Sintonia de controladores PID sob o enfoque da identificação paracontrole

Abstract

This thesis tackles two subjects related to control field, having in view process control applications. These subjects are Advanced PID Control and Identification for Control. In both topics, robust control has relevant influence, outlining the limits and potential for PID control application, by one side, or through the demand for appropriate models for controller design. Having in mind practical questions, and also open possibilities inboth fields, solutions are proposed for some core problems, related to PID retuning using closed-loop data. Regarding PID tuning, a review is made on MIGO method, recently proposed in literature, and a sub-otimal version of it is proposed, named SMIGO. This new method leads not only to PID retunig in a consistent way, but also to a systematic approach tothe transition between PI and PID structures, without recurring to model approximation or model reduction techniques, as often occurs in PID literature. A PID retuning method is proposed, based on SMIGO and H Loop-shaping, allowing the adjustment of robustness, performance or both. One option investigated in this thesis is the use of models obtained by indirect closed loop identification within the proposed retuning method, despite of singularity issues previously described in literature. In summary, this thesis proposes a specific approach for PID retuning, involving H loop-shaping, SMIGO method and indirect closed-loop identification. The proposed method is applied to a laboratory pilot plant.