一种考虑起振延迟的低频超声波短距高精度测量校准方法

利用超声波进行距离测量有着成本低、测量精度高的特点,因而在非接触距离测量中有着广泛应用。然而超声波换能器在接收低频信号过程中需要完成一个较长时间的起振过程,在短距(10 cm)测量场合中起振延迟在超声波飞行时间测量中占比可达50%以上,严重影响了超声波真实飞行时间的测量精度。本文提出了考虑超声波换能器延迟误差的距离测量公式,结合最小二乘法对超声波飞行距离、换能器延迟时间、温度和器件距离等参数进行了精确校准。在实验中,采用24.5 K超声波脉冲,使用基于到达时间差TDOA(Time Difference of Arrival)的方法对所提出方法进行了验证。实验证明,该方法在保证精度不丢失的情况下,避免了在不同环境温度下的多次采样和校准,解决了最小二乘法在低频超声波短距测量中可能存在的参数校准困难,对于各类短距离测量应用有较好的精度提升效果。所提出的测量和校准方法算法简单、实施方便,可基本满足各类短距测量需求。

Identifying and Calibrating Start-up Delay in Short-range High-precision Measurement with Low-frequency Ultrasonic

Distance measurement using ultrasonic is low cost and high precision, so it has been widely used in the non-contact distance measurement environment. However the sending and receiving processes of ultrasound need a long initial duration, which reduce the measuring accuracy to some degree. In this paper, the ultrasonic ranging formula considering the device start-up detection delay, device start-up detection delay time calculation method, combined with the method of least squares and precise calibration of relevant parameters. In the experiment, 24.5K ultrasonic pulse was used and the proposed method is verified with Time Difference of Arrival method. The results showed that the accuracy is remained while avoiding the duplicated sampling and calibration with different environment temperature. The proposal facilitates the parameter calibration with the least square method in the measurement of low frequency ultrasonic short range. It may improve the accuracy for the various types of short-distance measurement environment as well. Measurement and calibration methods proposed algorithm is simple and easy to implement, and various types of short-range measurement can basically satisfy the requests.