| The end-actuator is an important component of intra-row intelligent weeding machinery which can directly influence the effect of mechanical weeding. At present, there are only few types of end-actuator, and the research of intra-row intelligent weeding machinery mainly focus on automatic control, navigation technology, image acquisition and processing, etc. The research of end-actuator is relatively lack. Accordingly, the design of end-actuator which is simple and efficient is significance to the development of intra-row intelligent weeding machinery.During the evolution of soil-burrowing animal through hundred million years, their biological features have been optimized, including the macroscopic and microscopic structure of organs, the configuration and function, the viability adapting to their living environment, which provide good biomimetic prototypes for the development of bionic technology. Zokor(Myospalax psilurus) is a typical soil-borrowing animal, which live primarily underground and can highly adapt to that environment. The two fore claws of zokor are the main organs for excavating, which have efficient burrowing capabilities. Therefore, the fore claws of zokor are good biomimetic prototypes for designing soil-cutting component of agricultural machinery.In this study, the geometric characteristics of fore claws of zokor was observed and analyzed. The results shown that the toes of fore claw of zokor which were thick, strong and unique structure. The third toe of fore claw, which was the thickest, was chosen as the research object. The surface point clouds of the third toe were obtained through reverse engineering. The surface of the third toe of fore claw was reconstructed by reserve engineering software based on the point-line-curve modeling technology. The lower and upper contour curves of the third toe of fore claw were fitted and their second derivative and the curvature were calculated. The Gaussian function was chosen as the fitted function of longitudinal contour curve of the third toe and the Polynomial function was chosen as the fitted function of lateral contour curve of the third toe.A bionic weeding blade as an important end-actuator of intra-row weeding machinery, was designed based on the contour curve equation of the third toe of fore claw of zokor. An arc-weeding blade as contrast component was designed too. And other matched components with weeding blade for soil bin tests, were designed and assembled.The traction resistance of the weeding blade were tested using the test platform in the indoor soil bin. The forward velocity of the test platform was 200mm/s, 400mm/s, 600mm/s and 800mm/s, respectively. And the penetrating angle was 0°, 5°, 10°, 15°and 20°, respectively. The results show that the traction resistance of the weeding blade increased with the increase of forward velocity and penetrating angle. The traction resistance of weeding blade with high forward velocity and large penetrating angle was bigger than the weeding blade with low forward velocity and smaller angle. The traction resistance of the weeding blade reaches to the minimum at the forward velocity of 200 mm/s and penetrating angle of 0°. The traction resistance of the weeding blade reaches to the maximum at the forward velocity of 800 mm/s and penetrating angle of 15°. The traction resistance of bionic weeding blade with low forward velocity and small penetration angle was less than that of the arc-weeding blade. Therefore, the bionic weeding blade was suitable for the conditions of low forward velocity, while the arc-weeding blade was suitable for the conditions of high forward velocity.The finite element model of two kinds of weeding blade and soil were created in ABAQUS software. The interaction of weeding blade and soil model was simulated under the condition of penetrating angle of 0°and 15°, and forward velocity of 200 mm/s and 800 mm/s. The results show that the change of the Mises equivalent stress of the soil, which produced the initial time and end time of weeding blade cutting soil, was small. The disturbance and damage caused by weeding blade with penetrating angle of 15°was bigger than that of weeding blade with penetrating angle of 0°. The average values of reaction force of the ordinary weeding blade were 71.22 N and 86.35 N, respectively, at the forward velocity of 200 mm/s and penetrating angle of 0°and 15°. The average values of reaction force were 105.48 N and 122.67 N, respectively, at the forward velocity of 800 mm/s and the penetrating angle of 0°and 15°. The average values of reaction force of the bionic weeding blade were 63.71 N and 74.00 N, respectively, at the forward velocity of 200 mm/s and penetrating angle of 0°and 15°. The average values of reaction force were 78.09 N and 124.16 N, respectively, at the forward velocity of 800 mm/s and the penetrating angle of 0°and 15°. Compared the results of indoor soil bin test with that obtained from finite element analysis, the variations of traction force and reaction force were basically the same, which verify the accuracy of indoor soil bin test.In this study, a bionic weeding blade as an important end-actuator of intra-row intelligent weeding machinery, was designed based on the contour curve of the third toe of fore claw of zokor. The results of this work provide new ideas and methods, and laid a foundation for the designing of intra-row weeding machine, which has referential value for the development of intra-row weed control technology. |
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