The Design Of Ultrasonic Distance Measurement System Based On Damped Free Vibration

In the non-contact ranging system,the ultrasonic ranging in collision avoidance,object detection,medical detection,submarine positioning,robot navigation,unmanned combat platform and other civilian,military,and industrial production areas are widely used.An ultrasonic ranging system based on damp free vibration is designed in this paper,which improves the accuracy and stability of the distance measurement.The traditional ultrasonic ranging system based on the free vibration damping by measuring ultrasonic transit time ultrasonic ranging.However,after receiving the ultrasonic signal,the ultrasonic signal receiving terminal oscillator has found the damping free oscillation phenomenon,the oscillator is still vibrating,so that the time of the timer is prolonged,the transit time increased,affecting the accuracy of the range.Through the analysis of the generation,propagation and reception of ultrasonic wave,when the signal receiving terminal of the ultrasonic signal is finished,by analyzing and studying the damp free vibration of the oscillator which affects the timing of the timer,a method is put forward to determine the vibration of the oscillator by using the periodic frequency.This method could let the timer be stopped in time after the ultrasonic signal is received and eliminating the negative effect caused by the damp vibration of the vibrator.In design of ultrasonic ranging system with damped free vibration includes two aspects of hardware and software.In the hardware design,the transmitting terminal has designed the sine wave generating circuit,the power amplifier circuit and the ultrasonic signal transmitting circuit.And the receiving terminal has designed the Shaping circuit,the Filter circuit and the Gain compensation circuit.Through the STM32 control chip to complete the transmission of ultrasonic signal and the collection of receipt signal.In software design,it is proposed that the method of judging the vibration of the receiving terminal oscillator by using the periodic frequency.In particular,the amplitude spectrum and phase spectrum of each point are obtained by the FFT transform of A/D data processor which is sampled data by DSP.According to the amplitude spectrum of a point and its adjacent points corresponding to the amplitude frequency difference,can clearly draw the ultrasonic signal frequency changes of two adjacent points,so as to accurately determine the frequency of the ultrasonic ranging system has the inflection point of the damping free vibration.Through this turning point,it can accurately measure the transit time and improve the accuracy of the measurement.Many experiments show that the absolute error of the ultrasonic ranging system is kept in the range of 0.3mm.Moreover,the accuracy and stability are greatly improved by compared with the traditional similar technology.