Development of Wireless Magnetic Motion Capture System for Multi-Marker Detection

摘要

Wireless motion capture techniques for multi-point detection at close range are candidate for a new type of virtual input devices or an application for medical treatment. In such cases, particularly for measurements with the motion of fingers, the applied marker must be small and free from electric wiring to promote normal motion. In addition, the location and orientation of the marker must be known exactly during the measurement. Furthermore, if dead angle is likely to occur, optical method is unfavorable. To address this, we have proposed and developed a new type of magnetic motion capture system using a magnetically-coupled LC resonant marker [1]. The small sized marker uses a soft ferrite core with a coil, representing a minimal LC circuit with no battery, driven wirelessly by electromagnetic induction. The magnetic signal of the marker is detected by a matrix-designed search coil array. Our proposed system allows the approximate orientation and the position of a single marker to be determined accurate to within 1mm under the space of 150mm from the pick-up coil array. It also has a possibility of multi-point detection because the system allows the markers to have an individual frequency band. In this paper, we have extended the system to detect multi-marker and examine the accuracy of the system in detecting the positions and orientations.