ARM微處理器在超音波泥砂濃度偵測系統之應用

Application of ARM Microcontroller in Ultrasonic Measurements for Suspended Sediment Concentrations

嚴蕙嘉(Hui-Chia Yen)

指導教授 ： 李坤彥

國立臺灣大學/工學院/工程科學及海洋工程學研究所/碩士(2014年)

https://doi.org/10.6342/NTU.2014.02008

摘要

由於台灣河川湍急而陡峭，每當颱風季節，豪雨造成大量之泥砂沖刷而下，產生許多環境災害，若能即時監測水流中泥砂濃度分布狀態，將有助於進行相關措施之規劃，因此懸浮泥砂濃度資訊為瞭解水文環境特性之重要指標，而目前針對泥砂濃度量測方法之研究已有相當成果，惟各種方法仍有其水域或濃度範圍之限制，如傳統之取樣量測法具有較高之準確性，但卻耗費時間與人力，且無法長期監測，故本研究目的即利用超音波衰減法量測懸浮泥砂濃度，並以ARM 微控制器操控整體系統運作，發展一套即時監控之懸浮泥砂量測系統，並改善過去量測的缺點，提升對於水中泥砂分布監測與泥砂濃度推估之效能。
本論文藉由建立模擬現場之量測裝置，量測泥砂濃度與訊號衰減量之特性關係，實驗選用之懸浮泥砂種類分別為高嶺土及曾文水庫底泥，其架構採用一對超音波探頭搭配各自獨立之收發電路，探頭表面距離為20 cm，發射訊號頻率為1 MHz，而系統之主要控制核心為微控制器與人機介面，ARM 微控制器之功能為傳送控制發射端之訊號及資料傳輸，人機介面則為下達開始量測命令與即時顯示量測讀值並儲存等功能。
研究首先透過清水量測進行校正，並收集校正資訊做為轉換濃度之依據，實際量測待發射訊號穿透待測液後，訊號與懸浮粒子相互碰撞產生能量衰減，而懸浮粒子含量與接收訊號之衰減量成正向關係，藉此推估真實泥砂濃度。經由實驗與傳統烘乾法結果相互驗證，可具體顯示出不同懸浮材料及濃度與衰減量變化間相對應之趨勢關係，而本論文所設計之量測系統最大可量測濃度範圍為0 ~ 450,000 mg/L，遠高於過去研究之量測濃度限制，其濃度量測誤差量亦控制在6%內，在不同溫度下量測數值無顯著影響，此結果將有助於懸浮泥砂濃度量測系統之應用與發展。

關鍵字

泥砂濃度 ； 超音波 ； 超音波衰減法 ； ARM 微控制器 ； 人機介面

並列摘要

Because the rivers in Taiwan are short and steep, the great amount of sediment which scours through the rivers cause environmental disasters during the torrential rain season. Therefore, the suspended sediment concentration is the most important information for hydrological characteristics. Among of many methods used to measure suspended sediment concentrations, the bottle sampling is the most accurate method. However, time-consuming, working space limitation and non-continuous recording are disadvantages of the bottle sampling method. As the result, the development of the suspended sediment concentration measurement is the purpose of this study. ARM microcontroller is used to control the operation of the system to improve the performance of the sediment distribution monitoring and estimation of sediment concentration. Experiments were carried out by using two transducers with the operation frequency of 1 MHz. The distance between two transducers was set at 20 cm. A microcontroller was used to synchronize the transmitter and receiver, and the user interface was also developed to start the system, display and store the measured data. The relationship of the signal attenuation in dB scale and
concentration was established. Therefore, the concentrations could be determined by the measured signal attenuation. Experimental results show the concentration range from 0 mg/L to 450,000 mg/L can be determined and the measurement error can also be reduced to less than 6%. In addition, there is no significant impact on the measured data at different temperatures. Therefore, the proposed technique successfully detects suspended sediment concentration.

並列關鍵字

Suspended sediment concentration ； Ultrasound ； Ultrasound attenuation ； ARM microcontroller ； User interface

參考文獻

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