On GNSS/SINS Integrated Navigation Algorithm Based On UKF

Global Navigation Satellite System(GNSS)and Strapdown Inertial Navigation System(SINS)are studied in this thesis,and both kinds of navigation systems have their own defects in navigation.However,if the two are combined and navigated together,they can complement each other and get a better positioning result.For the GNSS/SINS integrated navigation system,different filtering algorithms have a great influence on the positioning accuracy.In this thesis,Unscented Kalman Filter(UKF)algorithm is adopted,and nonlinear systems can be better handled by this filtering method.The main contents of this thesis are as follows:Firstly,the navigation equations and solving algorithms for the attitude,velocity and position of SINS are derived,and a set of SINS measured navigation data is solved.The result shows that the SINS has higher positioning accuracy in a short time,but its navigation error will accumulate seriously over time,eventually leading to the divergence of positioning errors.Secondly,the principle of GNSS/SINS integrated navigation based on the difference between the position and velocity of SINS and GNSS as the input of Kalman filter is analyzed,and the state equation and the measurement equation based on the error correction of the arm value of the integrated navigation system are deduced.Finally,NovAtel's SPAN-LCI tactical-level Inertial Measurement Unit(IMU)navigation system and GNSS receiver are used to collect navigation data near the school,and the GNSS/SINS integrated navigation solution based on the Extended Kalman Filter(EKF)algorithm and the UKF algorithm is separately performed on the measured data.According to the result of Rauch-Tung-Striebel(RTS)smoothing,the positioning error of the GNSS/SINS integrated navigation system can be quickly converge,and the positional accuracy is kept at the centimeter level.The UKF algorithm has less fluctuation and higher precision than the positioning error obtained by using the EKF algorithm.The GNSS/SINS integrated navigation system based on UKF algorithm can not only compensate for the error accumulation of SINS when it navigates alone,but also avoid the problem of positioning interruption caused by short-term loss of signal in tunnels,high-rise buildings,woods and seas during GNSS single navigation.The experimental result shows that the UKF algorithm has higher positioning accuracy and better stability and reliability than the EKF algorithm.