库尔勒香梨动态频谱响应特性的研究

为了了解库尔勒香梨的动态频谱特性以实现香梨振动频谱法检测内部品质,本文对香梨进行脉冲激励测试,分析不同窗函数对香梨动态响应信号处理的效果,明确不同激励点、激励力、激励材料及香梨质量、果形和坚实度对其动态频谱响应的影响。结果表明,在动态信号分析过程中,采用非对称窗的exponent窗函数更适宜于香梨动态信号的截断处理,所获得的频谱响应信号信噪比高,信息泄露少;在香梨赤道区域不同激励点对香梨进行单点激励和感测,信号稳定性强,其动态频谱响应也基本一致;不同激励材料和激励力对香梨响应主频率无显著影响,当采用橡胶锤头且激励力范围为9~12N时,获得的动态信号较强,可获得与第二响应频率的幅值相差较大的响应主频率,更易于信号分析;香梨质量、果形和坚实度与响应主频率有较好的线性关系。

Characteristics of the Dynamic Spectral Response of Korla Pear

In this study, Korla pear was exposed to pulse excitation to determine the characteristics of its dynamic spectral response, and the frequency spectrum method was used to test its internal quality. The effect of different window functions on the dynamic spectral response curve of the pear was analyzed. Further, the influence of different excitation points, excitation forces, excitation materials as well as the mass, shape, and firmness of the fruit on the characteristics of dynamic spectral response of the Korla pear was determined. The results showed that during analysis of the dynamic signal of the pear, the exponential window function was more suitable to truncate the signal since the processed signal had high signal to noise ratio and less information leakage. Signals from a single excitation and dynamic signals from different excitation points on the equatorial region of the Korla pear were studied. The signal stability was strong and the responses of dynamic spectrum were generally consistent. Changes in excitation material and forces had no significant effect on the dominant response frequency. When a rubber head hammer was used and the excitation force was in the range of 9 to 12 N, the dynamic signal was strong. The dominant response frequency that showed a larger difference in terms of amplitude with the second response frequency was obtained, thus the dynamic signal could be analyzed easily. The mass, shape, and firmness of the fruit showed good linear correlation with the dominant response frequency.