Principles of Navigation in Surgical Robotics

In this paper, we propose a framework for the different types of navigational problems in surgical robotics. Using robots in medicine and especially in surgery requires an adequate representation of and reaction to a changing environment. This is achieved by modeling at different abstraction levels throughout the process, ranging from 3D imaging modalities which reflect the environment geometry to finding appropriate control parameters for actual motion. Between global navigation and control, we introduce the concept of local navigation into surgical robotics, i.e. concurrent creation and maintenance of a local environment map for navigation purposes. This intermediate level of sensory feedback and processing allows to react to changes in the environment. Furthermore, local navigation permits sampling of additional information which may be unattainable before process execution or only with reduced precision. We illustrate this idea of nested control loops on the basis of car driving and a specific surgical application – robot-based milling at the lateral skull base.