two-degree-of-freedom control scheme for robust centralized pi/pid controller design using constrained optimization

For a two-input two-output distillation column with heavy interactions and long dead times, a two-by-two pi/pid controller is designed. the design objectives are good setpoint regulation and appropriate load disturbance rejection. the constraints are on degree of robust stability, control e ort as well as peaks of the maximum singular value of sensitivity and complementary sensitivity matrices. as this set of design objectives and constraints is often con icting, a more exible control structure, a two-degree-of-freedom scheme, is proposed. the design problem is formulated as a constrained optimization problem and is solved by a powerful random-search optimization technique, the so-called vector-based swarm optimization. next, the performance of the proposed method in controlling a wood and berry distillation column is evaluated and compared with that of several well-known design techniques. because of using a exible control structure, a powerful optimization algorithm and a comprehensive set of design requirements, the proposed control strategy performs well in coping with con icting design objectives.