A look into robustness/performance and servo/regulation issues in PI tuning

This paper addresses the model-based tuning of Proportional-Integral (PI) controllers focusing on the robustness/performance and servo/regulation trade-offs. First, a tuning rule is derived analytically by solving a simple H∞ weighted sensitivity problem, where the weight is chosen so that two design parameters permit to adjust the considered conflicting objectives. This way, the resulting tuning expressions show clearly how the controller's parameters should be changed to shift each trade-off, giving insight into the tuning task. Then, we proceed to study the two trade-offs at hand and the interplay between them.