Influence of force disturbances on transparency in bilateral telemanipulation of soft environments

This paper addresses the influence of friction on the haptic transparency within soft tissue telemanipulation. In contrast to remote handling of hard environments, the level of the friction forces is thereby within the same order of magnitude as the interaction forces. Therefore, these friction forces may alter performance and haptic transparency considerably. Control schemes showing nice results within simulations using linear models, with frictionless virtual manipulators in a virtual environment, or where friction forces are negligible compared to the interaction forces, show totally different results when implemented on a real telemanipulator setup with a realistic friction level and in contact with a soft environment. In this paper, friction is added to the linear models of the master and slave actuators as an input force disturbance. The influence of these disturbances on haptic transparency then is investigated analytically for the most widely used teleoperator schemes. Thereby, effectiveness of using force sensors on master and/or slave side is evaluated, and validated through experiments on a one-dimensional test setup.