An Articulated Robotic Forceps Design With a Parallel Wrist- Gripper Mechanism and Parasitic Motion Compensation

In this paper, a novel four degrees-of-freedom (4DOF) articulated parallel forceps mechanism with a large orientation workspace (+/- 90 deg in pitch and yaw, 360 deg in roll rotations) is presented for robotic minimally invasive surgery. The proposed 3RSR-IUUP parallel mechanism utilizes a UUP center leg that can convert thrust motion of the 3RSR mechanism into gripping motion. This design eliminates the need for an additional gripper actuator, but also introduces the problem of unintentional gripper opening/ closing due to parasitic motion of the 3RSR mechanism. Here, position kinematics of the proposed mechanism, including the workspace, is analyzed in detail, and a solution to the parasitic motion problem is provided. Human-in-the-loop simulations with a haptic interface are also performed to confirm the feasibility of the proposed design.