Master Thesis by Christopher Otto
Title: Magnetic Motion Tracking System
University: Department of Electrical & Computer Engineering, University of Manitoba
Date: August 2006
Abstract
Current methodology such as constraint-induced therapy offers little to keep patients motivated to continue the duration of therapy. Other methods such as biofeedback via Virtual Reality using haptic or input devices using EMG both do not allow common objects to be instrumented to interface with low cost off-the-shelf gaming to motivate exercise, assessment and therapy. An embedded peripheral electronic device was created to interface between a pulsed DC magnetic six degree-of-freedom motion sensor and a USB compatible computer for purposes of instrumenting a wide range of objects and transforming them into a universal joystick or mouse device in order to play off-the-shelf commercial video games to make meaningful and multifunctional movements and exercises in practice and rehabilitation training fun and enjoyable.
Secondly, the Assessment Rehabilitation Tool (ART) was created to log the coordinates of a USB mouse and output of the peripheral electronic interface device synchronously drawing an on-screen bright cursor moving in predictable and random trajectories. With this tool the fidelity and responsiveness of the magnetic motion tracking sensor and peripheral electronic device could be measured against the standard computer mouse for both predictable and random motion trajectories typical of commercial video games.
Residual waveform cross-correlations showed an average error of 1.13+/-0.02% difference in correlation from a standard waveform between a USB mouse and the proposed system. The difference was 1.4+/-2.0% using non-standard objects including wands, a leather ball, and cart. Compared to the standard computer mouse the results show that the level difference is directly dependant on the object used and that some objects have distinct advantages in certain motions or axis. Overall it is shown that the sensor and embedded system compare in performance to a standard HID compliant mouse. This system has the accuracy and responsiveness that has not been previously possible, that allows a wide range of exercise activity to universally interface with off-the-shelf gaming products to motivate long-term rehabilitation therapy.