Snake-like robots for endoscopic surgery make it possible to reach deep-seated lesions. With the use of small flexible tendon-driven instruments, it is possible to perform bimanual micro-surgical tasks that are challenging for standard endoscopic surgeries. Existing devices, however, lack articulated wrists and rolling motion of the end-effector. This paper presents a new instrument design with a distal-roll gripper for snake-like robots. The developed 5 DoFs miniaturized instruments with a diameter of 3 mm enable the deployment into narrow endoluminal channels. Issues related to actuation coupling, tendon slack, and backlash are addressed. Experimental results show that the distal-roll gripper can rotate 106°, and the actuated joints can achieve good repeatability and accuracy with the proposed compensation control scheme.

Snake-like robots are commonly used in Minimally Invasive Surgery as they are able to reach areas deep inside the human body. These robots have instruments that are deployed out of the robot's head and controlled via tendons, which connect the instrument to motors at the proximal end. In most currently available systems the instruments are lacking a rolling motion of the end-effector.In this paper, we present a new instrument prototype for a snake-like robot that can perform a stable in-place rolling motion. The prototype has a diameter of 4mm, uses 13 tendons and has 6 degrees of freedom. The robot can bend and roll to high angles, and strongly improves the dexterity compared to an instrument without rolling capabilities. In the evaluation we show that the rolling-tip gripper can rotate about 165° and is capable of applying forces up to 6.5N.

Over the last few years, there has been a significant rise in designing small, agile and flexible medical systems that can navigate through natural orifices. In the case of endoscopic surgery, existing systems vary significantly from each other which raises the question of the existence of a general design that can do it all. In this context, this paper proposes to use a genetic algorithm combined with recorded suturing and anatomical data to automatically design a pair of robotic instruments for the i2Snake under strict mechanical constraints. The resulting automatically generated instrument designs include a 6 degrees of freedom instrument that can follow a predefined trajectory accurately and a more simple 4 degrees of freedom instrument that can accomplish most of the task. The results also showed the importance of having a prismatic joint to gain the precision required for endoscopic surgery.

Snake like continuum robots are increasingly used for minimally invasive surgery. Most robotic devices of this sort that have been reported to date are controlled in an open loop manner. Using shape sensing to provide closed loop feedback would allow for more accurate control of the robot's position and, hence, more precise surgery. Fiber Bragg Gratings, magnetic sensors and optical reflectance sensors have all been reported for this purpose but are often limited by their cost, size, stiffness or complexity of fabrication. To address this issue, we designed, manufactured and tested a prototype two-link robot with a built-in fiber-optic shape sensor that can deliver and control the position of a CO2-laser fiber for soft tissue ablation. The shape sensing is based on optical reflectance, and the device (which has a 4 mm outer diameter) is fabricated using 3D printing. Here we present proof-of-concept results demonstrating successful shape sensing - i.e. measurement of the angular displacement of the upper link of the robot relative to the lower link - in real time with a mean measurement error of only 0.7°.