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Online force identification with robust observers
For purposes of monitoring and damage prognosis it is important to know the external loads which act on a structural system. The knowledge of these loads enables us to make an assessment of damage after extreme events and updated forecasts of the remaining lifetime. In many practical applications it is not possible to measure the forces e.g. resulting from wind loads or traffic directly. Therefore, these forces are determined indirectly from the dynamic structural responses with an observer-based concept. In this work, a new method of simultaneous state and input estimation for a class of nonlinear systems, which is used in the area of control engineering, is adapted to online indirect force measurement. This method allows for the simultaneous reconstruction of unknown force functions and system states such as displacements and velocities. A major difference to previous force identification techniques is the online reconstruction, based on the robust observer principle. Upon satisfying some conditions, the observer design problem can be solved via a Riccati inequality or a LMI (linear matrix inequality)-based technique with asymptotic estimation guaranteed. The load reconstruction is illustrated by laboratory structure. The robust observer is designed on the basis of an analytical model. Even with noise corrupted measurement signals the observer shows a very good reconstruction of the input forces and states. The load identification was done with the help of two strain and two accelerometer transducers, which were used to drive the calculated observer. The observer performance was verified by using an additional force sensor.
Online force identification with robust observers
For purposes of monitoring and damage prognosis it is important to know the external loads which act on a structural system. The knowledge of these loads enables us to make an assessment of damage after extreme events and updated forecasts of the remaining lifetime. In many practical applications it is not possible to measure the forces e.g. resulting from wind loads or traffic directly. Therefore, these forces are determined indirectly from the dynamic structural responses with an observer-based concept. In this work, a new method of simultaneous state and input estimation for a class of nonlinear systems, which is used in the area of control engineering, is adapted to online indirect force measurement. This method allows for the simultaneous reconstruction of unknown force functions and system states such as displacements and velocities. A major difference to previous force identification techniques is the online reconstruction, based on the robust observer principle. Upon satisfying some conditions, the observer design problem can be solved via a Riccati inequality or a LMI (linear matrix inequality)-based technique with asymptotic estimation guaranteed. The load reconstruction is illustrated by laboratory structure. The robust observer is designed on the basis of an analytical model. Even with noise corrupted measurement signals the observer shows a very good reconstruction of the input forces and states. The load identification was done with the help of two strain and two accelerometer transducers, which were used to drive the calculated observer. The observer performance was verified by using an additional force sensor.
Online force identification with robust observers
Online-Kraftidentifikation mittels robuster Beobachter
Fritzen, C.P. (author) / Klinkov, M. (author)
2006
10 Seiten, 6 Bilder, 1 Tabelle, 12 Quellen
Conference paper
English
Online Force Reconstruction using Robust Observers
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