In this paper we present an application of robotic systems in minimally invasive surgery. We have assembled a bi-manual telemanipulator capable of delicate operations. Each robotic arm has eight degrees of freedom which enables free manipulation via trocar kinematics. In addition minimally invasive instruments were equipped with strain gauge force sensors that can measure forces along three translational directions of the instrument?s shaft. Forces are displayed to the user by means of two haptic devices which are also used for input. An endoscopic stereo-camera provides pictures from the region of operation to the user. In order to emulate a sterescopic impression, pictures can be displayed by means of either a head mounted display, a CRT-screen equipped with shutter technology or a 3D video projection.

With this system we have assessed the quality of force feedback and we have performed typical operations known from cardiac surgery. We also have shown that it is possible to perform certain recurrent tasks (like knot tying) automatically. Within this context we have implemented two application examples. In the first example a surgical knot is recorded and afterwards replayed with increased speed at the same position. The second example is the instantiation of a predefined knot at an arbitrary position.