Velocity Estimation Based On GNSS Carrier-phase And Doppler Observations

Velocity has important applications in vehicle navigation and positioning,unmanned aerial vehicle(UAV)automatic piloting,inertial navigation system(INS)calibration,precision-agriculture sowing and fertilization and airborne gravimetry.GNSS have rapidly developed in recent years,providing global,all-weather,highprecision,fast-response position,velocity and time(PVT)service.At present,GPS research generally focus on positioning and timing rather than velocity estimation.Based on these,we study the velocity estimation models based on GNSS Carrier-phase and Doppler observations.In view of the shortcomings of the existing GNSS velocity estimation methods,new improved methods are proposed,which provide a new idea for the GNSS velocity estimation algorithm.At the same time,the high-precision GNSS velocity estimation under complex dynamic conditions is realized,which significantly improves the velocity estimation accuracy under dynamic conditions such as turning,and has important practical value.The research content mainly includes two parts: one is the research and analysis of the existing GNSS velocity estimation methods,which are TDCPVE,DVE and PPPVE.The second is the improved GNSS velocity estimation algorithm and model research,which are TD-DVE and PPP-DVE.First,the corresponding function model and random model are established,then the corresponding test is carried out and the performance of the new methods are analyzed.The main contributions of this paper are as follows:(1)Analyzing the error sources and corresponding correction measures of three existing GNSS velocity estimation methods,static and dynamic data are used to test the three methods,and the advantages and applicability of different methods are analyzed and compared.(2)An improved method,TD-DVE,is proposed and studied.By combining different observations,the method increases redundant observations,improves the robustness of the single method,and makes up for the deficiency of the TDCPVE under the dynamic condition.(3)An improved method,PPP-DVE,is proposed and studied.This method adds Doppler velocity constraint in PPPVE model.Compared with the PPPVE,the new method effectively improves the velocity estimation accuracy under dynamic conditions such as turning.