Research On Optimization Method Of UAV POS Data

There is always a spatial distance between the phase center of the GPS antenna and the projection center of the aerial camera in the POS system,and there is always an angle deviation between the coordinate system of the inertial measurement device(IMU)and the aerial camera.In order to obtain the coordinates of the projection center of the aerial projector and the attitude angle of the aerial image from the three-dimensional coordinates of the center of the GPS antenna in the POS data and the attitude parameters of the IMU,the aerial triangulation of the survey area is carried out by the beam leveling method.Based on the systematic analysis of the research of POS data optimization method at home and abroad,this paper takes the survey area of Xihe county as an example for study:(1)the geometric spatial relationship between the three of the projection center is established from the GPS antenna phase center,IMU attitude angle and aerial camera,so are the equations of the coordinate system of the POS system,the IMU attitude angle and the image coordinates.By these observation equations,Non-photogrammetric observations of the joint adjustment of the mathematical model,according to the least squares principle,can be obtained by POS data adjustment value.(2)For this joint adjustment,we use the unit weight method and the empirical weighting method and the Helmert in the posterior variance component estimation to determine the observation value.Based on Visual Studio 10 integrated development environment and NET platform,a set of light beam area network joint adjustment system is compiled in C#language,and the experiment is carried out in the survey area.The influence law of different fixed weight method on the accuracy of empty three encryption results is analyzed.The experiment shows that the GPS antenna should be installed as close as possible to the astronomical projection center to reduce the positioning error.The three axes of the IMU gyro coordinate system should be consistent with the corresponding three axes of the camera-assisted coordinate system to ensure that the attitude angle is more accurate,so as to reduce the directional error;adjustment in the traditional fixed right of the unit rights and experience of the final decision on the final impact of the results is not very large,but the choice of experience compared to the use of units the number of iterations in the whole adjustment process is less.In the adjustment,the Helmut variance component is used to estimate the law,and the accuracy of the ground point is improved compared with that of the traditional method.The precision of the POS data obtained by the Helmert method is much higher than that obtained by the traditional method.In any case,the accuracy of the ground point is less than the plane accuracy.