2015 年 81 巻 824 号 p. 14-00555
The gigantic and long-period earthquake motions were observed in Tokyo, Osaka and other by the East Japan Earthquake of March 11, 2011. Therefore, the super high-rise buildings located in Tokyo were excited by large amplitude with about 1m and long time over 10minite. As the result, the life lines of the super high-rise buildings were took large damages. For corresponding to such an accident, it is important to measure the displacement vibration instantly and take a controlling technology. However, such devices are not yet exist to measure the displacement vibration waves with large magnitude and long period. This paper proposes a novel seismometer-type absolute displacement sensor aimed at detecting earthquake waves with a large magnitude and long period. The seismometer-type absolute displacement sensor is consisted of a sensor body with a moving mass and its supporting springs, feedback control circuits and a third order phase lag compensator. The natural frequency of the sensor body located at 6.4Hz originally is reduced to 0.23Hz using by acceleration feedback mainly and then moving stroke of the moving mass is compressed to 1mm to 1/630mm. Moreover the new natural frequency of 0.23Hz developed by feedback control is sifted to 0.055Hz by the third order phase lag compensator. Therefore the sensor has a measuring range from 0.08Hz to 10Hz, in addition to no drift problems by the use of feedback control way. In this way, the seismometer-type absolute displacement sensor with the amazing ability has been realized to measure the long period over 10 second of earthquake waves. In addition, the large magnitude to measure 630mm is expected, nevertheless a small size with moving stroke of 1mm. So far as we know, such a sensor for measuring absolute displacement is very novel in the world. In this paper the ability of the sensor will be shown by simulation and experiment.
