震動量測在工業應用上是非常重要的。本論文的主要目標是採用超音波相位差法來設計一量測震動和空氣中平均溫度的系統。此系統由一對40 kHz的超音波換能器來組成。在一個為發射、另一個為接收的操作模式下，來量測震動物體表面的動作。物體的相對動作，與發射端及接收端的連續超音波信號之間的相位差直接相關。利用新的重建方法，以擷取到的相位差角度變化可重建出物體的震動動作。由實驗得知，在發射與接收不同端的情況下此震動量測系統的準確度是 0.07 mm，在相同端的情況下是 0.98 mm。

　　本研究的另一項應用設計是藉著量測空氣中的音速變化，來換算出空氣中平均溫度的變化。我們利用FPGA設計出一數位相位差偵測模組，將發射端與接收端的連續超音波信號之間的相位差記錄下來，再由89C51單晶微控制器來分析及計算出空氣中的平均溫度值。當發射端與接收端的相對距離為 10 cm 時，理論上本系統的準確性為 0.05 ℃，溫度變化的反應時間為10 ms。此一採用超音波相位差法之新型震動及溫度量測系統的主要優點是高解析度、反應時間短可快速量測、採非接觸式並且在硬及軟體上易於實現。

　　Vibration measurements are very important in many industrial applications. The main aim of this dissertation is to design a measurement system based on an ultrasonic phase-shift method to measure vibration and average temperature in air. The instrument developed consists of a pair of 40 kHz ultrasonic transducers which are used as transmitter and receiver respectively to get the motion of a vibration object. The relative motion of the object modulates the phase angle between transmitted and received ultrasound signals. We developed an ingenious method to reconstruct the relative motion of an object from the acquired data of the phase angle changes. The measurement accuracy of the system in the reported experiments is within 0.07 mm in face to face direct mode, and 0.98 mm in round trip mode.

　　This study also presents a microcontroller-based ultrasonic system which can measure air temperature based on the variations of sound speed in the air. Changes of the sound speed are in turn determined by detecting the phase-shift variations of a 40 kHz continuous ultrasonic wave. In a test embodiment, two 40 kHz ultrasonic transducers are set face to face at a constant distance. Phase angle differences between transmitted and received signals are determined by a FPGA digital phase detector and then analyzed in an 89C51 single-chip microcontroller. Temperature is calculated and then sent to an LCD display and, optionally, to a PC. Theoretical accuracy of measurement is within 0.05 ℃ at an inter-transducer distance of 10 cm. Temperature variations are displayed within 10 ms. The main advantages of the vibration and temperature measurement system are high resolution, rapid temperature measurement, noncontact measurement and easy implementation.

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