Robotic hands offer advanced manipulation capabilities, while their complexity and cost often limit their real-world applications. In contrast, simple parallel grippers, though 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. By utilizing the stick-slip phenomenon, a simple controller was able to drive a grasped object to a desired position. However, due to the underactuated nature of the mechanism, direct control of the object's orientation was not possible. In this letter, we address the challenge of manipulating the entire state of the object. Hence, we present the excitation of a cyclic phenomenon where the object's center-of-mass rotates in a constant radius about the grasping point. With this cyclic motion, we propose an algorithm for manipulating the object to desired states. In addition to a full analytical analysis of the cyclic phenomenon, we propose the use of duty cycle modulation in operating the vibration actuator to provide more accurate manipulation. Finite element analysis, experiments and task demonstrations validate the proposed algorithm.

翻译：机械手提供了先进的操控能力，但其复杂性和成本往往限制了其实际应用。相比之下，简单的平行夹爪虽然经济实惠，但仅限于拾取-放置等基本任务。最近，有人提出了一种基于振动的机制来增强平行夹爪，使其能够对薄片物体进行手内操控。通过利用粘滑现象，一个简单的控制器能够将被抓取的物体驱动到期望位置。然而，由于该机构的欠驱动特性，无法直接控制物体的方向。在本文中，我们解决了操控物体完整状态的挑战。为此，我们提出了一种循环现象的激励方法，其中物体的质心围绕抓取点以恒定半径旋转。利用这种循环运动，我们提出了一种将物体操控至期望状态的算法。除了对循环现象进行完整的解析分析外，我们还提出在操作振动执行器时使用占空比调制，以提供更精确的操控。有限元分析、实验和任务演示验证了所提出的算法。