Research On Automatic System For Detecting And Grading Cracked Eggs

Egg is one of nourishing foods in our daily life. Getting rid of cracked eggs is an important procedure to guarantee good quality of processing eggs and decrease its cost. Detecting cracked eggs by hands is very difficulty for its bad working conditions and laboring intension, as well as the low efficiency and precision. Consequently, it's very urgent and valuable to find a scientific, applicable and fast detecting method for removing cracked eggs.In this task, the acoustic characteristics were used for detecting the cracked eggs. An automatic knocking device based on MCU was designed to make the eggshell emit characteristic sound. If there was an egg in the device, a photoelectric sensor would send a signal to the MCU. Then the MCU drove three step motors which were connected with knocking sticks to knock different parts of the eggs, the biggest part, the middle part and the smallest part. In order to process the real-time sound signal steadily, a testing and grading device based on DSP was designed. The sound signal from the eggshell was sent to the DSP through the amplifying circuit, the filter and the AD convertor. And there was an machine controlled by the DSP, which could get rid of the cracked eggs on time.At the same time, we made spectrum charts for the sound signals from different parts of the eggshell. And we found out remarkable frequency factors that were affected to distinguish cracked eggs and intact eggs. Considering statistical independence between those factors adequately, we chose the best factors and used the "Bayes" discriminance to establish the optimum distinguishing functions of in tact eggshells and cracked eggshell respectively.What's more, we used assemble language to exploit all the software of the MCU system and the DSP system. This could not only improve the executive efficiency of the system software, but also reduce the requirement for ROM and make the hardware system more simple.The working parameters of the automatic system for detecting and grading cracked eggs that designed in this paper was suitable for "the Automatic Equipment for Detecting and Grading Eggs", which was designed and made by the other persons of the task team few years ago. When the system worked steadily, it could detect 3600 eggs each hour. The detecting accuracy of the system was 93.22 percent for intact eggs and 85.61 percent for cracked eggs. And the total detecting accuracy was 89.2 percent.