| 三维激振果品采收机构优化设计与试验 |
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| 引用本文： | 杜小强,李松涛,贺磊盈,高旗,武传宇.三维激振果品采收机构优化设计与试验[J].农业工程学报,2017,33(16):48-55. |
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| 作者姓名： | 杜小强 李松涛 贺磊盈 高旗 武传宇 |
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| 作者单位： | 1. 浙江理工大学机械与自动控制学院,杭州310018;浙江省种植装备技术重点实验室,杭州310018;2. 浙江理工大学机械与自动控制学院,杭州,310018 |
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| 基金项目： | 国家自然科学基金资助项目（51475433，51505431）；浙江省高校中青年学科带头人培养项目；浙江理工大学科研创新团队专项（13020049-Y）；浙江理工大学521中青年拔尖人才项目 |
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| 摘 要： | 振动式采收因其能够快速有效地使果品脱落而成为目前常用的果品采收机构,但其采收效率仍然不高.本文提出通过三维激振载荷对果树同时施加沿树枝径向和轴向的激振作用,利用ANSYS建立果树模型,分析比较了一维、二维和三维激振载荷下果树上各点的加速度响应.根据三维激振位移载荷的生成方法及其果树动力学仿真结果,设计了三维激振采收机构,并基于遗传算法对该机构尺寸进行优化,以达到最大的输出加速度目标.最后加工了三维激振果品采收机构样机,并开展田间果树加速度响应试验,结果显示三维激振果品采收机构与偏心振动电机对果树激振的平均加速度变异系数分别为0.67和0.72,表明用三维激振采收方式能使果树各分支加速度分布更均匀,从而减少逐个树枝激振的次数,提高采收效率.
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| 关 键 词： | 机械化 振动 设计 果树 三维激振 加速度响应 优化 |
| 收稿时间： | 2017/3/8 0:00:00 |
| 修稿时间： | 2017/6/12 0:00:00 |
Optimal design and experiment on vibratory fruit harvesting mechanism with three-dimensional excitation |
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| Du Xiaoqiang,Li Songtao,He Leiying,Gao Qi and Wu Chuanyu.Optimal design and experiment on vibratory fruit harvesting mechanism with three-dimensional excitation[J].Transactions of the Chinese Society of Agricultural Engineering,2017,33(16):48-55. |
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| Authors: | Du Xiaoqiang Li Songtao He Leiying Gao Qi and Wu Chuanyu |
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| Institution: | 1.School of Mechanical Engineering and Automation, Zhejiang Sci-Tech University, Hangzhou 310018; 2. Zhejiang Provincial Key Laboratory of Transplanting Equipment and Technology, Hangzhou 310018,1. School of Mechanical Engineering and Automation, Zhejiang Sci-Tech University, Hangzhou 310018,1. School of Mechanical Engineering and Automation, Zhejiang Sci-Tech University, Hangzhou 310018,1. School of Mechanical Engineering and Automation, Zhejiang Sci-Tech University, Hangzhou 310018 and 1.School of Mechanical Engineering and Automation, Zhejiang Sci-Tech University, Hangzhou 310018; 2. Zhejiang Provincial Key Laboratory of Transplanting Equipment and Technology, Hangzhou 310018 |
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| Abstract: | Abstract: With the growth of orchard area and fruit yield in recent years, it is still a big problem for farmers to harvest fruit efficiently in China. Because the shaking-type harvester can make mature fruit detached quickly and effectively, the existing fruit harvesters are mostly shaking type. But the efficiency of shaking-type harvester is not high enough. To improve the harvesting efficiency, the three-dimensional shaking method was proposed and the vibratory harvesting mechanism with three-dimensional excitation was designed. Firstly, a Chinese hickory tree model was established for transient dynamics analysis by finite element software (ANSYS). One-dimensional and two-dimensional shaking method was discussed respectively, and then the influence of the loading direction on the acceleration response of tree was analyzed. Simulation results show that the loading direction of these 2 shaking methods has remarkable effect on the acceleration response, but it is difficult to make fruit tree branches produce enough big acceleration response in all directions. So, the three-dimensional shaking method was proposed on the basis of one-dimensional and two-dimensional shaking method, which has effect not only on the cross section direction of fruit tree''s branch, but also on the axial direction. After analyzing the acceleration response of different kinds of shaking methods and the three-dimensional displacement patterns with different speed ratios, the conclusions are as follows: 1) Fruit tree shaken by three-dimensional load has a more uniform acceleration than by one-dimensional and two-dimensional load; 2) it has the most uniform acceleration distribution when the speed ratio of crank in the spatial linkage shaking mechanism is 1:1. Secondly, according to the generation method of three-dimensional displacement load and the dynamics simulation result of fruit trees, the vibratory fruit harvesting mechanism with three-dimensional excitation was designed, which mainly consists of the case, the spatial linkage shaking mechanism, the driving mechanism and the clamping mechanism. The transmission ratio of the driving mechanism can be changed to obtain different three-dimensional displacement loads. And the kinematics analysis of the spatial linkage shaking mechanism was performed. Thirdly, after kinematics analysis of the spatial linkage shaking mechanism, the stroke and acceleration that were affected by the change of related parameters were calculated with MATLAB software. In order to achieve the optimization objective of the maximum acceleration, genetic algorithm was used to optimize parameters of this mechanism. The ranges of parameters were determined by constraints of the spatial linkage shaking mechanism. Then the optimization software was based on MATLAB platform and the optimization result indicates that the maximum output acceleration of the mechanism is 117.3 m/s2. A prototype of vibratory fruit harvesting mechanism with three-dimensional excitation was manufactured and assembled according to the result of parameter optimization. Then the dynamics response experiment of fruit tree was carried out. In order to evaluate the performance of the vibratory fruit harvesting mechanism with three-dimensional excitation, an eccentric block type vibration motor was used for comparison in the experiment, and the accelerations of test points on the fruit tree were measured by data acquisition and analysis instrument. Statistics results indicate that the test points on the tree have obvious acceleration response in 3 directions to the vibratory harvester with three-dimensional excitation, while obvious acceleration was only generated at the cross section of the branch by the eccentric block type vibration motor and the acceleration was small along the axis direction of the branch. Finally, the coefficient of variation was calculated according to the average acceleration result of the test points by 2 shaking methods. Results show that it has a smaller coefficient of variation when the tree is excited by the vibratory harvester with three-dimensional excitation, which means the vibratory harvester with three-dimensional excitation can make the branches vibrate in a uniform level. So the harvesting efficiency is expected to be improved with the excitation of few times. |
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| Keywords: | mechanization vibrations design fruit tree three dimensional vibration acceleration response optimization |
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