基于高速摄影的板栗果实振动脱落特性分析

Analysis of chestnut fruit shedding characteristics by vibration using high-speed videos

中国是世界板栗第一生产大国,但板栗的采收主要以人工采收为主,劳动强度大、效率低,机械振动采收的方式可有效提高板栗的采收效率。为研究板栗振动过程中的运动规律以及脱落特性,自制了果实振动脱落特性试验装置对板栗果实进行振动试验,利用高速摄影仪记录了果实振动全过程,并通过PCC软件对图像进行了跟踪、捕捉和分析。结果表明:板栗果实脱落分离方式复杂多样,主要有果柄与果枝分离脱落,以及板栗从栗苞中分离脱落的方式;板栗果实在不同激振参数组合下形成的水平与垂直响应位移差异较大,对应的响应运动轨迹也较多;水平激振模式下振幅5 mm、频率22 Hz,与振幅10 mm、频率6~10 Hz,以及垂直振动模式下振幅15 mm、频率6 Hz,这些组合激振形式均能将成熟度Ⅰ和Ⅱ的果实实现选择性采收,且激振时间设置为5~8 s较合适。此研究为理解板栗振动采收机理提供了一定的理论指导。

China is the largest chestnut producer in the world,but in China,chestnuts are mainly harvested manually with high labor intensity and inefficiency.Mechanical harvesting can effectively reduce the cost of chestnut harvest,improve harvest efficiency and safety,which is the inevitable trend of future development.The working principle of mechanical vibration harvesting is to apply external vibration with the certain frequency and amplitude to the fruit tree using a vibration device,forcing the fruit tree to obtain the vibration response.As a response to the vibration,the corresponding vibration inertial force of the fruit on the tree was created.When the inertial force is greater than the binding force between the fruit and the tree branch,the connection of the fruit with the branch is broken and the fruit will fall off from the tree.In order to study the movement principle and abscission characteristics of chestnuts in vibration process,the vibration tests of chestnut fruits were carried out by a self-made device.A single horizontal or vertical exciting force was applied to the chestnut fruit with branches,and the parameter variation of vibration frequency and amplitude was combined.The whole process of fruit vibration was recorded by a high-speed camera,and the images were tracked,captured,and analyzed by the PCC software.The results showed that,among various ways of chestnut fruit abscission and separation,the most important ways were the separation of the fruit stalk and fruit branch,and the chestnut from chestnut bud.The horizontal and vertical response displacements of chestnut fruits under different excitation parameter combinations were quite different,and the corresponding response motion track was also various.When the response motion track was more regular,the fruit abscission time was slightly longer than that under the disordered motion track.The horizontal excitation mode was set up as 5 mm amplitude,22 Hz frequency,and 10 mm amplitude,6-10 Hz frequency,while the vertical vibration mode was set as 15 mm amplitude,6 Hz frequency.The combination of these excitation forms could realize the selective harvest for the ripeness I and II fruits,and the excitation time was set within 5-8 s.This study provided a theoretical guidance for understanding the harvesting mechanism of the chestnut vibration.