Optimal feedforward compensators for systems with right-half plane zeros

• We propose new feedforward tuning rules for processes with right-half plane zeros.
• A simple guideline is given for desired and optimal disturbance rejection responses.
• Performance benefits are shown in simulation including a robustness analysis.

Feedforward from measurable disturbances is a powerful complement to feedback control to improve disturbance rejection capability. Recent works have remarked the necessity of a design strategy for those cases where the ideal feedforward controller is not realizable. In this paper, a simple shaping design procedure is presented together with straightforward rules to obtain optimal feedforward controllers for the case when the ideal compensator is not realizable due to right-half plane zeros in the process dynamics. Finally, some simulations and a robustness analysis demonstrate the benefits of the proposed tuning rules.