Factors influencing the performance of mechanical end effector during automatic transplanting of tomato seedlings

Abstract

A number of elements of probabilistic nature mightily influence the picking efficiency of a transplanting mechanism. There are two key factors to be considered in the development of seedling pickup devices. One is the mechanical features of the end effector, and the other is the horticultural features of the protray seedling. The investigation aimed to find the features affecting the transplanting of protray grown tomato seedlings using mechanical end-effectors. Various mechanical linkage-picking fingers were developed and tested with an experimental setup for gripping and releasing the seedling. Two different pneumatic cylinders triggered the mechanical end effector, one for holding the seedling and then ejecting the seedling from the protray. When all the seedlings were ejected from the initial line of the protray, the endless belt shifted the protray just below the end-effector mechanism. Assessments were carried out with moisture content of media (16 ±1, 18 ±1 and 21 ±1%), mechanical end-effector (sliding plate cam type, sliding end cam type and four bar type picking finger)  angle of end-effector needle (6, 8 and 10 deg.) to enhance the picking, transmission and dropping with low missing as well as harms for the seedlings. The minimum value of missing seedlings (6.55 %) and maximum success rate of picking (93.45 %) were noted at 18 ±1% of the growth media moisture content (M₂) and at 8 deg. angle of gripper needle (θ₂) with a sliding plate cam-type picking finger (F₁). The transplanting frequency was 840 seedlings h^-1.