Offset-free Receding Horizon Control of Constrained Linear Systems subject to Time-varying Setpoints and Persistent Unmeasured Disturbances

This paper addresses the design of a nonlinear time-invariant, dynamic state feedback receding horizon controller, which guarantees constraint satisfaction, robust stability and offset-free control of constrained, linear time-invariant systems in the presence of time-varying setpoints and unmeasured, persistent, additive disturbances. First, this objective is obtained by designing a dynamic, linear time-invariant, offset-free controller and an appropriate domain of attraction for this linear controller is defined. The linear (unconstrained) controller is then modified by adding a perturbation term, which is computed by a robust receding horizon controller. It is shown that the domain of attraction of the receding horizon controller contains that of the linear controller and an efficient implementation of the receding horizon controller is proposed. Proofs of robust constraint satisfaction, robust stability and offset-free control are given. The effectiveness of the proposed controller is illustrated on an example of a continuous stirred tank reactor.