Adaptive Decentralized PI Controller for Two Conical Tank Interacting Level System

The implementation of control algorithms for the Multi-Input/Multi-Output systems is often complicated due to variations in process dynamics that occur because of change in operating point and the characteristics of nonlinear dynamic coupling. In this paper, the authors proposed regime-based multi-model adaptive control strategy for decoupling-based decentralized PI controller for a Two Conical Tank Interacting Level System (TCTILS) which is a Two-Input Two-Output interacting nonlinear system that exhibits nonlinear dynamics and dynamic interaction. The controller design is divided into two parts: firstly, a decoupling matrix is designed in order to minimize the interaction effects for each pair of linearized operating regimes. Then, the decentralized PI controller is designed for the TCTILS using stability boundary equations method and real-coded GA for each pair of linearized operating regimes. The stability analysis of the TCTILS with the designed set of decentralized PI controllers and decouplers is investigated for each pair of linearized operating regimes by using multivariable Nyquist plot method. Using simulation and experimental studies, the effectiveness and practicality of the proposed scheme is demonstrated on TCTILS experimental setup. The results reveal encouraging input tracking and disturbance rejection capabilities. The regime-based multi-model adaptive control strategy minimizes interaction effects effectively and meet the design specifications for each loop independently in each linearized operating regime.