水培生菜低损柔性采收装置设计与试验

植物工厂水培生菜采收过程中易损伤菜叶，为提升采收质量，结合水培生菜农艺特征，设计了一款水培生菜低损柔性采收装置。利用图像处理检测水培生菜轮廓外切矩形，获取生菜株高及菜叶展开尺寸，进而通过柔性手指对菜叶的低损抓取、切割器对生菜茎的一次切除，实现水培生菜低损柔性采收。分析确定了柔性抓取机构、切茎机构、控制系统等关键部件的作业流程及结构参数。利用响应曲面试验方法，优化了柔性手指抓取高度比、抓取圆周比、柔性手指弯曲角的参数组合。试验结果表明，各因素影响采收成功率的显著性顺序为柔性手指弯曲角、抓取圆周比、抓取高度比，各因素对菜叶损伤面积的影响均极显著。利用二次拟合方程求得最优参数组合为抓取高度比0.55、抓取圆周比0.76、柔性手指弯曲角39.7°。对最优参数组合进行试验验证，结果表明，菜叶损伤面积为186mm2，采收成功率为96%，实现了水培生菜低损柔性采收。

Design and Experiment of Low Damage Flexible Harvesting Device for Hydroponic Lettuce

The leaves of hydroponic lettuce were easy to damage during the process of harvesting in the plant factory, to improve the harvesting quality for hydroponic lettuce, a flexible harvester with low damage was designed and manufactured combined with the agricultural technology of hydroponic lettuce. To realize flexible harvesting with low damage for hydroponic lettuce, image processing was used to detect the outer rectangle of hydroponic lettuce contour, and the plant height and leaf expansion size of lettuce were obtained. The lettuce leaves were grabbed by flexible fingers, and then the lettuce stem was removed by the cutting device. The working process and structure parameters of flexible grabbing device, stem cutting device, and control system were analyzed. The parameters combination of grabbing height ratio, grabbing diametrical ratio, and bending angle for flexible fingers were optimized by using response surface methodology. The optimizing test results showed that the order of significance for harvesting success rate was bending angle, grabbing diametrical ratio, grabbing height ratio, and the single factors had highly significant influence on the leaves damage area. The optimized combination of factors was solved by quadratic fitting function, and the value of grabbing height ratio, grabbing diametrical ratio and bending angle were 0.55, 0.76, 39.7°, respectively. The verification test showed that the leaves damage area was 186mm2, and the harvesting success rate was 96% under the optimized combination, which meant the low damage harvesting for hydroponic lettuce was realized.