Abstract
This paper proposes a new type of seismic system sensor based on the principle of servomechanism. The low natural frequency of the sensor is realized by using a positive feedback of relative displacement, relative velocity signal and negative feedback of relative acceleration.signal between the measured object and the inner mass of the sensor. Based on this principle, the sensor of a light mass and hard springs is constructed. It is shown that the sensor with small size and lightweight can have a low frequency measuring range. The results demonstrated by both theoretically and experimentally.
