摘要
油茶作为中国特有的木本油料作物,在空间上具有复杂的分枝结构,不同品种树体的形态结构和力学性能差异明显。为了研究油茶树在冠层振动采摘油茶果过程中能量传递规律以及获得最佳激振参数,本文建立5自由度油茶树的质量-弹性-阻尼动力学模型并测量和计算等效参数;以不同激振参数为输入,通过Matlab软件对动力学模型进行仿真,并设计二次旋转正交组合试验,仿真结果表明,油茶树各级枝之间能量传递过程中损失严重,从激振力所作用的枝条传递到路径末枝时能量剩余不到20%;且油茶树各级枝的动能峰值出现的时间具有滞后性,越靠近激振点的动能峰值出现越早。由于油茶树各级枝间能量传递损失严重,将一棵树进行2~3次振动采摘。利用Design-Expert 11.0.4软件的优化模块对激振参数进行优化求解,以一部分侧枝动能最大,主干动能最小为目标函数时,最佳振动参数组合为振动时间7.14 s、振动频率7.18 Hz、振幅52.41 mm;通过田间试验对油茶树能量传递规律进一步研究发现,能量沿着树枝内部传递时与各级枝之间的传递规律相同,即动能与传递距离成反比,传递的距离越远动能越小。并对仿真结果进行验证:田间试验结果与仿真结果的相对误差在10%以内,说明该动力学模型具有较高的可靠性;振动采摘部分的油茶果实和花苞平均脱落率分别为90.53%、14.39%,采摘效果较好,证明了从能量传递角度对激振参数优化的可行性。本文建立的动力学模型和预测的最佳振动参数组合可以为油茶果机械化采摘作业的工作参数设置提供参考。
Camellia oleifera is a unique woody edible oil tree species in China.Trees have complex branching structure in space and the morphological structure and mechanical properties of different tree species are different even among the same tree species.In order to study the energy transfer law and optimal excitation parameters of camellia tree during canopy vibration picking,a mass-elasticity-damping model of camellia tree with five degrees of freedom was established,including the trunk of camellia tree,two primary side branches and two secondary side branches.The equivalent parameters were measured and calculated by the rope pull test and logarithmic attenuation method.The simulation block diagram of differential motion equation was established by using Simulink component in Matlab software,and the excitation force under different excitation parameters was used as the input for simulation test.The simulation results showed that the energy loss was 80.9%during the transfer from the secondary branch C1 to C2,that was,less than 20%of the energy was left when the input branch was transferred to the end branch of the path.From the input position along the transfer path,the time for reaching the kinetic energy peak of each branch was extended once,indicating that there was hysteresis in the energy transfer process.The optimization module of Design-Expert 11.0.4 software was used to optimize and solve the excitation parameters,because of the serious loss of energy transfer between branches of camellia sinensis,a tree was picked by vibration for 2~3 times.When the objective function was to maximize the kinetic energy of some side branches and minimize the kinetic energy of the main trunk,and the optimal combination of vibration parameters was obtained as follows:vibration time was 7.14 s,vibration frequency was 7.18 Hz,and amplitude was 52.41 mm.Under this parameter combination,the kinetic energy of camellia trunk A was 2.59 J.The kinetic energy of the first branch B1 and B2 was 15.09 J and 9.64 J,respectively.The kinetic en
作者
伍德林
赵恩龙
姜山
王韦韦
袁嘉豪
王奎
WU Delin;ZHAO Enlong;JIANG Shan;WANG Weiwei;YUAN Jiahao;WANG Kui(School of Engineering,Anhui Agricultural University,Hefei 230036,China)
出处
《农业机械学报》
EI
CAS
CSCD
北大核心
2022年第8期23-33,共11页
Transactions of the Chinese Society for Agricultural Machinery
基金
安徽省自然科学基金项目(2208085ME132)
国家重点研发计划项目(2016YFD0702105)
关键词
油茶树
振动采摘
冠层振动
参数优化
仿真分析
能量传递
Camellia oleifera
vibration picking
canopy vibration
parameter optimization
simulation analysis
energy transfer
