Ship Heading Research Articles

Neural Prescribed Performance Control for Uncertain Marine Surface Vessels without Accurate Initial Errors

This paper deals with the problems concerned with the trajectory tracking control with prescribed performance for marine surface vessels without velocity measurements in uncertain dynamical environments, in the presence of parametric uncertainties, unknown disturbances, and unknown dead-zone. First, only the ship position and heading measurements are available and a high-gain observer is used to estimate the unmeasurable velocities. Second, by utilizing the prescribed performance control, the prescribed tracking control performance can be ensured, while the requirement for the initial error is removed via the preprocessing. At last, based on neural network approximation in combination with backstepping and Lyapunov synthesis, a robust adaptive neural control scheme is developed to handle the uncertainties and input dead-zone characteristics. Under the designed adaptive controller for marine surface vessels, all the signals in the closed-loop system are semiglobally uniformly ultimately bounded (SGUUB), and the prescribed transient and steady tracking control performance is guaranteed. Simulation studies are performed to demonstrate the effectiveness of the proposed method.

基于椭球极投影的三维船舶航线高精度绘制

为解决电子海图中三维船舶航线高精度绘制问题，给出了一种基于椭球极投影的绘制方法。首先，通过建立椭球极投影，将椭球面上的点与平面上的点作一一对应。其次，将港口和船舶位置信息投影到平面上，利用Hermite插值技术，构造一条平面插值曲线。然后将该平面曲线通过椭球极逆投影，得到一条地球面曲线。最后，基于船舶航向等信息，提出了三维航线长度优化及多组航线交点求解的算法，实现了三维航线自动生成及相关计算。数值实验表明本文方法较已有方法更具真实感，精度更高。 In order to solve the problem of 3D high accuracy rendering of ship route in electronic navigational chart, a method based on the ellipsoidal projection is presented. Firstly, the ellipsoidal projection is established, and the point on the ellipsoid is one-to-one corresponding to the point on the plane. Secondly, the port and ship position information is projected onto the plane, and a plane interpolation curve is constructed by using Hermite interpolation technique. Then using the inverse ellipsoidal projection, a curve on the earth surface is obtained. Based on the information of the ship heading, the algorithm of 3D route length optimization and multi-route intersection is presented. The automatic generation of 3D route and related calculation are realized. Finally, numerical experiments show that the method is more realistic and more accurate than the existing methods.

Ship heading and velocity analysis by wake detection in SAR images

With the aim of ship-route estimation, a wake detection method is developed and applied to COSMO/SkyMed and TerraSAR-X Stripmap SAR images over the Gulf of Naples, Italy. In order to mitigate the intrinsic limitations of the threshold logic, the algorithm identifies the wake features according to the hydrodynamic theory. A post-detection validation phase is performed to classify the features as real wake structures by means of merit indexes defined in the intensity domain. After wake reconstruction, ship heading is evaluated on the basis of turbulent wake direction and ship velocity is estimated by both techniques of azimuth shift and Kelvin pattern wavelength. The method is tested over 34 ship wakes identified by visual inspection in both HH and VV images at different incidence angles. For all wakes, no missed detections are reported and at least the turbulent and one narrow-V wakes are correctly identified, with ship heading successfully estimated. Also, the azimuth shift method is applied to estimate velocity for the 10 ships having route with sufficient angular separation from the satellite ground track. In one case ship velocity is successfully estimated with both methods, showing agreement within 14%.

Wake Component Detection in X-Band SAR Images for Ship Heading and Velocity Estimation

A new algorithm for ship wake detection is developed with the aim of ship heading and velocity estimation. It exploits the Radon transform and utilizes merit indexes in the intensity domain to validate the detected linear features as real components of the ship wake. Finally, ship velocity is estimated by state-of-the-art techniques of azimuth shift and Kelvin arm wavelength. The algorithm is applied to 13 X-band SAR images from the TerraSAR-X and COSMO/SkyMed missions with different polarization and incidence angles. Results show that the vast majority of wake features are correctly detected and validated also in critical situations, i.e., when multiple wake appearances or dark areas not related to wake features are imaged. The ship route estimations are validated with truth-at-sea in seven cases. Finally, it is also verified that the algorithm does not detect wakes in the surroundings of 10 ships without wake appearances.

