Design And Implementation Of Multi-configuration End-effector For Robot Assisted Minimally Invasive Surgery

Robot had been introduced into medical area to assist surgeons in operations,with its end effector performing a key role in handling the target issue. The robotarchitecture with rigid arm and dexterous end effector had been approved with bothexcellent trajectory precision and complete operation capability. To achievemulti-manipulation in robot assisted minimally invasive surgery (MIS), this thesis hadintegrated more than one configurations into an end effector mechanism. Presentedherein were outcomes in related aspects:The first topic began with requirement consideration and proposal of amulti-configuration end effectors in robot assisted MIS. With introduction andcomparison of open abdomen surgery, traditional and robot assisted MIS, the workingfeatures and drawbacks of correlative end effectors had been derived. To avoidinherently exchange of end effectors in robot assisted MIS, the single configurationend effector was proposed to be upgraded with a multi-configuration end effector. Thegeometric dimension of the multi-configuration end effector was restricted to reducetrauma to patient. Orientation joints were incorporated into the multi-configurationend effector to ensure enough dexterity inside patient abdomen. The basic mechanicalstructure of the end effector was preferred to be metamorphic, which could vary theend-effector among miniature and normal volumes. Three independent manipulatorswere assigned to the metamorphic mechanism, working as the cooperative units formulti-manipulation. And they would be controlled with a master-slave method ratherthan common program solutions.The second portion had constructed and analyzed a10DOF multi-configurationend-effector for robot assisted MIS. The metamorphic mechanism for the end-effectorwas derived from a slider crank mechanism. A wrist joint was added to the originalplanar mechanism to improve the dexterity. The minimum folded dimension of theend-effector was24mm, indicating an acceptable incision size to patient abdomenskin. Three independent finger-like manipulators were designed and installed to themetamorphic mechanism, and they could cooperate with each other in differentmanipulation configurations inside patient abdomen. Wheele, flexible metal tendonand sheath were employed as transmission method for the joints of the multi-configuration end-effector, including its metamorphic mechanism andfinger-like manipulators. The metamorphic process was described and analyzed withadjacency matrix and geometric method. The screw theory was used to establish andexploit the kinematics of the finger-like manipulators. Grasp theory was taken todescribe the manipulation models of the end-effector, which were with two and threefinger-like manipulators respectively.The third segment developed a master-slave control system for themulti-configuration end-effector. Considering the basic structure of said end-effector,a roughly isomorphic master control manipulator was prototyped for controlling itsmotion. The master control manipulator was consisted of two gesture joints and threefinger control manipulators. The forward kinematics of the master controlmanipulator was established with screw theory, meantime the inverse kinematics ofthe thumb manipulator in end-effector was derived for master-slave isomeric mapping.Based on the manipulation configurations of the end-effector, master-slave mappingmodels were analyzed and obtained. PMAC motion controller was selected as corehardware to set up the control system, which fulfilled the functional requirements forthe multi-configuration end-effector, including initialization, master-slave mappingand manipulation configuration variations.Lastly, with the tasks mentioned above finished, a set of phantom experimentshad been carried out due to different manipulation configurations of the end effector.And the result had approved the multi-manipulation capability of this novel device.