Gripping mode analysis of an active-passive composited driving self-adaptive gripper mechanism

To meet the need of diverse tasks during on-orbit service, a self-adaptive end effector based on an active-passive composited driver is proposed, which is a two-finger underactuated gripper. This paper focuses on the gripping mode analysis of the proposed gripper. Firstly, the kinematics of the gripper is explained. Secondly, the static equilibrium conditions are deduced from the input and the output virtual powers. Known from the statics, the contact forces in the equilibrium state between the gripper and the object rely not only on the geometrical configuration, but also on the contact locations. While the gripping mode of gripper depends on the contact forces in the constraint space, it leads to the mechanical adaptation of the gripper to the shape of the object based on different contact locations, resulting in different gripping modes, including parallel grip, encompassing grip. Finally, an experimental setup is implemented to analyze the capture process of the gripper towards different shaped objects, and the results validate the self-adaptability of the active-passive composited driving gripper, which lays the foundation for mechanical design and control strategy in future work.