Development of a surgical robotic arm not requiring positioning on an insertion port with semi-active joints

In this study, we develop a pneumatic surgical robotic arm not requiring positioning a RCM(Remote center of motion) of the robotic arm on an insertion port of a patient. We use a joint that do not have stiffness but have ability to output torque. We call this joint “semi-active joint”, and realize them with a pneumatic actuator with high backdrivability. Using the semi-active joint, the posture of the robot is formed passively by a constraint of the insertion port. Plus, the robotic arm can be expected to compensate external forces in abdomen. We controlled its end point in a constraint of the insertion port, and evaluated about accuracy of its movement and forces exerted to the insertion port.