Using data from extensive vibrational tests of the new aircraft Saab 2000 three different methods for vibration analysis are studied. These methods are ERA (eigen system realization algorithm), N4SID (a subspace method) and PEM (prediction error approach). We find that both the ERA and N4SID methods give good initial model parameter estimates that can be further improved by the use of PEM. We also find that all methods give good insights into the vibrational modes.
Analysis of vibrating structures is a very important industrial task. This concerns both tests and analysis for validating safety and comfort properties and most often involves analyzing structural modes and damping properties. A large number of methods for this have been developed and the area is both commercially important and scientifically interesting. The area has how-ever historically not been closely related to the traditional System Identification methodology.
Source: Linköping University
AuthorS: Abrahamsson, Tomas | McKelvey, Tomas | Ljung, Lennart