Optimal feedforward compensators for integrating plants

This paper addresses the design of feedforward compensators for integrating processes. Initially, the disturbance rejection problem for a classic two degrees-of-freedom control scheme with feedfoward is analyzed to highlight the problem caused by integrating dynamics. Afterwards, two simple tuning rules are derived to obtain undershoot-free responses based only a desired settling time or by satisfying a tradeoff between maximum peak and settling time specifications. Finally, some simulations are shown to prove the advantages of the proposed controller.