【作者】 莫牧；

【导师】 文友先；

【作者基本信息】 华中农业大学 ， 农业机械化工程， 2005， 硕士

【摘要】 剔除损壳蛋是食品加工中的一道重要工序。目前国内检测损壳蛋常采用人工法,该方法劳动强度大、效率和精度都很低。因此,探讨研制自动化损壳蛋检测系统是一项必要而有意义的工作。 本文设计了由单片机控制的鸡蛋破损检测系统,系统由声音拾取、信号放大、带通滤波、A/D转换、串口通信和自动分级等模块组成。利用该系统采集敲蛋信号,将离散化了的数字信号通过单片机与PC机的串行接口上传PC机以供处理。 运用数字信号处理技术,借助MATLAB软件,对获取的试验数据进行频谱分析,找出敲击好壳蛋与损壳蛋所产生声音信号在频域里的差异,并以好壳蛋与损壳蛋信号功率谱面积的平均值和极差值作为判别因子,依据Bayes判别原理,建立了如下区分好壳蛋与损壳蛋的判别函数。 好壳蛋判别函数: G_h=0.73870x₁+0.02314x₂+33.01895x₃-10.65950x₄-144.68168 损壳蛋判别函数: Gs=-0.59691x₁+0.09112x₂+31.22730x₃-10.26062x₄-102.99508 在软件设计方面,用C51语言描述了上述判别函数,编写了基于单片机的蛋壳破损检测程序。系统软件主要由主程序和中断服务程序组成。在主程序中,单片机一直处于等待敲蛋事件发生的循环之中。当敲蛋发生后,系统转入中断服务程序,在中断服务程序中完成信号的采样、存储和分析处理,并将处理结果送给分级机构,完成好壳蛋与损壳蛋的自动分级。 本系统以单片机为核心,成本低廉,运行稳定,最大特点是具有“即敲即采”的智能化特性。但由于受所选单片机最大主频与数据位数的限制,在试验速度和精度方面有些不足。更多还原

【Abstract】 Getting rid of cracked eggs is an important work in foods processing. The method of detecting cracked eggs is mainly by hand at present in China, which is not only high labour intensity,but also the low efficiency and poor precision.So it is essential and significative to develop a detecting system of eliminating the cracked eggs roboticizedly.In this paper, a detecting cracked eggs system was designed based on SCM. The system contains the following modules: sound collecting, signal amplifying, band-passed filtering, anology to digital conversion, serial port communication and automatic classification circuits. Using the system, we could collect the sound signals of knocking eggshells and transfer them to personal computer.Based on the digital signal processing technology and MATLAB, a large numbers of datum were analyzed throught power spectral. By this means we could find out the differences between the intact egg’s sound signals and the cracked egg’s in the frequency field, and then regarded their average and extreme difference of the power spectral area as the discriminant vectors, at last we established the following discriminant function of the two sound signals based on the principle of "Bayes" discriminant:G_h = -0.73870x₁+ 0.02314x₂ + 33.01895x₃ -10.65950x₄ -144.68168 G_s= -0.59691x₁+ 0.09112x₂+31.22730x₃ -10.26062x₄ -102.99508 We programmed the procedure of detecting cracked eggs based on SCM with C51 language. The system software includes the main program and interrupt service program. In the main program, the SCM is always waiting for knocking eggs. Once the knock happened, the program entered the interrupt service program, in which the system began to sample, storage and process the signals of knocking eggshells, at last sent the results to the classification institution.The most important character of the system is that it started to sample signals once a egg was knocked. For some limits in main frequency and data bits of SCM, the system is a little deficient in processing speed and precision.更多还原