7. Non-flat systems

Although the flatness property is very interesting for system control, it turns out that some system models do not possess it. Indeed, in some cases (excluding, of course, non-controllable models), components of the state are not accessible or expressible using a number, given by the number of controls, of variables and their derivatives. Despite this, special techniques can be used to apply the concepts of platitude , including model simplification and high-frequency control. Without going into detail, the first method consists in replacing certain terms of the initial model by approximate terms in which the influence...