西瓜生长期的振动预测方法研究

Study on forecast method for watermelon growth period based on vibration

通过自行设计的敲击振动检测系统对西瓜进行敲击振动检测,得到西瓜的频响函数,分别针对频响函数的第一响应频率f_1、第二响应频率f_2和第三响应频率f3建立预测西瓜生长期的数学模型,模型的确定系数R^2较高。且选取了f_1、f_2和f_3三个响应频率建立了预测西瓜生长期的多元非线性回归模型,模型的确定系数R^2可达0.830,均方根误差RMSE降低到2.095。该模型的建立为在线无损检测西瓜的生长期提供了理论参考。

The study was conducted by knocking on watermelon for its' vibration test with self-designed vibration test system,from which the frequency response function( FRF) of watermelon was obtained. The prediction mathematical model of watermelon's growth period was established by using the first response frequency( f_1),the second response frequency( f_2) and the third response frequency( f_3) of FRF,respectively. The determination coefficients R^2 of the three models were high. All the f_1,f_2 and f_3response frequency were selected to establish multivariate nonlinear regression model which could predict watermelon's growth period. The determination coefficient R^2 of the model could reach 0. 830,the root mean square error RMSE decreased to 2. 095. The establishment of the model provides a theoretical reference for the on-line nondestructive testing of watermelon's growth period.