Robotic Forceps with a Flexible Wrist Joint Made of Super Engineering Plastic

A pair of miniaturized robotic forceps with a flexible wrist joint has a problem of a trade-off relationship between rigid and flexible characteristics of the joint with metal parts. Regarding the problem, in this paper, we present a pair of robotic forceps in which the flexible wrist is made of super engineering plastic that is widely used for medical instruments because of its superior heat resistance, chemical stability, and mechanical strength. A prototype flexible wrist part is designed using polyetheretherketone (PEEK) with 12 machined slits, and the bending and grasping motions of the forceps are realized by wire actuation. The performance evaluation results show that the PEEK flexible joint can maintain its bending range even if an axial compressive force is exerted. It is durable to a compressive force of 30 N, and the relationship between the compression extent and the compression force is linear. The PEEK flexible joint is durable to bending up to 10000 times without markedly changing its bending mechanical property. Finally, it is rigid enough to output a force more than 1.2 N from the forceps gripper to the environment. Experimental results in this study indicate that the developed forceps has a basic feasible performance for robotic surgery.