sitan 中文意思是什麼

In this paper, the main research works are as follows : 1 ) survey and analysis previous work in auv navigation and summarize : as the cumulate error, the dead - reckoning and inertial navigation systems ca n ' t be used without other modified system ; the acoustic navigation system is used only in small range, and is very expensive. 2 ) two important approaches in geophysical navigation techniques are summarized, one is terrain contour based navigation, this approach is investigated keystone today ; the other is image based navigation, due to no perfect image sensors and image seabed map, this approach has seldom been practised. 3 ) two important terrain contour based navigation algorithms has been applied to auv, one is match algorithm - based terrain contour match ( tercom ) ; the other is kalman filter - based sandia inertia terrain - aided navigation ( sitan )

主要研究內容包括：一、總結分析了當前水下導航的常用方法和不足之處，指出基於航位推算的導航方法，存在著最大的問題就是導航誤差的積累問題，如果沒有修正系統，這種方法很難滿足使用要求；其次指出基於聲學的導航方法，造價昂貴，導航范圍有限，難以滿足自主水下航行器大范圍導航的需求；二、總結了當前水下地形輔助導航的主要技術路線，一是基於地形高程的匹配方法，這是當前研究的重點；二是基於地形圖像的匹配方法，由於缺乏良好的圖像傳感器，和可用的海底圖像地圖，目前這種方法還有待研究發展；三、將兩種地形高程匹配的常用方法應用到自主水下航行器上：以相關演算法為前提的地形輪廓匹配（ tercom ）方法和以卡爾曼濾波為基礎的桑迪亞慣性地形輔助導航（ sitan ）方法，前者演算法簡單可靠，但是導航精度不高，後者雖然精度比較高，但存在著演算法較為復雜、有可能發散和出現奇異值等問題。

The first algorithm is low precise but simple and credible, the second is high precise but complex and incredible. 4 ) developed four kinds of methods aimed to improve precision and credibility of navigation system. the first is parallel sandia inertia terrain - aided navigation ( psitan ) ; the second is tercom + sitan, it can restrain two important disadvantages of sitan ; the third is particle filter - based terrain - aided navigation ( pftan ), the particle filter can reduce the error of navigation ; the last is tercom + pftan, where tercom is looked as monitor to ensure the credibility of navigation system

採用并行sitan方法來提高導航精度，並克服奇異值問題；提出了tercom + sitan方法，綜合利用兩者的優點，在保持sitan導航精度的前提下，有效地克服了sitan的兩個缺點；提出了一種基於連續蒙特卡洛濾波（常被稱為particlefilter ）的地形匹配演算法（ pftan ） ，有效地克服了利用sitan時由於地形隨機線性化帶來的誤差，使導航精度有較大的提高；提出了tercom作為監視器的地形輔助導航思想，並將其應用到連續蒙特卡洛方法上，較大地增加了系統的可靠性和精度。

6. it is proved that different selection of measurements in kalman filter has no effects on consequences in sitan terrain auxiliary navigation

指出並證明了在sitan系統中，卡爾曼濾波器觀測量的不同選取對濾波結果沒有影響。