1. B. Alt, D. Katic and R. Jäkel are with Artiminds Robotics GmbH,Karlsruhe,Germany,76131
2. Institute for Anthropomatics and Robotics, Karlsruhe Institute of Technology,Karlsruhe,Germany,76131
3. Department for General, Visceral and Transplantation Surgery, Heidelberg University Hospital,Heidelberg,Germany,69120