Vibration-Based In-Hand Manipulation for Full Reconfiguration Control of Thin Objects
Robotic hands offer advanced manipulation capabilities, but their complexity and cost often limit their real-world applications. In contrast, simple parallel grippers, although affordable, are restricted to basic tasks like pick-and-place. Recently, a vibration-based mechanism was proposed to augment parallel grippers and enable in-hand manipulation capabilities for thin objects. Utilizing the stick-slip phenomenon, a simple controller successfully drove a grasped object to a desired position. However, the underactuated nature of the mechanism prevented direct control of the object's orientation. In this paper, we address the manipulation challenge of reconfiguring the object's position and orientation. Hence, we present the excitation of a cyclic phenomenon in which the object's center of mass rotates with a constant radius about the grasping point. Using this cyclic motion, we propose a strategy to manipulate the object to a desired configuration. Alongside an analytical study of the cyclic phenomenon, we propose using duty cycle modulation to operate the vibration actuator for more accurate manipulation. The proposed strategy is validated through finite element analysis, physical experiments and task-specific demonstrations.