On the Use of Fractional-Order PID Controllers for TITO Processes

In this paper we investigate the performance that can be achieved by using Fractional-Order Proportional-Integral-Derivative (FOPID) controllers for Multiple-Input-Multiple-Output (MIMO) industrial processes. In particular, we consider several well-known interacting process models taken from the literature and we tune the controllers by minimizing an optimization functional via genetic algorithms. We consider two different cost functions, one based on the integrated absolute error and the other one on the integrated square error. A comparison with standard integer-order Proportional-Integral-Derivative (PID) controller is performed so that the advantages of using decentralized FOPID controllers for set-point tracking and decoupling can be clearly evaluated.