Design and analysis of automatic whole row tomato seedling transplanter technology with integrated controlling system

Abstract

In the small-scale farming, transplantation of tomato is performed manually using hand drilling without considering the standard agronomy practices. To develop innovative products with reduced size and automatic operations, the analysis and design of the feeding, picking, and planting components of the automatic transplanting machine need to be the focus area. The integrated approaches of conceptual design, concepts evaluation and selection, synthesis and numerical modeling of mechanisms, path manipulator design, components and assembly SolidWorks modeling, Matlab and ADAMS software validation simulations, and PLC based control system design are used to develop the target technology. During design and analysis, a 128 cell standard plug tray, 42 mm grid depth, 110 mm average seedling height, 35 cm plant spacing, 40 cm row spacing, and 192 seedlings/min planting capacity were selected as design criteria. The results from kinematics analysis and optimal design of gripper indicated that the clamping and insertion angles should be in the ranges of 16 degrees-22 degrees and 10.6 degrees-14.8 degrees respectively to prevent damage. Furthermore, the optimum clamping angle (beta) and insertion angle (alpha) were found to be 20 degrees and 13.4 degrees respectively for successful clamping and picking of seedlings. A combination of linear and fourth order polynomial models have been developed to provide accurate trajectory plans for the path manipulator. The ADAMS software simulation results are directly fitted with the theoretical results, and the modeling of the seedling pickup mechanisms provides a basis for future bench tests. For a standard 128 cells plug tray, and target frequency of 192 seedlings/min, the pickup device with eight grippers is designed to effectively pick the whole row of tomato seedlings within 2.5 s. Finally, to synchronize the transplanting operations and ensure a continuous supply of signals, photoelectric positioning sensors, magnetic switches, pneumatic components, and PLC control unit are selected and positioned at the optimum locations.