Several challenges will be tackled, an important one being the design of a compact and sterilizable force measurement system. Because safety thresholds can only be defined related to local tissue stresses and strains, the acquired instrument forces and displacements will be translated to these local tissue stresses and strains by means of biomechanical models. Due the typical geometric and mechanical variability of biological tissue, it is necessary to make these models patient-specific. Moreover they should be able to process the force- and displacement information in realtime, to provide continuously varying safety thresholds to the teleoperation control system.