A Proposed System of Ship Trajectory Control Using Particle Swarm Optimization

This paper discussed the operation of Particle Swarm Optimization (PSO) to optimize a Fuzzy Model Reference Learning Controller (FMRLC) for ship. FMRLC is developed by synthesizing several basic ideas from fuzzy set and control theory. It can achieve the heading regulation of ship exposed to plant changes and disturbances by adjusting the rules in a direct fuzzy controller so that the overall system behaves like a “reference model”. It is shown that PSO can provide a very promising technique for the design of FMRLC for its simplicity and ease of use. The promising results from the experiment provide direct evidence for the feasibility and effectiveness of PSO for the optimization of FMRL controller for ship heading regulation.

Study of Ship Heading Control using RBF Neural Network

Along with the development of shipping business, ships are becoming bigger, faster and more intelligent. Thus better performance of maneuver is demanded. To research for better control strategies, it is necessary to adopt new control theories and techniques. The application of neural network techniques and backstepping algorithm in ship motion control became an important research area in recent years. Aiming at the nonlinear of ship motion, also for application of control strategy, control strategy based on the RBF neural network and backstepping algorithm is proposed. The strategy employs the RBF neural network to approximate and substitute the system, and employs adaptive law designed by backstepping algorithm to adjust the weight of the RBF neural network. Finally, the proposed strategy was applied in ship course tracking control simulation and the satisfying performances demonstrate the feasibility and effectiveness of the ship control strategy.

A Direct Torque Control Driven Vessel Actuator Device

Actuator is one of the most important auxiliary mechanisms used to control the ship heading. Focused on the existed shortages of conventional hydraulic driven vessel actuator as complex structure, low efficiency and response etc, by the analysis of torque variation to access the impact of direct torque control and design an actuator used direct torque control of which is simple and easy to implement. Simulation results show that this scheme can reduce system without dynamic performance, low-speed operation to expand the scope of the system, reducing the torque ripple, while improving the low-speed torque of the motor.

Research on Analysis Method of Differential Signal of Ship Heading without Mathematical Model

A kind of differential method is proposed for to eliminate noise disturbance and signal delay problems in ship heading control. First, an asymptotic observer is designed without ship motion dynamic parameters. Then, it proves that the observer is stable and the convergence conditions if given. At last, simulation result shows that the designed observer can suppress noise in ship heeding signals, and differential delay is improved.

Wave Filtering of Ship Dynamic Positioning System Using Particle Filter

This paper presents a nonlinear filter which is particle filter. The filter produces accurate estimates of low-frequency position and velocity only from measured values of ship position and heading in Dynamic Positioning System. The results of simulation confirm the validity and adaptability of the particle filter algorithm.

Tuning of Ship Heading Controller Based on Minimum Rate of Energy Dissipation and Multi-Attribute Decision Making Method

The PID control is most widely used in industry and its parameters setting is an important issue in the field of automatic control. In this paper, a novel tuning strategy based on multi-objective genetic algorithm (MOGA) and multi-attribute decision-making (MADM) method was proposed. The proposed strategy can balance the four performances simultaneously regarding accurate set-point tracking, disturbance attenuation, robust stability and energy consumption for actuator. The estimated Pareto-optimal set was obtained by MOGA and then an appropriate solution was selected from the set by ranking with a simple additive weighting method (SAW). To demonstrate the proposed strategy, an example of the ship course PID controller with filter for a 150,000-ton tanker with steering gear was studied. The results show that the PID controller is stable and robust with high dynamic quality.

자유자이로 위치 및 방위시스템의 오차에 관한 연구

This paper is to develop the position error equations including the attitude errors, the errors of nadir and ship's heading, and the errors of ship's position in the free-gyro positioning and directional system. In doing so, the determination of ship's position by two free gyro vectors was discussed and the algorithmic design of the free-gyro positioning and directional system was introduced briefly. Next, the errors of transformation matrices of the gyro and body frames, i.e. attitude errors, were examined and the attitude equations were also derived. The perturbations of the errors of the nadir angle including ship's heading were investigated in each stage from the sensor of rate of motion of the spin axis to the nadir angle obtained. Finally, the perturbation error equations of ship's position used the nadir angles were derived in the form of a linear error model and the concept of FDOP was also suggested by using covariance of position error.

