Stability Analysis for a Surgical Simulator

Kurzfassung

The MiRo system developed at the DLR for teleoperated surgeries, allows a surgeon to operate a patient from a remote location using the high accuracy and precision of its robotic arms. Nevertheless the development, implementation and use of such complex systems can be time and cost expensive. These problems can be solved by replacing the robotic arms and operational environment with a virtual reality. One of the major challenges of coupling a human operator with virtual environments lies on resembling the reality as good as possible to the user while guaranteeing stable interaction. Some works have already dealt with these questions and have proposed approaches such as virtual coupling for effectively communicating collision forces between user and VE. This thesis investigates the use of this approach by taking into account a virtual mass in the virtual environment. This enhancement not only provides force-feedback to the user when collisions occur, but also comprises the dynamic mass of the considered virtual object using virtual coupling. The investigated approach by this thesis considers the exact effect of time discretisation and time delays. Based on a unified time-discrete model of the considered system this thesis presents the virtual coupling’s stability boundaries, which show a high dependency on the virtual mass and time delays in the system. Furthermore a design analysis suggests optimal parameters for diverse implementations. Finally the results are validated by suitable experiments using an Omega.7 haptic device and a simulated environment.