During phase I and II, the ISIs are tested in clean rooms and are subjected to an important airflow disturbance.  Consequently, it is quite difficult to have good quality measurements at high frequencies (100Hz to 1KHz). To improve the quality of the transfer functions, we can split the high frequencies transfer functions measurements into multiple frequency bands but the “quick high frequency transfer functions measurements” become time consuming.

Measurement limitations:
- at HF, the drive is the limit
- at LF, the drive is small and the sensors saturate easily

To reduce the measurement time, we can drive 1 DOF at low frequency and different DOF at high frequency simultaneously. During a test, stage 1 was driven at low frequency while Stage 2 was driven at high frequencies. In the attached plots, there is a comparison when the TFs are measured by exciting one DOF at the time and 2 DOFs simultaneously. It matches. Only, a light difference is observed on the 2 first resonances of the ISI (probablydue to a light change of the plant between the two measurements)