With the prolific usage of vibration analysis to extract information about different structures (buildings and bridges etc.), vibration sensors have become an important device in Structural Health Monitoring (SHM). In this study, we tried to modify the previous generation of vibration sensors in the analog front end and build a new porotype for a vibration sensor with applications in SHM.
A vibration sensor system includes different modules. Each module has its own functionality. In a vibration sensor system, all these modules have to work together deliberately to form a sensor system. Among the modules that form a sensor system, analog sub-system is responsible to prepare the output signal of the seismic sensor for the analog-digital converter. Mass-spring velocity meter (geophone) which is one of the mostly used sensor in SHM is the main seismic sensor in our sensor prototype. In each geophone, vibrations below a certain frequency which is called corner frequency, is hard to detect because of geophone frequency response. Several techniques have been proposed in this study to modify the lower frequency response of the geophone.
We have verified the compensation techniques in two different situations. First, using a shake table, we excited the geophone with different frequencies and evaluated the compensated frequency response. For the final verification in a real test environment, we tested qualification of the geophone in detecting the vibration of a real building at low frequencies.