Adaptive Inverse Kinematics of a 9-DOF Surgical Robot for Effective Manipulation

In a robotic-assisted surgical system, fine and precise movement is essential. However, when the user wishes to cover a wider area during tele-operation, the configuration designed for precise motion may restrict the user and/or slow down the system's operation. This paper proposes a kinematics based method applicable to redundant manipulators to allow the user to make both fast and precise movements and reduce the burden on the user. In the proposed method, different kinematic configurations are selected automatically in real-time to adjust the speed of the robot's end-effector according to the velocity of the haptic device. The proposed method is tested on a 9 Degree-of-Freedom (DOF) system that is realized by attaching a 3-DOF servo driven surgical instrument to a 6-DOF manipulator through a custom interface. The validity of the proposed method is shown with experiments requiring dexterous manipulation using the 9DOF system. The results indicate that adoption of the proposed method in actual operations can facilitate reduction in surgery time and surgeon's effort, thereby help reduce the risk of tissue deformations and other complications in the patient.