Theoretical analysis of velocity, acceleration and torque calculation of a five-bar onion transplanting mechanism

The seedling transplanting mechanism is one of the key components of onion transplanter. Therefore, kinematic analysis of the transplanting mechanism is helpful to calculate the operational efficiency and performance of the device. The purpose of this study is to perform theoretical analysis of a five-bar mechanism to calculate the velocity, acceleration and input driving torque as well as to select the appropriate combination of link bars for smooth transplantation of onion seedlings. 3D model assembly of the mechanism was theoretically modelled and its motion was simulated by using commercial software. The five-bar mechanism is comprised of a driving link, driven link, connecting link, slider and the fixed slot. The movement of the slider was constrained to follow a fixed slot pathway, which was the combination of a straight line and a circular path along the driven link bar. Four number of simulation trials were conducted with different lengths of link bars for the selection of the appropriate link combination and respective peak velocities and accelerations. Driving torque was calculated at 30, 40, and 50 rpm speed of the driving link. The simulated velocities and accelerations of the end effector in 'X' and 'Y' directions for appropriate link combination were found as 0.36 m/sec, 0.73 m/sec and 4.5 m/sec², 4.7 m/sec² respectively. The required driving torque were observed 3.8 Nm at 30 rpm to complete the one cycle of onion seedling transplantation. The outcomes of this study would provide a significant reference for the validation and development of an efficient transplanting scheme for onion transplanting.