Design and Evaluation of a 3D Printed Reciprocating Actuation Mechanism with Cutting Trajectory Pattern for Green Wall Machines

Highlights 3D-printed prototype trimming machine for green wall maintenance. Scotch yoke driven reciprocating blade for efficient trimming of foliage. Mathematical model and simulation of reciprocating blade cutting trajectory. FarmBot-controlled trimming tool for vertical surface maintenance. ABSTRACT. This study utilized Computer-Aided Design (CAD) software for the design and 3D printing for the fabrication of prototype trimming machines. The primary objective of the trimming mechanism is to sever excessively long branches and leaves, with an effective cutting rate serving as the principal performance indicator. The prototype employs a Scotch yoke mechanism to generate reciprocating motion for a double-acting blade, characterized by a different set of structural parameters. A mathematical model describing the blade trajectory of the reciprocating double-acting cutter was derived. Subsequently, the Desmos graphing calculator was employed to generate cutting profiles for the prototypes, facilitating the calculation of their effective cutting rates. The analysis revealed that the maximum effective cutting rate of 78.38% was achieved when the cutting stroke was 1.5 times the blade height, under structural parameters of a blade width of 0.44 mm, a blade height of 20 mm, a land width of 23.5 mm, and a shear angle of 30°. Reducing the cutting stroke to 15 mm resulted in a decrease in the overall effective cutting rate but an increase in the cutting efficiency due to a reduction in the uncut area. Keywords: CAD/3D printing, Cutting trajectory, Green wall machines, Reciprocating cutter, Scotch yoke mechanism.