First results with MEMS tilt sensors on bridges

For the study “IB-ISEB” of the German Federal “Bundesamt für Straßenwesen” (BASt) NG LITEF has developed a MEMS based tilt sensor. The purpose of the study is structural health monitoring of bridges with the help of a self-sufficient sensor network. The tilt sensor of NG LITEF includes intelligent self-calibration procedures to allow for exceptional long term stability. These procedures utilize the concept of a neutral point, where bias contributions from parasitic capacities are minimized. The tilt sensor is realized at low power consumption with a cost-effective COTS microcontroller. It could be demonstrated both, in laboratory and in a real world application on the bridge “Neckartalbrücke” along the highway A81, that the concept of the neutral point allows for a simple, linear temperature model of the bias and for a high long term stability of the tilt sensors output, with absolute drifts well below 50 μg during the observation time.