Setup and Method for Remote Center of Motion Positioning Guidance During Robot-Assisted Surgery

During robot-assisted surgery, a Remote Center of Motion (RCM) is often implemented to constrain instrument motion through and about a specific point in space. Aligning and re-positioning this point during surgery is not trivial, as this is a defined, yet often non-visualised, point in space. When misaligned with the patient surrounding anatomy is excessively strained, potentially causing post-operative complications. Not being able to safely re-position the RCM for these purposes limits the use of surgical robotics. This work introduces a general approach relying on anatomy-based haptic fixtures to simplify and improve RCM positioning during robot-assisted 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 impedance-type system, the mechanical implementation is shown to offer at least one order of magnitude stiffness increase when compared to an equivalent virtual implementation.