**4. Experimental validation**

The system described in the previous sections was implemented and experimental tests were carried out to verify the correspondence between the design model and the real system. The experimental tests were first addressed to investigate the performance of each subsystem and in the second instance of the whole system. For this purpose several test rigs have been built in order to characterize the single components and the interactions between them. Experimental tests verified the nominal design expectations and have been used also to perform sensitivity analysis on different parameters of some components.
