基于张合式刀具的香蕉落梳末端执行器设计与试验

Design and Experiment of Banana De-handing End Effector Based on Opening-closing Cutter

摘要:

针对在智能化落梳过程中，刀具对香蕉果柄自适应性差且落梳成功率低等问题，本文根据香蕉果穗及果柄形态参数并结合落梳生产要求设计了一种新型末端执行器，利用可变落梳张合式刀具切割弧适应不同大小的香蕉果柄，从而实现香蕉连续落梳。设计了落梳末端执行器关键参数与主要结构；建立了落梳刀具插切香蕉果柄过程力学分析模型，并开展了强度仿真，结果表明在落梳过程中落梳刀具最大应力为58.147MPa，小于刀具材料屈服强度205MPa。搭建了落梳机器人试验平台，并得到影响落梳效果的显著性因素排序为落梳入切角、刀刃角、落梳速度。为获得最佳参数组合，以峰值切割力和切口质量作为评价指标，利用Design-Expert软件进行了三因素三水平组合试验，得到试验因素与评价指标间的数学回归模型。对回归模型进行多目标优化，得到最佳参数组合为：落梳速度2m/s、落梳入切角5.77°、刀刃角5°。最佳参数组合验证试验结果表明，峰值切割力为31.49N，切口质量为84分，与回归模型预测结果相对误差均小于5%，落梳成功率为92%，表明张合式香蕉落梳末端执行器能有效适应香蕉果柄形态且获得较好的切口质量。

Abstract:

In order to solve the problems of low adaptability of the tool to the banana crown and the low success rate of the banana in the process of intelligent de-handing, a type of end effector was designed according to the morphological parameters of the banana bunch and the crown and the production requirements of the de-handing. The cutting arc of the adjustable opening-closing de-handing tool was used to adapt to different sizes of the banana crown to achieve continuous banana de-handing. The key parameters and main structure of the de-handing end effector were designed. The mechanical analysis model of the process of cutting banana crown by the de-handing tool was established, and the strength simulation was carried out. The results showed that the maximum stress of the de-handing tool during the de-handing process was 58.147MPa, which was less than the yield strength of the tool material 205MPa. The test platform of robot de-handing was built, and the significant factors affecting the de-handing effect were sorted as the cutting angle of de-handing, the blade angle and the de-handing speed. In order to obtain the optimal parameter combination, taking the peak cutting force and incision quality as the evaluation indices, the combination test of three-factors and three-levels were carried out by using Design-Expert software, and the mathematical regression model between the experimental factors and the evaluation indexes was obtained. The multi-objective optimization of the regression model was carried out, and the optimal parameter combination was obtained as follows: the de-handing speed was 2m/s, the cutting angle of de-handing was 5.77°, and the blade angle was 5°. The results of the optimal parameter combination verification test showed that the peak cutting force was 31.49N, the incision quality was 84 points, the relative error with the prediction results of the regression model was less than 5%, and the success rate of the de-handing was 92%, indicating that the opening-closing end effector of banana de-handing can effectively adapt to the banana crown’s morphology and obtain better incision quality.