NONRESTRAINT MASTER SYSTEM FOR SURGICAL ROBOTS

Purpose: To overcome the anisotropic characteristics caused by nonuniform friction and singularity in mechanical master interfaces in minimally invasive surgical robot systems, we developed a nonrestraint optical master interface. Materials and Methods: The interface was developed using high-resolution infrared cameras and small reflection markers attached on handheld tongs. We derived 7-degrees of freedom (DOF) motion of the tongs from the kinematic solution of three markers. The accuracy of 3-DOF rotational motion was examined to verify the spatial resolution. The manipulability of the developed nonrestraint master system was evaluated by comparing it with a mechanical master interface (Phantom Premium, SensAble Inc.). Results: The rotational discrepancies were less than 1.72 degrees, 0.39 degrees, and 0.87 degrees for roll, pitch, and yaw, respectively. The motion comparisons, including straight line, circle, and eight-shape motions, indicated that the nonrestraint master could achieve movements that are more natural. Discussion: In vitro tests showed the feasibility of the proposed nonrestraint optical master interface for use with surgical robots. Because the proposed interface allows natural motion capability, more intuitive surgical motions are possible. In addition, the motion range are expected to increase and the problems associated with master-slave coupling are expected to reduce by our nonrestraint master interface.