Measurements of High-Frequency Oscillations by Optoelectronic and Inertial Sensors in a Hybrid Measurement System

High-frequency oscillations are important charges on buildings like bridges or straight towers. Especially oscillations, produced by external forces, e.g. braking of a train on a railway bridge or wind load stressing on a straight tower, are to be considered in the static calculations. Therefore for these buildings dynamic models are necessary. The geometrical determination of such high-frequency oscillations on real objects with real charges can be used to check a theoretical dynamic model of an object. In many cases, the oscillations are very short and the object movements are very smaD. So it is not possible to measure these movements with classical geodetical methods in a necessary measurement frequency. For observation of high-frequency oscillations we need instruments which can record and store the object motion in a fast frequency with a sufficient accuracy objectively and automatically. As such an instrument, at the Institut für Anwendungen der Geodäsie im Bauwesen (IAGB) an electronic camera was developed as an external sensor. The principle of this sensor is to be demonstrated in this paper with the measurement of the oscillations of the abutment of a railway bridge during brake of a train as an example. As a second sensor to record the oscillations an accelerometer was used as an instrument on the object itself. The heterogeneous signals of both sensors are evaluated in a joint model, using an adaptive Kaiman Filter.