Showing papers by "Xiumin Chu published in 2017"

Enhance the AIS data availability by screening and interpolation

Abstract: The AIS broadcasts the ship's navigation data automatically and autonomously through VHF band. It plays an important role in collision avoidance and maritime situational awareness. However, in inland waterways, it is common that the AIS data-link was obstructed by the river bank and mountains, or sometimes the AIS was encountered with the electromagnetic interference. Consequently, the AIS dynamic data is often lost and mixed with inaccurate, which may lead to misjudgment of the traffic situation. To address this problem, a method was proposed to enhance the availability of AIS data in this paper. Firstly, according to the ships' maneuverability, a set of factors, such as the moving distance, speed, acceleration, and course change rate, were designed to screen the inaccurate AIS data. Then, the piecewise cubic Hermite interpolation and cubic spline interpolation were employed to restore the AIS data. A real AIS trajectory was introduced to validate the accuracy of the two interpolation methods, which proves that the cubic spline interpolation performance is better than piecewise cubic Hermite interpolation. Field experiments in Wuhan reach of Yangtze River show that the method proposed in this paper is highly effective. The accuracy of the location is 3.5m, the speed accuracy is 0.05m/s, and the course accuracy is up to 0.7 degrees, the AIS data can be accurately repaired.

A variational approach for adaptive underwater sonar image denoising

Abstract: Underwater sonar imaging is a significant means for a variety of maritime work However, the sonar images are corrupted by signal dependent speckle noise, which restricts the potential practical applications In this paper, we propose a novel variational approach that addresses the adaptive sonar image denoising problem To accurately describe the signal dependent characteristic of noise for real sensors, we utilize a generalized noise model, which can be adapted to represent various types of noise With the generalized noise model, we formulate the denoising problem via a variational approach Finally, we present a modified primal and dual method to efficiently solve the variational minimization problem Experimental results on both simulated and real data validate the effectiveness and efficiency of our method

Coverage effectiveness analysis of AIS base station: A case study in Yangtze River

Abstract: AIS data are of great significance to ensure the safety of ship navigation and strengthen maritime management. The present study focuses on the situations of AIS data loss in practical applications to research coverage of AIS base station. The original AIS data is pre-processed in accordance with structure characteristics, including data packet, data filtering and so on. Data reconstruction has been performed by applying piecewise cubic Hermite interpolation function. In order to identify AIS data loss for different segments, the study area is divided into several sub-areas, on basis of which AIS data loss rate has been statistically computed and visually presented by using mapping technique. The characteristics of individual vessel passing through the area are investigated as well. By applying visual analysis method, the coverage of AIS base station at the upper Yangtze River is revealed. The present study provides novel insights into AIS base station arrangement strategies, thus AIS data loss rate could be reduced.

Enhance the Ais Data Availability by Screening and Interpolation

Abstract: The AIS broadcasts the ship’s navigation data automatically and autonomously through VHF band. It plays an important role in collision avoidance and maritime situational awareness.

A hybrid model for water level forecasting: A case study of Wuhan station

Abstract: Water level forecasting has been recognized as a classic problem in the field of time series analysis and is closely related to the maritime administration. A hybrid model is thus presented for a case study of Wuhan station which locates at the middle reach of the Yangtze River. The daily water level of the Wuhan station is affected by the upstream runoff and human activities (waterway regulation projects, sand mining etc.), which lead to the complexity of its short-term forecasting. Time sequences of daily water level are derived from the Changjiang Waterway Bureau, on basis of which a hybrid ANN-Kalman filtering model is established. Its performance is evaluated and compared with single ANN model. The forecasting results are overall favorable. The hybrid model could be further integrated with the Yangtze River Electronic Channel Chart Display and Information System and provides an alternative way of daily water level predictions.

Ship heading control based on backstepping and Least squares support vector machine

Abstract: In this paper, a composite method based on least squares support machine (LS-SVM) and backstepping is proposed for the ship heading control. In the method, the control object is set up as the response model, which could consider the delay of the ship's steering gear. Firstly, a feedback controller is designed by backstepping, and a feedforward inverse controller is trained by LS-SVM. Then the backstepping method and LS-SVM inverse model are combined to form a new controller by adapting their output weights. Finally, simulations using a single backstepping method as comparison are made with different disturbances to verify the effectiveness of the combined controller proposed in this paper.

Design method of USV course-tracker based on simulation and real vessel experiment

Abstract: The unmanned surface vessel (USV) can provide effective means for ocean exploration and traffic regulation, and has become a research hotspot in the field of marine shipping because of its low cost, high efficiency and other advantages. To realize the accurate control of USV movement can provide technical guarantee for the realization of USV autonomous navigation. The research of USV course control method of modeling, using white noise simulation environment for the operation of the boat course of interference, and the MPC (Model Predictive Control) algorithm based on state space is used to design the course controller. The value of the MPC controller such as the sampling frequency is obtained by the simulation method and the experimental method. The effects of the modified MPC controller and PID controller are compared and analyzed. Results show that the modified MPC controller in control USV course has fast convergence, good control USV course motion.