Customizable Power Grasps From Uncrewed Aerial Vehicles via a Soft “Wrapping” Gripper

Having uncrewed aerial vehicles (UAVs) pick loose objects up from the ground poses several challenges. While soft grippers are a potential solution, they must be appropriately designed to address positional errors of the UAV, perturbations to UAV dynamics during grasps, while maximizing the variety of objects that can be grasped. This article presents a customizable gripper with compliant 3-D printed “rib” structures that “wrap” around objects while bringing them to the center of a UAV. The gripper possesses a large circular work envelope and motorized planar actuation. By co-optimizing the rib thickness, contact surface pattern, print infill, and motor torque, the interaction between the soft morphology of the ribs and gripper actuation can be directed toward power grasping of a general object set. The co-optimization process utilizes Bayesian optimization, evaluating the objective of success rate in grasping via physical pick and place bench experiments that emulate UAV flight. The average success rate of the gripper in grasping the object set improved by 10.2%, but significant gains were made for several object groups, showing the efficacy of the co-optimization to customize the gripper for different grasping tasks. These results were validated with untrained objects and quadcopter field tests. The effects of gripper design and grasping on flight stability were also measured, and found to induce insignificant disturbances.