Design Of Automatic Knocking Device And Research On Acoustic Detection Of Eggshell Crack

The cracked eggs are easier to go bad compared with intact eggs, and its storage is shorter under the action of bacteria. Therefore, they must be removed to ensure food safety. This study has improved and optimized previous design, and gives a cracked eggs dynamic recognition system based on eggshell percussion detection technology. The system is fully functional, able to basically complete the task of automatic tapping, voice signals synchronous acquisition, analysis, crack identification, and removing. The paper also gives a lightweight automatic tapping device to meet the dynamic detection of cracked eggs, grading device. The main contents and conclusions are as follows:(1) A cracked eggs dynamic recognition system was established. The system chooses TMS320F28335 chip as the main processor, and the peripheral hardware circuit includes a sound collection circuit, signal conditioning circuit, an external A/D interface, grading driver circuit. The system can work stable and o achieve the basic function of recognition and classification. With an external interrupt, the System can collect the sound signals while the automatic knocking device knocking on the eggshell, and the acquisition time would be shortened to 23ms.(2) To meet the real-time detection process, this paper introduces a lightweight automatic knocking device. With the help of optical sensors, the device can identify the location of the egg online during processing and knock on its surface accurately and timely according to the movement of eggs. Three knocking was carried out.Automatic knocking device is stable, percussion moderate intensity, will not cause mechanical damage to the eggs, A complete implementation of the action time is only 72 ms maximum.(3) In this paper, the modular design has been adopted in the DSP design software, according to the implementation of process, it is divided into Several Parts as follow: initialize the module, the timer interrupt sampling module, data preprocessing module and driving module identification module and several independent classification modules, and its programming using C and assembly language programming method mix. With the support of Filter Library and FFT Library which are provided by TI corporation, software program of IIR digital filter and FFT is easily designed.(4) By analyzing test data, it's found that the difference of sound characteristic parameters between intact eggs and cracked eggs are as follow:the resonance peak, the power spectrum area, duration, ring count, down time, and energy count. Using the above parameters, a good shell eggs and egg shell damage identification model was established according to Bayes discriminant principle.