Development of a Novel Multipurpose Robotic End Effector for Fruitlet Thinning and Fruit Harvesting of Apples

Abstract

This paper presents a novel multipurpose end effector for robotic applications, characterised by its vacuum suction, rotation capabilities, modular design, and versatility in both apple thinning and harvesting. The key feature is enabling interchangeable suction cups by isolating the rotation mechanism from the suction mechanism. The suction cups sizes can then be changed based on the target fruit or fruitlet diameter sizes and damage protection requirement of the target. This end effector was first evaluated in both laboratory settings and real-world commercial apple orchards for apple fruitlets. In laboratory evaluation, the best performance occurred when its rotation axis was closely aligned with the fruit’s calyx-stem axis. The increased deviation between the two axes results in slippage and obstruction from surrounding fruits or fruitlets. Field tests in commercial orchards yielded a 66.1% success rate for apple thinning, and the main limitation was also due to the misalignment between the two axes. The end effector was also successfully preliminary field tested for apple harvesting, showing promise of its feasibility.