Multivariable decoupling set-point approach applied to a wastewater treatment plant

This paper presents a formulation for the inclusion of the second degree of freedom for MIMO system for decoupling purposes. The proposal is specially effective when combined with decentralized feedback controllers. Loop interaction is of the major problems in the control of MIMO systems, as interaction can be considered as a disturbance coming from all other loops, the design of the decentralized feedback controller is better understood as a disturbance rejection design. In this approach the set-point tracking capabilities may be not as good as expected. The proposed Two-Degree-of-Freedom (2-DoF) formulation provides a complement to the existing controller that can be automatically determined in terms of the available process and feedback controller information