A Uniformly Wide-Range Distributed DC Magnetic Generator Based on Residual Magnetic Field for Motion Measurement

A reliable dc magnetic field generator (DFG), which utilizes residual magnetic field in ferromagnetic material for uniformly distributed wide-range dc magnetic generation, is newly proposed in this article for motion measurement applications. Contrary to the conventional optical sensors for motion measurement applications, the inertial measurement units (IMUs) sensors are the most viable solution by virtue of high resolution and no sensor shadow issue although the sensors are closed together. In conventional IMU sensors, a geomagnetic field is used for the terrestrial magnetism sensors as a reference to calibrate the absolute positions. However, the geomagnetic field inside buildings, factories, or houses may be severely distorted and, therefore, is unreliable as an absolute reference for precise motion measurements. Thus, uniformly distributed dc magnetic generation is strongly required for reliable IMU sensor measurements. To provide convenient motion measurement environments, a U-shaped magnetic core is applied so that the users can easily access the measurement environments while the uniformed and reliable magnetic field is built. To enhance the uniformity of the magnetic field generation, the residual magnetic field is utilized so that the resultant magnetic vector is finally uniformed in the
$y$
-axis, i.e.,
$B_{\text {t}} \approx B_{y}$
in this article. All the detailed design procedure of the DFG for uniformly magnetic field generation and the appropriate coil shape selection are provided in this article. The experimental results verified by a
$30\times 30\times30$
cm small-scaled prototype, and a
$1.5\times 1.5\times1.5$
m real-scaled prototype of the DFG showed that the dc magnetic field uniformity
$\theta _{\mathrm {t}}$
is below 10.0° over 92% of the total volume.