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R. Seemann, F. Bruckner, M. Figl, A. Wagner, K. Schicho, W. Elmenreich:
"Applying a Real-Time Interface to an Optical Tracking System";
Talk: Workshop on Augmented Reality in Computer Aided Surgery, Interlaken, Switzerland; 2003-02-27 - 2003-03-01; in: "Proceedings of the Workshop on Augmented Reality in Computer Aided Surgery", (2003), 87.

Optical tracking systems such as NDI Polaris, Flashpoint, or ARTtrack1 are widely used in computer assisted surgery. They observe tools like drills marked with infrared reflecting orbs or diodes and return position and orientation of these on request. Since time intervals between replies vary, the application of standard filter algorithms that require perdiocal data with low jitter, is not possible without a respectable amount of error.
We implemented a real-time module for Linux that provides guaranteed frame rates, which are just limited by communication bandwidth. The driver runs under RTAI, a real-time kernel extension that decouples the Kernel from the real hardware by a real-time hardware abstraction layer. From several available real-time patches for the Linux kernel we selected RTAI because of excellent real-time support, good documentation, support of multiprocessor machines, and the property of being open source.
Our driver supports the implementation of real-time filter algorithms on top of the real-time device driver. Device-specific properties like the timing of the message scheduling are made transparent to the data consumers. Applications for instant visualization and data logging will be implemented in Linux user mode communicating with the real-time module.

http://www.vmars.tuwien.ac.at/php/pserver/extern/docdetail.php?DID=1194&viewmode=published&year=2003