Ocean Navigation Method Based on Multi-System and Multi-Source Data Fusion

Ocean Navigation Method Based on Multi-System and Multi-Source Data Fusion

Xiang Wang (Donghai Navigation Safety Administration (DNSA), Ministry of Transport (MOT), China), Jingxian Liu (School of Navigation, Wuhan University of Technology, China) and Zhao Liu (School of Navigation, Wuhan University of Technology, China)
DOI: 10.4018/978-1-7998-3038-2.ch001

Abstract

Ship navigation requires accurate positioning, navigation and timing (PNT) data. PNT data from a single source has uncertainties and potential risks. Wrong PNT data has a huge impact on ship maneuvering, and at the same time, it may cause huge losses to national assets and national security. This chapter proposes a data fusion algorithm based on single-frequency global navigation satellite system (GNSS) and inertial navigation system (INS) to obtain PNT data, which can improve the availability, accuracy, reliability, continuity, and robustness. The experimental results show that the data fusion method combining median filtering and Kalman filtering can improve the system's ability to acquire PNT data. When blocking GNSS acquisition of PNT data, relying on INS, you can still obtain PNT data, which can make up for the ability to obtain PNT data from GNSS.
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Introduction

Positioning, navigation and timing (PNT) data fusion is a key technology for describing time and space information.

Global Navigation Satellite System (GNSS) refers to all navigation satellite systems, including global, regional and enhanced navigation satellite systems, such as the United States' Global Positioning System (GPS), Russia's Global Navigation Satellite System (GLONASS), Europe's Galileo and China's BeiDou Navigation Satellite Navigation System (BDS).

On July 8, 2019, the positioning, navigation and timing (PNT) data of the Global Positioning System (GPS) position of Xingang and Dayawan Port Areas in Dalian, Liaoning Province, China was incorrect. As is shown in Figure 1, the PNT data of the “Blue Sky 1” vessel that berthed at the No. 1 berth in Xingang was incorrect. The PNT data shown that the location is on the south of the No. 0 berth of Xingang Terminal. The PNT data of the “Kun Lun You 106” ship that berthed at No. 16 berth in Xingang shown that the location is on the western mountainous area of the terminal. The situation of incorrect PNT data lasted for about 24 hours, bringing huge impact on ship maneuvering.

Figure 1.

Incorrect PNT data

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Ship maneuvering requires high-precision PNT data. This paper plans to combine the single-frequency GNSS with the PNT data of the inertial navigation system (INS) to improve the ability of the shipborne receiver to obtain PNT data. The dual-system platform adopts single-frequency global positioning system (GPS) and single-frequency Beidou navigation satellite system (BDS) with the method of dual-system PNT data fusion. At the same time, the information of the PNT from the INS can improve the availability, accuracy, reliability, continuity and robustness of the shipborne receiver to obtain PNT data.

There are many studies on GNSS in the world. Ocean transportation uses GPS/GLONASS systems that meet the performance standards of IMO receivers, but lacking the fusion of BDS. PNT research includes GNSS data fusion method for multi-satellite navigation system, GPS and INS fusion method, BDS and GPS fusion method, and the application of source PNT data in ship navigation. Based on the long-term maritime research, the authors found that multi-system and multi-source data fusion of PNT data has greater availability, accuracy, reliability, continuity, stability and robustness.

In this paper, multi-system and multi-source PNT data is used for data fusion. The median filtering method and Kalman filter combination algorithm is used to improve the system's ability of obtaining PNT data and the accuracy of system positioning, thus errors can be reduced.

The structure of this paper is as follows. In Section 2, we introduced single-frequency GNSS and INS data fusion methods to obtain PNT data as well as dynamic models and system state models. In Section 3, data fusion algorithm, including median filtering method and Kalman filtering method is introduced. In Section 4, experimental design is explained in detail. In Section 5, the experimental results show that, on the one hand, single-frequency BDS+GPS can improve the receiver's ability to obtain PNT data. On the other hand, obtaining PNT data by single-frequency GNSS and INS can significantly improve the availability accuracy, reliability, continuity and robustness of the system. Finally, it is the conclusion and the future research that will be carried out. Finally, a conclusion is drawn and the future research direction is summarized.

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Method

Overview

In this paper, the single-frequency observables of GPS and BDS were used as the PNT data source for single-frequency GNSS experiments.

The Inertial Navigation System (INS) is an autonomous navigation system that does not rely on external information and does not radiate energy to the outside. It can work continuously in the air, on the ground and under water. The working principle of INS is based on Newton's laws of mechanics. The time is integrated by measuring the acceleration of the vehicle in the inertial reference frame. At the same time, it is transformed into the navigation coordinate system, thereby effective speed, yaw angle and position information are obtained in the navigation coordinate system.

The PNT data of the single-frequency GNSS and the INS was data fused. The working flow chart is shown in Figure 2.

Figure 2.

Single-frequency GNSS and INS data fusion

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