Robust optimal controller design for a non-minimum phase boiler system with a saturable actuator

Abstract

Dealing with a multivariable non-minimum phase model of a boiler system, a LQG/LTR controller is designed which is well-known for its optimality and robustness. Firstly, the loop transfer function is shaped using LQG method; then, an observer is proposed with the aim of loop transfer recovery. Consequently, the designed controller is reduced to the lowest possible order for the sake of implementation easiness. Moreover, LQG design features are used to analyze stability margins when the system has a saturable actuator. Finally, numerical results demonstrate robustness of the system against the output disturbance, sensor response delay, and actuator saturability.