Design and Force Analysis of the Robot End-effector of a Semi-Automated Laparoscopic Instrument using Finite Element Analysis

Laparoscopic surgery is a procedure where small incisions are made compared of the conventional open surgery that involves large incisions. Despite having the benefit of faster healing and fewer scars, it is very difficult to operate due to tight spaces and awkward positions of the surgeons. To overcome such difficulties, a semi-automated laparoscopic instrument was designed. It features joint articulation and has 4 degrees of freedom (DOF). Verification of the design is needed to tell whether it meets the needed operation specification. In this paper, a design of the joint articulating end-effector with a grasper of laparoscopic instrument was presented. The finite element analysis (FEA) package of CATIA V5 was used for the design analysis. The constraints were determined upon starting the FEA while the connections and contacts between the parts were also determined. Several FEA connection types were determined based on the relationship among the parts. A 5-N force, based on the average human liver weight, was applied to the tip of the end-effector. Results presented the errors of the assembly analysis, Von Mises stress and maximum deformation of the assembly. It was concluded that the design was capable of the 4DOF movements, which are the following: rotation along the axis, 90° shaft bending, grasp clamping action and end-effector rotation. A more accurate finite element analysis was performed when the parts are assembled and the overall stress and deformation acquired was also within acceptable range of operation.