An approach to ulta-tightly coupled data fusion for handheld input devices in robotic surgery

This paper introduces an ultra-tightly coupled approach to data fusion of optical and inertial measurements. The two redundant sensor systems complement each other well, with the cameras providing absolute positions and the inertial measurements giving low latency information of derivatives. The targeted application is the tracking of handheld input devices for robotic surgery, where landmarks are not always visible to all cameras. Especially when bi-manual operation is considered, where one hand can move between the other hand and a camera, occlusions occur frequently. The ultra-tighly coupled data fusion uses 2D-camera measurements to correct pose estimations in an extended Kalman filter without an explicit 3D-reconstruction. Therefore marker measurements are used to support the pose estimation, even if the marker is only visible in one camera. Experiments were done with an inertial measurement unit and rectified stereo cameras that show the advantage of the approach for the application.