A low-cost excitation system for operational modal analysis (oma)

We introduce a low-cost excitation system for application in operational modal analysis (OMA) working with vibration motors as they can be found in mobile phones. In contrast to experimental modal analysis (EMA), OMA makes an impulse hammer with a force sensor obsolete. If, furthermore, the structural response is measured with a camera instead of multiple accelerometers, this setup does not require an expensive data acquisition system, because no signals need to be recorded synchronously. The excitation of the structure is carried out through vibration motors from mobile phones that can be freely distributed across the structure and which are controlled by a microcontroller. The excitation through many distributed light-weight motors, in contrast to usual methods like manually tapping on the structure, enables long measurements without interfering with the optical measurement. Camera based modal analysis makes very high spatial resolution possible without the need for many accelerometers or a scanning vibrometer. The setup is tested on two example structures and its potentials are evaluated.