Evaluation of gap-metric based multi-model control schemes for nonlinear systems: An experimental study

Many methods are proposed in the literature for control of nonlinear systems based on multi model approaches. Most of these methods are by simulation. An experimental investigation provides more understanding and also practical difficulties of nonlinear process control. This paper presents an experimental evaluation and comparison of gap metric based weighting methods for design of multi-model control schemes for control of levels in a spherical tank process and a conical tank process. IMC-PI controllers are designed for the corresponding linear models. A simulation study is first carried out to examine the performance of the level control on these nonlinear systems, in which the weights for local controllers combination are calculated by the weighting functions. The two weighting functions (1- δ and 1/δ) based on the gap metric value of particular linear model are calculated and used for constructing the global multi model controller. Level control in spherical and conical tank systems is studied to show the effective experimental implementation of the considered multi model control schemes.