Application of ARM Microcontroller in Ultrasonic Measurements for Suspended Sediment Concentrations

• Main Authors: Hui-Chia Yen, 嚴蕙嘉
• Other Authors: Kung-Yen Lee
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/02814648943705082635

碩士 === 國立臺灣大學 === 工程科學及海洋工程學研究所 === 102 === 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.