An Autonomous Procedure for Scoop Grasp Exploiting Hand Reconfigurability

This thesis presents a method to grasp objects using the novel Soft Scoop Gripper (SSG). The main features of this hand are represented by the scoop and by the reconfigurability of its fingers. The first acts as an embodied environmental constraint (EC), it allows to facilitate the grasp and improves its robustness while also reducing the planning effort. The second allows adopting a single strategy for grasping objects of different sizes. The thesis proposes three fingers’ configurations that are designed to deal with various objects. These configurations are the results of a preliminary grasp analysis of 12 initial settings. The grasp strategy we consider is the so-called scoop grasp, where the scoop adapts its orientation to the surface where it slides, while the soft fingers establish reliable contact with the object. The hand positioning for grasping the object is implemented using a recently proposed functional model for soft hands, the closure signature. Besides, we define criteria to discriminate the optimal fingers’ setting to approach a given object exploiting the position of the closure application point. Whereas, we implement a hybrid force-velocity controller to execute the sliding motion on the surface. We conducted 250 grasping trials with 13 different objects using the SSG attached to a collaborative robot arm. Experiments showed that the adopted heuristic criteria confirmed the initial hypothesis. The deliberate exploitation of environmental constraint enables achieving robustness in robotic grasping, providing robotic systems abilities that were inconceivable with rigid end-effectors.