本文提出兩個新的超音波測距方法，第一個為雙頻式測距法，其綜合使用兩種不頻率超音波叢波之所有可偵測的波峰波谷到達時間差數列來估算波前到達時間，作為飛行時間(TOF)測距法的依據，以提高傳統飛行時間測距法的準確度；另一為考量量測效率，為了能在固定時間內做更多次的量測，而發明的變頻式訊號取代先前的二次頻率發射，目的在於除了有好的量測準確度之外，希望能再固定時間內作最多次的距離量測，若能提高量測的準確度以及效率，對於未來『動態物體距離量測』工作有相當大的幫助。 由模擬數據可以驗證上述兩種訊號的到達時間測距分析方法都也很好的準確度，相較於傳統第一個跨越門檻時間之測距方法有相當大的改善，模擬量測數據顯示雙頻式訊號測距有4.15um的最大誤差量；變頻式訊號測距有3.61um最大誤差量，變頻式測距法準確度還比雙頻式測距法還要準確，且有較高的量測效率。以此理論驗證的兩種訊號量測法作為量測系統實作之依據。 對兩種量測法的實測數據作一討論，驗證本提出的兩種量測法理論之可行性，實現了一具有3m量測範圍，且有4mm準確度之變頻式超音波測距系統。 This paper proposes two new ultrasonic distance measurment methods. The first is the dual-frequency. In order to improve traditional ultrasonic distance measurement, it takes all detectable received waves to estimate the real time-of-flight. In addition, considering the measurement efficiency and accuracy, we develop a changed-frequency exciting signal instead of dual-frequency one. It can do more measurement in a constant time. Simulation results reveal that arrival time analyses of two measurement methods have much better accuracy than traditional measurement. The maximun error in dual-frequency measurement is 4.15um and 3.61um in changed-frequency. The real implementation is based on theoretical analys because the accuracy of two methods have been proved. In real measurement data analysis, we examine the feasibility and discuss the error source. Finally, we develop a measurement system with 4mm error accuracy in the 3m range.
