A control method for time-variant RCM constraint in hands-on RAMIS procedures

摘要

In robot assisted minimally invasive surgery long instruments are inserted inside the patient's body through tiny incisions in the patient's skin. During surgery, it is important to constraint the motion of the instrument not to stress the incision wall to avoid injuring the patient. Hence the incision point is desired to act like a remote center of motion (RCM). The breathing or/and heartbeat function means that the incision point is time-varying. With a general purpose manipulator such desired RCM should be actively imposed by the control function. In this work, we propose a control scheme that achieves this objective for hands-on procedures in which the robot is directly manipulated by the surgeon. The proposed control scheme is proved to satisfy the moving RCM constraint while the controlled robot is passive under the exertion of a human generalized force. Simulation and experimental results are given utilizing a KUKA LWR4+.