Nonsquare Multivariable Chemical Processes: A Hybrid Centralized Control Proposal

Hybrid Controller Based on Numerical Methods for Chemical Processes with a Long Time Delay

A hybrid control framework is proposed as an alternative for long time delays in chemical processes. The hybrid approach mixes the numerical methods in an internal mode control (IMC) structure, which uses the particle swarm optimization (PSO) algorithm to improve the adjustment of the controller parameters. Simulation tests are carried out on linear systems of high order and inverse response, both with dominant delay, and tests on a nonlinear process (chemical reactor). The performance of the proposed controller is stable and satisfactory despite nonlinearities in various operating conditions, set-point changes, process disturbances, and modeling errors. In addition, experimental tests were performed on a setup composed of two heaters and two temperature sensors mounted on an Arduino microcontroller-based board called the Temperature Control Laboratory (TCLab), with an additional software delay introduced. The merits and drawbacks of each scheme are analyzed using radar charts, comparing the control methods with different performance measures for set-point and disturbance changes. Furthermore, the new controller uses PSO to improve the tuning parameters.

Optimal full-state feedback observer integrated backstepping control of chemical processes with unknown internal dynamics

This paper studies the estimation and control problems of chemical processes with unknown internal dynamics. An observer with optimal full-state feedback characteristics for estimating the state variables and unknown dynamics is presented. Unlike other observers that need to know the frequency characteristics of the system, the pole of the proposed observer is determined automatically in a LQR formulation and the observer stability is also inherently ensured. In order to suppress the unknown internal dynamics, the proposed observer is then applied to the control design leading to an observer integrated backstepping control method. The proposed method does not depend on the detailed mathematical model of the system while the stability of the closed-loop system is guaranteed. The stability of the closed-loop system is proven in the Lyapunov sense. Extensive numerical simulations are presented to validate the proposed method.