Strategies for enhancing geometric nonlinear control of an industrial evaporator system

Abstract

Two strategies, adaptive input-output internal model control (AdIOIMC) and augmented input-output internal model control (AuIOIMC), for enhancing the nonlinear control of an industrial multistage evaporator system are proposed. Each strategy consists of a nonlinear state feedback control law, designed by the input-output linearization technique, to linearize feedback and stabilize the open-loop unstable evaporator and the internal model control (IMC) structure for the feedback-linearized system. The combination of the nonlinear state feedback control law and the IMC structure is referred to as input-output internal model control (IOIMC). The AuIOIMC is composed of an IOIMC structure and an additional loop through which the model error is fed back and added to the input of the IMC. For AdIOIMC, the model error is fed to an adaptation loop that adjusts the model parameter within the IMC structure of IOIMC. The advantages of the proposed AdIOIMC and AuIOIMC strategies on the industrial evaporator system were evaluated through simulation studies. The results show that both strategies provide improved regulatory control performance when compared to the MIMO GLC.