Preliminary Design of a Robotic System for Catching and Storing Fresh Market Apples

Abstract

This paper presents the preliminary design of a two-link planar manipulator for fresh market apple catching. Rather than use the harvesting manipulator to place picked apples in a storage container, the secondary system catches and stores apples at the point of fruit separation in order to minimize path length and improve cycle time. Monte Carlo simulations were used to select link lengths and joint limits. The design includes two low cost stepper motors and a vacuum assisted end-effector. After fabrication, laboratory studies were conducted to measure the system’s repeatability and validate the proof-of-concept. A conservative estimate of repeatability is 20 mm, which is within the catching end-effector’s effective workspace. During integrated system testing in the lab, the secondary system caught all harvested fruit. Likewise, the pick-and-catch technique resulted in an approximately 50 percent reduction in overall cycle time compared to the conventional pick-and-place method. Future work will include development of an end-effector prototype with soft elements to minimize fruit bruising.