在橋梁鋼索上廣泛設置系統監測去追蹤每一根鋼索的健康狀況，需要相當高的成本，因此為了能在橋樑上的鋼索大量布設感測器，本研究研發了基於低功耗嵌入式系統及高精度MEMS感測器的低成本鋼索監測裝置所構成之系統。此監測裝置基本架構包含了低功耗嵌入式系統、一顆高精度MEMS IMU、一顆高精度MEMS加速度計、一個24位元的MEMS ADC與LoRa無線傳輸模組。其運作模式為平時此系統會進入睡眠狀態，進行待命，當地震來時高精度IMU會喚醒系統進行量測，亦可利用敲擊方式喚醒。系統上的數位MEMS加速度計具有20Bit的解析度，可用來量測鋼索上的加速度，24位元的ADC配合電橋與應變計可用來量測鋼索的應變。本研究設計了一縮尺的實驗架構測試本系統的效能，實驗結果顯示本系統量測敲擊後鋼索的加速度，進行FFT分析後可轉換得到鋼索的力量，與實際的力量相比，本系統估測的誤差大約在5%以內，估測值與實際值具有良好的線性關係。黏貼在鋼索上的應變計所量測的應變值與鋼索力亦具良好的線性關係。在模擬鋼 索斷裂實驗，可以明顯看到，當構架上鋼索少了一根時，另一根鋼索 可以感受到明顯的變化，而在實際橋梁，如果遇到其中一根鋼索產生 預力損失時，其他鋼索力量也能明顯感受到變化。在鋼索自由振動實驗中，主要模擬加速度計感測器是否能夠利用地震後的微震來代替鋼索監測上所需要使用敲擊的方式，不僅可以節省人力，也可以監測地震後鋼索的健康度是否有造成影響，而在供耗的實驗中，以 10000mAh 的行動電源，低功耗感測版的睡眠模式可運作 19 年，在測量加速度 與應變也可以持續測量 1250 小時，足夠我們長時間進行監測鋼索。;Deploying a monitoring system to monitor the health of each bridge cable requires a high cost. Therefore, this research developed a cable monitoring system based on low-power embedded systems and high-precision MEMS sensors. The underlying architecture includes a low-power embedded system, a high-precision MEMS IMU, a high-precision MEMS accelerometer, a 24-bit MEMS ADC, and a LoRa wireless transmission module. First of all, the system will go to sleep mode, when an earthquake occurred, the high-precision IMU will wake up the system for measurement, and it can also be waked up by tapping. The digital MEMS accelerometer on the system has a resolution of 20 Bit, which can be used to measure the acceleration on the steel cable, and the 24-bit ADC with the bridge circuit and strain gauge can be used to measure the strain of the steel cable. In this study, a scaled experimental frame was designed to test the effectiveness of the system. The experimental results show that the measured acceleration of the steel cable can estimate the cable force via FFT analysis. Compared with the real force, the error of estimated force is within 5%, and the estimated value has an excellent linear relationship with the actual value. The strain measured by the strain gauge attached to the steel cable also has an excellent linear relationship with the cable force. The experimental results also saw that when one steel cable is missing on the frame, the frequency of the other steel cable has visible change.
