Improving Position Accuracy by Applying Particle Filter in Time-difference GPS Carrier Phase/IMU Tightly-coupled Navigation Systems
Yingwei Zhao, Hao Xiong, Xingshu Wang, Jiaxing Zheng, Dongkai Dai, National University of Defense Technology, China
In order to improve the position accuracy of the Kalman filter (KF) based pseudorange (PR) + time-differenced carrier phase (TDCP) GPS/IMU tightly-coupled navigation system, a novel navigation strategy based on the particle filter (PF) is proposed. The integration strategy includes two parts. The first part is a conventional PR+Doppler GPS/IMU tightly-coupled navigation system using the KF. The second part is a particle filter using modified TDCP as measurements. The modified TDCP measurement is defined as the carrier phase difference between the current and the reference GPS time epochs. It can help bound the position drift caused by the conventional TDCP, which is defined as the carrier phase difference between two successive GPS epochs. The modified TDCP measurement is then utilized to weight the particles generated from the a posteriori estimation of the PR+Doppler GPS/IMU tightly-coupled navigation Kalman filter. The position accuracy can be improved to the sub-meter level as shown in both static and kinematic experiments, if initialized with an accurate reference position.
Key words Particle filter. Time differenced carrier phase. IMU. Tightly-coupled. Position accuracy. Modified TDCP