蔬菜穴盘苗夹取损伤机理及取苗机构多目标优化方法

Vegetable plug seedlings of tomato and lettuce are used as the research objects in the project. Based on Micro-CT techniques, three-dimensional (3D) micro images of the internal structure of the seedling pot are obtained. Characterization methods about the internal micro structural morphology of seedling pots, which are multiphase, porous and composite material structures, will be studied.And the damage behavior of seedling pots in the picking-up process will be studied. The damaging mechanism of seedling pots what grasped and extracted by the seedling pick-up end-effector will be investigated. By tests and analysis, relationships between different potted parameters and mechanical properties of seedling pots shall be established, and force models of the seedling pick-up end-effector to plug seedlings shall also be obtained. Based on the interior damage behavior, morphological characteristics and mechanical property of seedling pots, the breeding process of the vegetable plug seedling and the multi-objective optimal method of picking seedling mechanism shall be proposed by characteristic quality, transplanting quality and transplanting speed ratio as the goals. Then an invention of new seedling pick-up device shall be done with low damages to plug seedlings and a high transplanting ratio. By this project research, it will be to break through the bottleneck of the core technology for automatic plug seedling transplanting in China, and solve the urgent problem that the seedling pick-up device can be unable to reach engineering application. Finally, design theory and method of the seedling pick-up device shall be established.

本项目以番茄和生菜典型的蔬菜穴盘苗为研究对象，应用Micro-CT获取苗钵的内部结构三维显微图像，研究苗钵多相、多孔、复合材料结构体内部微结构形态特征的表征方法、夹取过程中损伤行为，探索取苗末端执行器对苗钵夹取的损伤机理；通过测试与分析，建立不同制钵参数与苗钵力学特性之间的关系、取苗末端执行器对苗钵作用力模型；基于苗钵结构体内部损伤行为、结构形态特性、力学特性，以品质特性、移栽质量、移栽频率为目标，提出与蔬菜穴盘育苗工艺相配套的取苗机构多目标优化方法；创制具有自主知识产权的穴盘苗低损伤、高速取苗机构。本项目旨在突破我国穴盘苗自动移栽机核心技术的瓶颈，解决目前自动取苗机构无法突破工程化应用的问题，构建自动取苗机构设计理论。

针对穴盘苗自动移栽夹取过程苗钵结构形变演变和损伤机理不明、苗钵结构形态和力学特性数据短缺、机构设计与育苗工艺不相结合等问题，以典型的蔬菜穴盘苗为研究对象，研究并取得了以下主要结果：①基于Micro-CT研究了苗钵根系三维可视化方法和根系分布空间规律，能在不破坏的情况下实现穴盘苗根系原位三维的可视化，探明了苗钵内部结构形态特征和根系空间分布规律；探索了取苗末端执行器对苗钵夹取的损伤机理，发现孔隙的聚集和裂缝的形成是导致苗钵破损的主要原因，在夹针的顶端和周围分别是苗钵的易断裂区域和易破碎区域。②以穴盘苗根系分布、苗钵力学特性为目标，优化了适合夹取的穴盘苗培育方案，系统研究了与自动取苗相关的穴盘苗力学特性，建立不同制钵参数与苗钵力学特性的关系；基于刚柔耦合分析，研究了苗钵夹取响应规律，通过对夹取过程中钵体应力应变分析得到了低损伤的夹取针执行参数。③利用有效积温法，研究分析了不同育苗条件对壮苗指数、取苗成功率、伤钵率和伤苗率的影响，采用综合夹取评分法确定了穴盘苗的培育工艺，包括基质配比、施肥次数、压实度的最优组合，确定了边插入苗钵，边夹紧的取苗方式；以取苗成功率、投苗成功率、伤苗率、移栽频率为目标，优化确定了合理的取苗末端执行器开度、夹持深度和夹持力等结构参数；以满足夹取针垂直取苗、直立投苗以及穴盘平直输送要求，优化设计了一种具有最短取苗路径的低损伤高速取苗机构，通过性能试验，检验了自动取苗机构设计的合理性。.在国内外核心刊物上发表学术论文18篇，其中14篇被SCI、EI收录；申请发明专利56件，授权发明专利17件；申请实用新型专利10件，授权实用新型专利7件；通过中国机械工业联合会科技成果鉴定2项，结论均为“国际先进”。