封包中間值比率對誤差值的影響

我們發現接收端收到的所有 Beacon 封包中，越鄰近封包中間值所收 到的 Beacon 封包數值會越正確，所以我們提出使用全部 Beacon 封包中

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間 33%、66%、100%的封包進行 AVG、MED、RSSI 三種演算法的分析，

圖 4-11 為我們的分析附錄 B 中取總 Beacon 封包中間 33%、66%、100%

的封包數得到的結果。

圖4-11 總Beacon封包的中間33、66、100（percent）

圖 4-11 的數據結果顯示出，當我們使用越接近中間值的封包來進行 誤差值的運算時，三種估測方式的誤差值都會相對的降低，而 AVG 方法 是三種演算法中誤差值最低的，其平均誤差值達到 1.95 m。

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五、結論與未來展望

本論文提出在無線感測網路中 Range-free 的移動錨節點定位系統，

我們使用移動錨節點裝置指向性天線，針對指向性天線傳輸範圍具有方 向性的特性，移動錨節點沿著二維座標中的 X 軸發送 X 軸的座標封包與 沿著 Y 軸移動發送 Y 軸的座標封包，當感測器節點透過得到移動錨節點 的 X 軸與 Y 軸的座標進行簡單的數學運算後，感測器節點則可得到自己 的估測座標。我們由實際環境中評估我們所提出的定位系統之定位精確 度，實測的結果顯示我們的定位系統可以由指向性天線傳輸的角度越小 與封包傳輸的頻率越高來提升定位精確度，而我們使用 AVG、MED、RSSI 這三種演算法來計算感測器的座標，從數據顯示的結果看出 AVG 方法可 以提供較佳的精確度，其定位精確度達到平均誤差值 1.95 m。

在未來發展中，由於我們提出的定位方式使用移動錨節點沿著座標軸 進行直線的移動，之後我們將進行當移動錨節點不規則移動時指向性天 線指向固定方向的定位量測，最後我們將對本論文所提出的定位系統中 的移動錨節點進行路徑規劃。

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http://www.smartant.com/smartdesk/upload/datasheet/SAA04-053660.pd f

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附錄 A

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附錄 B

Median of beacon 33%

Median of beacon 66%

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Median of beacon 100%