A multi-model control of nonlinear systems: A cascade decoupled design procedure based on stability and performance

Recently, the multi-model controllers design was proposed in the literature based on integrating of the stability and performance criteria. Although these methods overcome the redundancy problem, the decomposition step is very complex and time consuming. In this paper, a cascade design of multi-model control is presented that is made from two sequential steps. In the first step, the nonlinear system is decomposed into a set of linear subsystems by just considering the stability criterion. In this step, the gap metric is used as a smart tool to measure the distance between linear subsystems. While the closed-loop stability is gained through the first step, the performance is improved in the second step by adding internal model controllers in a cascade structure. Therefore, the proposed idea supports designing a multi-model controller in a simple way by integrating the stability and performance criteria in two independent cascade steps. As a result, the proposed method avoids the model redundancy problem, has a simple structure, guarantees the robust stability, and improves the performance. Two nonlinear chemical processes are simulated to evaluate the proposed multi-model controller approach.