The control performance is verified in the simulated environment where the plant behaviour is reproduced through the fine model already introduced at point 2. 

Following the EICAS approach by using in particular the available automatic design methodology, the designer must always keep in mind the requirements to be satisfied by the control system. Recall three steps of the design:

1) the approximate model is chosen for meeting the control requirements;




2) the fine model is chosen for emphasizing the limits of the plant representation through the approximate model;




3) the control is designed for meeting the same pre-established requirements.

When the project is carried out properly it must be possible to verify through the simulation that the control system which was designed meets the pre-established requirements.

However it is possible to carry out also another important check.

If, starting from the approximate model, a control is designed for obtaining a performance better than the one defined as a validity limit of the approximate model itself, then - if the fine model was properly selected – the above control tested through the numerical simulation should result unstable. Such event will confirm that the design procedure was properly followed. The designer will then be able to push the required performance up to the limit at which the simulated system tends to become unstable and therefore to deteriorate its performance.