Research And Implementation Of Vessel Positioning Method Based On Two Shore Stations Of AIS

When vessels sail on the sea,they generally use the Global Navigation Satellite System(GNSS)to obtain the information of their own real-time position.However,GNSS depends on satellite positioning,and satellite signals are easily affected by buildings and environment(weather,cloud layer,electromagnetic interference,etc.),which have inherent fragility.Therefore,in the field of marine navigation,it is necessary to confirm an internationally recognized alternative system that can provide positioning when the GNSS system fails.In the e-navigation strategy research of International Maritime Organization(IMO),IMO lists AIS-R Mode as a terrestrial radio navigation system in the future..As the AIS system is a communication system,the distribution of the shore station is relatively sparse compared with the traditional positioning system(such as the Loran-C system).When the condition of signal coverage is good,which means that it can receive signals from three or more AIS shore stations,traditional ranging method can be used to realize positioning.However,when the condition of signal coverage is poor,that is,signals from only two AIS shore station can be received.Due to the problem of clock synchronization between AIS shore stations and the vessel,it is difficult to locate by using the traditional ranging or ranging difference method.This paper proposes a positioning algorithm based on two AIS shore stations,that is,an improved displacement vector positioning algorithm,which can solve the above problems well and effectively reduce positioning error of the vessel's in the condition of uniform linear motion and turning motion.This subject mainly realizes the verification and engineering establishment of the displacement vector positioning algorithm and the improved algorithm.Firstly,the theory of displacement vector positioning algorithm is introduced.And an improved displacement vector positioning algorithm is proposed in the condition of vessel's uniform linear motion and turning motion.Then the displacement vector positioning algorithm and the improved algorithm are simulated and verified under the platform of MATLAB,After that the engineering development of improved displacement vector positioning algorithm is realized under the platform of KEIL.Then the function of displaying interface of map is implemented under the platform of Qt.Finally,the software of map,platform of KEIL,platform of Qt and LPC2387 development board are equipped as the positioning platform to realize the display function of the positioning trajectory.Then Calculate and analyze the positioning accuracy.The research shows that the improved displacement vector positioning algorithm can realize positioning when the number of AIS shore stations is small.