Research On Calibration Of LDV/INS Integrated Navigation Systems By Time-differenced Carrier Phase Observation

As a high-precision velocity sensor,the laser Doppler velocimeter has the advantages of rapid response and non-contact measurement.Integrated with the inertial navigation system,it can form an autonomous navigation system and suppress the error divergence effectively,but accurate positioning requires accurate calibration of the system.Due to the high cost and the limitation of road segment choose in the commonly used differential GPS and landmark-assisted calibration methods,this paper focus on using time-differenced carrier phase observations for the calibration of LDV/INS integrated navigation system.The main part of this paper includes the following aspects:Firstly,the paper establishes a laser Doppler ve locimeter measurement error model.The principle of laser Doppler velocimeter measurement is deduced,which determines the installation angle and scale factor error need to be calibrated.The layout scheme of the integrated navigation system is also introduced.Then the paper introduces method for GPS time-differenced carrier phase observations to deliver velocity and position.After error compensation,the carrier phase observation is able to eliminate the ambiguity by difference,thus deliver velocity and position.Corrected PDOP value is utilized as the evaluation observation condit ion.Finally,static and dynamic experiments are carried out to verification the accuracy of this method.Thirdly,a GPS time-differenced carrier phase observations aided calibration model is established.The model applies GPS time-differenced carrier phase observations to estimate the velocity or the position as an external observation to calibrate the integrated navigation system,and proposes an iterative method to achieve fast and accurate convergence within short distance calibration period.The paper also analyzes the impact of external observations on calibration results theoretically.Finally,Simulation experiments and vehicle experiments are carried out for the calibration model.The experimental results show that the model can effectively calibrate the items by single receiver and the autonomous navigation radial positioning error after calibration is less than 0.1% of the whole process.The experimental results of the observation measurement error indicate that the horizontal reference information error affects the radial positioning accuracy by affecting the heading installation angle and the scale factor,and the balance reference information error affects the sky-direction positioning accuracy by affecting the pitch installation angle.