A Robotic System with Multichannel Flexible Parallel Manipulators for Single Port Access Surgery

Robot-assisted single port access surgery (SPAS) brings significant benefits to the patients. However, it is challenging due to the limited incision size and requirements in precision, load capacity, and dexterity. To address these challenges, this paper presents a multichannel SPAS robotic system consisting of two channels of 5-degree-of-freedom (DOF) flexible manipulators and an endoscope channel. Each channel of the manipulators is designed based on a 3-DOF parallel mechanism with three sets of super-elastic Ni-Ti rods and universal joints. This design optimizes the structure for flexibility and safety considerations with a simplified structure compared with conventional parallel mechanisms. Flexible shafts are used for torque transmission from the actuation unit, allowing the motors to be farther away from the patient-side robotic system. The kinematics of the manipulator is derived, and then the reachable workspace and dexterity are analyzed. Furthermore, a prototype of the proposed robotic system is presented and evaluated through adequate experiments. The flexibility of the manipulator is verified via stiffness characterization test. The results of the accuracy tests confirmed that the robotic system can implement manipulation arm with acceptable accuracy. The feasibility and effectiveness of applying the robotic system to the practical operation are also demonstrated through experimentations.