Analysis On Velocity Error Of INS-aided GNSS Receiver In High Dynamic Environment

Speed is the basic output information of navigation system. The method of using GNSS receiver to obtain vehicle’s speed is widely used with the advantages of all-weather and speed error does not accumulate, etc. But in high dynamic environment, receiver’s loop may lose lock easily. In order to improve the receiver’s adaptability in high dynamic environment, INS information is often used to aid receiver’s carrier loop. This thesis studies on the receiver’s Doppler error source and INS aiding methods in the high dynamic background. These works are researched:1. Based on characteristics of the difference between third-order carrier loop control rate and IF sampling rate in the software receiver’s implementation, a two-rate discrete model of carrier loop is established. Simulation results show that the model’s tracking error reaches 12.3585° in the constant 10g/s jerk dynamic and the Doppler error caused by the model’s dual-rate reaches 0.485m/s while in the dynamic of constant 100 g acceleration.2. Usually the rate of INS aiding information is 100 Hz. Based on the receiver’s dual-rate discrete model, a three-rate discrete model using velocity aiding method is established. Simulation results show loop’s performance is not improved. Further using acceleration aiding method, the simulations results show the aided loop’s tracking error becomes 0°in the constant 10g/s jerk dynamic and the oscillation amplitude of Doppler error is reduced, which proves the loop’s performance is improved obviously.3. Studying the velocity and acceleration aiding methods, the difference between these two methods is the error of aiding information to carrier loop is different. In the constant 10g/s jerk or 100 g acceleration dynamic, the aiding information accuracy of acceleration aiding method is higher than that of velocity aiding method, which proves acceleration aiding method is better.4. Considering the INS devices of different level of accuracy, the Doppler error and tracking error of velocity and acceleration methods are simulated, which provides basis for the selection of INS devices.