DESIGN OF AN AUTOMATED CALIBRATION DEVICE FOR ELECTROMAGNETIC TRACKING SYSTEMS By GARETH

By Gareth Douglas Cole, M.S. Washington State University May 2007 Chair: Sankar Jayaram Electromagnetic tracking systems used in virtual reality applications are subject to tracking error due to magnetic field distortions caused by metallic objects in the environment which increases with increased distance from the transmitter. These problems can lead to a significant decrease in tracking performance of position and orientation during simulations in the virtual environment, creating a need for a calibration method of the tracking system. The calibration method involves collecting a set of data pairs for the receiver using the electromagnetic system and a secondary reference system of true physical locations. The goal of this research was to design a suitable device to automatically collect data points for this physical reference system without causing further distortion to the magnetic field. The calibration device was designed in order to accurately position the electromagnetic receiver at user-specified grid points throughout the tracking environment, thereby allowing the calculation of position and orientation error at each location. The calibration device we designed is a three axis Cartesian positioner interfaced via serial port with computer software for an automated methodology. The main