We introduce a reconfigurable underactuated robot hand able to perform systematic prehensile in-hand manipulations regardless of object size or shape. The hand utilizes a two-degree-of-freedom five-bar linkage as the palm of the gripper, with three three-phalanx underactuated fingers, jointly controlled by a single actuator, connected to the mobile revolute joints of the palm. Three actuators are used in the robot hand system in total, one for controlling the force exerted on objects by the fingers through an underactuated tendon system, and two for changing the configuration of the palm and, thus, the positioning of the fingers. This novel layout allows decoupling grasping and manipulation, facilitating the planning and execution of in-hand manipulation operations. The reconfigurable palm provides the hand with a large grasping versatility, and allows easy computation of a map between task space and joint space for manipulation based on distance-based linkage kinematics. The motion of objects of different sizes and shapes from one pose to another is then straightforward and systematic, provided the objects are kept grasped. This is guaranteed independently and passively by the underactuated fingers using a custom tendon routing method, which allows no tendon length variation when the relative finger base positions change with palm reconfigurations. We analyze the theoretical grasping workspace and grasping and manipulation capability of the hand, present algorithms for computing the manipulation map and in-hand manipulation planning, and evaluate all these experimentally. Numerical and empirical results of several manipulation trajectories with objects of different size and shape clearly demonstrate the viability of the proposed concept.

我们介绍了一种可重新配置的欠驱动机器人手，无论物体大小或形状如何，都能执行系统的可抓握的手部操作。手采用二自由度五连杆机构作为抓手的手掌，三个三指骨欠驱动手指，由单个执行器共同控制，连接到手掌的移动旋转关节。机器人手系统中总共使用了三个致动器，一个用于通过欠驱动的肌腱系统控制手指施加在物体上的力，两个用于改变手掌的配置，从而改变手指的位置。这种新颖的布局允许将抓取和操纵解耦，促进手头操纵操作的规划和执行。可重新配置的手掌为手提供了广泛的抓握多功能性，并允许基于基于距离的联动运动学轻松计算任务空间和关节空间之间的映射以进行操作。如果物体被抓住，不同大小和形状的物体从一种姿势到另一种姿势的运动就变得简单而系统。这是通过使用自定义肌腱布线方法的欠驱动手指独立和被动地保证的，当相对手指基部位置随着手掌重新配置而变化时，肌腱长度不会发生变化。我们分析了手的理论抓取工作空间和抓取和操纵能力，提出了计算操纵图和手部操纵规划的算法，并通过实验评估了所有这些。