A GNSS/SINS Shipborne Integrated Navigation System Based On Vector Tracking

Intelligent and unmanned ships require shipboard navigation systems with higher stability,accuracy and anti-interference.The Global Navigation Satellite System(GNSS)is a traditional shipborne navigation system.However,satellite signals are easily affected by the environment,and the positioning drift of Scalar Tracking(ST)receivers is severe.The integrated navigation system composed of GNSS and strapdown inertial navigation system(SINS)can integrate each subsystem closely and complement each other’s advantages.The GNSS/SINS integrated navigation system has the all-weather and omni-directional characteristics of GNSS,and the autonomy and concealment of SINS.It can navigate in various environments.The traditional combination method is loose combination.GNSS assists SINS to correct errors,but GNSS is easily affected by the environment which causes the combined system fail to navigate.In ultra-tight coupled GNSS/SINS integrated navigation system,GNSS can correct SINS errors,and SINS can assist GNSS to complete loop tracking.In order to promote the development of shipborne navigation system,the research of GNSS/SINS shipborne integrated navigation system based on vector tracking(VT)is carried out in this paper.The main research results are as follows:Firstly,in order to improve the loop stability of the traditional GNSS receiver,the code loop based on the pseudo-range assistance and the carrier loop based on Unscented Kalman Filter(UKF)have been studied.They effectively improve the stability of the tracking loop.The proposed code loop can use the new pseudo-range to estimate the code frequency.The proposed carrier loop can optimize the configuration of loop parameters according to the dynamic stress intensity of the receiver and the signal-to-noise ratio.The tracking loop model of the GNSS receiver is established and the data is collected through GNSS intermediate frequency(IF)signal collector.Satellite data is used to verify the tracking performance of the loop filter.The results show that the proposed loop scheme improves the loop stability of the GNSS receiver.Secondly,in order to solve the problem that the loop of the VT receiver is easy to lose and has nothing to do with the user’s dynamics,a distributed integrated navigation filter is studied.The accuracy of the navigation system is improved.The distributed integrated navigation filtering algorithm can obtain effective phase difference and frequency difference according to the carrier-to-noise ratio.The corresponding pseudo-range difference and pseudo-range rate difference are calculated.The navigation results are continuously updated by the VT algorithm.A distributed navigation algorithm is improved and the data is collected through the GNSS IF signal collector.The data is used to verify the performance of the navigation system.Experiments verify that the proposed navigation system has higher accuracy in the weak signal environment.Thirdly,in order to solve the problem that GNSS signals are susceptible to the environment,a GNSS/SINS shipborne integrated navigation system is studied.This effectively improves the anti-interference of the shipborne integrated navigation system.When the GNSS is valid,the integrated navigation filter outputs the navigation results to correct the SINS error and assist the GNSS loop tracking.When GNSS is invalid,SINS can operate independently.A GNSS/SINS shipboard integrated navigation system model is proposed.The navigation system was verified in weak signal environment and shipboard navigation application respectively.