Research On Frequency Detection Of Aluminum Shell In Ultrasonic Sensor

There is a huge social demand of reversing radar ultrasonic sensor. But the pass rate is low, below 50% generally in batch production of the sensor. It means that a lot of resources is wasted when a large number of substandard goods is produced. Quality of the finished product is determined by the quality of the raw material. Aluminum shell is the important raw material of the sensor. It is required that use a effective means to detect the resonant frequency of shells, which ensure the consistency of the raw materials. The sensor housing is small in size and resonant frequency is high. In this project, it is not appropriate that apply the method used to detect the structure of large low resonance frequency parts.Based on the analysis of resonant frequency and the method of ultrasonic nondestructive testing, a resonant frequency detection prototype is designed by analyzing the resonant frequency of ultrasonic sensor at home and abroad. It mainly includes four aspects: principle requirement analysis, system hardware design, bottom drive design, data acquisition and analysis algorithm. Specific work is as follows:Firstly, the principle of passive vibration and resonance of the object is analyzed.The dynamic scanning measurement method is determined and the requirement analysis of the measurement method is carried out. The overall framework of the measurement system is divided into four parts: control, excitation, sampling, fixture. The qualitative analysis of the functions of each part,laid the foundation for the design of the measurement system.Second, the hardware part of the system is designed, included the production and integrated modulation. This paper introduces the structure and resources of DSP control board with TMS320C6748 as the core, designs AD9224-40 sampling circuit and related signal conditioning, voltage reference and clock circuit. It compares and determines the use of digital-to-analog converter to generate dynamic scanning signal, AD9705 circuit,digital interface circuit and power amplifier circuit; introduced the structure and function of the system mechanical support.Third, the design and debug the software of system.The principle of starting and starting the file of DSP, the principle of C6748 clock、interrupt、timer、EDMA3、UPP interface and EMIFA interface is analyzed and expounded in detail. Drivers of the sampling part and the incentive part is designed .Finally, the generation of waveform data and the compensation of the inherent frequency response of the system are deduced. The sensor shell is measured by the designed measurement system. The measurement data is analyzed by the correlation analysis method based on the empirical function to obtain the resonant frequency of the measured object.