逆クロスベアリングを用いた超音波バイオテレメトリーシステムの測位精度評価

Tracking system, one of the biotelemetry systems, detects signals from pingers using a receiver located on an observation boat. This system can be used without location constraints, unlike monitoring systems and positioning systems for which a receiver must be installed in the actual sea. But such a system cannot measure the pinger position in detail. In order to measure the pinger position in greater detail using a tracking system, a new method using “inverse cross bearing” was developed. This method determines the horizontal pinger position using the intersection point of more than two bearing lines from as many observation points. The vertical position of the pinger is measured by a depth sensor on the pinger itself. This system calculates the relative azimuth of the pinger using the receiving time differences among the four transducers. The GNSS compass, to convert the absolute azimuth of the pinger's relative azimuth, measures the ship's heading. To estimate the theoretical error factors, experiments were conducted in actual seas. The estimation results were compared to the results of the field experiments. In certain conditions, the estimated positioning accuracy was 14 m, and the measured value was 21 m. This discrepancy may be due to factors such as agitation of the ship.

Development of a novel forward dynamic programming method for weather routing

This paper presents a novel forward dynamic programming method for weather routing to minimise ship fuel consumption during a voyage. Compared with tradi- tional weather routing methods which only optimise the ship's heading, while the engine power or propeller rota- tion speed is set as a constant throughout the voyage, this new method considers both the ship power settings and heading controls. A float state technique is used to reduce the iterations required during optimisation and thus save computation time. This new method could lead to quasi- global optimal routing in comparison with the traditional weather routing methods.

Re-Mapping the Indian Ocean in Amitav Ghosh’s Sea of Poppies

With Sea of Poppies (2008), Amitav Ghosh re-enacts the history of the first wave of the Indian diaspora. He gathers many different characters on a ship heading for Mauritius Island. On board they learn how to manage change and how to live with their fears and dreams. Crossing the Indian Ocean, the characters are bound to be caught in a translation movement which makes cultures and languages collide. This paper analyses how Ghosh redefines migrancy through the prism of indentured labour, illustrating how the scattering movement of the diaspora and the confluent drive of globalisation intersect.

Solution of transfer alignment problem of SINS on moving bases via neural networks

PurposeIn order to accomplish real‐time alignment of Shipborne strapdown inertial navigation system (SINS) on moving bases, a novel solution method of utilizing neural networks for rapid transfer alignment of Shipborne SINS was investigated.Design/methodology/approachThe system error state equations and measurement equations of the Shipborne transfer alignment were established. Based on the nonlinear and time‐variant SINS model on moving bases, a neural network learning algorithm based on Kalman filtering was presented, and the methods of constructing and training of neural networks input‐output sample pairs suitable for Shipborne SINS were proposed.FindingsVelocity and attitude errors between the master and slave inertial navigation system (INS) are chosen as network's inputs, and the information of sample pairs is affluent, which can advance the stability and generalization of the neural networks. The neural networks algorithms based on Kalman filtering not only have the self‐learning ability, but also remain recursive optimal estimation capability of Kalman filtering. Through the introducing of the local level trajectory frame, the trained neural networks can be independent on a ship heading, and only dependent on the relative position errors between master with slave INS and the inertial sensor errors.Originality/valueThis article presents an innovative solution method of utilizing neural networks for rapid transfer alignment of Shipborne SINS.

