| Fresh fruits and processed products are two major consuming forms in the apple market, with the ratio of fresh product as high as 90%, while the rest is mainly processed products. To ensure the quality of apples, picking in time is of the first priority in the apple industry. The burdensomeness of picking job and labor shortage have been making the timely harvesting more and more difficult. Automatic picking can solve this problem. However, the mechanization and automation in fruit picking are still unable to match the development of apple production in China. Therefore, to develop the automatic apple picking robot with high efficiency is of significant meanings. So mobile platform,which is the foundation of the picking robot research,should be taken seriously.This project aims the mechanical system design of the mobile platform of apple picking robots through theoretical analysis and computer simulation to provide the foundation for further development of apple picking robots. The main study contents and conclusions are as follows.(1) The mechanical system design of mobile platform for apple picking robots. On the base of parts selection, determination of carrying method and fully considering keeping the reasonable space for all required equipment of the picking robot, the mechanical system of mobile platform for apple picking robots was designed.(2) The finite element analysis of designed frame using ABAQUS and HyperMesh software was carried out to check its strength and stiffness. Firstly, import the frame model of CATIA software to HyperMesh. Meanwhile, run the geometric clean-up to simplify the characteristics of elements, such as bolt holes, and also to extract the neutral surface; Then analyze the neutral surface model with grid division; After that, import processed grid file to the ABAQUS for stress analysis, mainly about the bending and torsion deformation stress. The analysis shows that the maximum stress value is 69.3 Mpa, far less than the yield limit of material (235 Mpa) and ultimate strength (420 Mpa), which confirms that the frame strength and stiffness meet the requirements of loading.(3) The dynamics simulation of the mobile platform via ADAMS software was made to investigate the dynamic performance of the platform. Firstly, the preliminary dynamic model was established and the weight distribution on the platform was balanced; The axle base was determined through optimization analysis; Then, Built the new dynamics model for optimized platform was built and further weight balance was made; By means of dynamics simulation via ADAMS. the ability of the whole vehicle in climbing the steering stability when making a turn, and the driving smoothness on a rectangular road were analyzed in detail. The analysis results show that the dynamic performance of the designed platform can meet the expected requirements.(4) One kind of motor selection program for picking robot design via the GUIDE function of MATLAB was developed. Through interface design and callback functions, basic motor parameter requirements can be calculated with the program. A convenient tool for motor selection during picking robot design was provided. |
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