Output Regulation of Linear Systems Subject to Input Constraints

This paper studies the output regulation problem for linear systems subject to input constraints. It presents a new controller that uses a conditional servocompensator. Previous work introduced the conditional servocompensator, which acts as a traditional servocompensator only in a neighborhood of the zero-error manifold, while acting as a stable system outside a boundary layer, leading to improvement in the transient response while achieving zero steady-state regulation error. Starting with a low-gain stabilizing state feedback controller, based on the solution of an algebraic Riccati equation, Lyapunov redesign is used to implement the state feedback control in a saturated high-gain feedback form that includes the conditional servocompensator. The design is extended to output feedback via a full-order high-gain observer.