Design of a tether-driven minimally invasive robotic surgical tool with decoupled degree-of-freedom wrist.

Abstract

Dexterous surgical tool wrists used in tele-operated robotic surgery typically have mechanically coupled pitch and yaw degree of freedom (DoF). This leads to complex control requirements. The design of a robotic surgical tool with a mechanically decoupled dexterous wrist which uses stationary tether guides to guide drive tethers is presented. The tethers are routed through the plane of symmetry of the tool and follow law of belting to mechanically decouple the wrist. An optimization procedure for the placement of the stationary tether guides to minimize the change in tether length is presented. Experimental and analytical results confirm the decoupled motion capability of the wrist. Also, the change in length of tether segments over the operating range of motion was found to be very small. A prototype has been fabricated through metal 3D printing and integrated to a tele-operated robotic setup to demonstrate its utility in surgical application.