Resumen
The transmission characteristics of the vibration excitation of rape plants are of great significance to the study of the harvesting loss and threshing mechanism of rape during harvesting. Aiming to examine the problem that the existing vibration measurement method cannot be well adapted to the vibration measurement of small plants such as rape, this article proposes a vibration measurement method based on high-speed photography and image recognition and uses this measurement method to study the vibration characteristics of rape plants in the three states, i.e., sweep frequency, standing frequency, and free attenuation, with a default hydraulic shaker. The results showed that the average measurement error of the vibration amplitude of this method was 0.0068 mm, and the relative measurement error of the amplitude at 20 Hz was 0.45%, which met the test requirements. Based on this measurement method, a sweep frequency test of rape plants was carried out. It was found that the first-order and second-order vibration modes of rape plants were concentrated in the first 15 Hz. The resonance range of rape plants mainly occurred at 6?7 Hz and 11?12 Hz. The standing frequency vibration test showed that rape plants had strong resonance at 6 Hz and 11 Hz, and grain falling was 1.192% and 0.992%, respectively, which was greater than those of other frequencies. The free attenuation vibration of the rape plant showed that the average attenuation coefficients of the mark points on the lateral branch at 20 cm, 30 cm, and 40 cm from the branch node were 0.542, 0.475, and 0.441, respectively, and the attenuation coefficient decreased as the distance between the mark point and the branch node increased. The amplitude attenuation coefficient of the main branch had little difference, and the average value was 0.797. This research can provide some reference for exploring the threshing mechanism of the rape drum and optimizing the header structure and parameters.