使用後處理-VRS定位技術提高緊耦合INS/GNSS整合演算法之精度分析

Abstract

Recently the useage of mobile mapping platform have been raised gradually in Taiwan. Currently mobile mapping technologies always apply INS/GNSS integrated system to get exterior orientation of image by Direct Georeferencing (DG). But the accuracy of DG is affected significantly by the accuracy of INS/GNSS integrated system because the error propagation from INS/GNSS integrated system to DG is linear. So the primary objective to increase the accuracy of mobile mapping system is to enhance the accuracy of INS/GNSS integrated system. This research investigates the impact different kinematic satellite positioning method on the positioning and orientation accuracy of an INS/GNSS integrated system. It uses raw measurements of INS/GNSS integrated system to perform three satellite positioning processes, including Differential GNSS (DGNSS), Precise Point Positioning (PPP) and post-processed Virtual Reference Station (VRS). The result shows the accuracy of using VRS in INS/GNSS integrated system satellite positioning is superior compared to other methods. Now the development of Network RTK (Network Real Time Kinematic, NRTK) in Taiwan is gradually becomimg mature. National Land Surveying and Mapping Center established e-GPS based on VRS and the provate company also set up a similar system known as Civil NET. Using post-processed VRS to do satellite positioning can save the cost of manpower which is needed in traditional DGNSS and still remain the accuracy which is needed in mobile mapping system.