A prototype master-slave system consisting of two MR-compatible manipulators with interchangeable surgical tools was designed, implemented, and evaluated. The manipulators are designed so as to fit into vertical-magnetic-field open-configuration MR imagers. They are also designed so that the surgical tool mounted at the tip of their arm is interchangeable. The MR compatibility of the manipulator including a surgical tool was evaluated by moving it close to a phantom in the field of view of an open-configuration MR imager. No noticeable deformation, but deterioration in the signal-to-noise ratio of approximately 10 percent, was observed in the MR images. Consulted clinicians then evaluated the manipulability of the master-slave system by maneuvering a pair of slave manipulators through an operation input device consisting of a pair of master manipulators. After several minutes of trial and error, they could perform each primitive motion for suturing tasks on training material mimicking human tissue.

Minimally invasive direct coronary artery bypass (MIDCAB) requires of surgeons precision of hand skill and mental concentration, since it needs to work on beating hearts. We propose a surgical robot system that compensates motions of organs during operations. The motion canceling robot system consists of three technologies; visual synchronization, motion synchronization and master-slave control. The visual stabilization provides the surgeon with the image of stabilized target point on the video monitor. The surgeon operates the master robot referring to the stabilized image. The motion stabilization, on the other hand, controls the slave robot being synchronized with the heart beat, which is the function of the master-slave control. Master-slave transforms the master motion and controls the slave robot. In this paper, we verify the effectiveness of the prototype system by in-vivo experiment.