Projeto de controladores PID por moldagem de malha para modelos não-paramétricos.

Abstract

There is a need for methods for the design of PID controllers that are simple, but that lead to closed-loop systems that meet the time and frequency specifications in order to be accepted in the industrial environment. In this work, two new methods for the design of PID controllers are described using a linear programming approach to optimize performance, subject to robustness constraints. The first method is based on molding the real component of the mesh gain transfer function. The second method is based on molding a reference mesh gain transfer function that forms a convex region on the Nyquist diagram that contains and limits the projected loop gain. The convex region is approximated by a set of lines for the formulation of a linear optimization problem. An optional performance specification related to the design loop gain crossover frequency is also presented. The class of stable linear single-input single-output time-invariant systems is considered and optimization problems are proposed, solved and analyzed. The techniques presented throughout this work are evaluated in simulated cases to verify their performance.