切割脱离式鲜食朝天椒采摘末端执行器设计与试验

Design and Experiment of Fresh Pepper Picking End Effector

摘要:

末端执行器是采收机器人重要组成部分，针对单生朝天椒果实朝天生长特征，本文设计了一款切割脱离式鲜食朝天椒采收末端执行器。针对朝天椒果实长度55～80 mm、果实最大直径9～13 mm、茎秆直径2～3 mm、茎秆长度20～30 mm，采用横断切、斜切、削切切割方式对品种“高辣878”朝天椒进行了生物特性试验，结果表明，在入切角70°、80°下朝天椒茎秆最大切割力为13.1 N。根据朝天椒生物特性设计了末端执行器，建立了末端剪切机构运动学与动态静力数学模型，并基于动态静力分析结果，以外部驱动力最小为目标采用遗传算法对末端执行器剪切机构杆件尺寸进行优化，优化得到曲柄长度为33 mm，连杆长度为60 mm，连杆延长杆长度为54 mm。为实现朝天椒茎秆切断，优化得到剪切机构需要外部驱动力矩0.94 N·m，根据优化结果选用舵机作为动力源。最后通过采收试验验证了朝天椒采收末端执行器的可行性。试验结果表明，末端执行器整体采收成功率为91.3%，验证了朝天椒末端执行器具有良好的采收性能。

Abstract:

The end effector is an important part of the harvesting robot. A fresh-eating pepper harvesting end effector was designed by using the cutting-off harvesting method for the growth characteristics of the single-growing pepper fruit. Firstly, the biological characteristics of Capsicum frutescens were tested. The physical parameters such as fruit length, fruit maximum diameter, stem diameter and stem length were measured. The maximum cutting force of Capsicum frutescens stem under different cutting methods and different cutting angles was tested. Secondly, according to the biological characteristics of Capsicum frutescens, the design of the end effector was carried out, and the kinematics and dynamic static mathematical model of the end shearing mechanism was established. Based on the results of dynamic static analysis, the genetic algorithm was used to optimize the rod size of the end actuator shearing mechanism. The length of the crank was 33 mm, the length of the connecting rod was 60 mm, and the length of the connecting rod extension rod was 54 mm. In order to realize the stem cutting of Capsicum frutescens, the shearing mechanism needed 0.94 N·m external driving torque. Therefore, the power source selected the steering gear with a load of 10 kg. Experiments showed that the overall harvesting success rate of the end effector was 91.3%, which verified the harvesting performance of the end effector of the capsicum, and had good harvesting performance, which provided an option for agricultural robots to harvest capsicum.