Peak seeking control using OBF-Wiener model based nonlinear IMC scheme

In this work, a nonlinear output error type model with Weiner structure has been developed for capturing dynamics of multivariable nonlinear systems with fading memory. The linear dynamic part of the Wiener model is parameterized using ortho-normal basis filters (OBF).The identified OBF-Wiener model is further used to derive a closed form multi-step quadratic control law in nonlinear internal model control framework. The efficacy of the proposed closed form control law is demonstrated by conducting simulation studies on peak seeking control of (a) Proton Exchange Membrane Fuel Cell (PEMFC) system and (b) Continuous Fermenter system. As these systems exhibit input multiplicities and change in the sign of the steady state gain(s) in the operating region, the resulting control problems are difficult to handle. In both the cases, the proposed control law achieves a smooth transition form a sub-optimal operating point to the optimum operating point without causing large variation in manipulated inputs.