Setup and Method for Remote Center of Motion Positioning Guidance During RobotAssisted Surgery During robotassisted surgery, a Remote Center of Motion (RCM) is often implemented to constrain instrument motion through and about a specific point in space. Aligning and repositioning this point during surgery is not trivial, as this is a defined, yet often nonvisualised, point in space. When misaligned with the patient surrounding anatomy is excessively strained, potentially causing postoperative complications. Not being able to safely reposition the RCM for these purposes limits the use of surgical robotics. This work introduces a general approach relying on anatomybased haptic fixtures to simplify and improve RCM positioning during robotassisted surgery. The proposed approach is extended with a novel method and mechanism to mechanically implement such fixtures. This is applied for the use case of vitreoretinal surgery, for which purpose a dedicated robotic setup and fixture mechanism was developed. These were used to conduct an initial experimental validation, during which the feasibility of both a virtual and mechanical implementation is reviewed. Initial outcomes suggest that both implementations are feasible. With the currently used impedancetype system, the mechanical implementation is shown to offer at least one order of magnitude stiffness increase when compared to an equivalent virtual implementation.

Toward Improving Patient Safety and Surgeon Comfort in a Synergic RobotAssisted Eye Surgery: A Comparative Study When robotic assistance is present into vitreoretinal surgery, the surgeon will experience reduced sensory input that is otherwise derived from the toolxe2x80x99s interaction with the eye wall (sclera). We speculate that disconnecting the surgeon from this sensory input may increase the risk of injury to the eye and affect the surgeonxe2x80x99s usual technique. On the other hand, robot autonomous motion to enhance patient safety might inhibit the surgeons tool manipulation and diminish surgeon comfort with the procedure. In this study, to investigate the parameters of patient safety and surgeon comfort in a robotassisted eye surgery, we implemented three different approaches designed to keep the scleral force in a safe range during a synergic eye manipulation task. To assess the surgeon comfort during these procedures, the amount of interference with the surgeons usual maneuvers has been analyzed by defining quantitative comfort metrics. The first two utilized scleral force control approaches are based on an adaptive force control method in which the robot actively counteracts any excessive force on the sclera. The third control method is based on a virtual fixture approach in which a virtual wall is created for the surgeon in the unsafe directions of manipulation. The performance of the utilized approaches was evaluated in user studies with two experienced retinal surgeons and the outcomes of the procedure were assessed using the defined safety and comfort metrics. Results of these analyses indicate the significance of the opted control paradigm on the outcome of a safe and comfortable robotassisted eye surgery.