Real-time simultaneous identification of structural systems and unknown inputs without collocated acceleration measurements based on MEKF-UI

Identifications of excitations and structural systems are two crucial factors in structural health monitoring. There have been some research works focusing on simultaneous identification of structural systems and unknown inputs. Among them, the approach based on the extended Kalman filter with unknown inputs (EKF-UI) has the superiority of implementing identification with limited measurements and in real-time fashion. However, in previous EKF-UI approaches, it is necessary to have the measurements of acceleration responses at the locations where unknown inputs applied. In this paper, it is proposed to circumvent the above limitations for real time simultaneous identification of structural systems and unknown inputs without using collocated acceleration measurements. The proposed method is based on a novel modal extended Kalman filter with unknown inputs (MEFK-UI), which is the combination of extended Kalman filter in modal domain and the recent EKF-UI developed by the authors. Simultaneous identification of structural modal co-ordinates and unknown modal inputs are first conducted in the reduced dimension by modal truncation technique. Moreover, data fusion of displacement and acceleration measurements is used to prevent in real time the low-frequency drifts in the identification results. Subsequently, structural systems including structural parameters and unknown external inputs are identified in real time. Such an approach is not available in the literature. Several numerical examples are used to demonstrate the effectiveness of the proposed method.