Development of Forceps Manipulator Using Pneumatic Soft Actuator for a Bending Joint of Forceps Tip

In this paper, a forceps manipulator using a pneumatic soft actuator for a flexion joint of forceps tip is developed. Many forceps manipulators are driven by wires, however there are problems such as friction between wires and parts and interference between wires. Therefore, this problem is solved by using the soft actuator, which performs bending of two degrees of freedom joint driven by air pressure instead of wires. The soft actuator is made of a silicone rubber and reinforced by two metal springs. It is easy to fabricate the soft actuator by using a metal spring. The outer spring restrains the radial expansion of the soft actuator, and the inner spring is placed in the center of the soft actuator to reinforce the bending stiffness. The actuator has four chambers, and it is possible to bend the soft actuator by inputting air into each chamber. An air gripper is mounted on the tip of the soft actuator. The bending angle of the forceps is estimated by the pressure in the chambers. The total length of the developed forceps is 340 mm, the weight is 23 g, and the maximum bending angle is 53 deg. By using the soft actuator for the bending joint itself, a simple and lightweight forceps manipulator with no driving unit at the rear end is realized.