지능시스템학회 2019 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.19 No.3

Because the maneuverability of ship at low speed is reduced significantly, ship berthing is one of most difficult duties that ship master usually has to face as arriving at the port. In order to make sure the safe accomplishment of ship berthing, all steps need to be performed properly. In fact of maritime safety, the tugboats and thrusters are commonly utilized to support crabbing motion of ship in final stage of berthing process before mooring. In addition, because of the nonlinear of ship dynamic on berthing, theories of artificial intelligence are suitable to mimic the actions of ship master in controlling ship berthing automatically. In this article, a support system is proposed to bring ship into berth automatically after using the maneuvering control system. Three fuzzy controllers are established for different tasks of the berthing algorithm. The first controller is designed to control the movement of ship in longitudinal direction toward to the normal of wharf with the ship’s propeller, while the task of second controller is to stabilize the relative bearing error with tugboat. The final controller is responsible for bring the ship into wharf according to crabbing motion with bow thruster and tugboat simultaneously. Finally, numerical simulations are carried out to validate the performance of the proposed system. The results show that the berthing support system has good performance for ship.