Robust trocar detection and localization during robot-assisted endoscopic surgery

In endoscopic surgery, trocars impose kinematic constraints. Whenever a robot manipulates endoscopic instruments, it needs to know the trocar location with respect to its base frame. In the literature, this knowledge is acquired thanks to an installation / registration procedure, prior to the operation. In this paper, we are considering a comanipulation scenario: Both the robot and the surgeon hold the instrument. All along a procedure, the instrument can be inserted into or removed from different trocars by the surgeon. It is needed to detect in real time whether the instrument is inserted in a trocar and to compute the fulcrum coordinates. The proposed algorithm is described in terms of both theory and practical realization. Its effectiveness is verified experimentally.