低支持剛性反発形磁気浮上装置におけるリング浮上磁石の突極化と浮上特性

　A repulsive magnetic levitation (maglev) device is proposed in which two ring-shaped stator permanent magnets and one ring-shaped floating permanent magnet repel each other, and a magnetic field from four air-core coils actively controls two horizontal axes of the floating permanent magnet. This device is applicable to measuring minute mass and vibration. The ring-shaped permanent magnet was stably levitated without contact for a while. However, as time passed, the floating permanent magnet oscillated around the central axis and then started to rotate, and finally became out of control. This paper presents that the floating ring permanent magnet with four salient poles overcomes that issues. Besides, this paper also reports the mass detection experiments by three measuring ranges of stiffness values.