What’s the ultrasonic ranging transducer

Views: 3 Author: Site Editor Publish Time: 2019-03-26 Origin: Site

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One can hear that the sound is generated by the vibration of the object. Its frequency of transducer for distance is in the range of 20HZ-20KHZ, the ultrasonic wave is more than 20KHZ, and the infrasound wave is lower than 20HZ. Commonly used ultrasonic frequencies are tens of KHZ-tens of MHZ. Since the ultrasonic directivity is strong, it is often measured by distance. The use of ultrasonic testing is often quick, convenient, simple to calculate, easy to achieve real-time control, and can meet industrial and practical requirements in terms of measurement accuracy. Therefore, it has been widely used in mobile robots, automobile safety, and ocean measurement. The present invention provides a liquid crystal display ranging device that utilizes an ultrasonic sensor and a microprocessor integrated with transmission and reception. Ultrasonic sensors are used to time-division on transmission and reception, and the distance between the obstacle and the ultrasonic distance sensor is calculated by the propagation velocity of the acoustic wave in the air and the time interval from the emission of the pulse to the reception of the reflected pulse.

Distance measuring transducer sensor is a parameter that needs to be detected in different situations and controls. Therefore, ranging is a problem to be solved in the data acquisition. Although there are many ways to measure distance, such as laser ranging, microwave ranging, infrared ranging and ultrasonic ranging. However, ultrasonic ranging is a simple and feasible method. Although ultrasonic ranging circuits are various, even special ultrasonic ranging integrated circuits have been used. However, some circuits are complicated, technically difficult, and some are difficult to debug, and some components are not easy to purchase. The circuit introduced in this paper is low in cost and reliable in performance. The components used are easy to purchase, and the principle of ranging is combined with the data processing of the single chip microcomputer to improve the measurement accuracy, the circuit is easy to implement, no debugging is required, and the work is stable.

In the daily life, there are various rangefinders. Compared with laser ranging and infrared ranging, ultrasonic waves are not sensitive to external light, color and electromagnetic fields. They are more suitable for harsh environments with darkness, strong electromagnetic interference, toxic, dust or smoke, and identify objects with poor transparency and diffuse reflectivity. It also has advantages. Moreover, the ultrasonic proximity transducer has the advantages of strong directivity, slow energy consumption, and long distance of propagation. Ultrasonic ranging is a non-contact measurement widely used in reversing anti-collision radar, robot proximity, ocean measurement, object recognition and other fields. Distance is a parameter that needs to be detected in different situations and controls. Therefore, ranging is a problem to be solved in the data acquisition.

An ultrasonic range finding sensor and a microprocessor integrated with the transmission and reception are utilized. Ultrasonic sensors are used to time-division on transmission and reception, and the distance between the obstacle and the ultrasonic range finder is calculated by the propagation velocity of the acoustic wave in the air and the time interval from the emission of the pulse to the reception of the reflected pulse. Therefore, measurements often used for distances, such as rangefinders and level gauges, can be achieved by ultrasound.

Ultrasonic distance measurement sensor usually takes the time-to-time method, that is, the distance of the measured object is calculated using s=vt/2. Where s is the distance between the transceiver and the object to be measured, v is the propagation velocity of the ultrasonic wave in the medium (v = 331.41+T/273m/s), and t is the round-trip time interval of the ultrasonic wave. The working principle is as follows: the ultrasonic wave emitted from the hair propagates in the air at the speed v, and is reflected back by the surface when reaching the object to be measured, and is received by the receiving head, and the round-trip time is t, and the distance of the measured object is calculated by s. T is the ambient temperature. This effect must be considered when the quantity accuracy is high. However, in general, this method can be discarded and the software can adjust and compensate.Since ultrasonic sensor transducers are also a kind of sound wave, the speed of sound c is related to temperature, and the speed of sound at several different temperatures is listed. In use, if the temperature does not change much, the speed of sound can be considered to be substantially constant. If the accuracy of the distance measurement is very high, it should be corrected by the method of temperature compensation. After the speed of sound is determined, the distance can be determined by measuring the time of the ultrasonic round trip. This is the principle of ultrasonic ranging.

The work of the system is a process of cooperation between software and hardware. First, the enable terminal is set by the microcomputer, and then sends a square wave signal of 40 kHz frequency through the piezoelectric transducer (ultrasonic transmitter) to transmit the signal and emit the ultrasonic wave, and at the same time, the timer is started when the timer is turned on. The signal is reflected back to the obstacle and is referred to herein as an echo. At the same time, the piezoelectric transducer (ultrasonic receiver) receives the echo and the received ultrasonic wave, and is amplified by the signal processing, and is sent to the comparator through the three-stage amplification to compare and output the comparison voltage. After the output voltage passes through the triode, The voltage is matched with the I/O port and finally sent to the microcomputer for processing. Finally, the LCD liquid crystal display is accompanied by wonderful music.