Research On Key Technologies For Strapdown Ground Vehicle Gravimetry

Accurate determination of the earth gravity field has a very important significance for studying the earth science,promoting the national economy and supporting the national defense construction.As an effective means to obtain high-precision gravity data,vehicle gravimetry has become a hotspot in recent years because of its slow speed and flexible maneuvering characteristics,but still faces many problems and challenges.It is important to study and break down the key technologies of the strapdown gravimetry based on ground vehicle,which will play an important role in the construction of gravity grading and refining the gravitational field in China.Based on the SGA-WZ02 gravimetry system developed by National University of Defense Technology,this paper studies the key technical methods of strapdown ground vehicle gravimetry.In order to improve the accuracy of vehicle gravimetry,the gravity measurement error model was derived.The thesis carried out in-depth study in ground vehicle gravimetry with different practical test environments such as using GNSS conditions,no-GNSS conditions and multi-source data fusion conditions.The main results are summarized as follows:First,the basic principle of vehicle gravimetry was studied.The position updating method was used to process the vehicle gravimetry data.The mathematical model of vehicle gravimetry was deduced and analysis of the error model was carried out.In order to evaluate the vehicle gravimetry results,the commonly used gravity accuracy assessment method was presented.Second,aiming at implementing vehicle gravimetry under the conditions of having GNSS observations,an improved SINS/GNSS vehicle gravimetric data processing method was proposed.Based on the comparison and quantitative analysis of GNSS under different conditions,the GNSS data anomaly detection and repair method in vehicle environment is proposed.Experimental results showed that the improved SINS/GNSS vehicle gravimetric method can obtain high precision and high resolution gravity results,which showed that this method was effective for vehicle gravimetry.Third,the feasibility of PPP technology for ground vehicle gravimetry was explored.Taking advantage of the positioning results obtained by PPP technology,vehicle gravimetry data was processed to evaluate the accuracy.The results showed that under the ideal condition of GNSS observation environment,the accuracy of gravity results obtained by the PPP method is comparable to what obtained by the differential GNSS method.Four,under the condition that no GNSS was available,the SINS/VEL vehicle gravimetric method aiding by velometer was proposed for gravitational data processing to complete the vehicle gravimetry task.The experimental results showed that the SINS/VEL vehicle gravimetric method was able to obtain the comparable gravity results with SINS/GNSS vehicle gravimetris method under the condition that the measurement environment was ideal and the test was carried out smoothly.In some gravitational measurements with poor GNSS observations,the SINS/VEL vehicle gravimetric method was found to be slightly better than the SINS/GNSS method,which showed a unique advantage in some special conditions.The SINS/VEL vehicle gravimetric method was able to be used to get rid of the heavy dependence of vehicle gravimetry on GNSS and widely broaden the range of vehicle gravimetry applications.Five,a multi-source data fusion method for vehicle gravity data processing was proposed.The results separately obtained by SINS/GNSS and SINS/VEL gravimetric method are combined to calculated a better result for vehicle gravimetry using position-correction and cross comparision method.The SINS/GNSS/VEL vehicle gravimetric centralized filtering and federated filtering methods were both proposed to deal with multi-source data fusion,which improved the accuracy and reliability of the vehicle gravimetry.