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| 基于高速摄影的冬枣果实振动脱落规律分析 |
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傅隆生1,2, 刘智豪1, 冯亚利1, 谢洪起1, 彭俊1,3, ELKAMIL Tola4, YAQOOB Majeed5, 崔永杰1,2
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| (1.西北农林科技大学 机械与电子工程学院, 陕西 杨凌 712100;2.农业部农业物联网重点实验室, 陕西 杨凌 712100;3.西安交通大学机械工程学院, 西安 710049;4.Precision Agriculture Research Chair, King Saud University, Riyadh 11451, Saudi Arabia;5.Faculty of Agricultural Engineering and Technology, University of Agriculture, Faisalabad 38000, Pakistan) |
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| 摘要: |
| 为研究冬枣振动采收过程中果实的运动规律和脱落轨迹，采用改装的电动往复锯连接自制振动采摘头对树枝进行高速振动，用高速相机记录不同振动频率（15、20、25 Hz）下冬枣果实的运动轨迹，对高速视频进行分析，计算在振动过程中的枣果脱落类型、脱落时间和运动轨迹，以及果实脱落时的速度、加速度和惯性力。结果表明：1）冬枣果实的主要脱落类型是旋倾型，15、20和25 Hz时，旋倾型脱落的果实个数比例分别为81%、66%和78%，参考已有研究经验，冬枣机械收获宜选用连续式振动设备；2）随着振动频率的增大，果实的平均脱落时间减小，3个频率的果实脱落时间分别为1.71、0.54和0.43 s，15 Hz时果实脱落时间与20和25 Hz时的果实脱落时间存在显著性差异，而20与25 Hz时的果实脱落时间无显著性差异；3）果实的速度和加速度随着振动频率的增大而增大，但不同频率的果实平均脱落惯性力不存在显著性差异，3个频率下分别为0.48、0.43和0.49 N。本研究结果可为机械收获装备的设计选型与研发提供理论依据。 |
| 关键词: 冬枣 振动收获 高速视频 分离力 脱落类型 |
| DOI：10.11841/j.issn.1007-4333.2018.08.15 |
| 投稿时间：2017-08-11 |
| 基金项目:陕西省重点研发计划一般项目-农业领域（2017NY-164）；国家自然科学基金青年科学基金项目（31301242）；中国博士后科学基金项目（2015M572602）；西北农林科技大学国际科技合作种子基金项目（A213021505） |
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| Analysis of winter jujube fruit motion in vibration harvesting based on high-speed videos |
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FU Longsheng1,2, LIU Zhihao1, FENG Yali1, XIE Hongqi1, PENG Jun1,3, ELKAMIL Tola4, YAQOOB Majeed5, CUI Yongjie1,2
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| (1.College of Mechanical and Electronic Engineering, Northwest A & F University, Yangling 712100, China;2.Key Laboratory of Agricultural Internet of Things, Ministry of Agriculture, Yangling 712100, China;3.College of Mechanical Engineering, Xi'an Jiaotong University, Xi'an 710049, China;4.Precision Agriculture Research Chair, King Saud University, Riyadh 11451, Saudi Arabia;5.Faculty of Agricultural Engineering and Technology, University of Agriculture, Faisalabad 38000, Pakistan) |
| Abstract: |
| Winter jujube fruit (WJF) is rich in nutrition,but its harvesting is labor-intensive.Therefore,it is necessary to study the mechanical harvesting of WJF.This study focused on the evaluation of the effect of different vibration frequencies on fruit motion,detaching time and detachment force during mechanical WJF harvesting with a shaker.The shaker was modified from a jigsaw by replacing its saw with a vibrating head.A high-speed camera in 750 fps was used to capture the fruit trajectory on 15 branches excited at the frequencies of 15,20 and 25 Hz.The fruit detaching time,motion patterns,acceleration and inertial force of fruit detaching from limbs were extracted from the high-speed videos.The results showed that the majority of the three identified motion patterns were tilting,column,and beam-column.The tilting motion were accounting for 81%,66% and 78% of all the motion patterns at 15,20 and 25 Hz,respectively.A continuous shaker thus could be used for mechanical harvesting of WJF.Fruit detaching times were significantly affected by the vibration frequency with fruits being fast detached at high frequencies,and their values at the three frequencies were 1.71,0.54 and 0.43 s,respectively.The fruit detaching time at 15 Hz was significantly different from that those at 20 Hz and 25 Hz,whereas there was no significant difference in fruit detaching time between 20 Hz and 25 Hz.The velocity and acceleration of WJF were increased with the increasing of vibration frequency,but the average inertial force of fruit detachment changed less.The detaching force of white ripe WJF was less than that of crisp ripe WJF.In conclusion,higher frequency generates high harvest efficiency,but when the frequency reached a certain value,the increase of frequency had less effect on the detaching time of fruit,and frequency also has little effect on inertia force of fruit detachment.Overall,the results indicate that 20 Hz might be the optimal vibrating frequency and it was possible to selectively harvest the crisp ripe fruit. |
| Key words: winter jujube fruit vibration harvesting high-speed video motion pattern fruit detachment |
