We have been studying strain sensors based on the inverse magnetostriction effect. In our previous research, we evaluated the sensitivity characteristics of an entire strain sensor by measuring the change in the direction of magnetic anisotropy when strain was applied to the sensor as an impedance change using a network analyzer. When a directional change in magnetic anisotropy occurs simultaneously across the entire sensor when strain is applied to the sensor, the impedance change becomes steeper, and the sensitivity improves. Therefore, in this study, the change in local magnetic anisotropy due to the inverse magnetostriction effect that occurs when strain is applied to the sensor was obtained from a local BH loop obtained using the Kerr effect, and the uniformity of the local magnetic anisotropy was evaluated. As a result, it was confirmed that the magnetic anisotropy varied from place to place when stress was applied. Since quantitative evaluation of local magnetic anisotropy and strain was possible through local BH loop measurement using a Kerr effect microscope, this measurement could be used to further increase the sensitivity of the sensor.

  Thin flexible steel plates are used in the manufacturing of household appliances and other products. Since the plates are conveyed by rollers during the manufacturing process, deterioration on the surface of the plates such as abrasions has become a problem. To solve this, non-contact gripping and conveyance of flexible steel plates using magnetic levitation technology have been proposed. A suitable method for levitating thin flexible plates, is a magnetic levitation system using electromagnets placed only at the edges of the plates. The previous control model considers only the horizontal direction. Levitation is possible with this model; however, under some conditions, it is not possible to suppress vertical vibration, and there is the possibility of plates falling off. Therefore, in this paper, a two-degree-of-freedom vibration control system that consider both horizontal and vertical directions is proposed for stable levitation. Moreover, the control performance was investigated by applying the optimal control theory to the proposed system.