Research On Two-antenna GPS/INS Integrated Navigation System

Integrated navigation technology can effectively improve the performance of navigation system. This paper focus on the theory analyzing, model building and simulation of two-antenna GPS/INS integrated system based on carrier phase.The azimuth is always a difficult problem in navigation, especially when the carrier is static or makes a linear motion. The azimuth can be determined by fixing two GPS in a certain distance along the longitudinal vector and making a carrier phase double difference between them. The attitude (2-dementions) integration of using two antennas signals and INS is proposed; the state equation and observation equation of two antennas signals with position, velocity INS is deduced. The result of simulation proves the solution above is feasible.The demand of precision such as airplane precision approach, spacecraft docking technique and strategic and tactical weapon precision guided is very high. The GPS carrier phase double difference measurements after eliminating most common errors are more accuracy and can achieve centimeter-level precision. The integration equations based on two antennas signals and double-differential carrier phase are deduced and the feasibility of the system also has been proved by the simulation.The resolution of integer ambiguity and correction of cycle slip are the two important factors for acquiring accurate result in the application of carrier phase. Based on current research, an algorithm of integer ambiguity determination and an algorithm of detection and correction of circle slip using supplementary data of INS is presented.The condition that system model and noise characteristic are uncertain may cause the divergence of Kalman filter. In view of the present research situation of AKF technique, an AKF algorithm for on-line estimation of the statistical feature of measurement noise, which has many advantages such as simple structure, real-time and practicable in engineering is adopted. The result shows that the algorithm is useful and adaptive with its high effectiveness and accuracy.