Wireless magnetic motion capture system using multiple LC resonant magnetic markers with high accuracy
Wireless magnetic motion capture system using multiple LC resonant magnetic markers with high accuracy
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DOI：
10.1016/j.sna.2007.09.011
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发表时间：
2008-04-10
影响因子：
4.6
通讯作者：
Kanetaka, Hiroyasu
中科院分区：
文献类型：
--
作者：
Hashi, Shuichiro;Toyoda, Masaharu;Kanetaka, Hiroyasu
本文介绍了一种采用多个LC共振磁标记的无线磁运动捕捉系统的原理，并演示了其应用。小巧轻便的标记器（直径4 mm，长度10 mm，重量0.63 g）使用软铁氧体磁芯和线圈，代表最小的LC电路，没有电池，由电磁感应无线驱动。标记被赋予范围从150到450 kHz的相应谐振频率。由25个拾波线圈组成的拾波线圈阵列检测标记的磁信号。标记由对应于所有谐振频率的叠加波激励，而通过拾取线圈感应的电压信号通过FFT分析在频谱中分离。无论标记的数量如何，每个谐振频率的电压幅度都可以容易地同时获得，因此所提出的系统可以检测多个标记。此外，由激励线圈和LC标记之间的互感引起的系统的位置误差进行了检查。发现由于LC标记物的共振引起的激励线圈的阻抗变化扰动用于标记物激励的磁场的强度。标记物越接近激励线圈，它就变得越大。这种波动引起标记信号中的误差，该误差由拾取线圈测量并且对于位置计算是必要的。然后，考虑到互感，补偿过程中的位置计算，以提高位置精度。在补偿之后，绝对位置精度被确定为在拾取线圈阵列的140 mm内小于2 mm。(C)2007 Elsevier B.V.保留所有权利。
The present paper reports the principle of a wireless magnetic motion capture system that uses multiple LC resonant magnetic markers and demonstrates its application. Small and lightweight markers (4 mm in diameter, 10 mm in length, and 0.63 g in weight) use a soft ferrite core and a coil, representing a minimal LC circuit with no battery, driven wirelessly by electromagnetic induction. The markers are given respective resonant frequencies ranging from 150 to 450 kHz. The magnetic signal of the marker is detected by a pick-up coil array consisting of 25 pick-up coils. The markers are excited by a superposed wave corresponding to all of the resonant frequencies, while the voltage signals induced through pick-up coils are separated in a frequency spectrum by FFT analysis. Regardless of the number of markers, the voltage amplitude for each resonant frequency can be easily obtained simultaneously, and thus the proposed system can detect multiple markers. In addition, the positional error of the system caused by a mutual inductance between the exciting coil and the LC marker was examined. The impedance change of the exciting coil due to a resonance of the LC marker was found to perturb the strength of the magnetic field used for marker excitation. The closer a marker approaches the exciting coil, the larger it becomes. This fluctuation induces an error in the marker signal, which is measured by the pick-up coils and is necessary for positional calculation. Then, considering the mutual inductance, a compensatory process was employed for positional calculation in order to improve the positional accuracy. After compensation, the absolute positional accuracy was determined to be less than 2 mm within 140 mm of the pick-up coil array. (C) 2007 Elsevier B.V. All rights reserved.