Pneumatically Driven Surgical Instrument with Attach/Detachment Mechanism and Force Sensibility

Abstract

In robotic-assisted surgery, translational and gripping force sensing at the instrument tip plays a significant role. On the other hand, for clinical use, the instrument must be separatable into a clean unit, an unclean, and a separator. This is because that its insertion part is required sterilization, although it has parts that cannot be sterilized such as actuators and sensors. However, the instruments that satisfy the requirement is not reported due to the mechanical interference and the force sensing method. In this paper, we developed a pneumatically driven surgical instrument with attachment/detachment (A/D) mechanism and force sensibility. It has a gripper and two-DOF wrist joint which are driven by pneumatic cylinders via wires. Estimation of both forces is based on the dynamics of the instrument. In the A/D mechanism, we adopt the magnets as the separator to reduces the number of parts and sliding parts. We proposed that by using the direction of the magnetic force, driving the instrument tip and working the A/D mechanism are controlled by an only linear motion of the cylinder. The controllers are developed and its performance is experimentally confirmed. The mean absolute error (MAE) of the translational force estimation is 0.05 N and the gripping is 0.09 N. It performance is approximately the same as our previous work which does not have the A/D mechanism. It shows the influence of the mechanism is negligibly small and the effectiveness of the A/D mechanism.