Control under Constraints via Output Feedback for Uncertain and LPV Systems
Robust Control, Reference Tracking, Control under Constraints, Uncertain Systems, Invariant Sets, LPV Systems, State Observers.
In recent decades, robust controllers, have been studied by experts in control systems to deal with problems inherent to dynamic systems subject to disturbances and variations of its parameters. However, beyond these problems, another important characteristic that is present in most practical cases is the existence of constraints, which may result from limitations in the system states, the control input or output. Both mentioned factors, if not dealt with properly in the controller synthesis step, can cause degradation of performance of the controlled system or even lead it to instability. Thus, this work presents a proposal of a robust controller that uses the theory of invariant sets to perform the reference tracking, ensuring that the system complies with the constraints despite the effect of bounded disturbances and variations of parameters. Invariant Polyhedra are used to ensure compliance with the constraints to systems with output feedback. An update procedure of system parameters and a state observer are used to cancel the error of constant references tracking. In addition, is provided a study of linear systems with time-varying parameters (LPV) and the state observer Set-Invariant Estimators.