Precise ultrasonic distance measurement method based on crosscorrelation algorithm
                                                        ZHANG Congpeng, LI Hong, ZHOU Bangping
           （School of Mechanical and Material Engineering, North China University of Technology University, Beijing 100144, China）

Abstract: In order to solve the problem that the traditional crosscorrelation algorithm has no selfadaptive characteristics, and a large amount of computation, to improve the accuracy of ultrasonic ranging, the intensity and duration of the ultrasonic echo signals at different distances were analyzed, combined with the vibration characteristics of the transducer and the attenuation characteristics of the acoustic wave, an algorithm for accurately locating the ultrasonic echo position was proposed. Firstly, the improved crosscorrelation algorithm was used to determine the range of the echo start position. Then the variance characteristics of each period of the echo signal were compared to obtain the starting position of the leading edge of the echo signal. The adaptability of the algorithm in low SNR environment was verified by simulation. And the measurement accuracy was verified by actual measurement experiments. The research results show that the ultrasonic ranging system with the algorithm has an absolute error <1.3 mm and a standard deviation ≤0.097 mm in the actual measurement range of 3 000 mm, which can meet most industrial measurement requirements.

Key words: ultrasonic ranging; crosscorrelation; variance comparison; volatility test; repeatability test