Design Of Distance Measurement System Based On Electrostatic Ultrasonic Transducer

This paper designed an ultrasonic distance measurement system based on electrostatic ultrasonic transducer and designed a HMI to display the working status and the measurement results of the distance measurement system.There are still some problems existed in ultrasonic ranging system,including low measuring accuracy,limited range and so on.To solve these problems,this paper studied the structure and basic working principle of electrostatic ultrasonic transducer and proposed a high-accuracy ultrasonic distance measurement scheme.And then the working status and measurement results of the distance measurement system were displayed through a friendly HMI.This paper designed the hardware circuit and the software system based on the structure and basic working principle of electrostatic ultrasonic transducer which was adopted as a prober.Hardware module included power module,signal sending and receiving module and Bluetooth driver module and so on.Software system consisted of the lower computer system and the upper computer system.Among them,the lower computer system established a thorough state machine to achieve the functions of the processing of signal,collecting temperature information,calculating distance and transmitting data to the upper computer by Bluetooth.The distance information,environment temperature and the communication state,between the upper computer system and the lower computer system,were monitored by the upper computer system.In order to guarantee the accuracy of the distance measurement system,it is important to avoid the interference from residual wave in the process of launching ultrasonic signal.Aiming to increase the driving voltage,PWM signal outputted by SCM was transmitted to ultrasonic sensor after boosted by transformer.Moreover,capacitance was matched with transformer to form a resonant circuit which consisted of secondary transformer and emitter,and it made the transmitted wave close to sine wave.At the same time,this paper designed a time-gain compensation circuit(TGC)to make the echo signal stable and to expand the measuring range.In the process of waiting for the echo signal,gain value of amplifier should be enlarged with the increasing of time to ensure that the echo signal cannot be submerged.Finally,experiment test platform was established for the test of relevant indicators of the system.Research shows that the measuring accuracy can reach 1mm,that the blind area is as low as 15cm and that the measurement range of the system reach 5m.Therefore,the system can provide a foundation for the high-accuracy distance measurement.