R.: BlueTrak - A wireless six degrees of freedom motion tracking system

We present a six degrees of freedom tracking system, which is wireless and scalable concerning the tracking volume and the number of devices being tracked. This is achieved by the modular design of the system consisting of two different types of modules: an arbitrary number of tracked user modules and a number of fixed reference modules. It provides a flexible setup for head tracking in virtual and augmented reality environments and for various other applications such as motion capture and analysis. The system combines inertial sensor data with ultrasonic ranging measurements to determine orientation and absolute position