Design of horizontal seismic sensor with spherical inverted pendulum and magnetic levitation

This paper presents the design and experiments of a two-dimensional horizontal seismic sensor with spherical inverted pendulum and magnetic levitation. This pendulum become stable in vertical position due to the magnetic levitation, which is created by two magnetic rings composed by many small magnetic structures encircle the pendulum, with the same type of poles face to the same direction. The effectiveness of the sensor has been examined in detecting earthquakes sensed in the city of Bandung during the second half year of 2010. Two earthquakes signal from two different origin captured on 29 November 2010 and on 4 April 2011 are presented in this paper. Qualitatively, the two earthqukes can be clearly distinguished by comparing the amplitudes.