Design and Test of a Lateral-Approaching and Horizontal-Pushing Transplanting Manipulator for Greenhouse Seedlings

Highlights A lateral-approaching and horizontal-pushing automatic transplanting manipulator was developed on the basis of cultural practice for vegetable production. The transplanting manipulator approached the seedlings using a circuitous path, which could get away from the seedling plants for extraction with low damages. Based on the modern mechatronics and pneumatic technology, a set of control system was designed to coordinate each function unit for flexible automation. Abstract. A lateral-approaching and horizontal-pushing transplanting manipulator for greenhouse seedlings was developed to minimize the damage of their stems and leaves during transplanting. The manipulator is composed of a pick-up robotic arm, an end-effector, two conveyors, and a control system. The robotic arm liking a spatial 3-DoF displacement mechanism to achieve a point-to-point circuitous locomotion of the end-effector was designed with the mechanism combination innovation method, which consisted of two crossing high-speed linear modules and a pushing slide cylinder. The end-effector of a pincette-type mechanism uses two cylinder fingers and four pins to pick up and release the seedlings. Each conveyor adopts a flat-belt transmission mode to move the plug tray/growth pot to the working position of the end-effector. The control system coordinates the flexible automation of each component. A physical prototype of the manipulator was constructed and its performance was tested under laboratory conditions. Through the high-speed camera test, the end-effector could approach plug seedling in lateral sliding way to effectively shelter the seedling plants. On the whole, the maximum holding angles of these seedling plants were larger than 45° with little effects on the subsequent growth. The corresponding performance tests showed that the average success ratios for automatic transplanting were up to 97.57% for typical pepper and cabbage seedlings. The lateral-approaching and horizontal-pushing transplanting performance was satisfactory. Keywords: Circuitous path, Greenhouse production, Low damage, Plug seedling, Transplanting.