The Correction of Shot and OBS Position in the 3D Seismic Experiment of the SW Indian Ocean Ridge

AbstractIn a three‐dimensional (3D) seismic experiment carried out at sea, due to the distance between GPS antenna on ship and the center of air gun sources in sea water, and some environmental factors such as wind and sea current, the survey ship may adjust its heading direction, which makes the real shot position deviate from designed shot track; meanwhile, the real locations of Ocean Bottom Seismometers (OBS)s on the seafloor may drift from designed points (deployed locations) since OBSs are of free‐fall type and usually affected by sea currents during its descending. So, the calibration of air‐gun shots and OBSs' positions are basic steps for later studies on fine seismic velocity tomography. Our research is mainly focused on the correction of shot and OBS positions with up‐to‐date data from a new 3D seismic experiment in the SW Indian Ocean Ridge. The shot positions were corrected with geometric relationship among ship's heading, GPS antenna and air‐gun array. The correction of OBS positions were based on travel time of direct water wave, Monte Carlo method and least square method. In addition, we discuss the relationship between reduced travel time curves of direct water wave and OBS's deviation. Our results show that OBS's locations generally drift from the designed points about 1 km with an error range of 0~20 m, and shots are adjusted to its actual positions. The correction results not only supply a fundamental database for the 3D seismic tomography in our study area, but also provide valuable experiences for 3D seismic survey in the South China Sea in future.

어선 AIS에서의 하이브리드 GPS/EM 컴퍼스에 의한 선수방위 안정화

The ship's heading information of hybrid GPS/EM compass were applied to the AIS of fishing vessel and examined the possibility of accuracy improvement. It is observed 453 each in AIS receiver of land among 3,982 each in AIS Rx/Tx transponder of the test ship at sea, and transmission interval according to the speed of ship is determined the 11.4% good transmitting data of the all information. In results, maximum compass error for the ship's heading of an EM compass was <TEX>$19.1^{\circ}$</TEX>. The variance of ship's heading owing to the speed of ship is surveyed. The COG (Course Over Ground) was changed extremely in <TEX>$180^{\circ}W-179^{\circ}E$</TEX> range under 4.9knots, and in <TEX>$24^{\circ}W-23^{\circ}E$</TEX> range over 4.9knots. Finally, using the ship's heading of EM compass and the COG from GPS for the autopilot system of a small fishing boat and the ship's heading information of AIS results in danger on the own ship's navigation safety and leads to make confusion both the others and VTS (Vessel Traffic Service) center. Therefore, the hybrid GPS/EM compass is identified as the best system for a small fishing boat and is allowed to offer continuously a ship's heading information with high accuracy and stability.

Statistical Analysis and Control of Ship

The first parts of this paper describe the statistical time series analysis of ship's motions. The actual time series data are identified by the uni and multi-variate autoregressive models whose orders are determined by Akaike's Information Criterion(AIC). Various functions to analyse the ship's motions are defined in time and frequency domains and some salient features of ship's motions are derived from the time series data of the actual ship's motions. The latter half parts are contributed to the control problems of ship's heading to the given course and tracking ones along the given line and the regulation of main engine propeller rpm. All methods are corroborated by actual experiments on board.

Matching radar and satellite images for ship trajectory estimation using the Hausdorff distance

A novel technique to obtain position, velocity and radar biases estimates of a ship is described by matching ship-borne radar images to geo-referenced satellite images. The matching is performed through the minimisation of the averaged partial Hausdorff distances between data points in each image. The minimisation rapidly yields robust geographical latitude and longitude position measurements, as well as ship heading and radar biases. The accuracy of the measurements is improved by feeding them into a Kalman filter that also allows estimates of the ship&apos;s velocity to be obtained. The method provides an alternative effective position sensor for GPS denied environments, which may also be employed for automatic radar calibration of bearing and range biases or for indoor autonomous mobile robot navigation.

A Theoretical Study on Free Gyroscopic Compass

The authors aim to establish the theory necessary for developing the free gyroscopic compass and focus on mainly two points. One is to suggest north-finding principle by the angular velocity of the earth's rotation, and the other is to suggest orthogonal coordinate transformations of the motion rate of the spin axis, which transforms the components of motion rate in the free gyro frame into those in the platform frame and that this transformed rate is, in turn, transformed into the NED(north-east-down) navigation frame. Subsequently, ship's heading is obtained by using the fore-aft and athwartship components of the motion rate of the spin axis in the NED frame. In addition it was found how to solve the transformation matrix necessary for transforming each frame.