Abstract:A stable non-destructive detection method based on the band magnitude features of acoustic vibration response was investigated for evaluating the stiffness of Korla pear. An experimental setup using piezoelectric beam sensors was developed and built for obtaining band magnitude features of Korla pear. The stability of the experimental system was analyzed. The band magnitude parameters were acquired by the normalized spectrum magnitude of response signal between 320 and 880 Hz. The correlation between eight band magnitude parameters and the stiffness measured with M-T method was studied. The stiffness detection model was acquired by principal component regression (PCR) analysis of the relationships between different band magnitude parameters and stiffness. The results of repeated excitation at the same point showed that the experimental system was stable and reliable. A low correlation was found between every band magnitude parameter and stiffness and the maximum correlation coefficient was only 0.63. The stiffness detection PCR model showed a good correlation. The correlation coefficient for calibration and validation of the model were 0.77 and 0.66, respectively, while the root mean square error of calibration and validation was 1.23 and 1.59, respectively. The detection sensitivity of the model was 51.56%. The modified model with mass had higher correlation coefficients and lower root mean square errors. The detection sensitivity (58.28%) of the modified model was more similar to that of M-T method for pear stiffness measurement. Therefore, this model can be used for non-destructive measurement of Korla pear internal quality.
