Design of a Flexural Transmission for a Dexterous Telesurgical Robot for Throat and Upper Airway: A Preliminary Result

INTRODUCTION It has been percieved by the community that one of the future significant challenges for designing surgical robots is the enhancement of robot’s mobility subject to the confined environments. Recently, Simaan, Taylor et al. [1-5] have developed a telesurgical robot for this kind of concerns. Their purpose is to design a highdexterious surgical robot which can effectively work in a confined environment such as the throat and upper airway. The aforementioned robotic system uses the masterand-slave concept as its structure. It basically consists of a da Vinci master, a stereoscopic capture and display subsystem, and a dual-arm robotic slave [5]. The master console is maneuvered by the surgeon to control the slave robotic arms, and the two slaves are supposed working together in a narrow space, like the throat and airway, to carry out the surgical operation cooperatively. Subject to the confined environment, the workspace of the slave robotic arms is limited by a long, narrow and irregularly shaped throat which can be described by a 50mm long cylinder with 40mm in diameter located 180-250mm axially down the throat [5]. Limited by the long and narrow channel, the slave arms are expected to do dexterous surgical operation such as suturing and tying knot via its end-efffectors which are located in the confined working space. Based on the design requirements and specifications as described above, the slave robotic arm has been sodesigned with a lengthy structure, Fig. 1(a). Basically, it is composed of a gross actuation unit, a hollow transmission tube and a distal dexterious unit (DDU) at which the surgical operation will be performed. The hollow transmission tube attachs the actuation unit and the DDU at its both ends, and it houses four superelastic wires for delivering the motor motion from the actuation unit to the DDU. The DDU adopts a multi-backbone snake-like robot [1] as shown in Fig. 1(b), from which the pitch-and-roll motion of the moving platform is controlled by the three outer wires (Element 3) and the grasping of the gripper is controlled by the central wire (Element 4). The whole robotic arm is engaged with a screw mechanism called the “z-θ stage” which is attached to the frame and is used to provide the yaw motion and the top-and-down motion for the DDU. Actuation unit (controlling the 3 DOFs of the DDU, i.e., pitch‐and‐roll motion and grasping)