In this paper, a master-slave surgical robot system with heartbeat synchronization mechanism for off-pump CABG suturing operation is developed. This robot system is composed of a master manipulator, a slave manipulator, a heartbeat sensing system and a compact flexible endoscope system. The heartbeat sensing system measures 6 DOF heartbeat motion in real-time. The position of the slave manipulator is controlled as synchronizing with heartbeat. The compact flexible endoscope is fixed to a heart using a soft coupling which is used in medical case, so that the relative position between a heart and the compact flexible endoscope is maintained constant. Moreover, the surgical robot system is controlled in master-slave control method for surgeon's tele-operation. Therefore this system is able to perform surgical procedure while the system synchronizes with the heartbeat. In order to evaluate the performance of the system, the synchronization ability test, the master-slave operation test in vivo, and the performance of suturing operation under synchronization were conducted. In the result of the first test, it was showed that the maximum error between desired position and experimental position in the synchronization control was less than 1mm. In the second test, it was confirmed that the system was able to suture a pericardia, which was not beating. In the third test, it became clear that the maximum error between the desired position and experimental position was less than 1.24 to 2mm and the system was able to suture an isolated tissue which was driven by a robotic heartbeat phantom in 1Hz.
