A METHOD TO PRE-PROCESS MEASUREMENTS FROM SHIPBORNE GRAVIMETRY USING IMU/GPS A CASE STUDY ALONG WESTERN COASTAL TAIWAN

發展預處理船載IMU/GPS重力值觀測量之方法－以台灣西部海岸為例

蕭宇伸(Yu-Shen Hsiao) ； 曾子榜(Tzu-Pang Tseng)

《中國土木水利工程學刊》 31卷4期 (2019/06) Pp. 361-368

https://doi.org/10.6652/JoCICHE.201906_31(4).0007

摘要

We develop an approach to pre-process measurements from shipborne gravimetry using both inertial measurement unit (IMU) and global positioning system (GPS), and explore the feasibility of applying tactical IMU to relevant geoscience applications. The shipborne data used in this paper were collected in the offshore area of western Taiwan on 19th May, 2012. The IMU directly measures the sum of the gravity, ship accelerations in vertical and Eötvös effect. In comparison, the GPS provides the ranging measurements as a function of the ship coordinates. Both the GPS-derived acceleration in vertical (gravity) and the direct gravity measurement from the IMU are pre-processed using the Gaussian filter. Different combinations of filter window widths are tested for a correlation analysis of both IMU-measured and GPS-derived accelerations. The correlation is up to 88.5% when the window width is set to 4.8 s for IMU data and 1 s for GPS data. The amplitudes of the IMU/GPS-derived gravity anomalies are approximately 40 ~ 50 and 20 ~ 30 mgal using the filter window widths of 200 ~ 500 s and 1000 ~ 1500 s, respectively. Overall, this study serves as an important reference for pre-processing the data from shipborne gravimetry using the IMU/GPS.

關鍵字

IMU ； GPS ； Gaussian filter ； shipborne gravimetry

並列摘要

本研究發展一方法來預處理利用慣性測量元件（IMU）與全球定位系統（GPS）所獲得之船載重力值。本文亦研究戰術型IMU於地球科學相關應用之可行性。研究中使用的船載資料於2012年5月19日在台灣西部海域所收集。觀測時，IMU提供重力、船體加速度與科氏力效應之和，而GPS則提供距離測量值以計算船體之坐標。研究中無論從IMU或GPS計算得到的觀測值均使用高斯濾波進行資料預處理，並針對濾波不同罩窗寬度組合計算以分析IMU與GPS加速度之相關性。研究顯示，當IMU與GPS分別使用罩窗寬度4.8秒和1秒處理資料，兩者相關性高達88.5%。在重力值濾波方面，當使用200～500秒和1000～1500秒的罩窗寬度時，IMU/GPS計算的重力異常值幅度分別約為40～50 mgal和20～30 mgal。整體而言，本研究提供IMU/GPS預處理船載重力測量資料之重要參考。

並列關鍵字

慣性測量元件 ； 全球定位系統 ； 高斯濾波 ； 船載重力測量

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