This paper proposes a novel seismometer-type absolute displacement sensor aimed at detecting earthquake waves with a large magnitude and long period. However, since the measuring range of the displacement sensor is higher than the natural frequency of itself, it is difficult to detect
This paper proposes a novel seismometer-type absolute displacement sensor aimed at detecting earthquake waves with a large magnitude and long period. However, since the measuring range of the displacement sensor is higher than the natural frequency of itself, it is difficult to detect a low frequency vibration below 1 Hz using conventional seismic-type displacement sensors.
In order to provide an absolute displacement detection which is capable of lowering the natural frequency and enlarging the detectable amplitude without causing a structural defect, the relative signals of displacement, velocity, and acceleration between a detected object and the auxiliary mass of the sensor are fed back into the sensor. In addition, phase lag compensation is inserted to adjust phase angles, which are below a frequency lower than 1Hz.
It has been demonstrated that a developed sensor with a small size and lightweight has a detecting range f