A Forceps Manipulator With Flexible 4-DOF Mechanism for Laparoscopic Surgery

In this paper, a forceps manipulator for minimally invasive surgery is developed. The developed forceps has 4-DOF inside the abdominal cavity so that pivoting motion around the entry point is reduced, avoiding the interference with other manipulators or surgeons. The 4-DOF motion is realized using flexible joints that are driven by push-pull wire of superelastic alloy, which make the mechanism of the forceps simple and, thus, low cost and reliable. Since the wires of the forceps are driven by compact pneumatic cylinders, the manipulator is lightweight and achieves high power-to-weight ratio. Kinematic and dynamic models of the proposed forceps are derived considering the flexibility of the joints and friction of the wires. A position control law of the endpoint of the forceps is shown and tracking performance is confirmed by an experiment.