Development of a soft gripper for replicating human grasps in forest nursery tasks

Abstract

This research aims to automate labour-intensive tasks in forest nurseries by developing a soft gripper that mimics human workers' grasps to perform the singulation and sorting of tree saplings. By analysing human workers and conducting experimental investigations, the required grasp types and grip forces were identified. The Fin Ray Effect (FRE) structure, noted for its adaptability to asymmetric shapes, was chosen as the gripper's basis. However, modifications were necessary to achieve the required power and pinch grasp types and to provide the desired grip forces. Simulation analysis explored various beam configurations and boundary conditions of FRE fingers, resulting in a proposed modified design. Experimental investigations confirmed that the proposed gripper effectively delivered required grasps and grip forces. The new design enabled three additional grasp types for FRE grippers and increased grip forces by over 200 %. This gripper design is suitable for industrial pick-and-place applications where precise pinching grasp and various power grasps with sufficient payload capacity are needed.