全球定位系統輔助之慣性導航系統數位化多重取樣週期之研究

本文是探討目前最新的導航系統，即全球定位系統(GPS)輔助之慣性導航系統(INS)數位化多重取樣時間之研究，以取兩者之長，而避其短，使其成爲精確、可靠、又便宜的導航系統。文中首先分析開迴路及閉迴路複合架構之特性及優缺點，並討論GPS脫鎖時，對整合系統之影響。由於閉迴路架構中，INS的誤差已隨時被校準及修正，所以導航效果亦較佳。而論文進一步的重點在探討以GPS輔助INS，在多重取樣週期的情況下，分散式開迴路及閉迴路架構之性能分析。研究方法是先以MATLAB程式進行各種狀況下的數位模擬，再轉成C語言之程式進行即時模擬比對。其中數位化的關鍵技術是將狀態轉移矩陣之解，以泰勒級數展開，依取樣週期之長短，取有限項以縮短計算時間，而後以C語言程式進行即時模擬比對。此外，在將連續系統方程式轉換成數位系統方程式時，本文有考慮系統及量測雜訊共變異矩陣。分別乘以及除以其取樣週期的修正法，以忠實反應數位化系統情況下，系統及量測雜訊共變異矩陣（均方根值）之大小。由數位即時模擬結果可知，GPS和INS取樣週期之比值不可太大，否則開迴路架構的導航整合效果會不好，而閉迴路架構則可容忍較大的比值，這是以往文獻中沒有提出並討論過的問題。

關鍵字

慣性參考系統；全球定位系統；取樣週期；卡門濾波器

並列摘要

This research is to study both the open-loop and closed-loop integrating structures of INS aided by GPS with multi-sampling periods. The integrating results are accomplished by MATLAB simulation first for reference, then the MATLAB programs are transformed into C-language for real time simulation. In order to reduce the computation time, the state transition matrix is approximated by deleting the high-order terms of its Taylor's series, the trade-off terms are depended on the magnitude of the sampling periods, In addition, the covariance matrices of both system and measurement noises are also modified for the digital and real time implementation to preserve the continuous root-mean-square values of the noises. By the results of digital and real time simulations, one can see that the ratio of sampling periods for the open-loop integration of GPS and INS should be less than 10, otherwise, the integrating results would be worse. However, the ratio of sampling periods is more robust for the closed-loop structure, This effect is not studied in the current literature. On the other hand, even if GPS loses track, since the INS errors is updated and calibrated in the closed-loop structure thus the navigation accuracy can be retained.

並列關鍵字

Inertial Navigation Systems INS ； Global Positioning System GPS ； Sampling Period ； Kalman Filter

國際替代計量

全球定位系統輔助之慣性導航系統數位化多重取樣週期之研究

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