Abstract
This paper proposes a novel absolute displacement sensor aimed at detecting long period and large amplitude. However, since the measuring range of the sensor is higher than the natural frequency of itself, it is difficult to measure the frequency with the conventional displacement sensor. 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 acceleration and velocity between a detected object and the internal mass of the sensor are feedback into the sensor. In addition, phase lag compensator is inserted to adjust phase angles. Theoretically, this sensor is able to detect a lower frequency range from 10Hz to 0.2Hz and the large amplitude with 100 times to the movable range of the sensor. It has been demonstrated that the developed sensor has 0.2Hz of the natural frequency and the measurement displacement amplitude has been expanded to 25 times at present.
