Study Ultrasonic Sensing Precision Measurement Method And Application

As a non-contact measurement method, ultrasonic detection methods is less susceptible to the light, electromagnetic fields, as well as the object color, it is widely used in the field of military navigation, metallurgy casting process, flow detection. The measurement of the propagation time is the physical basis of ultrasonic detection methods. However, how to improve the time resolution of the detection of the ultrasonic close range, how to effectively extract extremely weak ultrasonic signal of the long-range become the main research.In order to solve the problems above, We proposed differential single-frequency controlled pulse phase shift method to measure the ultrasonic tiny time difference and the resolution is2ns, and is applied in velocity and distance measurement. In ultrasonic heat meter, this method can improve the performance of small flow rate detection and increase measurement range of the instrument. Further research on the long distant measurement method, we use the nonlinear method to improve measurement accuracy.The main research work includes the following aspects:1) As the close-range case, the quality of ultrasonic signal is good, this paper Designs the time difference measuring circuit with center frequency of1MHz ultrasonic transducer based on differential single frequency controllable pulse phase shift method.2) This paper successfully designed an intelligent low-power ultrasonic heat meter based on the method described above, the functions of which include flowrate measurement, temperature detection, IRDA communication, data storage, empty pipe detection, M-bus communication, wireless communication, LCD display and other functions. We developed hardware of the system, embedded software of MSP430microprocessor. Through the test on industrial caliberation equipment, we found that our heat meter can measured0.02m/s to5m/s. When the flowrate is zero, the heatmeter works well. 3) As the long-range case, ultrasonic signal is extremely weak or even drowned in the noise which is difficult to detect, this paper proposed long-range ultrasonic time difference measurement method based on coupled chaotic synchronization system, given the design of the program, including introduced simulation and the application research on the Quantitative casting.In the end, future work is pointed out.