Research On Dynamic Vector Gravimetry Based On Deflection Of Vertical Measurement

Traditional method of vector gravity measurement, has higher requirements for hardware equipment. Vector gravity measurement accuracy is difficult to improve limited to accuracy of horizontal attitude. This dissertation starts with estimates from the Deflection of the Vertical, observes the Deflection of the Vertical(DOV) by means of establishing relational model of the gravity measurement system carrier attitude error and the deflection of the vertical, and observes horizontal component of vector gravity by means of establishing relational model of the deflection of the vertical,scalar gravity real time measurement and vector gravity horizontal component.The main research works of the dissertation are as follows:(1)In order to prevent the attitude error in Strapdown Inertial Navigation System/ Global Positioning System(SINS/GPS) caused by the Deflection of the Vertical(DOV), the system error caused by the gravity disturbance vector is analyzed firstly, an error equation considering the gravity disturbance vector is established, The influence of the gravity disturbance vector on the position and the attitude error is studied by simulation; Secondly, theoretical analysis the influence of the deflection of the vertical on the SINS/GPS integrated navigation system Based on the error model of the inertial navigation system. The correctness of theoretical analysis is verified by simulation which indicates that east attitude error is determined by north DOV and north attitude error is determined by east DOV.(2)Attitude reference of vector gravity measurement system is researches. Firstly, the attitude error is used as the state vector, equation of state equation is established according to the velocity error equation, the attitude error equation, the position error equation and Gyro bias equation, Then position and velocity information are obtained by GPS as observations. The attitude error of inertial measurement unit(IMU) is estimated by Kalman filter and finally combined with the attitude of IMU, which is As a reference attitude angle.(3)Method on DOV estimation through observing carrier attitude error of gravity measuring system is researched based on relational model of the gravity measurement system carrier attitude error and the deflection of the vertical. Observation equation is established by relational model of gravity measurement system carrier attitude error and the DOV, and state equation is established by SINS attitude error equation. High frequency component of DOV is finally computed through kalman filtering. The low frequency component is compensated by EGM2008 model. The simulation results show that the method has high repeatability accuracy, and can effectively measure the deflection of the vertical.(4)Method of estimating horizontal component of vector gravity based on real time measurement of scalar gravity is researched. The measurement system of vector gravity based on scalar gravity meter is designed, including SINS/GPS integrated navigation system, IMU measurement unit and scalar gravity meter. The relational model of vector gravity horizontal component, real-time measurement of scalar gravity and DOV is established, which is used as the observation equation to estimate the horizontal gravity component. And the second order Gauss-Markov model is introduced into the state equation. Simulation results show that compared to horizontal component of vector gravity estimated based on standard gravity value obtained by EGM2008 model, both east and north components of vector gravity which is based on the real-time measurement of scalar gravity are decreased, and the wave range of the waveform is smaller.