Control of a robotic gripper for grasping objects in no-gravity conditions

In space applications, it is conceivable that part of the robotic activities could involve the grasp and/or manipulation of free-floating objects in absence of gravity. In this case, synchronous application of contacts seems to represent a basic feature in order to efficiently grasp the floating items. In this sense, an additional difficulty is that objects may have irregular shape and/or be non well positioned in the gripper workspace. These difficulties cannot be handled in a simple way with standard 2-jaw grippers, with one (or two) degrees of freedom. In this paper, an activity for designing and experimenting a gripper for this type of operations is reported, and the first laboratory results are presented and discussed. Main features of the gripper are its kinematic configuration (3 fingers with 3 dof) and its sensorial equipment, features that improve the dexterity of this device if compared to more classical devices.