A Prismatic-Revolute-Revolute Joint Hand for Grasping From Unmanned Aerial Vehicles and Other Minimally Constrained Vehicles

Here, we present the design, fabrication, and evaluation of a prismatic-revolute-revolute joint hand called the model B that we developed for grasping from ungrounded vehicles. This hand relies on a prismatic proximal joint followed by revolute distal joints in each finger and is actuated by a single motor-and a tendon-based underactuated transmission. We evaluate this design's grasping capabilities both when fully constrained by a robotic arm and when minimally constrained and evaluate its performance in terms of general grasping capabilities and suitability for aerial grasping applications. The evaluation shows that the model B can securely grasp a wide range of objects using a wrap grasp due to the prismatic-revolute-revolute joint finger kinematics. We also show that the prismatic proximal joints and between finger coupling allows the hand to grasp objects under large positional uncertainty without exerting large reaction forces on the object or host vehicle.