After having chosen the approximate model, the control design follows the automatic control theory, taking into account the uncertainty of the plant representation through the model.

The control design in presence of uncertainty is tackled through  two different methodological approaches.

The most widespread one requires that the control be set up in-field. In this approach the model is used for a first attempt of the design.

The final control design is carried out experimentally: in this way the problem of the inherent model uncertainty is overcome.

The other one, the EICAS approach, follows a methodology, which is theoretically founded and was tested over years through several projects: it implements a control system with guaranteed performance within the uncertainty range of the model.

As a consequence what is performed is a true design according to the engineering significance of the word.

If the design has been carried out in the proper way and the control system is implemented in compliance with the project, the control system must operate fulfilling the design requirements without requiring any experimental adaptation.