传统的超声测距方法基于单频脉冲飞行时间，原理简单、应用灵活，但由于声波易受空气衰减以及电路噪声影响，其测量精度较低，多频连续波相位检测法可以达到较高的精度，但其受限于连续声波发射，应用范围较小。为兼顾测量精度与应用范围，提出一种采用多频超声脉冲发射的方法，利用各频段声波之间的固有时间差值，结合飞行时间法精确估计超声脉冲的到达时间，再通过温度补偿测量现场的声速，即可得到精确的被测距离。该方法能够拓展超声测距的应用范围，简化硬件设计，经实验验证，在3 m范围内，测量精度可以达到0.3 mm左右。%The traditional ultrasonic ranging method is based on time of flight using single frequency pulse. It is flexible in application but has low accuracy. Another high accurate method is based on multi-frequency continuous wave;however its application is limited by the continuous sound wave. In order to consider both measurement accuracy and application, this paper presents a novel method by using multi-frequency ultrasonic pulse. This method obtains accurate distance based on the sound velocity which is compensated by temperature and accurate time of flight estimated through the inherence time difference of different frequency pluses. Experimental results prove the measurement accuracy can achieve about 0. 3 mm for the distance up to 3 m.
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