Under the condition of small misalignment, including small tilt misalignment and small heading misalignment, the ZUPT based fine alignment can be applied to improve the alignment accuracy.
After the forward fine alignment process has been completed, the RTS smoother will be implemented with the knowledge of state estimates, state covariance, and state transition matrix derived from the forward ZUPT based Kalman filter.
Keith Vickery, Zupt
president comments: "Inertial metrology is a mature product and has been used for over eight years worldwide with great success.
Several researchers worked on various methods for detecting the ZUPT or the stationary state.
The rest of the paper is organized as follows: the Sensor Model and AHRS section introduces the sensor models and the fusion of IMU sensors for AHRS; MM for Detecting Intersections section describes the technique of detecting traffic signal from digital map and GPS/INS; ZUPT Theory and Detection of Stationary State section describes the proposed algorithm of stationary detection from AHRS and MM information; Experimental Results section presents the hardware setup and the result of the test for stationary detection followed by the performance analysis where the navigational performance with stationary update is presented and compared.
Yi, "Bridging GPS gaps in urban canyons: can ZUPT really help?" in Proceedings of the 58th Annual Meeting of the Institute of Navigation and CIGTF 21st Guidance Test Symposium, Albuquerque, NM, USA, 2002.
Caption: Figure 3: Trajectory measured by INS + ZUPT + KF for the first group of possible parameters (Group 1).
Caption: Figure 4: Trajectory measured by INS + ZUPT + UFIR for the first group of possible parameters (Group 1).