Ultrasonic technology is one of the

Ultrasonic technology is one of the common technologies based on physics, electronics, mechanics and material science. Ultrasonic technology is realized by transmitting audio signal through ultrasonic device, then transmitting and receiving. The measurement of the actual distance of ultrasonic wave is to get the actual distance between the two by understanding the propagation speed of ultrasonic wave in the air and the ultrasonic signal reflected back from the start of transmitting the ultrasonic wave to the receiving of the ultrasonic signal when touching the obstacle, and to get the total time used by the computer. Generally, the sound frequency that human can hear is about 18Hz ~ 20kHz. No matter what thing makes a sound lower than 18Hz or higher than 20kHz, people usually can't hear [7]. So the sound wave above 20kHz is called ultrasonic wave, which can spread in gas, liquid and solid. And its propagation speed in standard air is about 340m / s, which is very slow compared with light wave and electromagnetic wave. Moreover, most of the energy will be reflected out if the ultrasonic wave encounters different media during its propagation. Therefore, in some specific test occasions, we can make use of this principle characteristic of ultrasonic. Use the ultrasonic instrument to transmit a section of ultrasonic audio in any direction. The total time spent in the process of transmitting the ultrasonic wave to receiving the signal is the time spent in the process of transmitting the ultrasonic wave to contact with the obstacle and then sending it back. According to this principle, without considering the influence of external factors, under ideal conditions, the calculated distance can get more accurate data.