A pneumatic rotary actuator for forceps tip rotation

In this study, we propose a small rotary actuator mounted on the tip of a forceps manipulator for laparoscopic surgery. The proposed actuator comprises a soft actuator (SA) and a cylindrical cam mechanism that converts linear motion into rotary motion. The SA is made from silicone and driven pneumatically. Therefore, it is lightweight, inexpensive, and highly biocompatible. Using an SA, the entire rotary actuator can be made lighter and smaller. In addition, the actuator has the advantage of easy sterilization and disposability due to the absence of electrical parts in it. Furthermore, using air as the power source, one can control the rotation angle with only a simple control that is not affected by the forceps posture. In this study, we developed a prototype of the SA and measured its basic characteristics. Subsequently, we mounted the SA on the proposed rotary actuator and confirmed the basic characteristics of the actuator through cyclic motion and force measurement experiments. As a result of the experiments, a rotational angle of 70° or more was measured and the target motion range was achieved. In addition, we confirmed that the rotary actuator exerted a maximum torque of 3.0 N mm, which was sufficient for the needling task on a silicone seat.