Interpolating Control—Output Feedback Case

So far, in this manuscript, constrained state feedback control problems have been considered. However, in practice, direct information (measurement) of the complete state of dynamic systems may not be available. In this case, an observer could possibly be used for the state estimation. A serious drawback of the observer-based approaches is the observer error, which one has to include in the uncertainty. In addition, for constrained control systems whenever the constraints become active, the non-linearity is dominating and one cannot expect the separation principle to hold. Moreover there is no guarantee that the constraints will be satisfied along the closed-loop trajectories. In the chapter, we revisit the problem of state reconstruction through measurement and storage of appropriate previous measurements. Even if the state might be non-minimal, it is directly measurable and will provide an appropriate model for the control design with constraint handling guarantees. Finally, it will be shown how the interpolating control principles can lead to an output-feedback control design procedure.